2 ORAL SESSIONS 4 GS 33: Geochemistry: new understanding provides Geochemical characterization of Upper Cretaceous source new opportunities rocks in Morocco Chair: N. Cameron, A. Morabet Chakor Alami ONHYM, Rabat, Morocco Hydrocarbon generation modelling in the Atlantic margin basins of Morocco : the effect of water pressure The Upper Cretaceous source rocks in Morocco range in age from Cenomanian to Maastrichtian and they are Andy Carr encountered in most Moroccan sedimentary basins. They Advanced Geochemical Systems Ltd., Loughborough, outcrop in the Rif / Pre-Rif area at the North, in the middle Atlas Leicestershire, UK in the centre and in Tarfaya Basin in the South. Where they Hydrocarbon exploration has largely been controlled by the outcrop they occur as oil shale deposits. They have high TOC necessity to ensure the presence of a mature source rock values, high petroleum potential (S2) and are generally capable of generating either oil or gas. Current geochemical immature. models claim that hydrocarbon generation is controlled Upper Cretaceous source rocks were also encountered in primarily by temperature, and basins with deeply buried source exploration wells in the Tadla Basin in the central region, the rocks are therefore most likely to be gas-prone. However the Boujdour area in the south of Morocco and in the Moroccan evidence from deepwater basins appears to contradict this Atlantic offshore. All the geochemical data (TOC, Rock-Eval, understanding in that deepwater exploration in the Gulf of GC, GC-MS and isotopes) from ONHYM’s data base will be Mexico shows that oils appear to have been generated presented, together with oil-oil correlations and Oil-Source relatively recently even though the Upper Jurassic source rocks Rock correlations. A synthesis of all the geochemical studies have been buried at depths often exceeding 7 to 8 km of rock made at ONHYM will be presented and discussed. cover.

In the Atlantic margin basins ,of Morocco, the oil-prone Central Atlantic Petroleum Systems source rocks range in age from Lower Jurassic to Upper Nick Cameron, John Zumberge and Harold Illich Cretaceous in age (Jabour, 1993) and appear to be deeply GeoMark Research Ltd., Houston, Texas, USA buried (> 5 km) along the Moroccan Atlantic margin. The Jurassic source rocks in particular will either be gas or Multiple Petroleum Systems characterise the Atlantic overmature using the current approach to predicting margins of NW Africa (Senegal to Morocco), SW Europe hydrocarbon generation from source rocks. Physical theory (Portugal and Spain) and the Eastern Americas (USA and however differs from geochemical theory in that physical Canada). With much of this region remaining underexplored, chemists predict that water pressure should retard maturation application of this information provides a cost effective means and hydrocarbon generation reactions (Atkins and de Paula, of reducing risk in wildcat exploration. 2002). If this retardation occurs then oil generation would Offshore sources are predominantly associated with could still from source rocks buried to depths at which the Jurassic and Cretaceous clastics with reservoirs positioned current geochemical models would predict either gas up-dip of the kitchens or in the cover succession. An generation or no generation. equivalent to the Jurassic to early Cretaceous sourced gas Laboratory pyrolysis using water pressure show that fairway of Nova Scotia remains to be found in NW Africa. hydrocarbon generation is indeed retarded by water pressure DSDP coreholes suggest mid-Cretaceous, oil-prone sources as predicted by physical chemical theory (Carr et al., 2007). may be restricted to NW Africa. Biomarker correlations suggest Applying the water retardation model to the Atlantic margin carbonate sources associated with the Jurassic shelf edge basins of Morocco shows that there is significant potential for bank in NW Africa and SW Europe are more abundant than oil generation in the offshore basins. currently envisaged. So far Triassic lacustrine sourced oils derived from the syn-rift succession are only known from the Atkins P. and J. de Paula, 2002. Atkins’ Physical Chemistry. 7th eastern seaboard of the USA. Edition. Oxford University Press, Oxford. Contributing onshore source rocks range from Lower Carr A.D. et al., 2007. An experimental study into the effect of water Paleozoic to Miocene in age with the greatest variety occurring pressure on maturation and hydrocarbon generation; the implications for modelling hydrocarbon generation in geological basins. Meeting in Morocco. As is the case offshore, Jurassic and Cretaceous abstracts, AAPG Hedberg Conference, The Hague, 6-9 May 2007. horizons dominate. These include both clastic and carbonate sources, the former tending to be associated with the mid- Jabour H., 1993. Source rock characterisation of the Atlantic Cretaceous highstands, the latter with lagoonal settings continental margin of Morocco. Bulletin AAPG, 77, 2, p. 326. inboard of the carbonate bank. Silurian sources are developed regionally in Morocco and they offer, in conjunction with Ordovician, Devonian and Carboniferous sources, a range of

The First MAPG International Convention, Conference & Exhibition 5 Marrakech Convention Center, October 28 - 31, 2007 opportunities, both within the Palaeozoic and as migration Genesis of the source rocks and reservoir hydrocarbons of products into the Mesozoic. The Neoproterozoic of the the Scotian shelf and slope, offshore Eastern Canada Taoudeni Basin (Mauritiania) is attracting attention as a Prasanta K. Mukhopadhyay (Muki) source/seal/reservoir interval. Global Geoenergy Research Ltd., Halifax, Nova Scotia, Canada Deep-water prospectivity along the NW African margin: an integrated, remotely sensed technique to assess The genesis of the petroleum systems from Jurassic- Tertiary sediments of the Abenaki Subbasin, LaHave Platform, hydrocarbon potential and Sable Subbasin within the Scotian Basin, Eastern Canada Pedro Barreto and Mike Oehlers indicate presence of an (a) active and mature lacustrine, NPA Group. Edenbridge, Kent, UK marine, and mixed marine/terrestrial source rocks of kerogen It is often rewarding and desirable to high-grade Types I, II, II-III, and III within Bajocian to Tertiary age and (b) exploration acreage offshore by taking an integrated on- and numerous clastic and carbonate reservoirs within the Jurassic- offshore approach and in this paper we look at how onshore Cretaceous Mic Mac, Missisauga, Logan Canyon, and Banquereau (slope) formations that are filled with light oil, structures and seepage patterns surrounding the Agadir Basin condensate, and gas. in western Morocco, can be extrapolated into the offshore using GIS and interpretative, remote sensing techniques. Organic-rich oil-prone source rocks are not restricted only to the Verrill Canyon Formation but occur in various other Landsat Geocover, Shuttle Radar Topographic Mission intervals within the Early Jurassic to Tertiary sediments. No (SRTM) and geological mapping from published sources form widespread anoxic events have been recognized in the Upper the bases for the onshore component and Free Air Gravity, Jurassic sediments. More than 90% of the condensate- and bathymetry, geology maps and sections from published gas-prone source rocks occur within the mid-shelf areas in sources were added into the offshore realm. both subbasins, whereas oil-prone source rocks are concentrated in the more distal part and on the early rifting The onshore satellite imagery and DEM data were phase of the Scotian Basin. There are considerable variations interpreted using established photo-geological principles. in the maturity of various sections from the basin that are Onshore seep locations derived from public domain data were closely connected with the variations in heat flux due to salt added and compared to the structural trends and integrated movement and major crustal fractures. into the GIS model. Based on petroleum geochemical parameters (aromatic Similar techniques were used in the offshore where data biomarkers, pyrolysis-gas chromatography-mass allowed: published seismic and map data were linked with the spectrometry, and stable carbon isotopes), the genetic classes observed onshore trends and extended into the offshore. and the maturity of liquid hydrocarbons within the Scotian Seepage patterns were then interpreted using backscatter Basin (shelf and slope regions) have been formally defined. The intensity data derived from satellite radar (SAR) data. Once following five distinct hydrocarbon families could be recognized natural film slicks and pollution slicks had been removed from within the shelf and slope regions of the Scotian Basin the sample, repeating and higher ranked single seepage slicks although the hydrocarbons show a wide range of maturities with each family. were isolated and related to both onshore seepage patterns and regional structure. Family 1 - Condensates and gases with the Jurassic and Cretaceous (Mississauga and Mic Mac sandstone reservoirs; The results revealed some interesting correlations between example – Venture and Thebaud fields, Sable Subbasin): seepage distribution patterns and interpreted offshore originated from kerogen Type III and Type IIB terrestrial organic structural trends to the offshore Malm Carbonate Bank Front matter from the Mic Mac/Missisauga Formation, which are the and the Neocomian-Aptian Delta Front play fairways. terrestrial equivalent of Jurassic and Cretaceous Verrill Canyon Furthermore, geochemical slick sampling of the persistent Formation. The condensates and gases from the Annapolis G- offshore seeps can reduce risk by confirmation of the type and 24/B-24 from Sable Subbasin slope region belongs this group. maturity of the presumed Jurassic and Cretaceous source Family 2 – The light oils from the Cretaceous Cohasset and rocks in this basin. Panuke sandstone reservoirs within the LaHave Platform: derived from kerogen Type I/II lacustrine source rocks of Late Triassic to early Jurassic in age.

Family 3 – Condensate/Light Oils within the Cretaceous Mississauga reservoirs (example: Sable Island and Banquereau fields): derived from kerogen Type II-III mixed marine and

6 terrestrial source rocks from Jurassic and Cretaceous Verrill Therefore, the central portion of Rio Muni Basin is the most Canyon and Cretaceous Shortland Shale. prospective area because it combines the development of Upper Cretaceous turbidites with a late generation and Family 4 – Oil within the Banquereau Formation sandstone expulsion occurred during Tertiary times. This petroleum (example: Primrose field): originated from higher heat flux system was confirmed for several oil accumulations in the area. induced by the salt diapirs penetrated the kerogen Type II-III marine Banquereau Formation source rocks, GS 45: Prediction and characterization of deep Family 5 – Deep Panuke condensates and gases within water reservoirs Abenaki fractured limestone reservoirs, LaHave Platform: Chair: John M. Armentrout C. Kendal, Eric D. Scott derived from the overmature to mature distal marine Jurassic Verrill Canyon source rocks. Evaluating Deep Water Depositional Systems with Spectral Decomposition, Offshore Nile Delta Three main phases of hydrocarbon expulsion have been E. D. Scott observed within the Scotian Shelf (130-110 Ma, 90-70 Ma, and Abstract not received 60-40 Ma). The major episode of hydrocarbon expulsion occurred after the compaction of Logan Canyon Formation Hunting deep marine reservoir sandstones off Nova Scotia, reservoirs, which may be critical for the occurrence of condensates in the shelf region. However, in the Scotian slope, Canada hydrocarbon expulsion and accumulation mostly occurred John Gjelberg1, Boye Flood1, Trond Lien1, Mogens Ramm1, during the last 25 Ma. The multi-component kinetics of source Lars Russwurm1, Gyrd Sundsbø1, Ron Steel2 rocks could be the critical factor for the timing of hydrocarbon 1 Hydro Oil and Energy, Global Exploration, generation, expulsion, and accumulation within both the shelf 2 University of Texas, Austin. and deepwater reservoirs of the Scotian Basin. The Scotian Shelf on the Canadian East Coast has been subject for hydrocarbon exploration since the late sixties/early Basin modelling and thermal maturation in the Rio Muni seventies, and so far six gas fields with a total of 130 GSm3 Basin-Equatorial Guinea Offshore gas (= 4.6 Tcf ) have been developed. The current total gas Ricardo Veiga and Jordi Franques-Faixa production is close to 11.5 Mm3 gas/day (400 MMcf/day). All RepsolYPF, Regional Studies Group-Exploration. Paseo of the producing fields are located on the shelf itself, but during Castellana 280 Madrid (28046) Madrid Spain the last decades, an increasing exploration activity has been focused on the deepwater areas. Hydro has been involved in The Rio Muni basin (offshore Equatorial Guinea) is a proved this exploration activity since the NS98-3 land-sale, when we petroleum province with hydrocarbons generated in the where awarded shares in two deep-water blocks. The Aptian-Albian and Cenomanian source rocks with Upper Annapolis gas discovery was made in 2002 within reservoirs Cretaceous and Lower Tertiary clastic reservoirs. of Lower and Upper Missisauga Formation of Early Cretaceous The overburden and lateral variation of the heat flow control age (Hauterivian – Barremian age) in one of these blocks. the thermal maturity of the source rock. In the northern sector Most of the sandstones encountered in the deepwater (Cameroon), a higher overburden produces an over- wells are located in a limited stratigraphic interval of Early maturation. In contrast, new wells drilled in Rio Muni (southern Cretaceous age, and represents amalgamated and isolated area) reveal immature source rocks due to a local low heat flow. turbidites. However, the reservoir development within the Therefore, a north-south trend of maturation and hydrocarbons deepwater wells is relative poor and only a few tents of metres generation can be observed. In the north, the generation took of sand have been encountered in each well. In the Annapolis place during the Late Cretaceous, while in the south, it Field the two main reservoir intervals are approximately 20 and occurred during the Tertiary. 30 metres thick respectively, with a relative low net/gross ratio. The main reservoirs show two major sedimentary inputs. The reservoir sand development encountered in the few The first entry point is in Cameroon (Nkam delta). In this area deepwater wells drilled so far is somewhat surprisingly low the sediments are trapped in a wide platform with high compared to the extremely sand-rich development on the accommodation space. In contrast, a second entry point is Scotian Shelf itself. Core studies suggests that most of the located in the central Rio Muni basin. Here, the presence of Early Cretaceous sand on the shelf was deposited in a shallow major transform faults (Kribi and Ascencion) has generated a marine deltaic (bay dominated) and inner shelf environment, narrow platform with low accommodation space. As a result of with some elements of fluvial channels and thick mouth bar this paleogeography, well-defined channels and turbidites were accumulations. The distance between the wells within the developed during the deposition of the Upper Cretaceous palaeoshelf setting to the Annapolis well (deep water setting) is Megasequence. less than 40 km, and may represent a palaeoslope, but seismic

The First MAPG International Convention, Conference & Exhibition 7 Marrakech Convention Center, October 28 - 31, 2007 data do not reveal any well defined clinoforms in the area. pool of migrated hydrocarbons, the oil and gas can migrate up the fault into the trapping reservoirs sealed by the transgressive An important question concerning further exploration is if claystone. the relative poor sand development is representative for the whole deepwater area and, in case, what is the reason for this. Outcrops of deep-water facies of the Cobblestone sandstone Calculations on sedimentation rates suggest that this was a of the Fortress Mountain Formation, central North Slope, relative low sediment supply system. This, in combination with a relative wide palaeoshelf may suggest that the shelf itself had Alaska: possible analogs for reservoirs in the foredeep of the sufficient accommodate capacity to host most of the sand in Colville Basin the system, and that shelf by-pass only took place during Schenk, C.J. and Houseknecht, D.W. periods with relative long lasting low-stand. U.S. Geological Survey, MS 939, Box 25046, Denver, Colorado, 80225 USA ‘Deep-Water’ Deltas: Exploration Potential of Shelf/Margin Lowstand Prograding Wedges The Foothills area of the Alaskan North Slope is underexplored compared with other areas such as the Barrow John M. Armentrout Arch. The presence of adequate reservoir rock in the Foothills Cascade Stratigraphics, Damascus, Oregon, 97089 USA is a significant geologic uncertainty. Outcrops of the Aptian (?) Shelf/margin deltas are one of the most prolific reservoir informally named Cobblestone sandstone of the Fortress systems associated with ‘deep-water’ depositional settings Mountain Formation described from several locations indicate and are a primary source for gravity-flow sand displaced that potential reservoir rocks might be present in the foredeep further basinward. These deltaic sands are encased in outer of the Colville Basin. Four main deep-water clastic facies have neritic and upper bathyal claystones that provide both optimal been identified in outcrop: 1) solitary to amalgamated apparent sealing potential and a critical clue to their deposition at the massive sandstones from 0.2 to 4 m thick with a variety of shelf/margin. Shelf/margin deltas have four primary attributes subtle textures and structures; 2) texturally organized to that make them highly prospective exploration targets: disorganized conglomerate and very coarse-grained sandstones; 3) fine-grained sandstones exhibiting grading, Shelf-edge deltas prograde into relatively deep water parallel and ripple lamination, and fluid escape structures; and where wave energy is less attenuated than for similar shoreface 4) laminated siltstones and mudstones. Facies 1 sandstones environments inboard on the shelf. The high-energy wave are commonly oil-bearing in outcrop, and primarily represent dominated environment facilitates mechanical weathering of deposition from high-density sediment gravity flows in frontal the sands resulting in reservoirs that retain producible porosity splays or lobes. One 130-m-thick section contains six and permeability to depths of 6,200 meters (20,000 feet). depositional units with upward-thickening massive sandstones. Facies 2 represents proximal to distal channel Following shelf/margin delta deposition the transgression is deposits; disorganized textures are interpreted as having rapid across the relatively horizontal outer marine shelf and formed by debris flows. Facies 3 represents deposits from coastal plain. Coarse-clastic sediment is impounded low-density sediment gravity flows, and are mainly proximal progressively farther landward resulting in deposition of clean overbank and crevasse splay deposits. Facies 4 represents organic-rich and ductile clays on the outer shelf and upper more distal overbank deposition. Facies 1 and 2 are slope. These clays resist fracturing and provide fault-sealing interpreted as the main potential hydrocarbon reservoirs, and gouge making ideal seal for the deltaic sands. might be significant exploration targets in the Foothills of the Shelf-edge growth faulting is most active during differential Alaskan North Slope. loading when the sand-rich rivers are supplying high volumes of sediment to the shelf/margin. The sediment supply in-fills The role of high magnitude turbidity current events triggered the fault-generated accommodation space depositing thick by shelf-edge delta collapse in fashioning the stratigraphy multistoried sand packages in the hanging wall section. As the and sedimentation of delta-driven, deep-water systems fault continues growing the hanging wall is folded into a roll- Trevor Elliott and Andy Pulham over anticline placing the deltaic sands into a trapping University of Liverpool and Earth Science Associates C & T Inc configuration. The syndepositional movement of the fault facilitates burial of potential reservoir facies below the zone of Delta-driven deep-water systems are characterised by bioturbation enhancing preservation of primary reservoir bimodality in the magnitude and frequency of turbidity current quality. events. High magnitude/low frequency events result from During growth-fault movement there is relative extension of large-scale failure of shelf-edge deltas. Low magnitude/high the fault zone allowing fluids to move upward along the fault frequency events result from the attempt by the delta system plane. If the fault system taps into a hydrocarbon kitchen or to repair or heal the up-dip effects of the failure event. Deposition over much of the deep water system is dominated

8 by low magnitude events, but the high magnitude events permeability, and less detrital silt content. These transgressive dramatically re-sculpt the fan surface and thereby influence shales are enriched in iron-bearing clay minerals and deposition by the lower magnitude events. The stratigraphic authigenic pyrite. Greater shear wave velocities, larger shear record of delta-driven deep-water systems therefore includes moduli, and higher bulk density also characterize transgressive distinctive, but relatively cryptic, erosional, by-pass surfaces. Lewis shales. The most promising seal horizons are laterally These surfaces are akin to erosional unconformities, but are extensive, silt-poor, pyritic shales occurring in the uppermost produced by single, high magnitude turbidity current events transgressive systems tract. Stacking patterns of slow and fast caused by large- scale failure of shelf-edge deltas. Distinctive shale horizons can yield seismic responses comparable to features of these surfaces include unusual erosional features those interpreted as hydrocarbon-bearing reservoirs. (megaflutes), anomalous, thin lags overlain by fine-grained facies, and unusual depositional structures (single cross bed Pore Pressure Profiles in Deep Water Environments: Case sets of sand or gravel facies). These surfaces can be Studies from around the World. expressed in slope channel complexes, structurally confined Stephen A. O’Connor and Richard E Swarbrick, slope intrabasins and unconfined deep water fans. Recognition GeoPressure Technology Limited, Stockton Road, Durham, of these surfaces aids correlation by virtue of providing an DH1 3UZ, England. event stratigraphy, and lateral facies prediction at local and regional scales. They therefore have implications for reservoir Deep water sandstone reservoirs are commonly enveloped modelling, and exploration in distal, ultra-deep exploration in shales. Pore pressure profiles are based on direct settings. measurements in the reservoirs and porosity and shale property-based estimation in the non-reservoir section. Profiles Quaternary Mass Transport Deposits of the Nile Fan:Effect on from clastic sequences of deep marine shales with associated, Stratigraphy, Seafloor Features and Hydrocarbon Exploration thin reservoirs, reveal overburden/lithostatic parallel increase of Eric D. Scott pressure beneath a fluid retention depth (near top Abstract Not received overpressure). The depth to the fluid retention depth is controlled by clay content: many deep water shales have high clay content, explaining shallow onset of overpressure but Sedimentology and Petrophysical Character of Cretaceous adding shallow water flows as a drilling hazard in this Marine Shale Sequences on Passive Deep Water Margins: environment. Thick reservoir sections reveal local hydrostatic- Anomalous Seismic Response of Seal Horizons parallel profiles creating variable transition zones into adjacent William R. Almon, William C. Dawson and Eike Rietsch shales. At temperatures greater than about 100oC, however, there is a tendency for pressure profiles to converge with the Development of predictive models to estimate the overburden/lithostat, creating narrower drilling margins and distribution and petrophysical properties of potential mudstone more likelihood of seal breach. Lithostatic parallel profiles can flow barriers can reduce risks inherent to exploration and be used locally for pore pressure prediction, as long as exploitation programs. Such a predictive model, founded in reservoirs are not able to gain access to and drain sequence stratigraphy, requires calibration with outcrop and laterally/vertically to surface, and remain at temperatures less subsurface analogs. Detailed sedimentologic, petrophysical, than about 100oC. Care must also be taken where there is and geochemical analyses of Lewis Shale (Lower large reservoir structural relief, whereby lateral transfer may Maastrichtian) samples from SE Wyoming reveal considerable enhance crestal pressures. Pressures in many deep water variability in seismically significant rock properties. Lower reservoirs can be used to assess risk failure, particularly for Lewis strata represent late-stage transgressive deposits that stratigraphic traps. Examples will be used from Nile Delta, Gulf include a distinctive condensed interval. The overlying of Mexico, SE Asia and West African basins. progradational Lewis interval consists mostly of interstratified very silty shales and argillaceous siltstones. High-frequency sheet and lenticular sandstone bodies occur within the Shale Facies and Seal Variability in Deep Marine Depositional progradational Lewis package. Sealing capacity, as measured Systems by mercury injection capillary pressure analysis (MICP), varies William R. Almon, William C. Dawson and Kelly Dempster with fabric, texture, and compositional factors that are related Fine-grained lithotypes are dominant components of deep- to sequence stratigraphic position. Samples from the Lewis marine depositional systems. Analyses of Tertiary-aged Shale transgressive interval have significantly greater MICP samples from wells in deep marine basins reveal the common values (average 18,000 PSIA) and are markedly better seals presence of 8 major shale types: 1) well-laminated organically- relative to samples from the overlying Lewis Shale enriched shales; 2) slightly silty, weakly laminated shales; 3) progradational package (average 3,000 PSIA). Transgressive silty shales weakly laminated shales; 4) distinctly mottled silty shales with enhanced sealing capacity are characterized by shales; 5) very silty shales and argillaceous siltstones; 6) higher total organic carbon and hydrogen index values, lower calcareous shales and claystones; 7) shale clast

The First MAPG International Convention, Conference & Exhibition 9 Marrakech Convention Center, October 28 - 31, 2007 conglomerates; and 8) shales with contorted laminae. Most canyon-mouth ‘thicks’, and shelf-margin prograding importantly, these fine-grained strata are baffles and barriers to complexes. Each of the depositional elements occurs where fluid flow which ultimately control the migration and distribution dramatic geomorphic transitions provided accommodation of hydrocarbons. Mercury injection capillary pressure data space and consequent changes in flow velocity that result in indicate these shale facies comprise six distinct seal types. sand-prone facies being deposited. Exploration wells provide Seal types 1, 2 and 6 have significantly greater critical seal critical calibration of both potential reservoir and seal facies, pressures relative to seal types 3, and 4. Seal type 5 and confirmation of the predrill depositional model. consistently has the lowest sealing capacities. Shale facies and seal character vary systematically and exhibit a strong During times of tectonic emergence of the basin margin, correlation with sequence stratigraphic position, suggesting sand-prone sediment flux was very high and accumulation was that at least some depositional parameters influence sealing largely restricted to the deep-water depositional axis of the capacity. Individual shale facies appear to have different bulk forearc basin. As the basin margin subsided and sediment flux moduli and to be mappable on seismic surfaces. Silt-poor decreased due to denudation of the Sierra Nevada terrain, shales can have excellent to exceptional sealing behavior. depocenters transgressed first onto the outer shelf as Increased percentages of silt-sized detrital grains (> 20%) allow retrograde packages and subsequently toward the basin preservation of relatively large-diameter pore throats thereby margin where paleo-river systems supplied relative highstand inducing lower sealing capacities. Well-developed laminar prograding systems. Transgressive to early relative highstand fabrics, organic matter, and early marine carbonate mudstones blanketed the basinal areas providing regional cementation can significantly enhance seal character, whereas seals that separate geopressured compartments. bioturbation generally degrades overall seal behavior. Because of variations in fabric and texture, these shale types have Deepwater Carbonate Signal - the Central High Atlas as a different compaction (depth/porosity) trends. Consequently, type example using an “average” compaction trend can result in erroneous Christopher G and C Kendall, interpretations of burial history and timing of hydrocarbon University of South Carolina. migration events from basin models. Turbidite and other non-cohesive density flow carbonate sediments and mass-transport deposits (MTD) accumulate Deep-Water Plays in a Forearc Depositional System: Shelf- downslope from the carbonate margins of the Jurassic High Margin Deltas to Basin Floor Fans, Northern San Joaquin Atlas Basin as functions of local and global controls. Basin, California Downslope carbonate elements include channels sands, levee John M. Armentrout1, Denise H. Harrison2, David H. Suek3, sands, distal overbank supra fan mud sheets and slumped Steve D. Jones3, Paul J. Harrison2, David B. Codding4, Scott downslope small-scale soft-sediment deformation features. Lewis5 and Stephan Graham6 Tectonic history suggests that local uplift in the basin was 1 Cascade Stratigraphics, Damascus, Oregon, penecontemporaneous with deposition.

2 Fall-Line Exploration, Dillon, Colorado Deepwater carbonate sediments of High Atlas range from 3 Black Coral, Centennial, Colorado sand to mud prone with differerences tied to sediments eroded 4 Yates Petroleum, Artesia, New Mexico from the adjacent carbonate shelves and the Liassic basin 5 QuantStrat, Inc., Denver, Colorado 6 Stanford University, Palo Alto, California. margin. Finer carbonate mud sediments comprise at least 70% of total succession and is “mud-rich”. Closer to the Regional gravity-magnetic, reflection seismic and well data margin more “sand-rich” with a high net-to-gross ratio of are used to construct a depositional model for the Cretaceous carbonate sand and mud accumulations are thicker than the forearc deep-water gravity-flow depositional system of the mud-dominated successions basinward. Sediment transport northern San Joaquin Basin, California. This active-margin was driven by slope, tectonic movement and sea level change, forearc model is compared to the more traditional passive with mud bypassing the fans to reach the outer basin though margin model of seismic sequence stratigraphy. net-to-gross ratio patterns vary across the High Atlas Basin. Coarse-grained, sand-rich turbidite systems are uncommon. Regional 2D reflection profiles down the axis of fault Evidence of sea level change is expressed by basinwide controlled paleo-valley systems image a succession of sand- repeated and cyclic changes in the lithology and occurrence of prone depositionally thick bodies in inner-shelf, outer-shelf, condensed sequences with ammonites and organic and/or shelf-margin, canyon-mouth, toe-of-slope and basin floor radioactive shales. These condensed layers are believed to be settings. Analysis of a 3D seismic volume demonstrates that the result of high positions in the sea. each of these depositional elements can be placed into a sequence stratigraphic framework for this tectonically driven It is proposed climatic changes accentuating the signal of forearc depositional system. The lowstand depositional facies carbonate versus clastic shale beat, though most of basin fill include basin-floor fans, toe-of-slope prograding complexes, was carbonate. Carbonate sediment sequestration on upslope

10 shelves but local cementation reduced erosion of carbonates locally within the Carboniferous Markada Formation and during sea level lows. consist of silty shales, with organic-rich layers, present within the gas nd condensate window. GS 43: Tight reservoirs Chair : M. Zine, A. Moscariello The Paleozoic reservoir potential is yet to be discovered, particularly in the North-West Arabian Desert stretching from Western Iraq, Eastern Jordan and Syria and Northern Saudi Tight Paleozoic Reservoirs in North-West Arabia Arabia. Mohamed Zine IHS Energy, Geneva, Switzerland Connectivity of tight sandstone reservoirs in clastic -Exploration activities during the last two decade revealed transitional depositional environments: learnings from potential tight Paleozoic reservoirs in North-West Arabia. These subsurface and outcrop study. reservoirs are present in several horizons with different Andrea Moscariello 1,2, Manon Stoiver 2, Alberto Saez 3; petroleum systems. Stefan Luthi 2 and Birgit Dietrich1 1 Horizon Energy Partners, The Netherlands The older and deeper tight reservoirs are in the Upper 2 Technical University of Delft, The Netherlands Ordovician sandstones of the Khabour Formation (Iraq) and 3 University of Barcelona, Spain Dubaidib Formation (Jordan). The Silurian Akkas Formation is a new and potential tight sandstone reservoir in Iraq. The -Understanding effective connectivity of thin bedded Carboniferous Doubayat and Markada Formations are tight reservoirs in transitional depositional environments such as a carbonate and sandstone reservoirs respectively in Syria. terminal fluvial fan system is critical to model reservoirs formed in these environments. Layers such as thin, potentially clean The Khabour Sandstone gas reservoir was first discovered sandy and silty lobes can in fact represent in the subsurface in Khlesia-1 Well in NW Iraq in 1961. In the Akkas field (West high-permeability streaks which ultimately control well Iraq), the Khabour gas and condensate reservoir was production performance. However, accurate knowledge of discovered in 1993. It occurs in the Upper Ordovician K1-K4 architectural elements has to be coupled with a sound members and consists of fine grained sandstones with fracture understanding of petrographical variability and especially porosity up to 7.6% and permeability of 0.13mD. The Risha diagenetic modification of primary textural and reservoir Sandstone Member of the Upper Ordovician Dubaidib properties. For this purpose a detailed sedimentological study Formation was first discovered in Risha-3 Well in NE Jordan in 1986. The Risha reservoir is comprised of sandstone of a terminal fluvial fan system has been carried out in the interbedded with silty shale and has a low porosity (3-7%) but Tertiary Ebro Basin (Spain) in order to capture the key in some locations, known as sweet spots, the porosity reached architectural elements (e.g. thin sand terminal lobes, crevasse 12-15% with very low matrix permeability. There is evidence, splays) which control lateral connectivity between large sand however, of natural fractures in most of the wells. The bodies and the results compared with subsurface data in Ordovician petroleum system is envisaged for these reservoirs, Europe and North Africa. Capturing such sedimentological and where the source of the dry gas is the Ordovician shale. In the petrographical characteristics in 3D reservoir models, using case of the Khabour reservoir in the Akkas field, the Silurian also appropriate upscaling approach, is therefore critical to source contributed to the condensates presence in the field. be able to simulate correctly fluid flow behaviour within these reservoirs. The result of this study can hence be applied to The Silurian Akkas sandstone oil reservoir occurs in the subsurface cases (e.g. Permian Rotliegend Transition Zone in upper part of the Akkas Formation (upper Qaim Member) and the Southern North Sea, or thin bedded Devonian reservoirs consists of sandstones with porosity of 6.5% and permeability formed in distal fluvial systems in marginal marine settings in of 0.2mD. The Silurian “Hot Shale” is the source for the 40o North Africa), where the effective production from several tight API oil in this reservoir. gas fields is based on a reliable understanding of the suburface. In the Akash field, discovered in 1990, close to the Iraq border in Eastern Syria, the reservoir unit is the Carboniferous Doubayat Formation dolomite with a porosity <6% and Tight Gas Development Concepts for a Dutch Offshore permeability of 1,000mD. The oil is 38.8º API. The oil is Rotliegend Reservoir sourced from the Silurian shale, and possibly mixed with Upper R. Godderij1 and J.A. Kokkedee2 Cretaceous sourced oil. 1 Energie Beheer Nederland 2 Horizon Energy Partners In the Arak field in the Palmyra region of Central Syria, the Carboniferous Markada gas reservoir consists of fine-grained -This paper discusses the development of a complex sandstone layers and lenses with pinchout porosities, reaching Rotliegend reservoir located in the Dutch sector of the North 13%, interbedded with shale layers. The source rocks occur Sea. The field is strongly heterogeneous and poorly developed

The First MAPG International Convention, Conference & Exhibition 11 Marrakech Convention Center, October 28 - 31, 2007 with the majority of the gas bearing sands at permeability Formations of this section were deposited in marine below 1mDarcy and classified as ‘tight’. As a result of the low environments extending for outer to inner neritic with local porosities, the transition zone is large and extends almost over upwelling currents and lagoons, especially in boreholes the entire gas column to the top of the reservoir. Reservoir GIIP Akkas/1, KH5/1 and KH5/6. Zones of optimum organic matter is about 11 Bcm. accumulations are deposited in the zone of maximum flood system track (MFS) and within environmental changes of the To support development of this complex reservoir, a high stand system track (HST) in anoxic-dysoxic environment pragmatic but still detailed field development study was under seasonal pycnocline evidenced by more than 15% completed in three months. The study comprised the re- chitinozoa and scolecodonts with marine algae of Tasmanites, interpretation of available gas production tests, the Deflandrastrum , brasinophyte algae of non reworked organic construction of a 3D geological model in Petrel and the matter. Those environments underwent upwelling currents generation of a range of reservoir simulation models in Imex to evidenced by mixed occurrences of the acritarch N. carminae evaluate the gas benefits for various well designs. and Deunffia-Domasia in cold climate of the Arabian Shelf In this paper, the integrated reservoir modelling workflow Province along Northern Gondwana Continent, with nill allowing a fast track review of various development options will occurrence of reworked organic matters and rate of burial is be discussed in detail. The rapid screening of the impact of 4cmka . This rate of burial in such environments is evidencing various reservoir uncertainties to the potential gas reserves will burial efficiency of more than 5wt.% TOC. be demonstrated. Using the reservoir models, the benefits of Maturation assessments (figure 1) are on the basis of the underbalanced drilling (UBD) vis-à-vis reservoir fraccing have Thermal Alteration Indices (TAI) of the acritarchs Diexallophasis been evaluated. In addition, concepts around improved denticulata-Orthosphaeridium ternatus and Baltisphaeridium mobility of gas in reservoirs with a large transition zone will be constrictum while hydrocarbon generations potential are addressed. assessed by plotting organic matter types on the Bujaks (1970) graphical model. On the other hand, kerogen analysis of the Akkas Oil and Gas Field, Western Iraq assessment of Akkas and Khabour Formations have showed that the hydrocarbon generation potential in Silurian Akkas and Thompson Kerogen types A & B, total organic carbon (TOC) Ordovician Khabour Formations, up to 16%, especially for the hot shale of the Lower Silurian -Thamer Al-Ameri1 and Mohamed Zine2 Akkas Formation, very low asphaltene and sulphur, saturated 1 Department of Geology-College of Sciences/ University of and aromatic hydrocarbons of more than 96% and high peaks Baghdad-Jadiryah-Iraq. of C2-C20 gas chromatography could indicate predominant 2 IHS Energy/ Geneva/ Switzerland gas generation with some light oils. The associated gas are mainly methane and ethane. CH4, C2H6 and C3H8. Tow hundred and twenty samples of cores and cuttings Diagrammatic assimilation of stratigraphic cross sections collected from the Khabour and Akkas Formations in Akkas/ 1- connecting the studied boreholes collided with total organic 6, Khleisya/1, KH5/6 and KH 5/1 boreholes. They were carbon(TOC), maturation assessments and the kerogen type subjected to palynological and organic geochemical analysis. and quality as well as PetroMode software excel program for Accordingly, abundant acritarch (134 species belonging to 54 Basin Modeling of the whole succession in western Iraqi Desert genera) assemblage and a few spores (21 species belonging based on Transformation Ratios, depth of burial, TOC, to 16 genera) and Chitinozoa (43 species belonging to 12 maturations and well temperature, have indicated source genera) with variable types of sedimentary organic matters are potential for wet gas and condensates from depth 2750-3000 recognized in order to develop stratigraphic framework of the meters and dry gas from depth of 3570-3650 meters for studied area, while optical and chemical analysis are for borehole Akkas-1 only from the Ordovician Khabour Formation assessing the hydrocarbon generation and accumulation in of Caradocian and Llanvirnian stages respectively. While higher this basin. up from the Silurian, some oil might be generated from the lower Silurian Akkas formation in borehole Akkaz-1 and KH5/6. On the basis of acritarchs with tentative selections of These potential source rocks are extended towards Jordan, Chitinozoa and spores, the studied stratigraphic section southwest Iraqi Desert and Syria. Recorded oil and gas shows subdivided into the Ordovician Khabour, and Silurian Akkas in equivalent strata of Tanf and Swab Formations (equivalent to and Upper Devonian Kaista formations in a succession of ten Akkas and Khabour Formations) in the Akkaz-2 to Akkaz-5 palynozones (PZ1-PZ2) within a stratigraphic framework, each wells drilled later by Syrian Petroleum Company in Qaem refered to an equivalent stage of the geologic time scale units District could confirm hydrocarbon generation from the high of Fammenian down to Tremadocian stages , with organic matter black shales and accumulation in the lower unconformity boundary between Upper Devonian Kaista Palaeozoic strata of the studied areas within the sandstone Formation and Silurian Akkas Formation including the hiatus of pores and fractured shales of the same studied formations the Caledonian Orogeny in West Iraq. along closures of the structured anticline fold, sealed by the

12 non permeable shale interlayer, and fault of this field and along We propose mechanical scenarii aiming to describe the the unconformity boundary of the Upper Silurian Akkas main stages of formation of articulations which are narrow zone Formation with the Upper Devonian Kaista Formation (figure 2). of fracture concentration forming dip domain boundaries. This takes into account the role of inherited normal faults and more The gross gas reservoir column of the Khabour Formation recent fractures of atlasic age in curvature accommodation. is about 80 meters with average porosity of 10% and permeability of 500mD. On the other hand, the 42? API light oil Articulations can localize on inherited structures, or have a reservoir of the Lower Silurian hot shale is of 17% porosity and syn-folding origin, being created as instabilities during the fold 500 mD and comprise a sandstone unit inter- bedded within initiation, in particular through small reverse faults. In both the basal hot shale unit of gross thickness approximation of 10 cases, early zones of weakness localize curvature. Because meters and net thickness of 1.5 meters. they most often imply opening mode fracturing and more generally vertically persistent zones of damage concentration Close link between sedimentary facies, folds and fracture across the whole thickness of the folded unit, fold articulations zone distribution in the Atlantic High-Atlas (Morocco). could play a major role in the axial permeability of folded and Mostafa Amrhar1, Hassan Ouanaimi2, Loïc Bazalgette3,4 and fractured reservoirs. Jean Pierre Petit3. Key words: Folding, fracturing, accommodation, reservoirs, High- 1 Laboratoire GEOHYD, Département de Géologie, Faculté Atlas, Morocco. des Sciences de Marrakech, B.P. 3502, Amerchich, Marrakech 40000, Morocco. GS10: Salt Tectonic & Sedimentation 2 Département de Géologie, Ecole Normale Supérieure, B.P. Chair: Tari Gabor and Haddou Jabour S2400, Marrakech. 40000, Morocco. 3 GéofracNet, Laboratoire Dynamique de la Lithosphère, (UMR Shortening of salt diapirs and minibasins in both passive- 5573), c.c. 060, Université Montpellier II, Place margin and convergent-margin settings EugèneBataillon, 34095 Montpellier, cedex 5, France. Mark G. Rowan1 and Bruno C. Vendeville2 4 Now at Shell International Exploration and Production, 1 Rowan Consulting, Inc., Boulder, CO, USA; Carbonate Team, Kessler Park 1, Postbus 60, 2288GS, 2 Université des Sciences et Technologies de Lille I, Lille, Rijswijk, The Netherlands. France, In fractured reservoirs formed in shallow crust conditions, Foldbelts detached on salt are relatively simple when there fracture clustering is expected to have a very strong dynamic is no salt movement prior to shortening. Symmetrical salt- impact. The Moroccan western High-Atlas exhibits numerous cored folds, with or without reverse faults, are highly elongate folded structures related to the atlasic orogenesis were and have a regular wavelength. However, the presence of fracturing can be easily observed due to favourable mechano- preexisting diapirs and minibasins produces anomalous stratigraphical conditions. structural styles because of the associated strength anisotropy. In the cretaceous carbonates north of Agadir, studies on The weak diapirs localize contractional strain, whereas the the relations between folding and fracturing allowed us to strong minibasins remain largely undeformed. present a new aspects of localisation of fracturing during the In a physical model, elliptical minibasins separated by a development of curvature. polygonal array of deep silicone ridges, with diapirs at the ridge The folded series are characterized by intercalations of intersections, were shortened laterally. The diapirs were thick soft marly units and stiff mechanical units of rather grainy squeezed, the deep salt ridges formed contractional structures carbonate facies. The main folds are EW trending and are large with variable orientations, and the minibasins simply translated, scale (?>5 Km) affecting the whole sedimentary pile but smaller sometimes with a minor component of vertical-axis rotation. scale secondary structures (kinks, small scale folds) are Structural styles vary rapidly along strike, and there can be numerous all over the area and generally affect a single stiff elements of strike-slip or extensional deformation depending mechanical unit. on the ridge orientation and the differential translation of minibasins. If the preexisting pattern of diapirs and minibasins There is a good correlation between the carbonate is more linear, then contractional structures have more fractions, the stiffness and the fracture density of layers at the consistent trends. Squeezing of salt walls creates strain whole negative sequence scale. The upper sub-sequences, gradients that result in vertical welds with remnant diapirs at which are also the more marly ones, are less fractured than the the weld terminations. In all cases, squeezed diapirs typically lower ones, which contain higher carbonate proportions. extrude allochthonous salt, and structural asymmetry is more Smaller-scale heterogeneities of sedimentary origin as pronounced if shortening occurs after minibasins touch down channels or bed amalgamations have also shown a strong because salt welds are stronger, frictional detachments. influence on the initiation of intensely fractured zones.

The First MAPG International Convention, Conference & Exhibition 13 Marrakech Convention Center, October 28 - 31, 2007 Examples of foldbelts with preexisting diapirs and Deepwater Compressional Salt Tectonics along Passive minibasins occur in deepwater settings of passive margins, margins: examples from the Atlantic margins such as the northern Gulf of Mexico, offshore Brazil, offshore Ian Davison Angola, and offshore Morocco. Other examples are found in Earthmoves Ltd. 38-42 Upper Park Road, Camberley, Surrey, UK convergent-margin foldbelts such as the Flinders Ranges of South Australia, the Sierra Madre Oriental foreland basin of The Atlantic ocean margins contain some of the largest salt northeastern Mexico, and the Atlas Mountains of Morocco. basins along any passive margins in the World with Morocco, Nova Scotia, Santos-Campos-Espirito Santo and the Gabon- Gravity spreading and collapse of sedimentary overburden Congo-Angola Basin being the largest.. All of these basins along salt-bearing continental margins : Basic mechanical have produced important diapirs and salt pillows during the early phase of rifting and thermal subsidence, and these and kinematic characteristics illustrated by analogue structures are very often reactivated by later compression. The modelling compression can be caused by either: Bruno C. Vendeville1 and Virginie Gaullier2 1 Université des Sciences et Technologies de Lille 1 Bâtiment compression at the frontal toe of downslope gravity sliding SN-5, Sciences de la Terre UMR 8110 Cité Scientifique 59655 systems which produces important salt nappes and Villeneuve d’Ascq cedex, France compressional thrust and folds in the deepwater area; or 2 LEGEM - E.A. 3678 Bâtiment U, 2ème Etage Université de Perpignan, Via Domitia 52, Avenue Paul Alduy 66860 regional tectonic compression events, caused by plate Perpignan, France tectonics or hot spot development, where simultaneous folding can occur across 100+ km wide areas. Vigorous gravity-driven deformation is a common feature along continental margins that (1) include an evaporitic layer in This paper examines the different styles of compressional their sedimentary cover, and (2) have been subjected to structures which are produced along the Atantic margins. The significant flux of clastic sediments. The margin’s bathymetric tectonic style depends on the thickness of the salt, the slope represents a gravity instability that triggers a general thickness and strength of the overburden, and the tectonic collapse of the suprasalt overburden. This collapse is stresses. Large tectonic stresses can lead to thrusting and accommodated by proximal extension (upper slope and part of duplication of the salt, with imbricate seismic reflections the shelf), mid-slope translation, and distal shortening (lower present within the thrusted salt packets, which are probably slope and deep basin). Extension can lead to the formation of slivers of sedimentary overburden caught up in the thrusting salt ridges, salt diapirs, and large listric normal growth faults. and recumbent folding. Thicker overburden and thicker salt Shortening can generate buckle folds, salt-detached thrust with lower tectonic streses applied tends to favour fold faults, and allochthonous salt tongues. development. In this case large packets of sediments may have been already laid down over the salt structures which had The bathymetric slope, the primary parameter driving become inactive before their later compressional reactivation. deformation, is mainly controlled by the sediment influx. Therefore, gravity-driven deformation of the salt and its The effects of tectonic reactivation of continental margins overburden reflects the regional depositional history. When the can produce spectacular submarine mountain belts. In Angola depositional conditions generate or maintain a steep slope, salt for example, the frontal thrusted allochthonous salt sheet has tectonics is vigorous. When the overall slope angle is reduced produced 2 km of relief at the top of the Albian carbonate (sediment bypass, or shift of the regional depocenters away horizon. This was caused major uplift onshore starting at from the area), salt tectonics slows down or stops. Sediment approximately 30 Ma. Buried folds of this magnitude are also progradation or retrogradation causes shifts in the location of produced in the Moroccan offshore area during the Alpine-Rif the three deformation domains (extensional, translational, and orogeny, and these produced very large structural closures compressional), which results in reactivation of (1) diapirs or capable of trapping hydrocarbons in the Doukalla Basin. normal faults in compression, or (2) diapirs or folds and thrusts However, in some areas the late compression may have in extension. created faulting up to the sea bed and breached earlier hydrocarbon traps. The 3-D geometry of the salt structures is intimately related to the 3-D geometry of the sedimentary bodies. For example, sediment lobes generate complex networks of polygonal or subcircular depocenters (minibasins) bounded by salt ridges overlain by faulted roofs.

14 Salt Tectonics of the Continent-Ocean Transition, Deep-Water Revisiting the concept of “steady state withdrawal” in salt Angola systems: Minibasin evolution and seismic morphology Gyorgy Marton1 and Gregor Schoenborn2 Leslie J. Wood 1 Chevron International E&P 1500 Louisiana, Houston, TX, Quantitative Clastics Laboratory, Bureau of Economic Geology, 77002 Jackson School of Geosciences, University of Texas at Austin, 2 ChevronTexaco 6001 Bollinger Canyon Rd. San Ramon, CA Austin, Texas, USA 94583 Mini-basins developed over actively mobile salt substrates The Late Cretaceous to present salt-cored fold and thrust exhibit a level of stratigraphic architectural complexity that belt at the edge of the Aptian salt basin, offshore Angola, has often flies in the face of classic steady state salt withdrawal been interpreted based on seismic and potential field data. models. Classic fill-and-spill models, developed in the Tectonic processes, kinematic steps and deformation styles proximal, extension dominated mini-basins of the Gulf of are discussed and demonstrated using a series of regional Mexico (GOM) may not be applicable to mini-basins developed cross sections and restorations. in more structurally complex or distal settings. It stands to reason that systematic changes due to deformation should be Based on salt tectonic deformation style, the study area reflected in the geometry and morphology of the mini-basin fill has been divided into a northern fold belt and a southern fold and enable reconstruction of salt history. and thrust belt. Shortening along the measured section in the northern fold belt is on the order of a few kilometers. In Mini-basin have been examined in proximal and distal contrast, structural restoration demonstrates that to the south, supra-salt setting of the GOM, in the supra-shale setting of in the fold and thrust belt, up to 12 km of compressional strain northeastern South America and in the supra-salt setting of has been absorbed by the Tertiary section. offshore Morocco. Two minibasins near the GOM Sigsbee Escarpment were found to contain an ordered pattern of Salt occurs at three levels in the frontal deformation zone. tectonomorphic fill that includes four geometries; ponded, At the deepest level, autochthonous salt pinches out against draped wedged and complex. These geometric fill packages an outer high of oceanic basement at the western edge of the stack in systematic and repetitive sequences. Each fill type Angola salt basin. The second level comprises a deeply buried, has distinct “facies” comprising it. Interbasin debris flow regional salt canopy, located at the leading edge of the salt processes are more prominent during the Ponded Phase and province in the northern part of the study area, which formed diminish in occurrence as the bathymetric relief diminishes. as a salt glacier during the Late Cretaceous. Large-scale, Extrabasinal staged gravity events can form Wedged Phase compressional, salt-cored anticlines and active diapir geometries. Both Ponded and Wedged tectonomorphic complexes developed above this Cretaceous canopy, and phases show a strong probability to contain confined fans with landward, above an inflated salt pillow in Tertiary to present significant sandy reservoir potential. Basins examined over times. In the southern part of the study area, outboard of the supra-shale substrates show a dominance of ponded and Oligo-Miocene Congo Fan depocenter, and a zone of complex fills, lack the depth of supra-salt basins and develop maximum extension, large-scale, salt-cored folds and thrusts more through inflation of side walls than subsidence developed above interpreted oceanic crust. The third, and withdrawal. Finally, mini-basins developed in offshore Morocco shallowest, level of salt is organized into a mid to late Miocene show all of the elements identified in the GOM with multiple canopy belt, observed just inboard of the frontal structures. cycles of fill suggesting episodic uplift of margins and apparent In both the northern fold, and the southern fold and thrust present day ongoing subsidence. These fills are over 4 belts, large-scale structures initiated in the early Tertiary and seconds of Tertiary age channelized turbidites, mass transport have continued to develop gradually. Large anticlines deposits, slumps and deep water pelagic deposits. Current fill- developed by downbuilding; i.e., by salt injection into the fold and-spill models do not adequately describe the complex core and contemporaneous salt withdrawal from the adjacent interaction of structure and sedimentation taking place in the synclines. Folding and thrusting have been continuous up to mini-basins and complex, cyclic stratal fills suggests an the present, indicating a slow, but steady, deformation of the episodic process of salt movement. leading edge of the salt province, offshore Angola.

The First MAPG International Convention, Conference & Exhibition 15 Marrakech Convention Center, October 28 - 31, 2007 Allochthonous salt tectonics in the Flinders Ranges, South Some existing models for offshore Libya have interpreted a Australia: testing models of the subsurface with exposed widespread layer of halite lying at the Messinian unconformity analogs which thickens basinward. This interpretation was probably Mark G. Rowan1, Thomas E. Hearon IV2, P. Tyler Hannah2, based on the fact seismic reflection continuity was lost over Timothy F. Lawton2 and Katherine A. Giles2 much of the basin just beneath the unconformity. Recent data 1 Rowan Consulting, Inc. and current understanding of salt behavior do not support this 2 New Mexico State University interpretation. We interpret the presence of a relatively thin, high amplitude and high velocity, layer of non-halite evaporates Wells penetrating allochthonous salt often encounter (mainly anhydrite) to be associated with the Messinian structurally complex zones immediately beneath the salt. unconformity. Where this high amplitude and high velocity layer Strata may be folded, overturned, or repeated, and may be is absent or eroded, seismic continuity below the unconformity significantly older than the subsalt minibasin fill. A variety of is restored. models have been put forward to explain these observations and, by extension, the processes by which salt sheets True halite is interpreted to exist in offshore Libya only in the advance: (1) the basal-shear model, in which subsalt strata are far west of the Pelagian shelf near the Tunisian border. Beneath deformed during translation of the salt and its overburden; (2) the Pelagian shelf are a series of tight contractional folds that we the accretionary-wedge model, in which frontal thrust interpret to be salt cored. Basins adjacent to the folds have imbricates get overridden by the salt; (3) the debris-flow model, geometries characteristic of salt withdrawal and true salt diapers in which the “gumbo” represents slumps derived from the exist just to the west in Tunisian waters. The fold crests were scarp at the toe of the advancing sheet; and (4) the drape-fold bathymetric highs which served as nucleation sites for nummulitic model, in which strata are rotated in the evolving scarp. bank development, major reservoirs on the Pelagian shelf.

We test these models using analogs in the Flinders and Influence of Basement Fault Zones and Basin Inversion on Willouran Ranges of South Australia, where Neoproterozoic Salt Tectonics – Examples from the Mesozoic Mid-Polish evaporites and surrounding minibasin strata are exposed. Trough Selected study areas include a multi-level canopy that is Piotr Krzywiec partially welded and a salt sheet with a ramp-flat geometry at Polish Geological Institute, ul. Rakowiecka 4, 00-975 Warsaw, the base of salt. In both cases, preliminary results show that Poland debris flows containing clasts of the evaporite and its carapace are ubiquitous, and that halokinetic drape folding is locally Development of salt structures within intracontinental developed. We find little, if any, evidence of subsalt shearing or basins is often triggered by thick-skinned faulting of the sub- thrusting related to salt emplacement. The results, while not salt basement. During basin extension and subsidence salt necessarily representative of allochthonous salt bodies in other pillows start to grow above major basement normal fault zones basins, are compatible with well results from the Gulf of due to combined effect of basement faulting and differential Mexico. The implication is that allochthonous sheets advance sedimentation of the supra-salt cover. During later stages of primarily by salt inflation, slumping of the resulting scarp, and continued extension salt diapirs form, that might extrude onto breakout of the salt, with only minor components of subsalt the basin floor forming salt glaciers. Apart from salt structures shear or thrust imbrication. formed above basement fault zones also peripheral salt-related structures located at significant distance from the basin centre Salt sediment interaction Offshore Libya: “Where is the Salt?” and detached above salt could form due to mechanical Fiduk, J. Carl, Lynn E. Anderson, and Thomas R. Schultz decoupling between sub-salt basement and supra-salt cover. CGG Americas, Inc., Houston, TX, USA 77084 Basin inversion, triggered by regional compressional stresses, could also led to reactivation of salt structures. Compressed The presence of Messinian evaporites has been interpreted salt diapirs enter next phase of growth, their salt wings formed to be widespread across much of offshore Libya, particularly due to salt extrusion could act as detachments and focus within the Sirt Embayment. However, the presence of mobile development of salt-cored faults. halite appears to be restricted to only the westernmost offshore areas of Libya. The age of the mobile halite is The Permian to Cretaceous Mid-Polish Trough (MPT) interpreted to be Triassic/Jurassic and not related to Messinian evolved above the Tornquist–Teisseyre Zone (TTZ) – crustal- evaporate deposition. During 2004-2005, new 2D pre-stack scale boundary between the Precambrian and the Palaeozoic time migrated seismic data were acquired and used to Europe, and was filled with several kilometers of sediments examine the large-scale structural, depositional, and salt including thick Zechstein salts at its base. Extension along the tectonic features of the Libyan shelf and slope. The data cover TTZ resulted in development of complex system of salt approximately 38,000 line kilometers in water depths ranging structures, which in Late Triassic culminated in diapirism and from 15 to over 3000 meters. salt extrusion onto the basin floor. Within both basin flanks

16 peripheral syn-sedimentary grabens detached above Shale tectonics and its importance in hydrocarbon basin Zechstein salt evolved. Jurassic subsidence was connected to evolution: a rather muddy subject relatively minor salt movements, next major phase of salt Lesli J. Wood movements was caused by the Late Cretaceous inversion. Bureau of Economic Geology, Jackson School of Active growth of salt structures resulted in very complex Geosciences, The University of Texas at Austin, Austin, Texas sedimentary pattern in their immediate vicinity. Delamination 78713-8924, USA and folding of the supra-salt sedimentary cover facilitated development of salt wings. Some of salt structures have been What role does shale tectonics play in forming basins? subjected to asymmetric thrusting, possibly enhanced by How and why do subsurface shales move? Can they push gravitational gliding. strata, or do they simply move as they are squeezed? Can shale diapirs act as traps, similar to salt diapirs? Salt tectonics of the Transylvanian Basin (Romania) Shale mobilization (argillokinesis) appears to play an Csaba Krezsek1 and Albert W. Bally2 important role in the ongoing evolution of several major 1 Hydro ASA N-0236 Oslo, Norway hydrocarbon basins in the world and may even be critical to 2 Shell Research Laboratory their prospectivity. The southern Gulf of Mexico, Niger offshore, Bellaire, Texas, USA the Caspian Sea, northeastern Venezuela and Trinidad, The Transylvanian Basin is an intra-Carpathian back-arc Indonesia, offshore India, and the Mackenzie Delta of northern basin situated in the hinterland of the Carpathians fold and Canada are all excellent locations to examine the effects and thrust belt. The Mid to Late Miocene back-arc megasequence prospects associated with mobile shale systems. Unlike salt, comprises evaporites (mostly halite) covered by up to 3 km which will initiate movement and then maintain it under limited thick siliciclastics. impulses, shale requires overpressure to become ductile and may move from ductile to plastic to fluidized and back to The early salt tectonics was driven by the differential load of ductile several times throughout its active life. Overpressure is post-salt sediments. Relatively weak shortening observed in typically caused by some combination of burial compaction, the deeper parts of the basin was probably coeval with diagenesis of clays, kerogen maturation, and compressive extension on the shelf. The nature of early extension is difficult tectonics. Shale’s tendency toward pulses of inflation and to address because of the strong overprint of later events, deflation results in dynamic states of erosion, accumulation, including erosion and inversion. However, interpretation and eruption associated with mobile shale features. The active suggests that reactive/passive diapirism might have been fluid migration necessary to maintain these episodes forms already taken place. vents for hydrocarbon migration from sometimes deeply buried source rocks to shallower reservoirs and traps, setting up the The Late Miocene continental collision in the Eastern perfect prospective scenario. Oddly enough, however, Carpathians is associated with the rising Carpathians and Late numerous cases exist where these conduits have no damaging Miocene to Pliocene arc volcanism. Uplift of the Eastern effect on overlying reservoir seals. Traps associated with shale Carpathians induced up to 5 degrees westward tilt of the basin diapirs include detachment folding, diapir toplap, diapir top margins, which induced large-scale Mio-Pliocene gravity drape or rollover rims, radial faults and tilted fault blocks, spreading of the salt overburden. The spreading was erosional truncation and associated unconformity traps, lateral enhanced by the load and heat-flux of back arc volcanics also. mini-anticlines, and downbuilt anticlinal flank trap. We have The ‘mega-slide’ comprises three structural domains, as examined various shale structures and processes of follows: extensional weld (upslope), contractional folds (central) argillokinesis in several basins in the world, and we will discuss and contractional toe thrust (downslope). Early extensional their implications for the enormous proliferation of hydrocarbon diapirs were shortened and their rim-synclines highly inverted. opportunities in argillokinetic basins of the world. The central folds are mostly the result of late shortening. Basement involved thrusting uplifted the toe thrust domain by the Late Pliocene.

Salt structures resemble the upslope extensional and downslope compressional domains of gravity driven fold belts developed on passive margins. However, we emphasize that the triggering mechanisms are quite different.

The First MAPG International Convention, Conference & Exhibition 17 Marrakech Convention Center, October 28 - 31, 2007 Shale Tectonics and Sedimentation of the Offshore Niger Shale tectonics in the Alboran Sea (Western Mediterranean) Delta Juan I. Soto1, Asrar Talukder2 and María del Carmen Comas1 Christopher D. Connors1, Barbara Radovich2, Al Danforth3 1 Instituto Andaluz de Ciencias de la Tierra (CSIC-Universidad and Sujata Venkatraman4, de Granada) and Departamento de Geodinámica, Campus 1 Washington and Lee University, Lexington, Virginia, USA Fuentenueva s/n, 18002-Granada, Spain 2 Silver Grass Enterprises, Sugar Land, Texas, USA 2 IFM-GEOMAR, Wischhofstrasse 1-3, 24148 Kiel, Germany 3 Independent Consultant, Houston, Texas, USA The Alboran Sea in the Western Mediterranean was formed 4 GX Technology, Houston, Texas, USA during the Neogene by large-scale extension in a plate- We present a new regional analysis of the structure and convergence setting between the African and Eurasian plates. stratigraphy of the offshore Niger Delta from interpretation of In this tectonic scenario with diversely (in azimuth and plate- the new NigeriaSpan regional 2D seismic survey, acquired and motion rate) but continuous oblique convergence, basin processed by GX Technology. These data have optimal subsidence started abruptly by the Early Miocene characteristics (long-offset, long-recording time, prestack- accompanying westward migration of the Gibraltar Arc, the depth migrated) that provide advanced imaging of the orogenic loop formed by the Betic (in South Iberia) and Rif (in previously enigmatic mobile shale structures, as well as the North Africa) belts. Behind this Alpine arc, the Alboran basin is better understood fault-related folds. On the shelf we characterized by a thick sedimentary depocenter (> 8 km) that recognize the soling out of syndepositional, listric normal faults mimics the orogenic front. One of the key features of the West along a unambiguous detachment surface at over 11 km Alboran Basin (WAB) is the development of a significant diapir subsea. This detachment sits near the base of the Tertiary. province, feed by the lowermost sediments (early to middle This fundamental detachment in the contractional toe of the Miocene) that are formed of under-compacted shale and delta shallows to about 7 km subsea rather uniformly in the olistostromes. upper Eocene to lower Oligocene section. The inner slope is Using the 2D seismic survey of ConocoPhillips, and both translating and accommodating shortening from updip completing with previous commercial and scientific seismics, extension, and exhibits a ductile and complex shale response. we have analyzed the shale diapirism in the northern WAB. The In the past, these mobile shale structures have been poorly 3D geometry of the shale diapirs and their evolution during the imaged by seismic data and have sometimes been referred to Neogene, accompanying sedimentation and basin as ‘diapiric’ structures. Based on improved NigeriaSpan subsidence, have been characterized. imaging we interpret these as primarily contractional, asymmetric, sometimes thrusted, detachment folds with Shale diapirs show two orthogonal orientations, probably mobile, Eocene-Early Oligocene prodelta and marine shale controlled by deep structures in the basement, like half- chaotically deformed in the cores of these structures. Growth grabens and oblique, transfer structures. Diapirs develop commenced in the late Oligocene, and continues to the isolated and elongated shapes with sub-vertical walls, both present day on many of these structures. These long-lived parallel and perpendicular to the dip of the basement surface. structural highs often show later thrusting, with substantial cut- In the interference region between both trends diapirs tend to and-fill geometries and several unconformities on their crests. have a long-lived evolution, develop piercing structures and In places, adjacent basins sometimes show evacuation of the associated mud volcanoes in the seafloor. Allocthonous shale prodelta and marine shale out of the synclines forming welds tongues are common in the areas with maximum sedimentary on the underlying lower Tertiary strata. This structural and accumulations, where they advanced basinward during the stratigraphic style is in stark contrast to the deepwater middle-to-late Miocene. We conclude that shale diapirism in contractional toe of the delta which is primarily a brittle fold- the WAB depocenter is linked to deformation in the basin and-thrust belt of imbricate fault-bend, fault-propagation folds, margins, because pulses of shale diapir ascent and lateral and shear fault-bend folds. The Eocene-Early Oligocene advance follow immediately major episodes of extension in prodelta and marine shale is locally mobilized here into marginal syn-sedimentary faults. symmetric, shale-cored detachment folds. Growth strata on these fault-related folds, constrains timing from late Miocene to the present day, but individual structures do not generally show long-lived activity. Instead, thrusting in the more brittle toe tends to be a relatively systematic break-forward sequence.

18 SS03: Geology, Petroleum Systems, and Future The Early Jurassic Heracles Sequence, Scotian Basin, Oil/Gas Prospects of Eastern Canadian Conjugate Canada: Recognition of latest stage synrift tectonism and Margin Sediments correspondence to structures offshore Morocco Chair: R.A. (Sandy) MacMullin, Prasanta K. David E. Brown1, Sonya A. Dehler2, Keith Louden3 and Yue Mukhopadhyay Wu4 1 Canada-Nova Scotia Offshore Petroleum Board, 1791 Correlation of syn-rift structures between offshore Morocco Barrington Street, Halifax, Nova Scotia, B3J 3K9, Canada, and Nova Scotia, Canada 2 Geological Survey of Canada (Atlantic), Bedford Institute of Gabor C. Tari Oceanography, Dartmouth, Nova Scotia, Canada AllyGabor Geoscience, 6719 Avenue B, Bellaire, Texas 77401, [email protected] USA 4 Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada The reconstruction of the relative positions of the North American and African continents before the opening of the Seismic profiles on the Scotian shelf, slope and abyssal central Atlantic Ocean have either been based on plain offshore Eastern Canada reveal a previously morphological fits using coastlines and different isobaths, unrecognized earliest Jurassic post-salt / pre-breakup seafloor magnetic and fracture data or on matching pre- stratigraphic succession. The Heracles Sequence is observed breakup paleomagnetic poles of the stable cratons. None of on the shelf margin as an eastward-directed infill succession the existing reconstructions utilize syn-rift structures, which are within a series of half grabens having counter-regional, expected to be preserved on these conjugate passive margins. northwest-dipping boundary faults. On the slope, its inferred presence in the salt depocentre adjacent to the basin hingeline Based on 2D/3D reflection seismic and potential field data is masked by a thick wedge of later Mesozoic and Cenozoic acquired offshore Morocco, an anomalous basement high is sediments and salt structures. In deep water, it is recognized defined beneath the Tafelney Plateau. This high not only has a as a poorly-imaged but apparently extensive sequence bathymetric expression, but it has a pronounced signature in between interpreted basement and the late Sinemurian various satellite-based and shiptrack potential field data sets. breakup unconformity. At the eastern extremity of this region, Its NW trend is oblique both to the coastline/shelf-edge and it appears as westward-thickening wedges in highly rotated the expected orientation of Atlantic transform faults. The fault blocks. anomalous basement high beneath the Tafelney Plateau is interpreted as an accommodation zone analogous to many The Heracles Sequence is interpreted as the product of the well-studied examples in the present-day East African rift last phase of synrift tectonism prior to separation of the Nova system. It developed between two normal fault systems with Scotian and Moroccan conjugate margins in the late opposing polarities, i.e. SE-dipping syn-rift faults to the north of Sinemurian. Post-salt (early Hettangian) uplift of the mainland it and NW-dipping syn-rift faults to the south of it. The actual Nova Scotia shoulder region and the eventual rift spreading Early to Middle Jurassic breakup between Africa and North centre provided sources for sediments that prograded east- America occurred obliquely across the accommodation zone and westwards respectively into the main salt basin. leaving most of it on the Moroccan margin. Interpreted fluvial sequences advanced over marine evaporites ponded in depressions on a rifted basement setting and The correlation of syn-rift structural elements across the induced syndepositional halokenesis and the formation of salt- central Atlantic basin based on seismic reflection and potential evacuation synclines. Where thin on the margins (especially field data has important implications for hydrocarbon near the future spreading axis), the salt provided a detachment exploration in these frontier deepwater provinces. surface and facilitated the observed high rotation on loading- induced fault blocks during a final uplift phase. This interpretation buttresses other geophysical evidence that suggests the underlying basement may not be oceanic crust, as previously proposed, but rather highly attenuated and fractured continental crust or serpentinized mantle.

The recognition of this late stage pre-breakup synrift sequence in the Scotian Basin offers important insights on this phase of the rifting process, and possibly its Moroccan conjugate and other margins. It thus has significant implications regarding the recognition of the continental crust and crustal boundaries, age and timing of syntectonic deposition and salt tectonism, original distribution and extent

The First MAPG International Convention, Conference & Exhibition 19 Marrakech Convention Center, October 28 - 31, 2007 of marine evaporite sequences, timing and style of rifting, This under-explored basin contains only one well, which modelling of crustal heat flow, and petroleum systems has not yet been released to the public but is reported to have attributes and modelling. intersected hundreds of meters of high quality sandstone reservoirs. The seismic data was tied to wells in adjacent Laurentian Basin – A Strike Slip / Extensional Conjugate basins on the Scotian Shelf and Southern Grand Banks to help Depocentre to the Moroccan Margin decipher its stratigraphic and structural evolution. In this regard Phonse Fagan1 and and Michael Enachescu2 the basin can be subdivided into tectono-stratigraphic 1 A.J. Fagan Consulting Inc. and Memorial University, St. packages which can be correlated along strike to the John’s, Newfoundland and Labrador surrounding basins – including within the deep water 2 Memorial University, St. John’s, Newfoundland and Labrador, depocentres. This study also investigates the basin’s Canada petroleum systems including the possibility of Mesozoic reservoirs being sourced by Paleozoic source rocks. Gas- The Laurentian Basin, which covers an area of prone Mesozoic source rocks should exist within the pro-delta approximately 60,000 square km between the island of shales and interbedded marine shales of the Middle Jurassic to Newfoundland and province of Nova Scotia on the Atlantic Early Cretaceous succesions, similar to the source rock of the coast of Canada, lies at the intersection of the extensional Sable Subbasin gas fields. Scotian Margin and the extensional – strike slip domain of the Southern Grand Banks. A thick (up to 20 km) Mesozoic – Comparison of salt tectonic styles in Nova Scotia and Cenozoic succession downlaps onto oceanic crust to the south and onlaps the pre-rift Paleozoic sediments on the Morocco basin’s northern flank. A study (MacLean and Wade, 1992) of Gabor C. Tari the area’s petroleum potential, based on a regional seismic AllyGabor Geoscience, 6719 Avenue B, Bellaire, Texas 77401, grid, by the Geological Survey of Canada resulted in a resource USA estimate of 8-9 tcf of recoverable gas and 600-700 million A comparison of the present-day extent, the map-view and barrels recoverable oil at an average expectation. Despite its cross-sectional characteristics of the Late Triassic to Early recognized potential the basin has thus far seen little exploration because of a jurisdiction moratorium that was only Jurassic salt basins can be used to provide insights into the recently lifted. Current licensees have acquired 3D seismic over hydrocarbon potential of the underexplored deepwater regions selected parts of the basin and are expected to drill within the of both margins. If there are certain similarities between these next couple of years. margins, then one should expect some structurally analogous, salt-related play types. The basin’s evolution began with the Mesozoic rifting of the Paleozoic substrate that underlies much of the Grand Banks The Canadian margin was recently subdivided into several and Scotian Shelf and extends north-westward into the Gulf of segments based on pronounced, along-strike variations in the St. Lawrence. As the initial Triassic rift that separated the salt tectonic styles seen on a regional 2D data set. This Scotian Shelf from the Moroccan margin failed to split the crust interpretation suggests very large-scale allochthoneity (>80 of the Grand Banks, sea-floor spreading to the south of the km, locally) of the salt moving basinward from its Laurentian Basin had to be accommodated by strike slip autochthonous position. The amount of salt driving the movement along the Newfoundland Fracture Zone. Although deformation is clearly variable along strike. The differences the oceanic rift system ultimately stepped to the east of the between the “salt-rich” versus the “salt-poor” segments are Grand Banks the seaways opened up by the initial Scotian- primarily attributed to the underlying syn-rift basement Moroccan rift lead to the creation of the Grand Banks basins structure that determined the initial configuration of the salt and their deepening during mid Jurassic. sub-basins. This paper revisits the Laurentian basin with the use of a The Moroccan salt basin was subdivided in a different style, modern pre-stack time migrated GSC seismic grid which is outlining salt tectonic domains based on the most typical salt- supplemented by recent data from Geophysical Services Inc., related structural features. The central part of the Moroccan Western Geco, and GX Technology, along with public domain margin, compared to the Canadian margin, was strongly potential field data. Elements of geoscientific interest include affected by the middle Tertiary inversion of the Atlas system. the way in which the combined extensional and strike slip The impact on salt tectonics of the compressive Atlas event dynamics are expressed in the structure and stratigraphy of the basin. The fact that the basin also lies at the confluence of the appears to diminish rapidly to the south and to the north of the Paleozoic Avalon-Meguma suture zone and the Newfoundland Essaouira basin. Fracture Zone of Mesozoic provides the additional opportunity Some direct structural correlations of the salt basins can be to examine how the Scotian-Moroccan rifting was influenced made using a syn-rift reconstruction of these conjugate by the pre-existing crustal fabric. margins. Interestingly, most of the published plate tectonic reconstructions show a single salt basin during the Late

20 Triassic between Nova Scotia and Morocco. However, it is Petroleum Systems of the Scotian Basin and Its Implications suggested here that a subaerial volcanic ridge separated the of Finding Oil and Gas within deepwater Sable and Shelburne salt basins of Nova Scotia and Morocco during the late syn-rift Subbasins, Offshore Nova Scotia stage. Prasanta K. Mukhopadhyay (Muki)1, Paul J. Harvey2 and Kris Kendell2 Review of Nova Scotia’s Deepwater Drilling and Its Effect on 1 Global Geoenergy Research Ltd., Halifax, Nova Scotia, the CNSOPB’s 2002 Resource Assessment Canada Brenton Smith 2 Nova Scotia Department of Energy, Halifax, Nova Scotia, Canada Nova Scotia Offshore Petroleum Board, (CNSOPB), Canada Halifax, Nova Scotia, Canada The success at Marathon et al. Annapolis G-24 well and The deep water Scotian Slope is 850km long and covers failures in finding 30m gas-condensate charged sands within 80,000km2, but only ten wells targeted deep water sediments. Early Cretaceous sediments and the failure in finding In contrast, the shallow water shelf area of the Scotian Basin hydrocarbons in other four recently (2001-2004) drilled wells contains over 200 wells with past production from the has definitely triggered reevaluation of the petroleum systems Cohasset-Panuke oil fields, ongoing gas production from the within deepwater Scotian basin. Our preliminary analysis of the Sable Project, and the Deep Panuke gas field beginning the selected gas-charged zones within various deepwater wells development approval process. (example: gas/condensates charged sediments from the Annapolish G-24 well) in Scotian Basin suggests presence of Exploration focus shifted to the deepwater Scotian Slope similar hydrocarbon families of the Scotian shelf and shelf- because of the impressive hydrocarbon discoveries and high break region (condensates from the Venture field). Earlier success rates in deepwater of other circum-Atlantic basins petroleum systems work in the shelf and shelf-margin region of such as the Gulf of Mexico, offshore Brazil and West Africa, the Scotian Basin by Mukhopadhyay et al (2003, 2000, 1995) and recently Northwest Africa (Mauritania). on the discovered petroleum has indicated four major families In 2002 the Canada Nova Scotia Offshore Petroleum Board of hydrocarbons. (CNSOPB) published Hydrocarbon Potential of the A modified recent approach of the petroleum system risk Deep–Water Scotian Slope. The assessment consisted of 12 assessment within the southeast and south of Sable and geostatistical computation runs to capture the diversity of play Shelburne subbasins of the Scotian Basin, Eastern Canada areas and play types. Potential gas was estimated at 15 - has predicted the presence of four to six viable petroleum 41tcf with potential oil at 1.7 - 4.7 BB. At the time of this systems within turbidite fans and other salt-related reservoirs. report, only four deep water wells existed. It also predicted the possible hydrocarbon saturation in the Between 2002 and 2004 industry drilled six additional “hot spots”, evaluation of “oil’ versus “gas” zones, and the deepwater wells on the Scotian Slope. The results were one volume of possible expelled hydrocarbons within various gas discovery (Annapolis), one gas show (Newburn) and four sectors. This type of evaluation will reveal the controlling dry wells (Balvenie, Crimson, Weymouth and Torbrook). The factors, test sensitivities, analyze and minimize risks, improve first well proved that an active petroleum system existed in the predictions of hydrocarbon saturation in the “hot spots”, and deep water area but subsequent drilling illustrated the difficulty allow prediction of hydrocarbon volumes in complex reservoir involved in locating thick, reservoir quality sands. systems before drilling.

In 2006, the CNSOPB completed a post-drill analysis of all Although limited data is available within deepwater Sable ten deepwater wells and updated the 2002 deep water and Shelburne subbasins (within 500m-2100m water depth), resource assessment numbers. The recent drilling results our analysis encompasses the formation, timing, and fluidity of affected 3 of the original 12 geostatistical computations, several large allochthonous salt canopies that are closely predominantly pertaining to the presence and quality of connected to source rock anoxicity, bypassing of turbidite reservoir. The impact of the deepwater well results on the sands (in early Tertiary and middle Cretaceous); and the undiscovered gas and oil potential is minimal. survival of hydrocarbons within various play types. Early mobilization of Jurassic salt forming large canopies (especially This presentation will summarize the 10 deepwater well within Cretaceous and Tertiary sediments of the Sable Slope) results and explain the updated assessment results. The report possibly originated from increased sedimentation rate and which that this presentation is based on will be made public abundant hydrocarbon migration. Organic-rich amorphous early in 2007. organic facies that have anoxic signatures are likely to be present in intervals within local “microbasins”. These “microbasins”. The higher heatflow within deepwater Sable Subbasin have primarily developed in association with rapid

The First MAPG International Convention, Conference & Exhibition 21 Marrakech Convention Center, October 28 - 31, 2007 salt diapirism forming mainly gas and condensate charged Logan Canyon Formation light oil and condensates in the reservoirs. The presence of pockmarks and other geochemical Cohasset and Panuke fields. Discrete aromatic biomarkers and petroleum system modeling anomalies in various parts of (thiophenes or dibenzothiophenes) and stable carbon isotopes the Scotian Slope indicates probable gas seepage. of saturate and aromatic fractions of these oil and condensates, and one dimensional petroleum system Current studies indicate that the dispersal of turbidite modeling indicate that these oils have low maturity, high sands in Eocene/Miocene or Mid-Cretaceous may possibly be saturate fractions and are mostly derived from the lacustrine charged with three petroleum system hydrocarbons (gas- Type I or 1-II source rocks from the Early Jurassic source rocks condensate, light oil-gas and heavy oil-gas) within the Sable (possibly from the Mohican Group) similar to the Newark Basin (beyond 2500m water depth) and Shubenacadie-Shelburne in East Coast USA. The hydrocarbons have been migrated just Slopes (beyond 1500m) of the Scotian Basin. Late Jurassic after the reservoir formation through both vertical and lateral sands could also be major targets for gas charged reservoirs migration from that candidate source rock and not from the within the central Scotian Slope. distal marine late Jurassic Verrill Canyon source rock. The reservoir geochemistry of both Mississauga and Logan Canyon Overview of the Geology and the Petroleum Systems oils suggests distinct compartmentalization of various Associated with the Jurassic Aged Carbonate Bank, Scotian reservoirs and possibly changed due to multi-phase migration Basin, Offshore Nova Scotia and fractionation of heavier hydrocarbons. Paul J. Harvey1 and Prasanta K. Mukhopadhyay2 1 Nova Scotia Department of Energy, Halifax, Nova Scotia, Thermochronology evidence for Tertiary Inversion of the Canada Continental Margin of Nova Scotia, Canada [email protected] Marcos Zentilli and Alexander M. Grist, 2 Global Geoenergy Research Ltd, Halifax, Nova Scotia, Dalhousie University, Halifax, Nova Scotia, B3H 4J1 Canada Canada Southern Nova Scotia in Atlantic Canada is underlain by The Cohasset and Panuke oil-condensate fields are the Meguma Terrane, crystalline basement composed of located on the western margin of the Sable Subbasin on the Cambrian to Devonian marine strata with a likely Moroccan Scotian shelf. The Cohasset-Panuke Project began production source, which were folded, metamorphosed and intruded (ca. in 1992 and reached its economic limit and production 380 Ma) by granitoid batholiths during the Acadian Orogeny. terminated on December 17, 1999. The project produced a Considerable erosion followed, and by the Early Carboniferous total of 44.5 million barrels over its seven-year life. (ca. 350 Ma) coarse clastics - followed by extensive marine carbonates and evaporites - were deposited non-conformably The condensate in both fields has accumulated in on exhumed granitoids and metamorphic rocks. The elongated anticlines trapped both stratigraphically and Carboniferous-to-Permian Maritimes Basin developed, structurally as the result of sands draped over the underlying accumulating clastic sediments in excess of 12 km in its high formed by the thick carbonate section of the Abenaki depocentre further north. Maximum burial of the basin was Formation deposited neat the Shelf edge. attained in the Late Carboniferous (ca. 300 Ma), and the The Cohasset field discovered in 1973 consists of up to youngest sediments preserved in this basin are Lower Permian fifteen stacked sandstone reservoirs located within the Lower in age. Our apatite fission track thermochronology studies have Logan Canyon Formation through the Naskapi Formation and shown that basin inversion led to erosion of ca. 5 km of strata the Upper Missisauga Formation. The Panuke Field discovered in the Late Triassic, coinciding with the Atlantic break-up in 1986 consists of a series of five stacked reservoirs unconformity, and preceding extensive but short-lived basaltic sandstones located entirely within the upper part of the magmatism (ca. 200 Ma). Offshore Nova Scotia forms part of Missisauga Formation. the present Atlantic passive margin, an active depositional basin from the Late Triassic-Early Jurassic to the present. In The whole sequence seems regressive with a proximal such a passive margin it was expected that rocks deep in lagoonal-estuary system overlying the various pulses of offshore wells would be at their maximum temperature today. proximal to distal estuarine mouth bar sheets. Each fluvial However, our extensive apatite fission track thermochronology pulse was dominated and eventually overwhelmed by marine study indicates that rocks in offshore wells were tens of influences after the sand packages were deposited over both degrees hotter (e.g. within the oil window) than at present, and fields at which time the shorelines moved seaward. that substantial post-Paleocene cooling has occurred. Although higher paleo-mean annual surface temperatures in Geochemical fingerprinting suggests that the Abenaki the Late Cretaceous may account for some of the thermal Formation limestone and Misaine shale within the La Have anomaly detected, the most probable cause for this cooling is Platform and Abenaki Subbasin did not have enough inversion of the margin and erosion of ca. 1 km of post-Albian hydrocarbon potential to generate low GOR Mississauga and cover from onland and offshore, probably in the Eocene -

22 Oligocene. The traditional view of gradual exhumation and The Penobscot prospect offshore Nova Scotia, Canada: a new peneplanation of the Nova Scotia margin since the Triassic- look at an old opportunity Jurassic is therefore untenable. This Tertiary inversion has Kris Kendell important implications for hydrocarbon maturation, the Nova Scotia Department of Energy, Halifax, Nova Scotia, distribution of deep-water sand bodies, overpressures, and Canada post-Paleocene canyons and unconformities. The Penobscot B-41 well targeted Early Cretaceous deltaic Review of the Canada Nova Scotia Offshore Petroleum sands which drape over the Jurassic Abenaki carbonate bank Board’s Digital Data Management Centre margin. It encountered oil and gas zones totaling 60 feet of net pay. There are similar aged deltaic sands present offshore Carl Makrides Morocco. This minor discovery is very similar to the Cohasset- Canada Nova Scotia Offshore Petroleum Board, Halifax, Nova Panuke oil discovery which produced 44 million barrels of light Scotia, Canada crude oil. Nova Scotia Resources Ltd conducted a 3D seismic This paper will review the planning and implementation survey in 1992 which encompasses both the Penobscot B-41 steps undertaken by the Canada Nova Scotia Offshore and L-30 wells. Within this survey, several other structures Petroleum Board (CNSOPB) in establishing a digital Data across different geologic formations are mapped but still Management Centre (DMC) for Nova Scotia offshore remain undrilled. Potential hydrocarbon reservoirs may exist in exploration and production data. Since April, 2005 the both the Jurassic carbonate and in Cretaceous aged Mid- CNSOPB has been working toward the development of the Missisauga sands, both of which are proven reservoirs offshore DMC and it is anticipated that the facility will be operational by Nova Scotia. Although the size of this prize is unproven, its early 4th quarter 2007. Significant effort has been expended proximity to infrastructure of the currently producing Sable in researching available technology, reviewing existing national Offshore Energy Project may make it an economically feasible exploration and production databases, obtaining government play. Analogous structural closures similar to the Cohasset- budgetary approval and in developing a balanced data Panuke discovery and the Penobscot prospect may exist disclosure policy. The DMC is designed to provide easy and throughout both the Scotian margin and the Moroccan efficient access, to Nova Scotia offshore petroleum data, using succession. an internet based Geographic Information Systems (GIS) front- end. Initially, the DMC will manage and distribute the following A view from across a major transform/transfer zone: digital petroleum data: well logs and reports/data, seismic Petroleum exploration potential on the Atlantic Margin of images, GIS and production data. In the future the DMC could Newfoundland and Labrador, Canada be expanded to include: operational, safety, environmental, Michael Enachescu1, John Hogg2 and Paul Einarsson3 fisheries data etc. The DMC should promote activity and 1 Memorial University, St. Johns, Newfoundland and Labrador investment in the region by allowing new explorers to rapidly 2 ConocoPhillips Canada Limited, Calgary, Alberta and review all available digital exploration and production data 3 Geophysical Service Inc., Calgary, Alberta, Canada thereby lowering exploration risk. The DMC will also prevent the loss of data, reduce data storage costs and facilitate Recoverable reserves of more than 2 .7 billion barrels of oil, scientific research by the regulatory Boards, industry, 6 Tcf of gas, and 355 million barrels of natural gas liquids have governments, universities etc. The DMC is also intended to act been discovered in the Jeanne d’Arc Basin to date. as a “pilot project” in the establishment of a National Data Production from three giant oil fields-Hibernia, Terra Nova and Centre (NDC) for digital petroleum data, which in time may link White Rose has attained 400,000 bopd from the Jeanne d’Arc, several regulatory Boards and government departments which is only one of the many Mesozoic extensional basins across Canada. Exploration activities in the Nova Scotia located on or surrounding the Grand Banks of Newfoundland, offshore area have been occurring for over 45 years while Canada. production of oil and gas is a relatively recent activity. Prior to the development of the DMC, the CNSOPB did not have an According to plate tectonic reconstructions, during the effective and efficient system for managing the growing volume Late Triassic-Early Jurassic, the Grand Banks of Newfoundland of digital petroleum data due to the lack of appropriate was located within an elongated, NE-SW trending intra- personnel and facilities. A good data management system is cratonic rifted area extending from Gulf of Mexico to crucial to effectively manage oil and gas resources, particularly northeastern Europe. This Pangea wide mega-rift included in a high cost environment such as offshore Eastern Canada. newly formed sedimentary basins, now present offshore Nova Scotia and Newfoundland and Labrador and also basins on their respective conjugate margins, offshore Morocco and Iberia. A transform zone known as the Newfoundland Transform Zone, probably inherited from the Paleozoic Wilson cycle, separated during the early Mesozoic the northern basins

The First MAPG International Convention, Conference & Exhibition 23 Marrakech Convention Center, October 28 - 31, 2007 from the southern ones. Thick salt deposited during this period As another example of basin scale analysis, in 2006, GXT and subsequent salt tectonism is a common characteristics to acquired Beaufort-MackenzieSPAN, which is yielding new all basins located across the transfer zone. During the opening insights into the nature of the offshore Beaufort Foldbelt, of the Atlantic Ocean, the transform zone became a major suggesting that the belt consists of detachment folds with a ocean transfer zone known as the Newfoundland -Gibraltar. 10km average wavelength and very little faulting, as opposed This transform/transfer played a major role in segmenting the to the reigning interpretation of a series of north-verging break-up of the North Atlantic and conduced to separate basin imbricated fault-bend and/or fault-propagation folds. evolution and different petroleum systems across its transect. It is our contention that SPAN data sets, in conjunction with While the Atlantic basins offshore Newfoundland continued other detailed “prospect and/or exploration level” surveys, will their development through two more extensional stages in Late aid the industry in the definition of petroleum systems and new Jurassic-Early Cretaceous and subsequently in Late early plays, especially at great depth and in a range of water depths Cretaceous to mid-Cretaceous, the basins south of the along continental margins. Newfoundland-Gibraltar transform/transfer zone have already entered in mid-Jurassic their thermal subsidence stage. The Sedimentary Infill as a Response to Tectonic Inversion in the key to Grand Banks petroleum discoveries is the a) presence US and Canadian Arctic, Identified by Regional 2D of abundant Kimmeridgian-aged marine source rock deposited Geomechanical Restoration in euxinic basins; b) existence of multiple alluvial to marginal Jordi Franques-Faixa, Irene Gomez, Robert Gruenwald, marine reservoirs c) numerous fault and salt induced traps and Manuel Gutierrez, Xavier Legrand, Raul Rodriguez, Gonzalo d) preservation and maturation of the synrift sequence under a Ruiz and Ricardo Veiga thick postrift-syndrift predominantly shaly sequence, RepsolYpf, Paseo de la Castellana 280, 28046 Madrid, Spain conditions met only in a small number of basins. Rather than basin-wide, petroleum success on the southern margins of Geomechanical driven restoration, using the “Finite Nova Scotia and Morocco is probably restricted to secluded Element Method”, honors the physical laws which govern the sub-basins that meet similar characteristics. rock deformation. This new approach has significant potential for petroleum applications as compared to usual geometric Deep Seismic Imaging of Continental Margins: Examples restoration based on the surface conservation. An example in from the 9-km long offset, 18 second NovaSPANTM and the US-Canadian Artic area illustrates how faults and reservoir Beaufort-MackenzieSPANTM Data Sets compartmentalization, hydrocarbon migration pathways, and Menno G. Dinkelman hydrocarbon traps can be understood in a context of complex Chief Geologist, GX Technology, Houston, Texas 77042 tectonic processes. This understanding can be exploited in decision making and reducing risk. In 2002 GX Technology Corportation (GXT) initiated a worldwide 2-D seismic continental-margin reconnaisance 2D Geomechanical reconstructions based on regional program using a 9-km long cable and recording to 18 seismic interpretation along three regional cross-sections from seconds. These SPAN™ programs have been designed to West to East (Chukchi Sea, Beaufort Sea and Sverdrup Basin), provide regional basin-wide PSDM (Prestack Depth Migrated) well data and geochemical data were used to investigate and data sets to image down to the base of the crust. Since then, compare the influence of the tectonic activity on the GXT has acquired several tens of thousands kilometers of such sedimentary infill of the Artic Alaska Plate and the Sverdrup data across continental margins worldwide. Basin

The NovaSPAN data was acquired in 2003 and consists of This study shows analogies between pre-rift and Early 3,400 km of seismic lines shot across the Nova Scotia Margin. Jurassic rift phases until Upper Jurassic. Changes in This data provides a comprehensive regional geological depositional style in the post rift sequence (post Jurassic) framework which when integrated with well data allows overlying a regional unconformity, are related with basin visualizing, in depth domain, how key elements of the basin characteristic tectonics. architecture evolved through time. We have observed rotated Counterclockwise opening of the Canadian Basin results in crustal blocks in the deep water beyond the slope and a diachronous deformation of the Arctic Alaska Plate. A allochthonous salt basins. These might have been caused by positive structural inversion occurs from Late Jurassic in the transtension along a transform fault zone which in turn might western part, propagating eastward during Early Cretaceous be suggestive of shifts and changes in the basement hinge time. Then a continuous infill of the Colville Foreland Basin zone. The SPAN survey concept thus provides the coverage overrides the Proto Barrow arch and leads to a northward length and depth of imaging to reveal how complex basin deepening of the Beaufort Sea in a basin inversion process. tectonics are controlled by structural deformation and sediment loading through time. At present day, the burial of a Lower Cretaceous source

24 rock to the north east of Barrow Arch defines a secondary High Atlas morphology: insight from the drainage pattern petroleum system in the Beaufort Sea. Julien Babault1, Jean Van Den Driessche2, Alain Crave2 and Antonio Teixell1 Key Words: Geomechanic Restoration, Arctic, Petroleum System, 1 Departament de Geologia, Universitat Autònoma de Finite Element Method Barcelona, 08193-Bellaterra, Spain Session: The tectonics of vertical movements, 2 Géosciences Rennes, UMR CNRS 6118, Université de mountain building and subsidence, Morocco Rennes 1, Rennes, France. The High Atlas is a linear intracontinental mountain range, Coupled lithosphere mantle circulation models around 600 km in length, orientated approximately ENE-WSW. H.-P. Bunge Its width ranges from 50 km to around 100 km. The mean Department of Earth Sciences, Ludwig Maximilians University elevation in the axial part of the chain is 2200 m with peaks Munich, D 80333 Munich, Germany above 4000 m. This results from uplift related both to lithospheric-scale thermal doming, mostly parallel to the trend High resolution computer models of deep Earth circulation of the chain, and to weak crustal thickening during Cenozoic coupled to models of the lithosphere now provide times. A striking feature of the morphology of the High Atlas is the occurrence of both transverse and longitudinal drainage unprecedented opportunity to study the linkages between characterized by deep fluvial incision of more than 1000 m in deep-seated dynamic processes in the Earth’s interior and the axial zone of the chain. Most of the transverse component their tectonic and topographic response at the surface. Mass of the drainage appears to postdate the longitudinal anomalies in the Earth’s mantle are a key controlling factor, component as shown by the occurrence of recent or incipient because they initiate up- and downwelling flow and thereby captures. The longitudinal drainage is inherited from an early stage of organization controlled by the tectonic structures in elevate or depress the surface over extended regions for the post-Paleozoic cover that developed during upper crustal prolonged periods of time. folding and thrusting. Rapid amplification of N-S regional slope by ~1000 m of thermal uplift triggers: (i) incision of the To model tectonic evolution in response to deep-seated longitudinal drainage and (ii) processes of internal drainage solid-earth processes, it is essential to combine detailed mass capture by transverse streams creating a new organization of budget considerations of the mantle with the dynamic the drainage system toward the regional slope. Such evolution considerations embedded in modern models of the mantle from a longitudinal to a transverse-dominated drainage network may also represent a common way of fluvial network circulation. There exists well-known a-priori information on the development in mountain belts where the amplification of the mass budget of the mantle in the form of density models regional slope simply results from long-lived lithospheric derived from histories of subduction. Here we report on one convergence, not from asthenospheric uplift. such effort to directly quantify the thermally induced mantle density structure from a history of plate motion assimilated in Vertical movements of the Moroccan Atlas domain during global mantle circulation models. Key advances to the dynamic Cenozoic Yves Missenard1, Jocelyn Barbarand2, Omar Saddiqi3, model include (1) a thermodynamically self-consistent Pascale Leturmy1, Dominique Frizon de Lamotte1, Hermann formulation of the mantle mineralogy and (2) a very high Zeyen2 and Fatima Zhara El Haimer3 numerical resolution sufficient to resolve (for the first time) 1 Université de Cergy-Pontoise, Département des sciences de global mantle flow at Earthlike convective vigour. The latter is la Terre et de l’environnement (CNRS, UMR 7072), 5 mail Gay needed to resolve thermal boundary layers at the appropriate Lussac, 95 031 Cergy cedex, France 2 Département des Sciences de la Terre (UMR 8148 IDES), time- and length-scales. We apply our model to compute Université de Paris-Sud, Bat. 504, F-91405 Orsay Cedex, global plate motion, and focus in particular on the evolution of France plate boundary forces. We will show results for the Nazca / 3 Université Hassan II Aïn Chok, Faculté des Sciences, South America plate boundary, demonstrating the the recent Département de Géologie, route d’El Jadida, BP5366 Mâarif – changes in plate motion of that region can be modeled Casablanca, Maroc accurately from our approach. The topography of continental lithosphere results of a wide variety of processes occurring at different spatial and time scales. Their study still remains a strong matter of debate, often as a consequence of complicated interactions between them. The Atlas domain constitutes a tremendous natural

The First MAPG International Convention, Conference & Exhibition 25 Marrakech Convention Center, October 28 - 31, 2007 laboratory to study these processes. The geological evolution on the South Atlas Fault Zone in both the Souss and of this area is now well constrained and many available field Ouarzazate basins where deformed Quaternary levels permit data allow us to reconstruct the history of vertical movements to estimate slip rates on individual faults on the order of 0.1 since Triassic. At that time two rifting phases are distinguished, mm/yr. Such low slip rates imply that large observational time- different in age and direction. The first one is Triassic in the window is needed to analyze active deformation in low Western High Atlas; the second one is middle Liassic in the seismicity regions. However, the complex 3D geometry of Central High Atlas and Middle Atlas. From Cenomano-Turonian reverse or thrust faults may cause difficulty to relate surface to Lower Eocene, the whole area topography is regular at low observations with the deeper faults that have the potential to altitude, as testified by the deposition of low bathymetry facies. nucleate big earthquakes. On-going seismological analyses Two main tectonic phases occurred during Upper Eocene and should permit to precise such seismogenic potential. Finally, Plio-Quaternary. They are separated by a Miocene wide further studies are necessary to interpret the Anti Atlas subsidence event. A Neogene large scale uplift also affects the seismicity. whole area. Numerical modelling constraints on the uplift of the Atlas In this study, we focus on the South Atlas Front, on which mountains in Morocco all of the previously cited events have been recorded, to highlight the nature and effect of the processes controlling the Daniel Garcia-Castellanos1, Ivone Jiménez-Munt1, Antonio topography during Cenozoic. We combine geological data, Teixell2, Manel Fernàndez1, Maria-Luisa Arboleya2 and Jaume geophysical constrains and new apatite fission-track results. Vergés1 This allows us to distinguish the effects of five main processes 1. Institute of Earth Sciences ‘Jaume Almera’ CSIC, Lluis Sole on the topography: crustal shortening, lithospheric thinning, i Sabarís s/n, 08028 Barcelona. Spain lithospheric flexure and buckling and finally local volcanic 2. Departament de Geologia, Universitat Autònoma Barcelona, doming. Their ages and the strong interactions with the 08193 Bellaterra, Spain structural heritage are also discussed. These results are Despite the Moroccan Atlas being among the highest generalized to the whole Atlas domain and considered in the alpine orogens, it is characterized by minor tectonic shortening general geodynamic context. and nearly absence of foreland sediments. Dating of volcanic rocks, structural, and isostatic studies, suggest that a mantle- Active tectonics of the High Atlas sourced buoyant force is responsible for about half of its Michel Sébrier1, Lionel Siame2, El Mostafa Zouine3, Thierry present topography, but the mechanism responsible for such Winter4, Yves Missenard5 and Pascale Leturmy5 load and the timing of its emplacement remain unknown. Here, 1 UMR Tectonique, CNRS-Université Pierre et Marie Curie, we estimate the amount of erosion along two geological case 129, 4 Place Jussieu, 75252 Paris cedex 05, France, transects that we use to constrain a cross-section numerical 2 CEREGE, Europôle de l’Arbois, Aix-en-Provence, France, model incorporating simple approaches to tectonic shortening, 3 ENS Rabat-Takadoum, Rabat, Maroc, buoyant subcrustal loading, flexural isostasy, and 4 BRGM, Orleans, France, erosion/sedimentation. Parameterization of this model 5 UMR Tectonique, CNRS-Université de Cergy-Pontoise, indicates that, fixing the tectonic parameters, large erosion France rates imply smaller foreland basins because erosion reduces thrust loading and thus reduces the space available for Active tectonic studies in the Moroccan High Atlas have sediments in the foreland. Finding a set of parameters that three main interests: (1) to document an active intraplate, slow- reproduces the present absence of sediment in the forelands, deforming mountainous system, (2) to determine the amount estimated erosion volumes, shortening rates and mean orogen of present shortening that is accommodated south of the topography brings quantitative constraints on the age of African-Eurasian plate boundary region, and (3) to analyze a subcrustal buoyant loading. desert analogue of the Western European compressional seismogenic provinces; namely, Pyrenees and Western Alps. Geophysical and geodetic studies in the Atlas Mountains of We aim to present a general overview of the active tectonic studies and first results that have been recently developed in Morocco: past, present and future perspectives the Moroccan High Atlas within the framework of the SAFE P. Ayarza1, A. Teixell2, F. Alvarez-Lobato1, M.L. Arboleya2, A. European project and French-Moroccan,Volubilis program. Kchikach3, M. Amrhar3, M. Charroud4, A.J. Gil5, R. Review of seismological and structural data coupled with new Carbonell6, J. Galindo7, E. Tesón2, A. Ruíz5 and C. de Lacy5. data on topography, geomorphology, and Quaternary geology 1 Departamento de Geología, Facultad de Ciencias, allowed delineating the major active faults of the High Atlas. Universidad de Salamanca, Salamanca, 37008, Spain These are the North and South border faults of which fault 2 Departament de Geologia, Universitat Autònoma de segmentations agree with potential Mwmax ranging between Barcelona, Bellaterra, 08193, Spain 6.1 and 6.4. Detail active tectonics analyses were performed 3 Faculté des Sciences et Techniques, Université Cadi-Ayyad,

26 BP549, Marrakech, Marocco The lithospheric structure across the NW Moroccan margin. 4 Département de Géologie, Faculté des Sciences et Evidences for large-scale tectonic inversion Techniques Fès-Saïss, Université Sidi Mohammed Ben M. Fernàndez1, I. Jiménez-Munt1, J. Vergés1, H. Zeyen2, J. Abdellah, BP 2202, Fes, Morocco Fullea1 and D. García-Castellanos1 5 Departamento de Ingeniería Cartográfica, Geodésica y 1 Group of Dynamics of the Lithosphere (GDL), Institute of Fotogrametría, Escuela Politécnica Superior de Jaén, Jaén, Earth Sciences “Jaume Almera”, CSIC, Lluis Solé i Sabarís s/n, 23071, Spain 08028 Barcelona, Spain 6 Instituto de Ciencias de la Tierra ‘Jaume Almera’, CSIC, 2 UMR 8148 IDES, Université Paris-Sud – CNRS ; Barcelona, 08028 Département des Sciences de la Terre, Bât. 504, 91405 Orsay 7 Departamento de Geodinámica, Facultad de Ciencias, Cedex, France Universidad de Granada, Granada, 18071, Spain We have modelled the lithospheric structure across the NW The Atlas Mountains of Morocco have been the target of Moroccan margin using an integrated methodology that several geophysical studies: gravity (Hildenbrand et al., 1988), combines elevation, heat flow, gravity, geoid and seismic data. refraction (Makris et al., 1985; Tadili et al., 1986; Wigger et al., The modelled profile is 1400 km long and extends NW-SE from 1992) and MT (Schwarz et al., 1992) surveys have been carried the Iberian Abyssal Plane to the Sahara Platform, crossing the out during the 80’s and 90’s and have helped to establish Gorringe Bank, the west Iberian-Africa plate boundary, the some of the main characteristics of this intracontinental Moroccan continental margin, and the Atlas Mountains. orogen, such as its overall structure and modest crustal Offshore, the profile coincides with the IAM-4 seismic reflection thickness. Later studies, based on structural geology (Teixell et survey and with the wide-angle and reflection survey SISMAR al., 2003; Arboleya et al., 2004), higher resolution gravity Profile-4. Onshore, no seismic data are available and the profile surveying (Ayarza et al., 2005) and multidisciplinary potential follows previous modelled lithospheric profiles. The most field modeling (Zeyen et al., 2005; Teixell et al., 2005; outstanding result is a prominent lithospheric thickening Missenard et al., 2006), indicated that the High Atlas crust is beneath the Moroccan continental margin with thickness too thin to support its topography and that a mantle values of around 200-220 km. This thickening, which appeared contribution is required. An astenospheric upwelling, which much more moderate in previous models, is the result of triggered the Eocene-to-recent Atlas magmatic activity was applying the crustal and density structure proposed from then proposed as the main cause of its topography. SISMAR survey. Another prominent feature is the reported existence of a high velocity lower crust beneath the margin, as Despite of the advances in the knowledge of the Atlas imaged from SISMAR survey. We analyze the possible extend crustal and lithospheric structure and in the origin of its and origin of this high velocity lower crustal body and discuss topography, some questions remain. One of the most the nature of the lithospheric thickening beneath the Moroccan important is related with the precise Atlas crustal thickness, continental margin, which seems to affect also the Riff and the which has been deduced from low resolution wide-angle and central-western Betics. refraction data, local receiver functions information and gravity modeling. Crustal thickness happens to be the key to establish the position of the lithosphere-astenosphere boundary and Preliminary magnetostratigraphic dating of the Ouarzazate therefore, to asses the real contribution of the mantle to the basin: implications for the timing of mountain building in the topography and accordingly the actual uplift. High Atlas of Morocco E. Teson1, E.L. Pueyo2, A. Barnolas2, A. Teixell1, J. Agustí3 With this target, two projects have been launched. Firstly, a and M. Furió4 high-resolution wide-angle and refraction experiment across 1. Dept. de Geologia, Universitat Autònoma de Barcelona, two 300 km-long transects has been planned across the 08193-Bellaterra, Spain Middle Atlas-High Atlas and Anti-Atlas. The station spacing 2 Área de Estudios Geológicos, Instituto Geológico y Minero designed for this experiment is between 300-500 m, and de España, Spain should give detailed vertical-incidence and wide-angle 3 ICREA-Institut de Paleoecologia Humana, Universitat Rovira information of the main velocity boundaries down to a depth of i Virgili, 43005-Tarragona, Spain almost 100 km. Secondly, a non-permanent network of GPS 4 Institut de Paleontología M.Crusafont, 08201-Sabadell, stations has been settled around the Ouarzazate Basin. This Spain network is aimed to control the recent vertical and horizontal movements that affect the area in an attempt to constrain the The Cenozoic Ouarzazate basin contains the best record of current deformation rates in the Atlas system. the building of the High Atlas mountains of Morocco. The infill of this foreland basin is characterised by terrestrial red beds, imprecisely dated so far. An ongoing magnetostratigraphic study in these formations aims to constrain their age, sedimentation rates and the timing of deformation in the

The First MAPG International Convention, Conference & Exhibition 27 Marrakech Convention Center, October 28 - 31, 2007 adjacent High Atlas chain. Two profiles covering the entire The Cretaceous topographic evolution of Africa - siliciclastic basin infill are being studied. The first comprises the lower part, sediment budget corresponding to the Hadida Formation which conformably F. Guillocheau, N. Rolland, C. Helm, J.P. Colin, C. Brezinsky, J. overlies dated Middle Eocene marine carbonates. The second Braun, C. Robin, D. Rouby and M. Simoes covers most of the unconformable Ait Ouglif and Ait Kandoula Formations, previously ascribed to the Oligocene and Géosciences Rennes, UMR6118 CNRS - Université de Neogene. The Hadida profile consists of ~ 490 m of red Rennes1, 35042 Rennes cedex, FranceIn the frame of the sandstone, shale and gypsum, deposited in coastal sabkha to TOPOAFRICA Project, a paleogeographic database (ArcGIS) aeolian and distal alluvial fan environments. 102 standard of the African plate (including Arabia) during Cretaceous times samples were collected with a portable drilling machine. The has been built. The main objectives of this project are (1) to Amekchoud section (208 cores) is ~780 m thick, comprising a focus on the continental domain paleogeography in order to basal level of conglomerates (Ait Ouglif Fm.), channelised quantify the paleoelevations variations through this time interval sandstones, shales and lacustrine carbonates (Ait Kandoula and (2) to quantify the siliciclastic sediment budget and then Fm.). On top of the measured section, the uppermost Ait the continental erosion through Cretaceous times. Because Kandoula Fm. is made of ~ 300 m of conglomerates and landscape response to spatially varying tectonic and climatic shales that are the subject of ongoing analysis. Paleomagnetic forcing can be quite complex, a direct inversion of the analyses (thermal demagnetization) conducted in the “Jaume geological data into estimates of paleotopography is not Almera” CSIC laboratory allow characterising stable and possible. We have therefore use a new numerical model of double polarity and high coercivity components unblocking sediment production and transport at the continental scale, between 500 and 670°C. which will form the basis of the quantitative inversion of the observations to yield estimates of past topography. An initial correlation between the local polarity sequence and the GPTS has been strongly based on the magnetozone Focussing on North Africa, the Cretaceous is a period of pattern. The Amekchoud base may start at chron C5ABn low relief creation. The Early Cretaceous siliciclastic flux mainly (Serravalian), chron C5n is undoubtedly defined, and the profile record high wave length (x100 km) deformations occurring probably ends at chron C4An (Tortonian). This interpretation is along the northern Guinea Gulf (opening of the Equatorial consistent with the micromammal remains found at the top of Atlantic). The northward-induced topographical gradient is the section, which include Myocricetodon sp., Africanomys sp. altered by the reactivation of the Panafrican and Hercynian and Muridae indet. Myocricetodon sp. that is close to the short to medium wave length structures during two critical Myocricetodon seboui-M. ouaichi group; therefore, a late periods: the Barremian/Aptian boundary and the Late Aptian- Miocene age is supported for this upper part of the section. Early Albian periods. The Cenomanian, major marine flooding The Hadida section is not so unambiguously defined and could of North Africa, is a period of flat topography, with remnant start at chron C20N (Lutetian), probably ending at C13r relief along the Sirt Rift. The Late Cretaceous deformations (Priabonian-Rupelian). In both profiles the accumulation rate (Late Turonian to Campanian) do not create significative relief in curves are steady and support our preliminary calibration, North Africa, even they highly control the geometries of the although data in progress are expected to reduce basins (flexural pattern of the “phosphates” basins of Morroco, uncertainties. growth of the Mzab High,…).

The Eocene Hadida Formation, regarded as the first Cenozoic structure, volcanism, and evolution of relief in the foreland basin deposit, predates local deformation in the High central and eastern Anti-Atlas (Morocco) Atlas frontal thrust belt, and may be attributed to early J. Guimerà1, M.L. Arboleya2 and A. Teixell2 mountain building in the internal parts of the orogen. It is 1 Departament de Geodinàmica i Geofísica, Facultat de followed by a marked hiatus of ~ 20 m yr, which appears Geologia, Universitat de Barcelona, Martí i Franqués s/n. widespread in southern Morocco; generalized deformation in 08028 Barcelona, Spain the frontal thrust belt occurred in this period. Sedimentation 2 Departament de Geologia, Universitat Autònoma de was resumed in mid-Miocene times (Ait Ouglif and Ait Barcelona, 08193 Bellaterra, Spain Kandoula Formations), contemporaneously with continued thrusting. Our data thus suggest that the main thrusting in the The Anti-Atlas mountainous region is located South of the southern High Atlas frontal thrust belt took place from the late High Atlas and its southern foreland basins (the Warzazat and Oligocene – early Miocene to the early Pliocene. Souss basins). A Proterozoic Pan-African basement is overlaid by post Pan-African Upper Proterozoic and Paleozoic rocks slightly deformed during the Variscan orogeny. Upper Cretaceous rocks (of continental and marine origin) are found in isolated outcrops South and West of the Warzazat basin and around the eastern termination of the Anti-Atlas relief. A

28 poligenic erosional surface (the High Erosional Surface, HES) Unexpected Jurassic to Neogene vertical movements in developed on top of older the rocks before the Miocene “stable” parts of NW Africa (Choubert, 1952). Mid Miocene to Pliocene (Pontian) Aït B. Ghorbal1,2,*, G. Bertotti1,*, P. Andriessen2,* and J. Kandoula Fm (of alluvial and lacustrine origin) lays on the older Foeken3 rocks in the northern part of the Anti-Atlas; in some places it is 1 Tectonic Unit, FALW, V.U. Amsterdam, Netherlands. located within paleovalleys downcut in the HES, while in others 2 Isotopen Geochemie Unit, FALW, V.U. Amsterdam, it lays on top of the HES. A North-facing erosional escarpment Netherlands. truncates the HES in the northern slopes of the Jbel Saghro 3 Isotope Geoscience Unit, Scottish Universities Environmental and marks the south boundary of the Aït Kandoula Fm in that Research Centre, East Kilbride, G75 0QF, United Kingom area. Late Cenozoic phonolitic volcanism occurred in Jbel * Netherlands Research Centre for Integrated Solid Earth Saghro and most extensively in Jbel Sirwa, where the remains Science: ISES of the Sirwa volcano reaches 3304 m. Considered as a meta-stable area of NW Africa from Reverse faults of decakilometric to kilometric-scale with Paleozoic to Cenozoic time, the low-thermal history of the vertical slips of 500 m to several tens of meters involve the Moroccan Meseta was assessed for the first time by apatite (U- Neogene rocks. The major structures related to the uplift of the Th)/He (AHe) and Fission track (AFT) data. Thermal evolutions Anti-Atlas, have been analysed by means of contour maps of of the Rehamna and Rommani inliers were constrained by low the present attitude of several surfaces of reference (basal thermochronology tools and tectonic factors. The Post- unconformity of Upper Cretaceous and Neogene sedimentary Hercynian granites and their contact metamorphic corteges and volcanic rocks, and HES) and by generalised geological (303-270Ma) indicate a long residence at low temperature with cross-sections. The present topographic elevation of the Anti- two exhumation phases. The main exhumation which is Atlas is over 1500 m in extensive areas of it, and exceeds 2000 following subsidence contemporaneous to the Atlantic m in several places. The structures causing this elevated opening yields AFT and AHe ages of 160-120 Ma. After minor topography can be summarised as fellows: 1) A broad NNW- subsidence with Cretaceous to Eocene sediment deposits SSE-oriented anticline, 120 km in wavelength, which deforms thicknesses of less than 1,5km, the second exhumation phase the Upper Cretaceous and Neogene rocks of the Sirwa region. describes a thermal history related to the Alpine orogeny with 2) This anticline is coeval with the Tertiary reactivation of the E- AHe ages around 50-30 Ma. The two vertical movement W Anti-Atlas Major Fault –located South of the Sirwa– as a events are disjoined by the major marine transgression during South-vergent reverse fault. 3) Another major gentle anticline, the Cenomanian-Turonian. This new insight reopens the oriented WSW-ENE and more than 100 km long originated the debate of the “Moroccan Arch” and the role of the western relief of the Jbel Saghro; no thrust faults crop out in its limbs. Meseta during the Atlantic rifting. The Proterozoic basement reaches 2500 m in the Jbel Saghro and Jbel Sirwa regions while it is at 1400 m in an intervening Mesozoic denudation of the Moroccan Atlas constrained by structural depression in the area where the Draa river crosses apatite fission-track thermochronology the Anti-Atlas massif. J. Barbarand1, B. Saint Bézar2 and M. Pagel1 A first stage (pre mid-late Miocene?) of growth of the Jbel 1. Univ. Paris Sud, UMR CNRS 8148 IDES, Bâtiment 504, Saghro anticline is evidenced by the erosional escarpment in Orsay cedex, F-91405 the northern limb of the anticline. A second, main stage of 2. Univ. Paris Sud, UMR CNRS 7072 Tectonique, Bâtiment growth, postdates the Aït Kandoula Fm and the Neogene 504, Orsay cedex, F-91405 volcanic rocks. The Sirwa anticline and the reverse The High and Middle Atlas mountains constitute inverted remobilisation of the Major Anti-Atlas Fault also occurred basins with Triassic to Jurassic sedimentary rocks now at high during this stage. The resulting structural depression in elevations. It is generally admitted that inversion is mostly between allowed the entrenchment of the Draa river gorge. concentrated to the basins and does not affect the local Choubert, G. (1952): Histoire Géologique du domaine de l’Anti-Atlas. borders (Moroccan meseta, Haute Moulouya, Anti-Atlas). This Géologie du Maroc, fasc. I. Service géologique, Notes et Mémoires, no study aims to constrain - age of inversion, amount of erosion, 100, pp. 75-195. Casablanca. differences between domains- this hypothesis.

Sampling has been carried out on both side of the High Atlas Mountain, northward on the Moroccan meseta and southward on the Anti-Atlas and the Red beds unit.

Preliminary results show that FT ages are much younger than expected on both side of the High Atlas with ages ranging between 114±5 and 188±9 Ma. FT lengths are about 12 μm

The First MAPG International Convention, Conference & Exhibition 29 Marrakech Convention Center, October 28 - 31, 2007 with a negatively skewed distribution. Modelling of these data occurred during the late Pliocene, with a fault-ramp fault using AFTASolve suggests a phase of temperature decrease located on a main detachment fault, related to the Rif arc between 160 and 120 Ma. Amount of erosion might be southward propagation. In the region of Casablanca, a estimated to 2-3 km using basic thermal properties. Samples stacked sequence of clustered raised beaches and notches closer to the South Atlasic front show younger ages (135±18 record a pulsed uplift synchronic with the Quaternary global to 47±9 Ma) ; these ages are interpreted to be linked with the sea level drop. Two major steps are related with about 1 Ma Tertiary uplift associated with the main phase of the High Atlas and 400-300 ka events. This tectonical activity is recorded in building. form of faulted beaches-dunes complexes and probably some moderate co-seimic activities. The main coastal paleocliff is The main conclusion of this study is that the overall area related with a change of longshore erosion driven by a main has undergone a regional uplift during the Late Jurassic – Early climate change younger that 1 Ma. The main inland paleocliff Cretaceous which finds its geodynamical evidences by the is also related with a climate degradation, probably associated transition from marine deposition (Middle Jurassic limestones) with enhanced storminess and SW storms. to continental deposition (Red Beds) and by the high thickness of the remaining Red Beds. Expression of the Atlas inversion tectonics in deepwater offshore Morocco: influence of syn-rift structures on post-rift Late Neogene and Quaternary reactivation of a paleozoic deformation basement: the western Morroco platform. Results from a Gabor C. Tari1 and Mahmoud Zizi2 morphostructural analysis based on DEM, field data and 1. AllyGabor Geoscience, Bellaire, Texas, USA datings 2. Ziz Geo Consulting, 47 Av Fall Oumeir Agdal Apt 7 Rabat, Brigitte Van Vliet-Lanoe1-2, Pascal Leroy2 Ait Brahim3, Nadia Morocco Mhammdi4, D. Lefèvre5 and Nissrine Maad2-6 1. UMR PDBS, USTLille, Villeneuve d’Ascq, France Neogene to Recent inversion of the Atlas system, as the 2. UMR Domaines Océaniques , UBO, Brest, France result of African-Eurasian plate convergence, is well 3. University Mohammed V, Rabat, Maroc documented onshore Morocco. However, recently acquired 4. Institut Scientifique, Rabat, Maroc and vintage academic reflection seismic data in the offshore 5. Université Montpellier III, UMR 5140, France Essaouira segment of the Atlantic passive margin of Morocco 6. University chouaib Doukkali, El Jadida , Maroc show the presence of inverted structures of mid-Tertiary age in the deep-water area as well. The combined analysis of DEM and satelite images analysis allowed to define a Quaternary style of deformation of These unusual structures are best imaged outboard of the the Western Morroco platform from Larache to Safi. This work widespread salt basin of Late Triassic/Early Jurassic age, some is combined with field observations and datings from the 200 km to the west from the coastline in water depth of 2,000- recent litterature. The Rharb depression represents a 4,000 m, but still over highly extended continental crust. The wrenched forearc basin activated at least since the Upper anticlines have a general NW-SE/WNW-ESE trend determined Miocene. South of this zone, after a major flexure, the platform first by a regional-scale 2D seismic reflection data set, also is deformed by long wavelength deformations controlled by the confirmed by a subsequent 3D seismic survey. faulting of the Variscan basement. The zone of Casablanca Compressionally reactivated syn-rift normal faults are corresponds to a major riedel pattern which controls local responsible for these inverted structures which clearly involved uplift and valley incision. This suggests that the global the pre-Mesozoic basement. subsidence of the Morocco Atlantic margin is strongly affected The areal extent of the inverted structures coincides with by the basement reactivation under control of the Africa-Iberia that of the deepwater Tafelney Plateau and show not only collision. Upper Cretaceous coincides with an offshore anticlines as the result of the overall N-S compressional stress sequence showing a transition towards a prograding regime field, but also a broad, neotectonic updoming of the Tafelney that leads to the topography of the present-day margin. It is Plateau as the offshore continuation of the uplifting Atlas trend. associated with a major marine abrasion surface cropping This interpretation is supported by several observations: a) the south of Rabat and covered by upper Cretaceous onshore of unusual concave-upward bathymetric profile of the Tafelney Kenitra. This evolution is guided by a basement flexure which Plateau, b) lack of a pronounced shelf-break; c) pronounced was activated prior to the Messinian as a major valley incision truncation of Tertiary and Cretaceous rocks at the seafloor; d) predated the Messinian flooding of most the platform south of isopaching and flattening on several Tertiary seismic horizons Rabat, attesting an early bulging of this region, probably from and e) analogue, well-exposed E-W trending anticlines in the the early Miocene. Flooding was progressive, probably from onshore Essaouira Basin. the Tortonian. The maximum Messinian flooding surface is limited inland by a marine paleocliff and some rias, well The localization of late post-rift inversion and neotectonic preserved from Safi to the Oued Melah. A major deformation

30 arching within the Tafelney Plateau is the result of its syn-rift Atlantic and Tethyan geodynamic impact on the evolution structural inheritence, as it acted as a high-relief and subsidence history of north African margins accommodation zone during the opening of the Central N. Ellouz-Zimmermann, M. Patriat, R. Bartolome, R. Bracene Atlantic. and J.L. Faure IFP, Dept of Geology , 1-4 av de Bois-Préau, 92856 Rueil- Geology evolution of the Atlantic margin basins of Morocco Malmaison cedex, France M. Hafid1, G. Tari2, D. Bouhadioui3, A. Ait Salem3, I. Mousaid1, H. Echarfaoui1, M. Nahim3, M. Dakki3, F. Samaka3 The passive margin of the central Morocco exhibits: (1) a and F. Oumalch3 singular geodynamic position showing the interplay with 1 Laboratoire interdesciplinaire en resources naturelles et en Tethyan and Atlantic opening history during Mesozoic times, environnement,B.P. 133 Faculté des scxeinces, Univesité Ibn (2) marks the along-strike transition between volcanic (to the Tofail, Kénitra, Maroc South) to non-volcanic margins (to the North). (3) rapid lateral 2 AllyGabor Geosciences 6719 Avenue B, Bellaire Texas USA. changes in the nature of subsidence processes linked with the 3. ONHYM Avenue Al Fadila B.P. 8030, Rabat location and importance of both rifting phases and N-S alpine shortening. The subsidence of several regions of Atlantic and The Atlantic margin of Morocco extends over some 2.934 Alpine Morocco have been modelled: the Atlantic margin, the km from Cap Spartel in the north to Lagouira in the South. It is Essaouira and Missour basins, the Middle and High Atlas and one of the oldest passive margins on earth and it is conjugate the Hauts Plateaux. The Moroccan margin endured a long- to the Nova Scotia margin of North America. Because of its key term rifting related heating phase lasting 100 Ma, which started position within the central Atlantic ocean, and its promising at the end of Triassic time. hydrocarbon potential it was the object of extensive research programs and industrial exploration studies. The results of At a large scale, strong variations in time and amplitude of these works reveal that, with the exception of the segments the subsidence rates in the analysed basins reflect their adjacent to the Rif and the Atlas mountains where relationship to the structural location. Morocco, as well as the complications due to the Alpine orogeny were superimposed whole N. African margin (in Algeria and Tunisia), were highly on typical passive margin processes, the Moroccan Atlantic compartimentalized since early Mesozoic times. From the margin shows a broad homogeneity in its geodynamic beginning of the Triassic onwards, and due to the first identified evolution. This evolution can be subdivided into two main Tethyan extension phase, locally amplified by Atlantic one, the phases: a rifting phase that started in late Triassic to Early initiation of the basins strongly depends on the tectonic Jurassic times, followed by a drifting phase which initiated heritage, as thickness variations and heterogeneities which are around 180–170 Ma. In the present work we propose to due to highly structured Paleozoic basement which define the review the main stratigraphic and structural features that crustal weak zones. characterize each of these two phases within the Atlantic Tectonic evolution and subsidence history will be Moroccan margin as a whole, followed by a geological compared all over the N. African Margin, from extensive to description of individual offshore and onshore basins that compressive alpine events. compose this margin starting from north to south. The description is essentially based on regional seismic transects Quantitative Meso-/Cenozoic Development of the Eastern and borehole data. Central Atlantic Continental Shelf, Western High Atlas, Syn-rift salt presently forms a widespread diapiric province Morocco that extends along the Moroccan Atlantic margin over some Rainer Zühlke1, Mohammed-Said Bouaouda2, Brahim 900 km. Its northern edge is offset and overlapped by the Rif- Ouajhain2, Thilo Bechstädt1 and Reinhold Leinfelder3 Betic thrust belt, its eastern limit makes an inland incursion into 1 Institute of Geology and Paleontology, Ruprecht Karl the Essaouira-Agadir onshore basin and its southern edge University, Im Neuenheimer Feld 234, D-69120 Heidelberg, extends into the Tarfaya-Laayoun basin. Its western limit Germany roughly coincides with the S1 magnetic anomaly. Salt is 2 Laboratory of Marine Geosciences, Chouaib Doukkali present in the sections of most onshore and offshore basins University, Faculty of Sciences, Box 20, El Jadida, 24000- and has generally played an important role in their post Triassic Morocco tectono-sedimentary evolution. This important role, however, 3 Museum für Naturkunde, Humboldt-Universität zu Berlin, D- contrasts with the relatively fewer previous works that were 10099 Berlin, Germany solely devoted to salt tectonics with respect to other aspects of the geology of these basins. We propose here to illustrate The Agadir Basin, Morocco, includes the Late Paleozoic to this role by selected regional reflection seismic transects and to Cenozoic eastern continental shelf of the Central Atlantic. try to understand the areal/temporal distribution of salt in the Biostratigraphy, lithofacies and sequence stratigraphic analysis Atlantic Moroccan basins. as well as flexural basin modeling has been performed for a

The First MAPG International Convention, Conference & Exhibition 31 Marrakech Convention Center, October 28 - 31, 2007 116 km long transect between Im-n-Tanout and north of changes. The size of the deposits gradually decreases Agadir. The basin development can be subdivided into 8 downdip. stages: (1) early rift, late Permian to top Anisian, 259.3-234.4 My; (2) rift climax, Ladinian to top Carnian, 234.4-220.7 My; (3) The fine-grained turbidites are typical for passive margins sag, Norian to top early Pliensbachian, 220.7-191.5 My; (4) and in a few cases fit an active margin. Downdip the grain size early drift, late Pliensbachian to top Tithonian, 191.5-144.2 My, decreases very little and 50-80% of all the fine deposits S1 magnetic anomaly to chronozone M19; (5) mature drift, become transported into the outer fan. In a few cases with Berriasian to top Cenomanian 144.2-93.5 My, M19 to intra- active margins the grain size is just fine-grained. Normally C34; (6) mature drift with initial Atlasian deformation, 93.5-34.7 deposition becomes important at the base-of-slope. Active My, Turonian to late Eocene, intra-C34 to C13; (7) Atlasian margins may have their deposition start around the shelf- deformation, 34.7-19.0 My, late Eocene to early Miocene, C13 break. to C6; (8) Atlasian uplift and basin inversion; 19.0-0.0, Early Because of the fine grain-sizes and high silica percentages Miocene to recent, post-C6. Changes in thermo-tectonic a seismic approach can not provide all the details of passive subsidence in the Agadir Basin correlate with major plate- margin deposits. It is necessary to also make serious use of tectonic reconfigurations in the Central and North Atlantic depositional characteristics. domain: (1) major shifts of the sea-floor spreading axis; (2) major changes in sea-floor spreading halfrates; (3) the Lithostratigraphy and provenance of the syn-orogenic stepwise migration of crustal extension and sea-floor terrigenous deposits of the El Haouz “Dorsale Calcaire” spreading to the North Atlantic and; (4) relative motions of the African and Eurasian plates since the Turonian. Two different (Northern Internal Rif, Morocco): a review of its tectono- long-term, large-scale stress fields and plate-force sedimentary evolution. mechanisms controlled the Pliensbachian to recent Hlila R 1, Zaghloul M.N. 2, Sanz de Galdeano C.3, Puglisi D.4, development of the Agadir Basin. In the early 1- Département de géologie, Faculté des Sciences, Tétouan. Pliensbachian/middle Toarcian (193.1/186.5 My) to [email protected] Cenomanian (93.5, intra-C34) ridge-push intra-plate forces 2- Département de Géologie, Faculté des sciences et varied because of shifts in the sea-floor spreading axis and techniques, changes in sea-floor spreading halfrates in the Central Atlantic. Tanger. [email protected] Variations in ridge-push intra-plate forces modulated the 3- Instituto Andaluz de Ciencias de la tierra, Facultad de overall extensional stress fields and thermo-tectonic Ciencias, universidad de Granada. subsidence rates on the northwest African continental margin. 4- Dipartimento di Scienze Geologiche, University of Catania In Turonian to late Eocene and recent times ridge-push forces (Italy) were transmitted by strike-slip and thrusting along the New lithologic and petrographic data are carried out from convergent African-Eurasian plate boundary. syn-orogenic terrigenous deposits of the Internal and External GS 01: Provenance and sedimentary features of Haouz “Dorsale Calcaire” in ordere to detect provenance and to reconstruct their tectono-sedimentary evolution. turbiditic sedimentation within Tertiary basins of centrooccidental Alpine Mediterranean belts. Within the Haouz “Dorsale Calcaire” (HDC)° Eocene- Chair: M. N. Zaghloul, V. Perrone Oligocene pelagic and hemipelagic successions are followed by important syn-orogenic terrigenous deposits. Their facies Source-to-sink, difference between Coarse-Grained And show abundant amount of basement detritus and some wood- Fine-Grained Turbidites debris bearing and also carbonate fraction issued from A. H. Bouma Ghomarides nappes, their Jurassic-Tertiary cover and from the HDC itself. No two turbidite deposits are completely the same. We can divide the deposits in several ways, which result in too The arenites of some syn-orogenic terrigenous sections of many names that causes confusion because each person the internal HDC probably of Upper Oligocene?, are almost defines the characteristics somewhat different. Therefore a completely represented by carbonate lithic fragments. simple main system is better, while secondary names can then Whereas those of External HDC of Early Miocene show a low be added. textural maturity with abundant siliciclastic matrix very frequent lithic fragment, mainly represented by epimetamorphites and Coarse-grained turbidites are typical for active margins. abundant quartz Those are characterized by a high-to-low medium percentage of gravel and variable amounts of the finer components. The The turbiditic sand flow and related sedimentation could front of a mountain is seldom more than 500 km from the reflect a rejuvenation of accused relieves which enhance earth coastline, resulting in little time of significant geochemical and erosion processes mainly and subsequently the

32 sedimentation of these syn-orogenic successions that seem to Petrographic features of Oligocene to Lower Miocene be related to a depositional systems feed by narrow marine volcaniclastic turbidites in the Apenninic Chain (Italy) canyons incising the structured HDC during the structuration of S. Perrotta1, S. Critelli2, A. Di Staso3, M. Mattioli1 & V. the internal Domain and mainly its frontal area into « piggy- Perrone1 back basins » or « mixed-mode piggy back basins » mainly 1 Istituto di Scienze della Terra dell’Università Carlo Bo – during Upper Oligocene-Early Miocene. Campus Scientifico – Località Crocicchia, 61029 – URBINO (Italy) Key words : “Dorsale Calcaire” , provenance, 2 Dipartimento di Scienze della Terra dell’Università della Lithostratigraphy, piggy-back basins, mixed-mode piggy back Calabria – Via P. Bucci, 87020 ARCAVACATA di RENDE (Italy). basins, 3 Dipartimento si Scienze della Terra dell’Università Federico II – Largo San Marcellino 10, 80138 NAPOLI (Italy). Lithostratigraphy and provenance of the syn-orogenic terrigenous deposits of the “Dorsale Calcaire” (s. s.) Turbiditic successions, rich in volcanic clasts and ranging in (Northern Internal Rif, Morocco): tectono-sedimentary age betwwen the early Oligocene and the early Miocene, are evolution and palinspastic reconstruction. widespread in the Apenninic Chain and in the Sicilian M.N., Zaghloul1 & D.Puglisi2, R. Hlila3 Maghrebids. Their deposition was related with an Europe- 1 Département de géologie, Faculté des Sciences, Tétouan dipping subduction and considered contemporary with the 2 Université Abdelmalek Essaadi, Département des Sciences activity of a volcanic arc located on the Sardinia block and on de la Terre, FST - Tanger (Maroc) the building chain docked to it. 3 Dipartimento di Scienze Geologiche, University of Catania In Northern Apennines volcaniclastic successions (Italy) (Petrignacola and Aveto Sandstones) are considered early The “Dorsale Calcaire” s. s. between Tétouan and Jebha Oligocene in age on the basis of paleontological and shows a stratigraphic succession mainly consisting of a geochronological data. However, the occurrence of Triassic-Liassic carbonate platform followed by Middle Jurassic Miogypsina–bearing beds demonstrates they reach the early up to Paleocene-Lower Eocene condensed successions. The Miocene. Tertiary succession usually shows Paleocene-Eocene Petrographic studies evidenced different structural features carbonatoclastic lithofacies evolving to Late Oligocene- in the North-Apenninic and South-Apenninic-Sicilian Burdigalian terrigenous and siliciclastic deposits. formations. These latter are characterized by low sorting and The lithostratigraphy of the Upper Oligocene up to Upper textural immaturity. Volcanic grains show angular shape, Burdigalian syn-orogenic terrigenous and siliciclastic deposits microlithic and lathwork textures, single crystals of subhedral of the “Dorsale Calcaire” s.s., displays a generalized plagioclase and femic minerals, phenocrysts of plagioclase in coarsening-thickening upward trend and laterally, from the cryptocrystalline and vitric groundmass. Vitric particles and Internal to external areas, their petrofacies evolve from ash-turbidites are present. The grains are not affected by calcarenites to litharenites with more than 50% of siliciclastic chemical alteration. All these features testify the rapid erosion detritus and locally also with some granitic pebbles inherited of a still active andesitic-rhyolitic arc. mainly from Ghomaride nappes basement. The tertiary North-Apenninic volcanoclastics include the same typology structuration of the “Dorsale Calcaire” as “piggy-back basins” of grains, but they show higher alteration grade, whereas vitric or “mixed-mode piggy-back basins” occurred since Chattian particles and ash-turbidites are lacking. The arenites show high up to Upper Burdigalian. Since the Upper Burdigalian the sorting and grains characterized by subangular to subrounded whole of the Internal Domain thrusted the Mauritanian foredeep shape, suggesting transport from a distant source-area and and this later start to be involved into thrusted and stacked provenance from a no-active volcanic arc. sheets. The Flysch Basin closure is fossilized by the deposition of transgressive Langhian deposits of the Lower Beni Issef In conclusion, the Apenninic volcaniclastic arenites are “Post-nappes” Formation. characterized by epiclastic detritus, deriving from recycling of pyroclastic deposits and/or lavas in subaerial environments. In Key words : Dorsale Calcaire, syn-orogenic, terrigenous, siliciclastic South-Apennines a pyroclastic supply and petrographic piggy-back basins” or “mixed-mode piggy-back basins features testify a deposition contemporary with the volcanic activity, whereas in North-Apennines detritus originated from lavas and tuffs of an older no-active arc. These data explain the discrepancies between the paleontological and geochronological data in the North-Apenninic deposits.

The First MAPG International Convention, Conference & Exhibition 33 Marrakech Convention Center, October 28 - 31, 2007 The Oligocene calciturbiditic event in the Western First evidence of Upper Oligocene Strata within the Internal Mediterranean Chains Tanger Unit and the Melloussa Unit (Northern External Rif, S. Critelli1, A. Di Staso2, V. Perrone3, S. Perrotta3 & M.N. Morocco) : New scenario for the palaeogeography of the Zaghloul4 Massylian Domain (s.l.). 1 Dipartimento di Scienze della Terra dell’Università della M.N. Zaghloul1, A. Di Staso2, V. Perrone3 and M. Durand Calabria – Via Bucci, 87020 ARCAVACATA di RENDE (Italy) Delga4 2 Dipartimento di Scienze della Terra dell’Università 1 Département des Sciences de la Terre, Université “Federico II” – Largo San Marcellino, 10, 80138 NAPOLI (Italy) Abdelmalek Essaadi FST Tanger (Morocco) 3 Istituto di Scienze della Terra dell’Università “Carlo Bo” – 2 Dipartimento di Scienze della Terra, University Federico II of Campus Scientifico – Località Crocicchia Crocicchia, 61029 – Napoli (Italy) URBINO (Italy) 3 Istituto di Scienze della Terra dell’Università “Carlo Bo” di 4 Département de Sciences de la Terre, Faculté de Sciences et Urbino (Italy) Techniques de l’Université Abdel Malek Essâadi TANGIER 4 Rue Charles- Lefebvre, 77210 Avon (France) (Morocco) Nannoplanckton associations indicating an age not older In the Betic, Maghrebian and Apenninic, units originated by than Chattian have been recognized within metre-thick the early Miocene deformation of a remnant oceanic area yellowish marls belonging to the Massylian successions of the (Mauretanian, Sicilide, North-Calabrian, Calvana and Canetolo Melloussa nappe in the Beni Harchan area. Lithologically Nappes) are known. This oceanic area represented a branch of similar Upper Oligocene strata have been also evidenced in the the Tethys, separated from the Piedmontese-Ligurian- Internal (“oriental”) Tanger Unit, south of Tétouan, in a section Nevadofilabride Ocean by a Mesomediterranean starting with grey calcareous beds, alternating with marls, microcontinent. followed by metre-thick marly key-beds, associated with Carbonate turbidite formations, up to 700 m thick, micaceous centimetre- to decimetre-thick arenaceous beds. consisting of whitish calcilutites, calcisiltites and minor The occurrence of Upper Oligocene strata within both bioclastic calcarenites, or of greyish calcarenites with abundant Internal Tanger Unit and Melloussa Unit, within very similar siliciclastic content, characterize the units originated from the lithofacies, suggest these units were narrowly deposited, oceanic area. probably within a same Massylian Domain. Consequently, the All these calciturbiditic formations resulted Oligocene in Internal Tanger Unit formerly considered as belonging to the age. Bioclasts, consisting of macroforaminifers, calcareous External Intrarifian sub-Domain, very likely have to be assigned algae, echinoids, crinoids and rare bivalves, represent typical to the Massylian Domain. Whereas, External Tanger Unit (or Heterozoan associations, indicating cool water environment Tanger Unit s.s.), as well as the Ketama and Loukkous Units with a mean temperature of 15-18 °C. are assigned to the External Intrarifian sub-Domain.

Age and features of the turbiditic formations can be Key words: Internal Tanger Unit, Masslyan Domain, Intrarifian Domain, interprerted admitting the existence of open non-tropical Meloussa-chouamat nappe. shelves, in which Upper Cretaceous-Eocene not yet diagenised mud, silt, sand and bioclasts, were re-mobilized and re-sedimented in the contiguous deep basins, as a consequence of the Oligocene strong sea-level fall. In some areas, the erosion affected deeply the sediments and reached the pre-Alpine basement, producing abundant phyllitic and extrabasinal carbonatic grains. So, both the lack of Eocene- Oligocene sediments in many carbonate platforms and the abundance in contiguous basins of Oligocene turbidites, made up mainly of Cretaceous-Eocenic sediments and fossils, may be explained.

The occurrence of these deposits in orogenic sectors in which carbonate platform lack, as the Northern Apennines, and the presence of Middle Jurassic-Lower Cretaceous neritic clasts of unknown provenance in all these formations, as well as in the overlying foredeep and up-thrust deposits, make necessary to locate on the southern and eastern margin of the Mesomediterranean microcontinent a probably continuous belt of carbonate platforms.

34 GS 03: “Stratigraphie séquentielle”, carrefour de Cobiella, J. and Olóriz, F., 2007. Oxfordian?Berriasian stratigraphy of nos connaissances des séries alpines de plateforme, the North American paleomargin in western Cuba. Correlation with pente et de bassin central and eastern Cuba and eastern Gulf of Mexico sections. Chair: K. El Kadiri, F. Oloriz Constraints for the Proto-Caribbean and Gulf of Mexico early geological history. AAPG Bulletin [in litt.] Key words: Biostratigraphy, Eco-sedimentary conditions, Relative Sea- Tectono-eustatic sequence interpretation — a key for level, Upper Jurassic, lowermost Cretaceous, Paleogeography, interpreting mid-to-major palaeoenvironmental changes in Mexico, Cuba, Gulf area the Mexico-Caribbean Area during the Late Jurassic and Earliest Cretaceous Architecture and dynamics of a Maghrebian carbonate Olóriz, Federico1, Cobiella, Jorge2, Villaseñor and Ana Bertha3 platform-basin transition around the Triassic/Jurassic 1 Dept. Estratigrafía y Paleontología, Facultad de Ciencias, Boundary: Sciacca zone, Sicily. Universidad de Granada. Campus Fuentenueva, 18071, Di Stefano, P., Cacciatore, M.S., Zarcone, G. Spain. Università di Palermo, Dipartimento di Geologia e Geodesia, 2 Dept. Geología, Universidad de Pinar del Rio, Cuba Via Archirafi, 22 - 90123 Palermo 3 Dept. Paleontología, Inst. Geología, UNAM, CU- 04510, Facies architecture and the evolution of a carbonate México, DF. platform-basin hinge zone through the Triassic-Jurassic boundary interval, are reconstructed in the Sciacca area Jurassic and Cretaceous rocks in the Mexico-Caribbean (Central-Southern Sicily). area have been reported since the 19th Century. Significant progress was made during the second half of the 20th Century. During Norian-Rhaetian times the carbonate platform was Updating stratigraphy with identification of major geological bounded by a Dachstein-type barrier reef. Prograding oolitic- skeletal margins replaced the Triassic reefs during lowermost events recorded in Upper Jurassic to lowermost Cretaceous Jurassic, owing to the drastic biotic crisis coupled to sea-level sections has been recently revisited (Olóriz et al., 2003; fall and tectonic perturbations. Cobiella & Olóriz in litt.; and references therein). Base-of-slope facies consisting of carbonate debris-flow Major-to-mid, geodynamically forced, episodes of and turbidites were emplaced into the adjacent basin since late paleoenvironmental change can be selected for recognition of Rhaetian time. Clastics were provided by tectonically- controlled reef-margin collapses, and by oolitic-skeletal grains Tectono-Eustatic Sequences (TES). In the Mexico-Caribbean that were produced in the adjacent carbonate platform. area and around the Gulf of Mexico Basin, TES interpretation provides insights for interpreting relevant phases of the Pliensbachian drowning of the platform and the switching geological history during the Late Jurassic and the earliest to pelagic carbonate productivity were coupled to tectonic reactivations of the hinge zone, as documented by large Cretaceous. Higher variability in 3rd-TES versus comparative bodies of “in situ” breccias, with a Jurassic pelagic matrix, persistence in 2nd-TES across the studied area accords with large polyphase neptunian dykes and widespread submarine the expected stratigraphical hierarchy, and shows differential magmatism. The conversion of the neritic carbonate platform records of environmental changes in response to geodynamic to the pelagic platform gave rise to the cessation of the clastic forcing. Regional differences increased from the latest input into the adjacent basin. Oxfordian-to-earliest Kimmeridgian to the Early-Middle At present, the carbonate platform-basin transition is Berriasian. imbricated in the external zone of the Maghrebian chain, and its NNW-SSE orientation is nearly orthogonal to the direction of On this basis and in terms of 3rd-TES (>1 to 8Ma) and 2nd- the Neogene thrust propagation. The observed structural TES (>10 to <20Ma), the present contribution provides the first relationships indicate that this paleotectonic alignment has interpretation of both the so-called “Upper Jurassic played as major right lateral escape during the Maghrebian Supercycle” in northern Mexico and the northern Gulf Rim, and mountain building. Its orientation is parallel to the Malta escarpment and to the margins of the Triassic/Jurassic the “Carbonate Cycle” southwards in the north American Streppenosa basin, in the subsurface of the Ragusa plateau. palaeomargin involving Cuban sections and palaeogreographically related areas. In addition, the correlation The platform-basin transition can be considered as a potential of interpreted TES is evaluated across the Mexico- segment of the rifted Southern margin of the Permo-Triassic Ionian basin. Caribbean and Gulf areas, as well as with respect to the distant western Tethys. Keywords: Triassic, Jurassic, carbonate platform, reef, paleotectonics, Sicily. References Olóriz, F., Villaseñor, A.B. and González-Arreola, C., 2003. Major lithostratigraphic units in land-outcrops of north-central mexico and the subsurface along the northern rim of Gulf of Mexico Basin (Upper Jurassic-lowermost Cretaceous): a proposal for correlation of tectono- eustatic sequences. J South Amer. Earth Sci. 16, 3, 119-142.

The First MAPG International Convention, Conference & Exhibition 35 Marrakech Convention Center, October 28 - 31, 2007 Jurassic radiolarite pulses from the Dorsale Calcaire Sequence strartigraphy of the Neogene sedimentary basin of (Internal Rif Belt, Northern Morocco) : Lithostratigraphic and Boudinar (Easternal Rif, Morocco). biostratigraphic review Azdimousa Ali1, Rezqi Halima1, Bourgois Jacques2, Asebriy Khalil El Kadiri1; Mark Horstemeyer2, Federico Oloriz-Saez3 ; Lahcen3, and Poupeau Gérard4 Haitham El Kadiri2, Liemlahi Hoda1 and Ahmed Chalouan4 1Faculté des Sciences, Département de Géologie, 60000 1 Univ. Abdelm.Essaadi, Fac. Sciences, Geology Department, Oujda Cedex, Maroc BP. 2121, 93003 Tetouan (Morocco) 2 Université Pierre-et-Marie Curie, Boîte 119, 4, place Jussieu, 2 Mississippi State University, CAVS, Box 5405 Mississippi 75252 Paris Cedx, France. State, MS 39762-5405, United 3 Université Mohamed.V, Institut Scientifique, BP 114, Agdal, states of America, Rabat, Maroc. 3 Univ. Granada, Fac Ciencias, Dep. Estratigrafia & 4 Université Mortaigne, Bordeaux I, France. Paleontologia, Granada (Spain). The sequential stratigraphy in the Neogene sedimentary 4 Univ. Mohammed V, Sciences Faculty, Geology Department, basin of Boudinar, supplemented by micopaleontologic Agdal, 10000 Rabat, determinations and radiochronological datings, made it A consistent stratigraphic synthesis of radiolaritic sections possible to explain the disturbances in the eustatic evolution separately outcropping in distinct units of the Dorsale Calcaire and to better include the geodynamic history of the basin. This and the J. Moussa Groups has been obtained. In the studied study allowed us: 1/ to solve the problems of age and lateral sections, the stratigraphic context has been highlighted on the correlations of the sequences and sedimentary unconformities; basis of: i) biochronological control constrained by ammonites 2/ to propose ages for series up to now poorly dated; 3/ to and other biochronological markers; and ii) tacking into decipher the architecture of the various sedimentary bodies; 4/ account sedimentary unconformities that commonly occur in to determine the respective part of the effects related to both the underlying and overlying strata, as well as within eustatism and tectonics in the local evolution of the sea level; radiolaritic sections. The main results are: i) the precise 5/ to characterize the importance of the sedimentary evidence about the significance of “radiolarite diachronism” contribution and the variations of the eustatic sea level that orderly occurred from the palaeogeographically outermost recorded settings (Predorsalian units) northwards to innermost margin segments and; ii) to interpret this diachronism in the context of a tectono-eustasy forcing radiolaritic sedimentation to occur in The sedimentary history of the Boudinar basin does not discontinuous episodes separated by stratigraphical gaps. The present evaporitic levels related to the messinian salinity crisis. latter proved to be causally linked to paleoenvironmental stress In Boudinar, the shore of the sea of this time was to be too responsible for the main biotic turnovers affecting radiolarian much low to allow such sedimentation in the basin. The great communities and ecosistems. power of the regressive messinian terms seems to be related to an important detrital contribution and a tectonic subsidence. On the whole, seven radiolarite pulses showing both The emergence of the basin of Boudinar at the end of lithological and biostratigraphical significance were identified in Messinian is associated the retreat of the marine level and the middle – upper Jurassic section. The main evolutionary renewals of activity tectonic and volcanic. In the area broken turnovers could have occurred during the time span, and down in the North-West of the basin, the pliocene stratigraphical gap, separating two given radiolarite pulses, sedimentation developed which shows a return to conditions rather than ramdomly during the life-duration of radiolarian of open sea and a continuity of messinian sedimentation. The multispecies assemblies and their corresponding depositional absence of the marine sedimentation of upper Pliocene in the history. Our approach is consistent with the Biosequence / Boudinar basin is caused by a tectonic emergence in Golden-Hooks concepts, and most probably represents a compression which is continues until the current one. complementary approach to the “unitary-association–based biostratigraphy proposed by the Eurorad’s Working Group. Key words: sequence stratygraphy, geodynamic, Neogene, Boudinar, Morocco In addition, this approach is expected to provide a clue for both correlation of coeval radiolarite sections throughout the Alpine realm, and application of sequence stratigraphy to cherty-pelagic successions throughout the Jurassic in the same area.

Key words: Dorsale calcaire, Rif, Jurassic, Radiolarites, Biosequences

36 Evolution of sedimentary systems tracts in the Tarfaya Basin GS 15: Stratigraphy, environments, climates, and (Moroccan Atlantic Margin) from the Lower Cretaceous to the petroleum systems of the Triassic and Earliest Present: Interaction of structural evolution, climate and Jurassic of the subtropics Pangea Chair: P. E. Olsen eustasy L. El Jorfi1, M.P. Süss 1, T. Aigner 1, N. Mhammdi 2 and El Mourabet 3 High-resolution Transect from the Tropics to the Temperate 1 Department of Geosciences, University of Tübingen, zone in Triassic Pangea Sigwartstr. 10, Tübingen, Germany Paul E. Olsen1, Dennis V. Kent1,2, Mohammed Et Touhami3 2 Scientific Institute, BP 703, Av. Ibn Batouta, Rabat, and Peter M. LeTourneau1 Morocco 1 Lamont-Doherty Earth Observatory, Palisades, NY 10964, 3 ONHYM, Avenue Al Fadila 10050, Rabat, Morocco USA, 2 Department of Geological Sciences, Rutgers University, 2D marine seismic reflections data from the Tarfaya Atlantic Piscataway, NJ 08554, USA, margin of southern Morocco, interpreted in the light of well logs 3 LGVBS, Département des Sciences de la Terre, Université data, allowed us to define a structural and stratigraphic Mohamed Premier, 60,000 Oujda, Morocco framework of the Tarfaya basin from the Lower Cretaceous to the Present and to quantify the interplay between the Cyclostratigraphic and magnetostratigraphic correlation of developing structure, sedimentary systems and the resulting rift basin strata allow correlation of individual ~20 ky lacustrine sequence stratigraphic architecture. cycles across 36° of paleolatitude (pl) from the tropics through the subtropics and into the temperate latitudes. Using the In the first step of this study, the stratigraphic framework of Newark Basin Astronomically Calibrated Geomagnetic Time the area was established by the application of a general Scale (NBAGPTS) as a standard, we have examined an interval seismo- and tectonostratigraphic analysis. We define four main corresponding with polarity chrons E17n to E18n spanning ~2 tectonostratigraphic stages: the prerift (Precambrian- m.y., correlative with the Sevetian Substage of the Norian Palaeozoic) corresponds to Hercynian deformation, the synrift Stage of the Late Triassic, in the Culpeper basin (14° N pl, (Late Triassic-Early Jurassic) characterized by half graben Virginia, USA), the Newark basin (15° N pl, New Jersey, USA), structures which are bounded by NE-SW striking listric normal the Argana basin (19° pl, Morocco), the Fundy basin (20° pl, faults and filled with continentally derived shales and Nova Scotia, Canada), the Bristol Channel basin (27° pl, sandstone, the post rift (Upper Jurassic-Upper Cretaceous) Somerset, Great Britian), and the Jamesonland basin (41° pl, marked by the installation of the carbonate platform of the Jamesonland, Greenland). From south to north, facies change Upper Jurassic which underwent variable subsidence. With are: 1) alternating deepwater perennial lake and non-evaporite- erosional base level lowered, thick sequence of continental to bearing playa sequences (Culpeper); 2) deepwater perennial marine-deltaic clastic sediments was deposited at the Early lake and evaporite-bearing playa (Newark); 3) shallow perennial Cretaceous period. The Middle and Upper Cretaceous marked lake and efflorescent salt crust playa (Argana and Fundy); 4) by a general transgression of eustatic origin and the inversion very shallow perennial lake and non-evaporite-bearing playa of the Tertiary expressed by tectonic instability that is linked to (Bristol Channel); and 5) shallow carbonate perennial lake and the evolution of the Atlas and Rif belts and interferes with non-evaporite-bearing playa (Jamesonland). These facies glacio-eustaticy starting in the Oligocene with the Antarctic and transitions correspond to humid to semiarid, semiarid to arid, Arctic glaciations. temperate to semiarid, humid temperate to semiarid climates. This high-resolution template, within its larget spatio-temporal context, allows us to distinguish between paleogeographic changes through zonal climate belts, from true climate change.

Sedimentary Processes and Deposits of Saline Lakes, Saline Pans, and Playas in Early Mesozoic Rocks of Subtropical Pangea Joseph P. Smoot U.S. Geological Survey, M.S. 926A, National Center, Reston, VA 20192 U.S.A.,

The early Mesozoic sedimentary rocks of the Pangean rift basins in Morocco and eastern North America accumulated in continental settings for over 35 million years. During this extended time span, many of the basins experienced periods

The First MAPG International Convention, Conference & Exhibition 37 Marrakech Convention Center, October 28 - 31, 2007 of aridity resulting in the formation of saline or desert facies. crystals randomly distributed in mudstone with upward- Comparisons of fabrics in the early Mesozoic rocks to modern coarsening successions; 2) Saline Pans, flat-beds of evaporite environments provide the building blocks to reconstruct the crystals with long axes vertically or radially oriented to geometry of basin facies and predict the distribution of mudstone or carbonate bedding planes, crystal terminations lithologies in the subsurface. By understanding the processes are planed off and vertical solution voids are common, that produce assemblages of sedimentary fabrics, we can randomly distributed euhedral crystals in partings between reconstruct the distribution of environments that may have no crystal layers show no size distribution; 3) Saline mudflats, direct analog in the modern world. mudstones or carbonates contain randomly distributed euhedral crystals that may produce upward-fining sequences Four major lacustrine desert facies are found in the early to more anhedral crystals that are restricted to cracks or Mesozoic of the study area: Perennial saline lakes, saline pans, lenses, massive mudstones with irregular patches of silt or saline mudflats, and dry playa mudflats. Perennial saline lakes sand, massive mudstones comprised of poorly sorted rounded may accumulate hundreds of meters of sediment without mud intraclasts that fill crack patterns or surround angular reaching supersaturation with evaporite minerals. The controls mudstone fragments; 4) Dry mudflat, massive mudstone with on include the chemistry of the inflow waters, the depth of the abundant ovate to flattened cement-filled voids (vesicles) and lake, and the residence time of water within the basin. irregular sinuous to jagged cracks which may be partially filled Evaporite mineral precipitation includes cumulus crystals with cement, laminated to thin-bedded mudstone with formed at the water-air interface, crusts formed at the abundant mudstone-filled cracks that are filled with vesicles - sediment-water interface, and intrasediment crystals formed evaporite soils may form in areas with fresh groundwater if the from brines sinking into the sediments. Crystals formed in upper areas are dry enough – and plants may grow at the perennial lakes are often reworked by waves or turbidites, surface while rain reworks solutes downward to produce an particularly in shallow lakes. Saline pans are ephemeral lakes upward-coarsening crystal profile. in which evaporite crusts develop during wet stages that are disrupted by efflorescent crusts during dry stages and partially Outcrops of the Argana basin in Morocco and the Fundy dissolved during intermittent transgressions. The evaporite basin in Nova Scotia show abundant evidence of saline chemistry is controlled by the dissolution of efflorescent crusts mudflats that were covered with halite efflorescent crusts. in a process called chemical focusing. Sinking brines form Subsurface equivalents probably contain perennial saline lake intrasediment crystals beneath the surface. Saline mudflats deposits of mixed halite and gypsum and saline pan deposits are subaerial plains with groundwater brines near the sediment dominated by halite. The Newark basin in the eastern U.S. surface. Evaporation of pore water causes minerals to form contains a variety of deposits including perennial saline lakes within the sediment. In general, the largest crystals form in the with calcite pseudomorphs after possible sodium carbonates, wettest areas and smaller crystals form in areas that are only saline mudflats with upward-fining crystal sequences and intermittently wet. Efflorescent crusts form at the sediment-air fabrics indicating powdery efflorescent salt crusts. There is no interface by the complete evaporation of pore water. Salt evidence of saline pan deposits equivalent to these deposits. crystals and brine spray may be blown into areas with deeper Dry playa mudflats dominated by vesicular fabrics produce groundwater tables, even in different basins. In these continuous beds in the central basin indicating conditions with situations, the solutes may be cycled downward into the deep groundwater tables. Root-disrupted mudstones with sediment by rainfall then concentrated by evaporation into gypsum soil features indicate wetter conditions that support intrasediment evaporites or efflorescent salt crusts. Dry surface vegetation but dry enough for windblown solutes to be mudflats are areas with deep groundwater tables. Saline preserved in the upper soil profile. minerals only form if they are introduced by the wind. Sedimentation by sheetflooding or ponding is punctuated by Sediment Distribution of Upper Triassic Reservoirs in SW prolonged periods of desiccation. A complex array of cross- Morocco: Evidence for Inter-Rift-Basin Connection Between cutting mudcracks act as sediment traps and air-filled vesicles the Argana Sub-basin and the Central Essaouira Basin commonly develop during flooding stages. Nadine K. Mader1,2, Jonathan Redfern1, El Ouataoui Sedimentary features produced in these different settings Abedelmajid3 include: 1) Perennial Saline Lakes, laminated to thin-bedded 1 North Africa Research Group, School of Earth, Atmospheric mudstones with laminae consisting of fine evaporite crystals or and Environmental Sciences, University of Manchester, beds of crystals with mudstone or carbonate partings, crystal Williamson Building, Oxford Road, Manchester, M13 9 PL, UK, beds in which crystals are subhedral to rounded and 2 current Address: Hess Ltd, Level 9. The Adelphi Building, 1- distributed into lenticular beds or graded beds, crystals with 11 John Adam Street, London WC2N 6AG, UK long axes vertically or radially oriented to the bedding plane 3 ONAREP 34, Avenue Al Fadila, 10050, Rabat, Morocco and crystal terminations preserved, irregular bedding Determining sediment provenance and facies distribution thicknesses with angular boundaries and projections, euhedral of major fluvial systems is a key element in understanding the

38 Triassic petroleum systems of SW Morocco. This study subsequent Alpine orogeny. The palaeolatitude of these basins examined Upper Triassic continental deposits in core from the in earliest Jurassic coordinates was centered in arid climes central Essaouira Basin and extensive outcrop from the Argana around 23°N. These basins have facies broadly similar to the Sub-Basin, both sub-basins of the large Agadir-Essaouira Fundy basin (Nova Scotia, Canada) but also show some Basin, in order to develop a model to predict reservoir similarities to the Triassic age sequences of the Newark basin distribution. (New Jersey, USA).

The Upper Triassic reservoirs in the Meskala Field within the In the Central and Western High Atlas stratigraphic central Essaouira Basin display distal end-member facies of a sections are divided into four tectonostratigraphic sequences fluvial system feeding the basin, previously thought to have (TSI – TS IV) that are at least locally separated by synrift been derived mainly from the Argana Basin to the SW. unconformities corresponding to presumed extensional pulses. However, the time equivalent sandstone deposits in the Argana Elsewhere in Morocco, maybe with the exception of the Basin (Tadrart Ouadou Sandstone Member T6) display Essaouira basin, the basins appear to consist nearly entirely of palaeocurrents that indicate transport to the SW/S. This TS III and TSIV. suggests that during the Upper Triassic, the southern part of the Argana Sub-Basin acted as the main depocentre for fluvial The oldest tectonostratigraphic sequence (TSI) (F1-F2 of sandstones derived from the Massif Ancien to the E/NE. Facies Biron, 1982; T1-T2 of Tixeront, 1973), Permian in age analysis suggests fluvial transport was directed into the (Tatarian?), comprises alluvial fan conglomerates that grade neighbouring Souss Basin to the SW/S. into fluvial sandstones and mudstones.

With the westward shift of active rifting of the central TSII (F3-F4 of Biron, 1982; T3-T5 of Tixeront, 1973), Atlantic margin, these basins are interpreted to have acted as Ladinian?-Carnian in age, overlies TSI unconformably in both fill- and spill type basins, where sediment was stored and Central and Western High Atlas. It consists of fluvial and recycled before being eventually transported N along the lacustrine clastic rocks with an especially well developed evolving rift. The results of this study have significant cyclical lacustrine sequence in the Argana basin. implications for facies distribution in the central Essaouira In the Central and Western High Atlas, an angular Basin, and suggest that the T6 fluvial sandstones exposed in unconformity at least locally separates TSII and TSIII (F5-F6 of the Argana Valley are not the direct, proximal sediment source Biron, 1982; T6-T8 of Tixeront, 1973). In the other basins, TSIII for the time-equivalent reservoir sandstones in central (séries argileuse et salifère inférieures of BRPM, 1955) rest Essaouira. Instead of direct SE to NW fluvial flow from the unconformably on the Paleozoic basement. It is Norian?- Argana Sub-Basin into the Essaouira Basin to supply the fine- Rheatian in age and consists in its basal unit of fluvial grained reservoir sandstones, a more complex transport conglomerate and sandstone and prominent eolian system feeding the central Essaouira Basin from the South is sandstones. The latter grade vertically into massive gypsiferous proposed. mudstones and sandstones arranged into distinctive sand patch cycles overlain conformably by CAMP flows. The Tectonostratigraphy, Biostratigraphy, and uppermost few meters of the pre-basalt sediments has a well Magnetostratigraphy of Late Triassic-Early Jurassic Red developed cyclicity with very thin black and gray shales. This beds in Morocco: An Overview. sequence, present throughout Morocco, contains, at least in Mohammed Et-Touhami1, Paul E. Olsen2, Dennis V. Kent2,3, the Argana basin, the Triassic-Jurassic boundary based on and Sarah J. Fowell4, Jessica H. Whiteside5 palynology. It represents the lower part of succeeding 1LGVBS, Département des Sciences de la Terre, Université tectonostratigraphic sequence TSIV, although there is no Mohamed Premier, 60,000 Oujda, Morocco, known physical evidence for an unconformity in the exposed 2 Lamont-Doherty Earth Observatory, Palisades, NY 10964, strata. USA The Central High Atlas outcrops show the thickest CAMP 3 Department of Geological Sciences, Rutgers University, sequence in all of Morocco that comprises four multiple flow Piscataway, NJ 08554, USA formations, which termed from the bottom up, the lower unit, 4 Geology and Geophysics, University of Alaska Fairbanks, the intermediate unit, the upper unit, and the recurrent flow Fairbanks, AK 99775, USA (Bertrand, 1991). The later is of high-Fe high-Ti quartz- 5 Department of Geological Sciences, Brown University, 324 normative composition (HFTQ) as are the Hook Mountain and Brook Street, Box 1846, Providence RI 02912, USA Hampden basalts (Newark basin and Hartford basins Late Triassic–Early Jurassic predominately continental red respectively). The other units are high-Ti quartz-normative beds formed during the Triassic/Jurassic rifting of Pangea crop tholeiites (HTQ) as are the Mt. Zion Church, Aspers, Orange out over large portions of northern Morocco, comprising Mountain, Talcott, East Hill, and North Mountain basalts several sedimentary basins now partly dismembered by the (Culpeper, Gettysburg, Newark, Pomeraug, Hartford, and

The First MAPG International Convention, Conference & Exhibition 39 Marrakech Convention Center, October 28 - 31, 2007 Fundy basins, respectively). The 40Ar/39Ar ages of the High Tixeront, M., 1973. Lithostratigraphie et mineralisations cupriferes et Atlas basalt flows are indistinguishable from their North uraniferes stratiformes syngenetiques et familieres des formations American counterparts (Marzoli et al., 2004), although no high- detritiques permo-triasiques du couloir d’Argana, Haut Atlas occidental (Maroc). Notes Serv. Geol. Maroc Tome 33, Notes Mem. Fe quartz-normative (HFQ) or low-Ti quartz-normative (LTQ) Serv. Geol., vol. 249, pp. 147–177. flows, present in the Newark basin, have been identified in the Central High Atlas. In the other Moroccan basins, there are Central Atlasic and Western Atlasic/Atlantic Permian to Early only one or two basaltic units of HTQ composition. Throughout, the basaltic units are interbedded or overlain by Liassic Rifts and their Tertiary Inversion limestone-rich cyclical sequences. These preserve a gradient El Hassane El Arabi1 and Mohamad Hafid2 from fully continental facies in western Morocco, comparable 1 Département de géologie, Faculté des sciences, B.P5366- to those in the Fundy basin outcrops, to fully marine facies with Maarif, Université Hassan II-Aïn-Chock, Casablanca, Morocco, newly discovered well-preserved echinoderms in easternmost 2 Laboratoire de géophysique et d’environnement, Morocco, thereby documenting a marine connection from département de géologie, faculté des sciences, BP 133, western-most Tethyan basins during at least part of the rift Université Ibn Tofaïl, Kénitra, Morocco sequence. The carbonate-dominated thin units are succeeded Field and subsurface data were used to compare Permian- by predominately red clastic rocks which are unconformably early Liassic extentional systems and their Tertiary inversion in overlain by post-rift Early Jurassic conglomerates and marine the Central High Atlas and the Essaouira-Agadir segment of strata. Atlantic margin where the Atlas fold belt intersects the passive In the subsurface of several Moroccan basins, the cyclical margin. red beds of TSIII and TSIV give way to thick salt sequences Structural and lithostratigraphic analysis show that Upper (série salifère inférieure et série salifère supérieure of BRPM, Permian to Infra-Liassic red bed formations that extensively 1955), with an order of magnitude higher accumulation rates. crop out along the Telouet traverse in the Central High Atlas In these settings the Triassic-Jurassic boundary is entirely can be subdivided into five unconformity-bounded within bedded halite and potash salts (e.g. Khémisset basin). tectonostratigraphic sequences each of which is characterized The paleomagnetic polarity stratigraphy of outcropping by its own lithologic and biostrtigraphic signature. The aerial Bigoudine Formation in the Argana basin (TSIII and lower TSIV) distribution of these stratigraphic units suggests an upper allows correlation with the Newark GPTS. This correlation: (1) Permian to Sinemurian S-SE migration of subsiding areas and, indicates that the deposition of the Bigoudine began at about thus, of the High Atlas rift axis. They resulted from an 218 Ma and ended at about 201 Ma, with the conformable essentially distensive tectonic regime under which the Central outpouring of the Argana Basalt and (2) demonstrate that the High Atlas trough opened as a dissymmetric complex basin major cyclical wet climatic intervals in the Newark basin bounded by EW to ENE-WSW oriented major faults. sequence can be recognized in the Argana basin and therefore In the Western High Atlas and its adjacent Atlantic margin the synchrony of major climate changes caused by the very segment seismic data indicates that the Triassic-early Liassic long term celestial mechanical cycles of a very large part of time is characterized by NE to SW half-grabens linked by EW central Pangea. The polarity stratigraphy also affords tight striking transfer faults and overlain by a wide considerably less correlation to the Newark basin extending to individual 20 ky faulted, salt-rich sag basin with extensive basalt flows. Here cycles, especially in the lower half of the Bigoudine Formation. also the red bed formations that filled these structures consist Bertrand, H., 1991. The Mesozoic tholeiitic province of Northwest of at least four tectonostratigraphic sequences that can be Africa; a volcanotectonic record of the early opening of Central Atlantic. correlated with similar stratigraphic units defined by previous In: Kampunzu, A.B., Lubala, T. (Eds.), Magmatism in Extensional work in the Argana outcrops. Seismic data also suggests that Structural Settings; The Phanerozoic African Plate. Springer-Verlag, the distension has migration from East to West and that the Berlin, pp. 147–188. sag basin which forms the transition from the rifting to the Biron, P. E., 1982. Le Permo-Trias de la region de l’Ourika (Haut Atlas drifting phase is sealed by a seismically conspicuous de Marrakech, Maroc). Lithostratigraphie, sédimentologie, tectonique unconformity of pre-Carixian/Domerian age, commonly et minéralisation. Thèse de 3ème cycle, Université de Grenoble, considered as the Break-up unconformity. The sag sequences France, 170 p. pinchout eastward and northeastward against the pre- Jurassic. This pinchout coincides with the west flank of the BRPM, 1955. Bassin salifère de Khémisset, rapport de fin de sondage West Moroccan Arch (“dorsale du massif Hercynien central” of Potasse Khémisset-Bataille 1 (PKB1). rapport inédit. 15 p. Marzoli, A., Bertrand, H., Knight, K.B., Cirilli, S., Buratti, N., Vérati, C., Du Dresnay) that separates the Tethys domain from the Atlantic Nomade, S., Renne, P.R., Youbi, N., Martini, R., Allenbach, K., domain. The Proterozoic–Paleozoic block of the High Atlas Neuwerth, R., Rapaille, C., Zaninetti, L., Bellieni, G., 2004. Synchrony (Massif Ancient) lies at the southern end of this West Moroccan of the Central Atlantic magmatic province and the Triassic–Jurassic Arch. Our Stratigraphic and structural data from the Triassic boundary climatic and biotic crisis. Geology 32, 973–976. sedimentary basins of the High Atlas of Marrakech, in particular

40 of the Eççour basin, indicates that this ancient block formed a present: (i) a thin (0.2 - 0.4 m) basal lava crust, less vesicular, paleogeographic high during this period, with the basement sometimes with pipe vesicles; (ii) a dense lava core, block acting as an east–west trending horst, separating two corresponding to 40 to 60 % of the flow thickness (< 20 m), large half-grabens to the north and to the south. The marginal with vesicle cylinders and platy joints at the base and top; and half-grabens, which were filled by red beds essentially of (iii) an upper lava crust, 1 - 13.5 m thick, formed by alternating continental origin, were most likely linked via transverse dense and vesicular levels, that presents tumuli and squeeze pathways. up structures. The lobes are S-type (spongy), vesicular, without pipe vesicles or, more frequently, P-type (pipe) with pipe We have for the first time in Morocco, palynologically vesicles, vesicular base and a less vesicular or dense core. characterized the Middle Triassic (Middle Anisian) in the High Simple flows are 3.5 to 30 m thick. Each flow maintains a Atlas of Marrakech. The stratigraphic, tectonic and constant thickness over considerable distances. The simple paleogeographic implications of this discovery are analysed in flows appear as simple cooling units, without multiple lobes. this presentation and possible correlations with the Atlantic Some flows present flow-top breccia. The compound basins are also discussed. Finally the control of the Tertiary pahoehoe flows of the Lower Formation show excellent and Atlasic compression by pre-existing rifting structures is unambiguous evidence of endogenous growth by inflation, discussed. suggesting slow emplacement during sustained eruptive episodes. The CAMP Basalts in the Argana basin (Western High Atlas, Morocco). Physical Volcanology, Petrology and Geochemistry. The lava flows of the Argana basin display primary H. El Hachimi1, H., Assafar1 , N. Youbi1, A. Marzoli2, H. mineralogy typical of tholeiitic basalts: plagioclase, Bertrand3, J. Madeira4, L. T. Martins5, J.M. Munhá5, J. clinopyroxene, minor olivine (more common in the lowermost Mata5, G. Bellieni2 , C. Vérati6, Kh.M. Bensaleh1, H. Ibouh7 lava flow from the Lower Formation) and Fe-Ti oxides. Strong and M. Ben Abbou8 alteration is represented by chlorite, zeolite, amorphous silica 1 Department of Geology, Faculty of Sciences-Semlalia, Cadi and calcite often found filling vesicles or substituting for the Ayyad University, Prince Moulay Abdellah Boulevard, P.O. Box mesostasis. 2390, Marrakech, Morocco, Tel. +212.44.434649 The basalts from the two formations, yield distinct 2 Dipartimento Di Mineralogia e Petrologia, Università Di geochemical compositions. Their major and trace element Padova, I-35137, Italy concentration and ratios match respectively the composition of 3 Laboratoire des Sciences de la Terre, Ecole Normale the Lower and Intermediate Formation from the central High Supérieure de Lyon et UCBL, 46, Allée d’Italie, 69364 Lyon Atlas (Bertrand et al.,1982; Marzoli et al. 2004). Cedex 07, France 4 LATTEX, Departamento de Geologia, Faculdade de Ciências, Bertrand H., J. Dostal, and C. Dupuy (1982). Geochemistry of Universidade de Lisboa, Portugal. Mesozoic tholeiites from Morocco. Earth and Planetary Science Letters 5 Centro de Geologia, Departamento de Geologia, Faculdade , 58, 225-239. de Ciências, Universidade de Lisboa, Portugal. Marzoli A., Bertrand H. , Knight K., Cirilli S., Verati C. , Nomade S., 6 UMR Géosciences AZUR, Laboratoire de Géochimie – Martini R. , Youbi N. , Allenbach K., Neuwerth R., Buratti N., Rapaille Géochronologie, Université de Nice Sophia Antipolis Parc C., Zaninetti L., Bellieni G., and Renne P. R. (2004) . Synchrony of the Valrose 06108 NICE Cedex 02 France Central Atlantic magmatic province and the Triassic-Jurassic boundary 7 Department of Geology, Faculty of Sciences and Technics- climatic and biotic crisis. Geology, Geological Society of America, Guéliz, Cadi Ayyad University, Marrakech, Morocco. Boulder, November Volume 32, n° 11, pp. 973-976 8 Department of Geology, Faculty of Sciences Dhar Al Mahraz, Sidi Mohammed Ben Abdellah University, Fes, Morocco. 3D Modelling of (Upper Triassic) Continental Mixed Fluvial Systems Integrating Digital Outcrop Images with High- The Argana Basin volcanic pile is the westernmost witness Resolution Sedimentology: High Atlas , Morocco of CAMP (Central Atlantic Magmatic Province) in Morocco. It Ivan Fabuel-Perez, Jonathan Redfern, Dave Hodgetts comprises two volcanologically distinct lava flow fields. The University of Manchester, School of Earth, Atmospheric and lower lava field is a succession of 3 to 13 flows, 60 to 135 m Environmental Sciences, Williamson Building, Oxford Road, thick, while the upper one, composed of 2 to 6 flows, is 60 m M13 9PL Manchester, UK, thick. A sediment layer or a paleosol (0.50-1m) separates the two formations. The lavas are compound pahoehoe flows and The Upper Triassic Oukaimeden Sandstones Formation simple flows. The first type is almost exclusive of the Lower (F5) comprises continental red bed fluvial/aeolian sediments Formation (equivalent to the Lower Formation of the Central deposited within a series of Triassic rift basins in Central High Atlas), while the second type dominates the Upper Morocco. The study area in the High Atlas offers extensive Formation (correlative of the Intermediate Formation of the outcrops, in-excess of 200 m high and extending for many Central High Atlas). Most lava lobes in the compound flows kilometres, in a series of narrow tectonic belts bounded by

The First MAPG International Convention, Conference & Exhibition 41 Marrakech Convention Center, October 28 - 31, 2007 major Tertiary reverse faults with an ENE-WSW orientation. The environments to the West. Some palynological assemblages formation is composed of upward-fining sandstones often found near the base of the Manuel Formation have been dated containing trough cross-bedding and current and oscillation as Early Karnian (Late Triassic), but the age of the basal ripples within stacked lenticular shaped sand bodies conglomerates of this formation is still unknown. interpreted to be channels. These bedforms often display erosional bases with conglomeratic lags containing rounded The deposition of these siliciclastic deposits was controlled pebbles of quartz, chert and felsic volcanics. Interbedded more simultaneously by a syn-sedimentary extensional tectonics, tabular shaped units with planar cross bedding are interpreted expressed in NE-SW normal faults that subdivided the basin in to be large fluvial bars. Varying amounts of interbedded parallel contrasting areas of slow and rapid subsidence, a siltstones and mudstones are also present, with some climatic control expressed in short lived, extensive flood events lamination and occasional bioturbation, interpreted to be followed by long periods of inactivity of the fluvial systems and overbank floodplain and shallow lacustrine deposits. pedogenic processes and an eustatic control, expressed in a LST organization of the sedimentary sequences among two The application of high resolution 3D laser (LIDAR) and major transgressive pulses. Differential Global Positioning System (DGPS) mapping to these outcrops, combined with collection of traditional This siliciclastic unit can be traced from the Spanish sedimentological data (sedimentary facies logs, palaeocurrent Mediterranean Coastline to southern Portugal (Grès de Silves information, gamma ray logs etc.), provides a detailed dataset Formation) and can be identified in some oil wells in the from which several Œclose to deterministic‚ reservoir models Guadalquivir Basin to the South. It can be also correlated with have been produced. Thirty one separate LIDAR scan similar deposits elsewere in Europe, such as the Grès à positions containing over a billion data points have been Roseaux in NE France, the Grès de Donnemarie in the Paris collected covering a total area 5 km long by 250 m high, along Basin, the Schilfsandstein in the German Basin or the Attret with a high resolution field dataset consisting of 12 Formation in Belgium. All of them should be related to a sedimentary logs 3 composite gamma ray sections and common major tectonic event related to the southwards analyses of the different geo-objects. propagation of the North Atlantic Sea in this period of time.

This study has developed new approaches and The Early Infill of the Triassic Fundy Basin: Architecture of the methodologies in order to integrate the different data into a 3D Wolfville Formation and Basin Evolution. georeferenced framework from which geostatistical information Sophie Leleu, Brian P.J. Williams, Adrian J. Hartley on object geometries and facies distributions can be obtained University Of Aberdeen, King’s College, Aberdeen, AB24 3UE, to populate the final reservoir model. These outcrops are an Scotland, UK, important analogue for the TAGI formation (Triassic Argilo- Gréseux Inférieur) representing one of the most productive The Fundy Basin forms one of a series of early Mesozoic rift siliciclastic reservoirs in central Algeria, and offer an excellent basins developed along the north-western Atlantic margin. It location to develop generic reservoir models for continental forms the conjugate margin to Morocco in the Central Atlantic. deposition systems. Syn-rift continental sediments were deposited during early Late Triassic times in the Fundy Basin. The sedimentary succession Siliclastic Continental Deposits in the Karnian (Late Triassic comprises the lower fluvio-aeolian Wolfville Fm, the overlying of the SE and S Iberian Peninsula: Tectonic, Climatic, and ephemeral fluvial/playa Blomidon Fm capped by basaltic lava Eustatic Controls (Olsen et al., 1989; Wade et al., 1996). Three sub-basins are present in the Fundy Basin: the Fundy sub-basin, the Minas Alfredo Arche1, José López-Gómez1, José Bienvenido Díez2 sub-basin to the east and the Chignecto sub-basin to the 1 Instituto de Geología Económica, CSIC-UCM, Facultad de north. Geología, Universidad Complutense, 28040 Madrid, Spain. 2 Departamento de Recursos Naturales, Facultad de Ciencias, The Late Anisian-Carnian Wolfville Fm displays a complex Universidad de Vigo, 36310 Vigo, Spain. interplay of coarse and fine-grained fluvial sandstones, aeolian dune deposits and alluvial fan sediments. This study focuses The classic Keuper Facies of SE and S Iberian Peninsula on the stratigraphy of, and correlation within the fluvial contain a siliciclastic intercalation denominated K-2 Unit or deposits. The palaeogeography of the Wolfville Fm is analysed Manuel Sandstone Formation. The Keuper Facies lie by determining the size of the braided river system and by conformably on the well dayted (Ladinian, Middle Triassic) taking an allostratigraphic approach to the recognition and marine carbonates of the Muschelkalk Facies. The studied correlation of extensive bounding surfaces in the Minas sub- siliciclastic deposits can be subdivided into three minor, basin. Comparison of the Minas sub-basin sediments with superimposed coarsening-upwards cycles that show a lateral deposits from the Chignecto sub-basin suggests that a major change from inter- supratidal hypersaline coastal sebkha fluvial system flowed to the northeast. environments to the East to fluvial-alluvial plain continental

42 The bounding surfaces and cycles within both coarse and The isotopic excursion seen in Morocco, eastern North fine-grained fluvial units allow correlation across the basin and America, and indeed globally is the signature of the massive have the potential to predict sand-fairways for reservoir carbon cycle disruption that occurred at the Tr-J boundary. exploration. Should the Central High Atlas basalts post-date that excursion, as suggested by our preliminary d13Corg results, there would Carbon Isotopic Excursion Below CAMP Basalts be no known examples of CAMP basalts contemporaneous Jessica, H. Whiteside1, Paul E. Olsen2 and Mohammed Et- with or predating the Tr-J boundary and direct causation of the Touhami3 mass extinction by the CAMP will be difficult to support. We 1 Department of Geological Sciences, Brown University, 324 are in the process of examining other sections in the Argana Brook Street, Box 1846, Providence RI 02912, USA, basin and as well as reexamining the Central High Atlas 2 Lamont-Doherty Earth Observatory of Columbia University, sections using compound specific d13C of biomarkers, to test Palisades, New York USA the generality and meaning of the pre-basalt patterns. 3 LGVBS, Département des Sciences de la Terre, Université Knight, K.B., Nomade, S., Renne, P.R., Marzoli, A., Betrand, H., and Mohamed Premier, 60,000 Oujda, Morocco Youbi, N., 2004, The Central Atlantic Magmatic Province at the Triassic-Jurassic boundary: paleomagnetic and 40Ar/30Ar evidence The Triassic-Jurassic (Tr-J) boundary marks one of the from Morocco for brief, episodic volcanism. Earth and Planetary most severe Phanerozoic mass extinctions. With a turnover of Science Letters, v. 228, p. 143-160. at least 50% of continental biodiversity, the event set the ecological stage for the ascent of dinosaur-dominated Marzoli, A., Bertrand, H., Knight, K.B., Cirilli, S., Buratti, N., Vérati, C., ecosystems. Our previous work on the Tr-J boundary in Nomade, S., Renne, P.R., Youbi, N., Martini, R., Allenbach, K., Neuwerth, R., Rapaille, C., Zaninetti, L., and Bellieni, G., 2004, eastern North American continental rift basins and work by Synchrony of the Central Atlantic magmatic province and the Triassic- others in marine and continental deposits demonstrate an Jurassic boundary climatic and biotic crisis. Geology, v. 32, p. associated modest Ir anomaly, a “fern spike,” a stomatal 973–976. density (CO2) anomaly, and a pair of negative d13Corg excursions separated by a positive excursion. While these The CAMP Controversy, New Data from the Argana Basin, observations have been interpreted as condign with an Morocco extraterrestrial impact, much if not all of this evidence is also M.H.L. Deenen1, M.J. Reitsma1,2, W. Krijgsman1, C.G. consonant with the temporally proximate voluminous flood Langereis1, M.J. van Bergen2, H. El Hachimi3, and H. Chellai3 basalts of the Central Atlantic magmatic province (CAMP). 1 Paleomagnetic laboratory, Utrecht University, Budapestlaan However, data from eastern North America suggest that all 17, 3584 CD Utrecht, The Netherlands, CAMP flows post-date the extinction level by tens of 2 Department of Earth Sciences, Utrecht University, thousands of years, making causation difficult to support. Budapestlaan 4, 3585 CD Utrecht, The Netherlands Nonetheless, Marzoli et al. (2004) and Knight et al. (2004) 3 Department of geology, Cadi Ayyad University, Boulevard interpret magnetic reversals within the Central High Atlas Prince Moulay Abdellah, Marakech, Morocco basalts of Morocco as indicating that most of the lavas predate or were synchronous with the Tr-J boundary, making a The Central Atlantic Magmatic Province (CAMP) formed plausible case for the CAMP as the cause of the extinction. during the pre-rift stage of the Atlantic Ocean. The amount of flood basalts is of the same order of magnitude as the outflow A predictive corollary of the Marzoli-Knight hypothesis is during the Deccan and Siberian Traps. The timing of the CAMP that the initial d13C excursion seen globally should be within or basalts falls within error with the age of the Triassic/Jurassic above the Moroccan CAMP but not below it. To test this extinction event implying a causal relation. However, a prediction, we examined the carbon isotopic composition of palynological turnover event associated with the Tr-J boundary bulk organic material (d13Corg) through palyniferous strata predates the lavas in all sections in eastern North America. This below the lower basalt sequence of the Central High Atlas. palynological event coincides with a modest iridium anomaly, While the Triassic index species Patinasporites densus does which led to the proposal for a bolide impact as the cause for appear in the highest palyniferous sample as reported by the TR-J mass extinction. More recently, studies showed, by Marzoli et al. (2004), our isotopic data suggests the presence comparing the geochemical composition, that the oldest of a pronounced isotopic excursion below the oldest basalt, basalts from the High Atlas (Morocco) are absent in North consistent with profiles from the Fundy basin of Canada and America, implying that the CAMP event does coincide with the the Newark basin of the USA. These results are: 1) inconsistent palynological Tr-J boundary. with the hypothesis of Marzoli et al. (2004) and Knight (2004) that the lower Central High Atlas basalts predate the Triassic- We selected the Argana Basin in west Morocco to solve Jurassic boundary; and 2) consistent with some reworking of the CAMP controversy using a multidisciplinary approach on Triassic palynomorphs at least locally into the first few 10s of the T-J sequences. Cyclostratigraphic and centimeters of Early Jurassic strata. magnetostratigraphic research is being used to investigate the

The First MAPG International Convention, Conference & Exhibition 43 Marrakech Convention Center, October 28 - 31, 2007 astronomical forcing of the Argana sediments, which would main Pan African shortening event, coeval to that described allow a direct correlation to the Newark sequences (USA). In elsewhere in the Anti-Atlas, ii) D2/S2 brittle-ductile deformation addition, we analysed the Argana CAMP basalts for trace developed during the Late- to post-Pan African extensional element data. Furthermore, we sampled the basalts for event. In the Igherm inlier, it consists of a large-scale low angle paleomagnetic directions to investigate the normal detachment developed and separates the uplifting magnetostratigraphic correlation of the different CAMP units. lower metamorphic unit from the upper fragile one. Along the detachment fault, the two units were overprinted by the S2 Geochemical results indicate that the CAMP basalts from mylonitic foliation. Parallel, high to low angle normal faults Argana fit the lower and intermediate basalt units of the High induced tilting blocks at the upper unit as well as in the Atlas. The oldest basalts in Newark resemble the composition neighbouring sedimentary basins. Such main detachment fault of the intermediate unit which implies that the lower unit is engenders normal stacking characterized by `younger on missing. However, the oldest basalts in Fundy basin, Canada, older’ overlapping structures. do match with the composition of the lower unit found in Morocco. While the paleomagnetic study is still in progress, we Tectonic features of the Irherm inlier are consistent with the can already conclude that both basalt units erupted in a short “metamorphic core complex” model, leading to the timespan (<20 kyr) and that the onset of volcanism was most exhumation of the Palaeoproterozoic dome. This probably synchronous with the palynological T/J boundary. tectonometamorphic example is ongoing to be identified into others surrounding inliers and must subsequently, integrate the GS 21 : Geodynamics of west-African craton and its Late- to Post-Pan African collapse reconstitution of the boundaries Western Anti-Atlas. Chair : N. Ennih, A. Belfoul Key words: Anti-Atlas / Pan African / Exhumation / dome / Late- orogenic Extension. The Aït Makhlouf massif (IGherm Inlier, Western Anti-Atlas, Morocco): an example of Late-Pan-African Metamorphic Post-Panafrican structural inheritance: An Hemi-Graben Core Complex geometry of the North-Western Border of West-African Moulid Oudra1, El-Hassan Beraaouz2 et Abderrahmane Craton (South-Western Anti-Atlas, Morocco). Soulaimani3 Mhamed Alaeddine Belfoul1, Farid Faik1, et Mohamed 1 Laboratoire de Géologie Structurale et de Cartographie Bouabdelli2. Thématique (GESCAT), Département de Géologie, Faculté des 1 GESCAT laboratory (Laboratoire de Géologie Structurale et Sciences, Université Ibn Zohr, BP : 8106, Agadir, Maroc. de Cartographie Thématique) Department of Geology, Faculty 2 Laboratoire de Géologie Appliquée et de Géoenvironnement of Science, Ibn Zohr University, Po Box: 8106, Agadir 80000, (LAGAGE), Département de Géologie, Faculté des Sciences, Morocco. Université Ibn Zohr, BP : 8106, Agadir, Maroc. 2 “GEODE : Terre et Patrimoine” Sarl, BP 7004 Sidi Abbad - 3 Laboratoire Géostructures, Géomatériaux et Ressources 40014 –Marrakech, Morocco. Hydriques GEOHYD, Faculté des Sciences Semlalia, Université Cadi Ayyad, Marrakech, Maroc. The Palaeozoic history of the NW edge of Gondwana is attributed to post-Pan African inherited structures. Its history The Precambrian rocks of Igherm inlier (Western Anti-Atlas) reveals a polycyclic and very heterogeneous evolution. exhibit three main tectonometamorphic units metamorphosed under contrasted conditions. The lower unit, with a This study was devoted to the field characterisation and Palaeoproterozoic ductile basement (Kerdous Group) and linkage of events in the South-western Anti-Atlas and its metamorphic rocks ranging from low-grade phyllites to southernmost cartographic extension between Zemmour and amphibolite facies, intruded by several eburnean granitoids. Ouled Dhlim. The principal aim was to assess whether this The Neoproterozoic Cover consists of: i) a brittle-ductile thick cartographic linkage represents an actual geodynamic affinity. layered quartzites and carbonates (Taghdoute Group), intruded To achieve this, the study focussed upon aspects of the by doleritic dyke swarms and sills, and; ii) the uncomfortably tectono-sedimentary evolution of the period prior to Hercynian overlaying late Neoproterozoic volcanoclastic series of the compression. “Ouarzazate Supergroup”, confined to surrounding basins, filled up by conglomerates and volcanoclastic rocks in an Furthermore, this study provided insights into the creation extensional environment context. of Palaeozoic sedimentary basins in the area. NNE-SSW orientated half grabens opened towards the west by jerked Two main successive tectonic events are recognized: i) extensional listric faulting, controlled by post-Pan African D1/S1 ductile compressive event associated to NE-SW wrench tectonics, which in turn reflects a regional geodynamic trending folds and regional foliation, affecting both the lower characteristic observed throughout the SW Anti-Atlas, in the metamorphic unit and the Quartzite series. It represents the linkage area of Zemmour-Ouled Dhlim and further south in the

44 northern part of Mauritanides. This faulting corresponds to a This geodynamic evolution leads to the first stage of post- continuum of crustale extension originating with eocambrian panafrican extension in the Anti-Atlas, which allowed the wide rifting. In the western Anti-Atlas these rift dynamics correspond eocambrian marine invasion. to simple extension, contrasting with the Mauritanides and the Key words: Anti-Atlas; block collapses; rifting; basalt; West-African rest of the Ant-Atlas where transtension dominates. Craton. This mode of structural configuration implies movement of the West African craton which seems to have withdrawn The Agoundis-Ounein Group, High-Atlas, Morocco: towards the SE during Palaeozoic basin formation. A witness of the Cambrian Rift. Abdellatif Aarab1, Mohamed Bouabdelli2 Key words: Gondwana, half grabens, post-Pan African structures, 1 Department of geology, ENS Rabat. Po Box: 3168 Rabat- south-western Anti-Atlas, Zemmour-Ouled Dhlim, Morocco. Massira, Rabat 2 GEODE : Terre et Patrimoine” Sarl, BP 7004 Sidi Abbad - The early palaeozoic extension of the West African Craton 40014 –Marrakech, Morocco. northern edge (Western Anti-Atlas, Morocco). Farid Faik1, Mhamed Alaeddine Belfoul1 et Mohamed In the Agoundis-Ounein within the “Massif Ancien” of the Bouabdelli2. High-Atlas, lower Palaeozoic rocks consist of basaltic lavas 1 GESCAT laboratory (Laboratoire de Géologie Structurale et associated with a marine sedimentation. These lavas are lightly de Cartographie Thématique) Department of Geology, Faculty differentiated and show a tholeiitic continental signature that of Science, Ibn Zohr University, Po Box: 8106, Agadir 80000, evolves to alkaline toward the summit of the Agoundis-Ounein Morocco. succession. The sedimentary formations are composed of 2 “GEODE : Terre et Patrimoine” Sarl, BP 7004 Sidi Abbad - limestones and dolomies with silts. Both lavas and sedimentary 40014 –Marrakech, Morocco. formation overlay the rhyolite basement through a clear angular discordance. The geological evolution of the Anti-Atlas is widely controlled by the setting and the behaviour of the northern The basement is affected by submeridian folds and a faults edge of the West-African craton. During terminal network. Neoproterozoic-basal Paleozoic, the Western Anti-Atlas undergoes an important extension, characterized especially by The rhyolites are by here, calcalkaline Ediacarians terms continental detrital and volcano-detrital deposits that compose related to the late Pan African orogeny while elsewhere they are the “group of Ouarzazate”, followed by carbonated and detrital andesitic and rhyolitic. The upper basaltic lavas belong to late facies as result of the cambrian transgression. Ediacarian-early Cambrian.

The terminal Neoproterozoic deposits show important The sedimentary and volcanic units of the Agoundis- variations in facies as well as in thicknesses that testify grabens Ounein group testify of a rift extension and couldn’t be and hemigrabens blocks brutal collapses. This detrital explained only by a simple block tilting device. sedimentation emphasises also, an important eruptive volcanic During the late Ediacarian early Cambrian time, the tectonic activity, where ejectas type show a continental character. context corresponds to a transtensional regime with a This extensive tectonic persists during the lower and senestral dynamic. This transtension is bidirectional, and maintained at least, all along the middle Cambrian. It is operates successively on an equatorial then a NE-SW underlined by several structures mainly such as direction. Syn to post rift sedimentary type, extensive tectonics synsedimentary disturbances (disharmonic levels, slumps, elements and the magmatic event, are such powerful olistoliths…), thickness changes, series variances, as well as recorders of an extensional environment dynamic that basaltic volcanism which is described for the first time in the prevailed during the early palaeozoic time. Similarly, this middle Cambrian of Tata area. extension concerned Africa, Iberia, the south Europe and other continental palaeo-masses around the Yapetus and Rheic sea Grabens and hemigrabens blocks breakdown are due to spaces opened at the beginning of the Palaeozoic. the West-African Craton northern edge dislocation that is occurred since the beginning of the post-Panafrican rifting. By its geological features, the group of the Agoundis- This rifting is connected to the opening of the Iapetus Ocean at Ounein illustrates the Cambrian rifting at the north-western the end of Neoproterozoic. In terms of plate megatectonic edge of the Palaeo-Gondwana. setting, the oceanic spreading is carried out by a coupled Key words: Early Cambrian, Paleo-Gondwana, continental tholeiite, Atlas migration: Avalon toward the NW trend and Meguma to the North edge of the West-African Craton.

The First MAPG International Convention, Conference & Exhibition 45 Marrakech Convention Center, October 28 - 31, 2007 The role of the West African craton in the post visean inversion, the former normal faults that limited the dislocated structuration of the Moroccan Meseta and Anti-Atlas basement blocks of the West-African Craton. Abdellah Lakhloufi The uplift of the basement blocks generates beds Laboratoire de Géologie structurale et appliquée, ENS BP. shortening and flexures at the cover sole. These tectonic 5118 Rabat behaviours lead to explain how the direction folds of the palaeozoic Anti-Atlas cover occurred on various trends: NS, To the East of the coastal Meseta, the lands are structured NNE-SSW, NE-SW and E-W. by folds trending ENE-WSW. The structural data at sidi Bettache (BSB) and Brachwa Maaziz (BBM) basins plead in Within chronology, E-W folds are earlier and interact with favor of a counter clockwise rotational movement towards the the NS fold into domes and basins interferences system. NNW of the Zaer-Oulmès Block. Otherwise, the eastern These structures are interpreted here, as the result of an early Meseta shows the same structural outlines, with a deformation northern compressive episode which introduces an uprising of generally more excessive than in Western Meseta. That implies the basement blocks. Thus induces a crumpling of the cover a counter clockwise rotational movement of this one towards by “folds forced on accidents of the base” according to « the NNW. Trishear fold model » (Erslev, 1991).

The structural outlines at the coastal Block are NNW-SSE Major Subequatorial compression sets the NNE-SSW to NNE-SSW trend. To the E of the Western Meseta Shear folding in the cover, as well as vertical and horizontal Zone, the sub E-W folds are refolded by the sub N-S folds movements along E-W and NE-SW faults. This compression is within a width band. controlled by the migration of the West-African Craton towards the West and with its Laurentia collision. This migration The Anti-Atlas presents the same structural outlines that at induces, in the Anti-Atlas, a dextral transpressif movement the Meseta. In the eastern Anti-Atlas, the folding is ENE-WSW between the northern edge of the craton and the southern while the crossed folds are known at the central Anti-Atlas. The atlasic fault (Tizi-N-Test Fault). extreme W of the Anti-Atlas is structured by N-S folds and it's linked up by Soulaïmani and El Attari to the Mauritanide range. Thus, the Eastern part of the Western Anti-Atlas is structured by tectonics inversion according to “Thick-skinned These structural considerations are in favor of the role of tectonics” style. Paradoxically, this contrasts with the “thin- the W African Craton in the hercynian structuration of the Anti- skinned tectonics” tectonic, well developed in the south- Atlas and the Meseta at the time of the last stages of the western part of the Anti-Atlas (Guelmim-Zemmour-Ouled formation of the Pangea. These allow replacing the post visean Dhlim). structural events of the Moroccan hercynian range in their periatlantic Paleozoic context marked by the building of: Key words: Tectonic inversion; basement blocks; folds forced, thick- skin; West-African craton. Appalachian range in the SE edge of the North American Craton; Mauritanide range in the Wedge of the WAC; Western Bibliography: Europe and NW African hercynian ranges. ERSLEV E. A. (1991): “Trishear fault-propagation folding”. Geology, V. GS 19 : Phanero- and Palaeozoic Evolution of the 19, p. 617-620. NW African, West European and NE American belts Chair : A. Tahiri, F. Simancas, A. El Hassani Viséan basin fill of the Jerada synclinorium (NE Morocco) – sedimentary dynamics and geodynamic implications Basement blocks’ behaviour and impact upon the Hercynian Hans-Georg Herbig and Markus Aretz Universität zu Köln, Institut für Geologie und Mineralogie, structuration of the Western Anti-Atlas (Morocco) Zülpicher Str. Morocco – Carboniferous – basin fill – basin Farid Faik1, Mhamed Alaeddine Belfoul1 and Mohamed architecture – geodynamic model Bouabdelli2 1 GESCAT laboratory (Laboratoire de Géologie Structurale et The Carboniferous Jerada Synclinorium is one of the de Cartographie Thématique) Department of Geology, Faculty Variscan massifs of the Eastern Moroccan Meseta. A mostly of Science, Ibn Zohr University, Po Box: 8106, Agadir 80000, Viséan basin fill megacycle (Herbig et al. 2006) is Morocco. unconformably overlain by a paralic Namurian–Westphalian C 2 GEODE : Terre et Patrimoine” Sarl, BP 7004 Sidi Abbad - succession. The basin fill sequence starts with rhyolithic, 40014 –Marrakech, Morocco. andesitic and dacitic volcanosedimentary rocks (Oued Defla Formation). They are bound to roughly W-E trending, The basement/cover unit of the Western Anti-Atlas, in the syndepositional active fault systems and either formed a Eastern part of the Kerdous inleer, is subjected to a NW-SE submarine palaeorelief and/or intruded onto an inclined basin crustal shortening. This compression rejuvenates, by tectonic

46 floor. Overlying bedded cherts and intercalated pyroclastics limb and a lateral ramp with approximately NNE-SSW strike, (Çafçaf Formation) started to level the relief. The Oued El located at the eastern closure. The tectonic movement is Koriche Formation on top is a toe-of-slope deposit. It contains distributed along a high number of thrust faults related to up to hectameter sized limestone olistolites at the southern multiple detachment levels, which, in turn, are connected to a flank of the Jerada synclinorium, indicating reworking of a basal sole main detachment. The seismic image provided by southern carbonate platform at an active fault system. Water the IBERSEIS profile shows the existence of these north- depth increased towards the N-NE, since at the northern flank dipping imbricate fan thrust systems, which converge into only calciturbiditic fines occur. Goniatite-bearing, deeper detachment levels located at 12-15 km-depth. The predominantly shaly slope deposits follow (Oued Es-Sassi structural model defined for the PGA could also be applied to Formation), which according to increasing fossil content and other major regional structures in the South Portuguese Zone decreasing grain sizes again indicate more basinal conditions (Simancas et al., 2004). In fact, the VCA reproduces exactly the in the northeast. The basin fill is completed by prograding same model and the IPB as a whole represents a major shallow-marine carbonate facies including different reef facies imbricate sheet of a Variscan orogenic wedge. (Aretz et al., this meeting) and first local input of siliclastic Keywords: imbricate thrust systems, fault-propagation folds, South sediment from the north (Koudiat Es-Senn Formation). Emersion at the end of the Viséan is well shown by a Portuguese Zone cartographic unconformity at the southern flank of the synclinorium. At the northern flank, emersion is proved by a Moroccan Meseta and SW Iberia lithostratigraphic subaerial ignimbrite and the erosive base of lower Namurian correlations of Upper Neoproterozoic and Palaeozoic siliciclastics. The geodynamic setting of the Jerada Basin is Abdelfatah Tahiri1, Fernando Simancas2, Hassan El Hadi3, controversial. Obviously, it is part of a larger basin comprising Francisco Lodeiro2, Antonio Azor2, David Poyatos2 at least parts of the eastern Meseta. Basin fill and basin 1 Institut scientifique, Rabat, Maroc; dynamics point to a continental margin type back arc basin, 2 Faculté des Sciences, Département de Géodynamique, which is strongly dissected by strike-slip fault systems due to Granada, Espagne. oblique, south-directed subduction occurring further north, 3 Faculté des Sciences Casa Ben Msik, Département de resp. northwest. Géologie, Casablanca

Herbig, H.-G. et al. (2006): The Viséan of the Jerada Moroccan Meseta and SW Iberia show Upper synclinorium (NE Morocco): lithostratigraphy, facies, and Neoproterozoic and Palaeozoic (mainly Lower Palaeozoic) depositional setting. – Kölner Forum Geol. Paläont., 15, 36-37. complete series, folded, deformed, metamorphosed and granitized by different palaeozoic phases (caledonian and Seismic and structural data from the Puebla de Guzmán variscan). Below principal lithostratigraphical correlations. Anticline: An overview of crustal architecture in the Iberian Upper Neoproterozoic Pyrite Belt (SW Iberia) -Iberian Meseta, Ossa Morena and Central Iberian Elena Mª Mantero1, Encarnación García-Navarro1, Francisco (southerner part) Zones: Negra serie (phyllades and dark M. Alonso-Chaves1 and Antonio Azor2 quartzites), calcalkaline volcano-sedimentary subduction 1 Departamento de Geodinámica y Paleontología, Universidad complex. de Huelva, Campus Universitario “El Carmen”, 21007 Huelva, -Morrocan Meseta (Central Moroccan massif, Coastal Spain Meseta) : schists and metamorphic limestones ; volcano- 2 Departamento de Geodinámica, Universidad de Granada, sedimentary complex (dolomites, rhyolites). Campus Fuentenueva, 18071, Granada, Spain Lower Cambrian The Puebla de Guzmán Anticline (PGA) is one of the main structural features of the Spanish sector of the Iberian Pyrite -Iberian Meseta (Ossa Morena) : volcano-sedimentary Belt (IPB), along with the Valverde del Camino Antiform (VCA). complex, carbonates (with Archeocyatides), arkose and Two main tectonic deformation phases have been recognized metamorphosed greywackes (Lower Cambrian base). in the PGA, the antiform being essentially a second phase -Morrocan Meseta (Coastal Meseta, Western Jebilet, structure with some previous deformation inherited from the Rehamna) : limestones (with Archeocyatides), arkoses, schists first phase. Seismic and field data support the interpretation of and volcano-sedimentary complex (Middle Cambrian). its internal architecture as an antiform with its southern limb affected by a south-vergent imbricate thrust system (Simancas Middle Cambrian et al., 2004; Mantero et al., 2006). Actually, the antiform is a -Iberian Meseta (Ossa Morena) : Volcano-sedimentary thrust propagation fold linked to the development of the complex with pillow lavas level (dated of Mid Cambrian) southern-limb thrust system. Its geometry is characterized by indicated of an continental rifting developped in Ossa Morena the presence of a frontal ramp (N100ºE) ahead of its southern

The First MAPG International Convention, Conference & Exhibition 47 Marrakech Convention Center, October 28 - 31, 2007 Zone with oceanic domains borders. The Cambrian-Ordovician important material damages. The magnitude of these boundary is not well defined, it is marked by conglomerates earthquakes ranges from 3 to 5. level. Extensive brittle deformations analyses have been -Morrocan Meseta (Coastal Meseta, Jebilet, Rehamna): occurred during Neogene-Quaternary time. The most active Paradoxides schist formation (Acadian); Western mesetean rift tectonic deformation is related to the reactivating of pre- flysch with basic and acid volcano-sedimentary complex existing NW-SE and E-W trending strike-slip faulting. (Rhebbar River, Sidi Said Maachou, Bou Acila); El Hank Paleostress and calculated focal mechanism solutions for the quartzites; Arenig conglomerates. recent earthquake show that the active stress field is a NW-SE trending compression. These results are consistent with focal Ordovician (Lower part) mechanism solutions and neotectonic data and can be incorporated in the convergent plate model for the European -Iberian Meseta: Central Iberian Zones: detritical series with and African plates. Armorican quartzites Formations; Ossa Morena Zone: detritical Formation of Barrancos. In this paper, complementary approaches (seismotectonic, seismology and geodesy) will be used to optimise the field -Morrocan Meseta (Coastal Meseta, Jebilet, Rehamna) : measurements and to evaluate the seismic risk. “Schistes en dalles” and Oulmès Formations without Armorican quartzites. Key Words: Seismotectonic, geodesy, seismic risk, oriental Tunisia

Key words : Upper Neoproterozoic, Palaeozoic, Moroccan Meseta, SW Iberia, lithostratigraphic correlations Active deformation and paleoseismology of northern Morocco: onshore and offshore faults and the source of the GS 24: Risque sismique en Méditerranée great 1755 earthquake and tsunami occidentale M.-A. Gutscher1, P. LeRoy1, D. Graindorge1, N. Babonneau1, Chair : L. Ait Brahim , B. Tadili N. Maad1, M. Sahabi2, L. Ait-Brahim3 1 UMR6538 Domaines Océaniques, IUEM/UBO Plouzané Active deformation and seismic risk in the Oriental Tunisia 2 Univ. El Jadida Raouf Ghribi1, Noamen Rebai2 and Samir Bouaziz3 3 Univ. de Rabat 1 University of Sfax, National Engineering School, Laboratory The northern Morocco/ Gulf of Cadiz region has been the “Water-Energy-Environment” BP. W. 3038 Sfax-Tunisia site of strong historical seismicity. In particular the earthquake 2 University of Tunis II, Sciences Faculty, Geology Department of 1 Nov. 1755 (the Great “Lisbon“ earthquake), with an 1060 Tunis. estimated magnitude of 8.7, caused widespread damage in 3 University of Sfax, National Engineering School, Laboratory NW Morocco. Tsunami waves heights of 5-15 m were “Water-Energy-Environment” BP. W. 3038 Sfax-Tunisia. observed along the Moroccan Atlantic coast. Recent The Oriental Tunisian platform (Tunisian Sahel), occupying geophysical results reveal an east dipping subduction zone, the biggest part of the Tunisian oriental coastal fringe, beneath the Gulf of Cadiz and Gibraltar arc, with signs of corresponds to a vast collapsed flat shape and tilted block, recent activity. As 11 out of the 12 M8.5 earthquakes in the resulting in irregular topography. This domain is characterized past 100 years occurred in subduction zones, the Cadiz- by discontinuous cliffs, vast littoral plain and of vast valleys and Gibraltar subduction is a very strong candidate for the 1755 salty depressions. The coastline of the Tunisian Sahel, long of event. The results of swath mapping bathymetry, and marine more than 700km, shows a succession Mio-Pliocene seismic profiles (HR, MCSand OBS) in the Gulf of Cadiz are sequences and mixed continental and marine Quaternary presented. They image a 1-10 km thick, eastward thickening deposits affected by intensive deformations and translating pile of deformed sediments, with W, NW and SW vergent ramp some variations important variations of sea level changes thrusts, above a gently east dipping layer of undeformed recorded. This domain constitutes the eastern part of the sediments. This structure is an accretionary wedge, which seismic zone bordering the northern African plate as indicated shows signs of continued tectonic activity including: numerous by the large seismic events that occurred periodically. The active mud volcanoes (indicating active dewatering processes), Coastal area, more particularly concerned by the seismic risk, folding and thrusting seen in high-resolution seismic profiles is bordered to the west by the NW-SE trending Atlasic fold and and the seafloor morphology, which shows a basement high to the South by the stable Saharian platform marked by NW- (Coral Patch Ridge) actively indenting the deformation front. SE faults system. This region is known by recent intra-plate The underlying crust is thin (7-10 km thick), gently east dipping compressive deformation included in the global geodynamic and likely oceanic in nature. Thermal modeling of the context of convergence between the African and Eurasian subduction fault plane, indicates a potential seismogenic zone plates. In fact, in the last decade several earthquakes caused with a downdip width of 200 km. The absence of instrumentally recorded subduction interface earthquakes

48 suggests the presence of locked zone (like Nankai or New catalogues of the historical seismicity from 1045 to Cascadia), with a long recurrence interval (about 1500- 2005 (Peláez and Al 2006), and instrumental from 1900 to 2000yrs) for great earthquakes, as supported by available 2005 (Tadili and Ait Brahim 2006) as well as active faults (Ait sedimentological data. A model with a co-seismic slip of 10 m Brahim 2006) were elaborated. The most influential parameters and a long term subduction velocity of 5-6 mm/yr is consistent having effects on the definition of the characteristics of the with this recurrence interval. Numerical modeling of the 1755 source areas were predetermined with an acceptable tsunami also suggests a strong contribution from the precision. subduction faultplane. High resolution seismic profiles from the Moroccan platform at the SE limit of the accretionary wedge New elaborate zoning that includes 12 sismotectonic show signs of faulting and folding which post-date the last zones, each one corresponding to a volume of the earth’s glacial lowstand. Onshore evidence of recent deformation is crust, were analyzed and interpreted. The data were used to offered by folding of Pleistocene (Villefranchian) sediments in determine its static and dynamic states. Each sismotectonic the Lalla Zara hills (northern limit of the Rharb basin) as well as zone presents homogeneity of the potential sismogene and its 10-15° tilting of more recent Pliocene sediments. Future work mode of deformation obtained with using the data on the will focus on the relation between active faults imaged offshore seismicity, the strain and the stresses. For the zones made up and potentially active structures onshore, which may be related of faults, we specified each time, the geometrical to a network of E-W to ENE-WSW trending faults, like the characteristics, the chronology of the various motions Jebba and Nekor faults, which cross the Rif and connect to the corresponding to the succesives tectonic episodes and the Mediterranean coast of Morocco. associated seismicity and the associated seismicity.

Keywords : Paleoseismology ; 1755 earthquake ; Tsunami ; This new zoning will be of a great contribution for the future Morocco probabilistic studies for the definition of the seismic risk and the determination of accelerations of the ground in the north of New sismotectonic zoning of Northern Morocco Morocco. L.A. Brahim1, B.A. Tadili2, S. El Hajji,3, A Abdelouaf i,3., and J.Laassiri3 Present-day kinematics of Ibero-Maghrebian Region as 1 Dpt. des Sciences de la Terre, Univ. Mohammed V, Rabat, observed by GPS Data Marruecos R.M.S. Fernandes1,2, J.M. Miranda3, L. Matias3, L. Bastos4, 2 Dpt. de Physique du Globe, Institut Scientifique, Agdal, R. Azzouzi5 Rabat, Marruecos 1 University of Beira Interior, IDL, CGUL, Covilhã, Portugal 3 Dpt. de Mathématiques et Informatique, Univ. Mohammed V, 2 DEOS, TUDelft, The Netherlands Rabat, Marruecos 3 University of Lisbon, IDL, CGUL, Covilhã, Portugal 4 University of Porto, Astronomical Observatory, Portugal In this work, a new sismotectonic zoning of the North of 5 Institut Agronomique et Vétérinaire Hassan II de Rabat, Morocco is proposed. It is based on a new database which Morocco includes recent work (some affirmation where questionable) in the fields: In this work, we present results of the continuous processing of a network of permanent GPS stations distributed - Geology (active faults, travel rates, geometrical over Iberian Peninsula and North Africa. This task is carried out characteristics, chronology of the various recent tectonic in the framework of GEODAC and GOMA, collaborative phases). projects endorsed by the partners together with other - Geophysics (instrumental and historical seismicity, focal European and Northern Africa Institutions. These projects mechanisms, nature crust). intend to support the efforts of the scientific community that is studying the Earth’s processes along the Nubian-Eurasian - As well as the geodynamic context of the convergence of plate boundary, with a particular focus on the Maghrebian the plates Africa-Europe in the area going from the Atlantic region. Ocean to the Mediterranean sea passing by the Straits of Gibraltar. We have derived a uniform velocity field using the stations with observations spanning 3.5 years or longer. Most of Iberia New zoning sismotectonic suggested is not limited to the can act as a reference to derive the relative motions since it borders of the north of Morocco. It takes into account all the forms a stable block fixed relative to Eurasia with smaller seismic sources (from 100 to 400 km) able to generate strong residuals (below the computed accuracy for each station). earthquakes destroying purposes on Morocco, such that of Stations in Morocco exhibit a motion close to what would be Lisbon in 1755 on the level of the transforming fault Azores- expected for stable Nubia (also all below the computed Gibraltar. accuracies). The most distinctive behaviour is found at stations along the southern coast of Spain and the northern coast of

The First MAPG International Convention, Conference & Exhibition 49 Marrakech Convention Center, October 28 - 31, 2007 Morocco, where larger and more westward velocities are GS 17 : Geodynamics of mountain belts found. Some stations in southern Iberia show differences with Chair : A. Chalouan, A. Michard respect to stable Eurasia that are distinctly larger than computed accuracies. This is also clearly observed in the 600 Ma of peri-Gondwana plate tectonics and geodynamic derived strain rate field, which shows significant deformation evolution rates in this region. Gérard M. Stampfli1, Cyril Hochard1, Caroline Wilhem1 and Juergen von Raumer2 We discuss that the observed kinematics are not only a 1 University of Lausanne, IGP, Anthropole, CH 1015 Lausanne consequence of the Nubian-Eurasian plate convergence, but 2 University of Fribourg, Sciences de la Terre, CH 1700 also a result of local lithospheric processes, particularly the Fribourg effect of the Gibraltar slab, as previously suggested by other authors. A new global plate tectonic scheme has been developed for the last 600 Ma, based on a large database including major Key words: Crustal Deformation, Nubia-Eurasia Plate Boundary, Global Positioning System (GPS) geodynamic events affecting key-areas and related to plate boundary conditions in space and time. This new scheme is The significance of the active tectonics and seismicity in the made in a GIS based software, allowing plate velocities and other plate characteristics to be measured along the geological Central Part of the Betic Cordillera (Granada and Guadix- time. This scheme is totally different from continental drift Baza Basins, Southern Spain) models proposed so far, as continents are now imbedded in C. Sanz de Galdeano1, C. López Casado2 and J.A. Peláez3 plates, and thus, plate boundary conditions became a severe 1 IACT, CSIC-Univ. of Granada, Spain, constraining factor in reconstructing the palaeodynamics of the 2 Dpt. of Theoretical Physics, Univ. of Granada, Spain moving continents. Analysis of continental margins 3 Dpt. of Physics, Univ. of Jaén, Spain stratigraphy, sedimentology, magmatism and tectonics, is the The Betic Cordillera is the most tectonic and seismically key factor in this effort to integrate palaeogeography and active region of the Iberian Peninsula, where several large geodynamics. Gondwana and its periphery have been historical and instrumental earthquakes have produced local analysed in detail, in order to propose a new fit where but significant effects in the past. Its central part is to a great continental fragments, now dispersed in many continental extent occupied by the Granada and Guadix-Baza basins, in areas, can find their original place. These fragments are part of addition to the important mass of Sierra Nevada. Specially, in major terranes that left Gondwana mainly in the Palaeozoic, the Granada Basin, there are important active faults with such as Avalonia, the Hun super-terrane, the Galatian super- associated seismicity. In contrast, in the Guadix-Baza basin terrane, the Cimmerian super-terrane. Some were active faults are less important, with the exception of the Baza amalgamated to Laurasia first, to be reunited with Gondwana fault, being the seismicity clearly lower. later on. This is the case of the Moroccan Meseta, first part of an active peri-Gondwanan margin in the early Palaeozoic, then The majority of these active faults correspond to NW-SE drifting away from it, together with the Galatian super-terrane faults that greatly contribute to the present ENE-WSW and opening of Palaeotethys, to be accreted to Laurussia in extension, nowadays suffered by the Betic Cordillera. This the Devonian-Carboniferous and soon after to Gondwana extension is combined with a perpendicular NNW-SSE (Pangea) again. During the Jurassic it drifted away from compression that, since the Late Miocene, formed the great Laurasia together with Gondwana. anticlinorium of Sierra Nevada. Nevertheless, most Keywords : plate tectonics, Gondwana, Palaeozoic, Mesozoic earthquakes present extensional, and in some cases strike slip, focal mechanisms, indicating the importance of the extension and transpression, at least in shallow structural Paleostress magnitudes in active foreland fold-thrust belts levels. from tectonic analysis of calcite twins. Examples from Taiwan and the Zagros Key words : Betic Cordillera, Active tectonic, seismicity, earthquakes Olivier Lacombe1, Khalid Amrouch1,2 and Frédéric Mouthereau1 1 Université P. et M. Curie - Paris 6, Paris, France 2 Institut Français du Pétrole, Rueil-Malmaison, France

Computerized inversion of calcite twin data provides 5 parameters among the 6 of the complete stress tensor : it is to date the only technique which allows simultaneous calculation of principal stress orientations and differential stress magnitudes from a twin set.

50 In the western Taiwan Foothills, twins collected within axes of anisotropy that result from this analysis seem to show Pliocene reef limestones on top of outer anticlines reveal large a smooth rotation of fast directions following more or less a pre-folding and smaller post-folding differential stresses related trend parallel to the coastline, that is SW-NE in the Betics and to the Plio-Quaternary WNW compression: folding presumably North-South near the Gibraltar strait. A similar rotation is caused rapid uplift and erosion, leading to both decreasing apparent in measures of Pn anisotropy suggesting tentatively lithostatic load and differential stresses. Stress estimates at the that the deformation is vertically coherent through the upper scale of individual folds as well as entire orogens support a mantle of Betics and Gibraltar arc. first-order control on differential stress levels by the depth of overburden, and therefore a frictional strength of the upper The second technique that we address here uses the crust as revealed by contemporary stress measurements. dispersion of body waves that traverse the upper mantle in the Alboran Sea. These show a characteristic dispersion behavior In the Zagros, twins from veins and host rocks of late that is consistent with propagation through a subducted Cretaceous to Miocene age reveal a late folding NNE lithosphere that still contains its low-velocity crustal waveguide. compression related to Arabia-Eurasia collision. Differential Similar waveform behavior has been shown previously for well- stresses are unexpectedly low and roughly constant across the established subduction zones around the Pacific. More Simply Folded Belt (SFB) : they disagree with previously importantly, it appears difficult to explain this kind of dispersion reported stress values which are much higher and show a under the Alboran Sea by mechanisms that do not include strong decay across both the belts and their undeformed subduction. The observation thus imposes a strong constraint forelands. The relative homogeneity of differential stresses on the structure of the upper mantle under the Alboran Sea agrees with the homogeneously distributed shortening across and its nature. This is especially useful since the region is not the SFB, in contrast to classical fold-thrust wedges. This well-illuminated by seismic rays for tomography. supports buckling of the cover sequence over the weak Key words: Seismology, Anisotropy, Subduction, Delamination Hormuz salt as the dominant mechanism of deformation. Internal viscous-plastic processes help to keep stress level in this detached cover beyond the frictional yield, thus lowering Intraplate deformation in the Iberian Peninsula and Morocco its seismogenic potential. Subsequent to the Pyrenean Collision R.Vegas,1 G. DeVicente1 and A.J. Olaiz1 These studies underline the potential of calcite twins Dpto. Geodinámica, Universidad Complutense de Madrid. C. analyses in constraining both deformation mechanisms in José Antonio Novais, 2, 28040-Madrid, Spain. foreland fold belts and upper crust mechanics. Intraplate deformation, basins and ranges within the Key words : Calcite twins, differential stresses, foreland fold-thrust continental interiors, is currently ascribed either to belts. astenospheric ascent or to plate-boundary effective stress transmission. In the case of the broad, westernmost The mantle under Betics and Gibraltar Arc from seismic continental Africa (Nubia)-Eurasia interface, between the anisotropy and body-wave dispersion Pyrenees and the Atlas System, the arrangement of Götz Bokelmann1, Emeline Maufroy2, Luisa Buontempo3, mountainous ranges and basins points to a single process of Jose Morales3 , Guilhem Barruol1 topographic evolution that can be explained as a pure-shear 1 Géosciences Montpellier, CNRS, Université Montpellier II, model of crustal shortening. In this tectonic situation, Iberia 34095 Montpellier, France (the Iberian Peninsula) used to be firmly attached to Africa 2 Géosciences Azur, Sophia Antipolis, 06560 Valbonne, during most part of the Tertiary, in such a way that N-S France compressive stresses could be transmitted from the Pyrenean 3 Instituto Andaluz de Geofísica, Universidad de Granada, collisional boundary. This tectonic scenario implies that most 18071 Granada, Spain part of the Tertiary Eurasia-África convergence was not accommodated along the Iberia-Africa interface, but in the We study the geodynamic situation of the Gibraltar arc Pyrenean plate- boundary. Moreover, recent paleomagnetic region, for which there does not appear to exist a consensus data show indistinguishable paleopoles for Jurassic dykes in yet. Indeed, a variety of tectonic models have been proposed southern Morocco and central Iberia – a fact that precludes for the region, including subduction, continental delamination, major N-S displacement between Africa and Iberia in post- and convective removal, and we will try to distinguish between Jurassic times. In this context, the early Oligocene up to late these models. For this purpose we study seismic anisotropy in Miocene (postcollisional) N-S plate convergence is assumed in the region, and also the dispersion of body waves. the interior of both Iberian and Moroccan interiors by means of Since seismic anisotropy can constrain deformation in the the formation of several intraplate mountain chains and basins. mantle, and thus flow, we are studying the splitting of Shortening in the Rif-Betics external zones must be conversely teleseismic SKS phases in Southern Spain. Interestingly, fast related to “local” driven mechanisms other than N-S

The First MAPG International Convention, Conference & Exhibition 51 Marrakech Convention Center, October 28 - 31, 2007 convergence. The remaining NNW-SSE convergence, latest Acknowledgements : This study was supported by grants CGL2006- Miocene up to Present, is being also accommodated in a 08638/BTE and CTM2005-08071-C03-01/MAR (Spain). broad zone straddling Iberia and Morocco, at the same time as a diffuse new plate boundary is being formed between them. Styles of the Tertiary paroxysmal tectonic phases. Towards a new model of the chain evolution. Mode of building of the Betic-Rif orogenic Arc (westernmost Hamou Djellit Mediterranean): a structural, seismic and paleomagnetic Centre de Recherche en Astronomie, Astrophysique et approach. Géophysique. A. Crespo-Blanc1,2, J. C. Balanyá3, I. Expósito3, M. Díaz BP 63, route de l’Observatoire, Bouzaréah 16340 Algiers, Azpiroz3, F. Torcal3 and M. Luján2 Algeria. 1 Dpto. de Geodinámica, Universidad de Granada, Campus The structural edifice of the Alpine Algerian belt shows from Fuentenueva s/n, 18071 Granada. Email: [email protected] the bottom to the top and from the North to the South:- An old 2 Instituto Andaluz de Ciencias de la Tierra. CSIC-Universidad basement (Kabylian basement), crystalline series of pre- de Granada, 18071 Granada. Triassic age; - a platform formation (Kabylian Dorsal), Trias to 3 Dpto. de Sistemas Físicos, Químicos y Naturales, Oligocene, - allochtonous detrital formations (Kabylian flyschs); Universidad Pablo de Olavide, Cra. de Utrera km 1, 41013 - Southerly, in lower position, the Tellian units, are themselves Sevilla. overthrusted on the Hodnean para-autochtonous domain. The Gibraltar Arc System, which includes the Alboran Over the precedent units, lies the Numidian flysch, occupying Basin, the Betic-Rif orogen and the Cadiz Gulf accretionary the highest position in the edifice. It regroups terms ranging prism, derives from the Europe-Africa plate convergence from the Aquitanian to the Burdigalian. coupled with the westward motion of the arc hinterland The structural edifice of the Algerian Alpine chain is the (Alboran Domain). A multidisciplinary approach integrating result of the additional effects of at least three different tectonic geological, structural, seismic and previously published phases: - D1, an E-W dextral transpressive strike-slip fault, paleomagnetic data was realized. Although focusing on the before the Eocene; - D2, a gravital phase of the tectonic, external domain of the northern branch of the Gibraltar Arc (the occurred during middle to upper Eocene; - D3, a compressive South Iberian paleomargin-derived units and Flysch Trough tectonic phase during the upper Oligocen, is characterized by units), data of its southern branch and of its internal zone (the simple shearings with southern vergencies, on E-W plans Alboran Domain common to both sides), are also included. Our results permit to identify: dipping towards the North, to which are associated fault- related folds (flat and ramp) or advanced broken folds. a) lateral variations of the structural style in the external domains and a fan pattern of transport directions associated GS 27 : Remote Sensing and GIS applied to with folding and thrusting around the Arc; Geosciences Chair : A. Emran, A. Bannari b) an inventory of structures that evidence strain partitioning, that is structures that accommodated suborthogonal shortening (fold-and-thrust belts developed Analytic mapping of faults affecting the Anti-Atlasic Chain from the paleomargin- and the Flysch Through-derived units), (maroc) and normal faults, conjugate strike-slip faults, and distributed N. El Mortaji1A. Fekkak2 and M. Er-Raji minor structures that accommodated arc-parallel stretching; 1 Department of Geology, Faculty of Sciences, BP 20, 24000 El Jadida, Morocco c) a 3D distribution of seismic focci which shows that 2. Royal Centre of Remote sensing (CRTS) Rabat, Morocco almost all intermediate seismicity is located within the tightest part of the Gibraltar Arc- and focal mechanisms solutions In the Moroccan Anti-Atlas, and due to the absence of well within the whole Betic-Rif orogen that reflect large-scale strain developed vegetation, remove sensing is an effective tool for partitioning. geologists, in lithologic and structural mapping, and also in the field of mining exploration. All these type of data allows us to establish a coherent tectonic evolution of the Gibraltar Arc, in particular in terms of The analysis, the photo-interpretation and the application mass transfer at regional scale in the external domain, from of different filters on images scenes (TM and ETM+ of Landsat) Miocene onwards. They also provide additional constraints on covering the Anti-Atlas, allowed to establish a lineament map the mode of formation of this Arc, which was close to a of the different populations of faults, structuring the range, in piedmont glacier type mode. the perspective of creating the faulting evolution of the Anti-

Key words: Betic-Rif, Gibraltar Arc, geological and geophysical data, Atlas’s Proterozoïc. kinematic pattern

52 Many kinds of faults are distinguished by crossing varied Since heritage has a strong spatial aspect, GIS based on formations since the Paleoproterzoic till the quaternary. FOSS are well suited tools to record and preserve, store and communicate human and natural heritage topics. Concerning the Precambrian fields, four principal kinds can be identified (N060°E to N090°E, N0 to N150°E, N100°E to Further, the use of spatial analysis and mapping tools can N140°E, and N020°E to 040°E). be used to put the heritage content in a wider context by blending it with remote sensing data. FOSS GIS enables the In the oriental Anti-Atlas, the more abundant faults are preservation of heritage information and its use by other fields, N060E to N090E; they are kilometric faults with apparent such as historic studies and archaeology, but also the creation sinistral strike slip movement affecting all Proterozoïc of analogue products, such as paper maps, geopedagogic formations, and even Paleozoïc. The kind N0 to N150E toys and displays. presents a dextral strike slip movement; it affects the upper and lower formations without crossing N060E to N090E faults. Keywords: FOSS, Geopark, Moroccan Atlas Mountains, natural and The third kind N020 to N040°E presents a weak extension cultural heritage which affects even the paleozoic field. 3-D geological maps: a pioneering tool for underground In addition the three kinds that we find in the oriental geology domain, the central Anti-atlas is characterized by the faults Damien Dhont1, Pascal Luxey2, Janine Somma3 N100 to N140 forming the Anti-Atlas Major Fault which divides 1 CNRS- UMR 5212: Modélisation et Imagerie en Géosciences the chain in two domains: oriental and occidental. - Pau, CURS-IPRA, Université de Pau et des Pays de l’Adour, In the occidental part, faults are less apparent than the two avenue de l’Université, 64013 Pau cedex, France. first fields, because of the dominance of Infracambrien 2 Dynamic Graphics Inc., 1015 Atlantic Avenue, Alameda, CA formations. Faults have generally the same directions as in the 94501-1154, USA. E-mail : oriental Anti-Atlas. 3 Laboratoire de Télédétection, Département de Géographie, FLSH, Université Saint Joseph, BP175 208 Beirut, Lebanon. Key words: Faults, Remote sensing, Proterozoic, Anti-Atlas Modern geology needs accurate representation of The role of FOSS GIS for various applications in heritage underground volumes. Because 3D geological modelling has preservation of the Atlas Mountain Ranges, Morocco been so far based on the interpretation of expensive 2D and 3D seismic surveys for the oil industry, it has not been much Peter Löwe, & Ralf Löwner used in water exploration and exploitation. We present a way GeoForschungsZentrum Potsdam, Telegrafenberg A3, 14473 to generate accurate and efficient 3D geological maps using Potsdam, Germany already existing and inexpensive data sets, in a context of fresh The Atlas Mountain Ranges of Morocco has the ideal water management in the Beirut watershed (Lebanon). Our natural and cultural resources to use them for sustainable approach is based only on surface information coming from a development to advantage the local Berber population. published geological map, remotely sensed data, and a Digital Therefore, the Geopark concept, as defined by the UNESCO, Elevation Model (DEM). In order to generate the 3D geological is an instrument to protect and conserve this highly sensitive map, we used a 3D geological modeller that combines and heritage and to sustain the economic future of the region. To extrapolates the surface information into a coherent 3D data foster communication among the stakeholders for such an set, to represent volumes. We also simulate the porosity of one undertaking, a Geographic Information System-based (GIS) potential aquifer as an example of a method to quantify data infrastructure could be set up to compile relevant data groundwater reserves. and produce maps to support the fact finding and discussion Middle East and North African regions are recognized as process. the driest and most water scarce in the world. This lack of Hereby, Free Open Source Software (FOSS) facilitates the water is increasingly affecting economic and social realisation and guarantee international interchangeability and development. This area represents 5% of the world population independence from proprietary technologies. It enables the with less than 1% of available world’s freshwater resources. use of sophisticated software tools for research, teaching and While conventional water availability remains relatively commerce. Apart from other benefits this approach enables constant, the demand is increasing sharply as a result of the application of such tools in fields which for financial reasons population growth, increase in household income, and could otherwise not afford them. irrigation development. To meet this increasing demand, groundwater is being extracted well beyond the renewal rate. At least in Europe this is applied also to regional institutions Knowledge of underground geology, directly linked to focusing on heritage preservation. underground water resources, is therefore a key factor for industrial growth and social welfare. It will soon become crucial

The First MAPG International Convention, Conference & Exhibition 53 Marrakech Convention Center, October 28 - 31, 2007 in societies under development. Our pioneering technique variations of the topographic surface, indicating discontinuities provides for the first time a unique way to qualify and quantify being able to be of geological origin: lithological and, or, fresh water reservoirs, allowing decision makers to plan ahead structural. However, these deformations are barrier to the for appropriate water exploitation. localization and the quantification of these objects.

Key words : 3D, modelling, water, resources We modelled the geometric deformations of the SAR sensor and we propose a graphic method allowing to quantify Conception object oriented d and integration a geological the dip of the geological object. Knowing parameters of data basis in a mobile GIS: acquisition, this model can be inverted in order to compute the Geological Electronic Notebook dip and strike of the slope that has generated the geometric Noamen Rebai1, Samir Bouaziz2, Mohamed Soussi3, deformation between a scene in radar geometry and a scene Mohamed Moncef Turki1 in orthorectified geometry. This graphic method is not affected 1. Faculté des Sciences de Tunis ; Département de Géologie by artifacts of the Digital Elevation Models and its derived -2092 El Manar 2, Tunis-Tunisia calculations. The ground validation of this method has been 2 Ecole Nationale d’Ingénieurs de Sfax. Route de Soukra 3038 achieved in the southern Tunisian Atlas and attests of a Sfax-Tunisia standard deviation lower than 7°. In the absence of ground data, this method can thus be used to increase dips points The study aims to facilitate the geological survey necessary to the realization of a 3D geological model. understanding by developing a GIS tool integrated treatment Key Words: RADAR, dip, modeling and graphic representation using object oriented concept.

This tools integrates a database called “Satellite Database” Contribution of the GPS in the Exploration of the pipeline that is a database with several objects clustered around a core. State by the use of the Intelligent Pig The core consists of fundamental data including tectonic Mohamed Choura paleontology, etc surrounded by modules of treatment or Researcher, University of Sciences of Sfax, Geotechnical calculation and modules of graphic representation. Laboratory, BP 802, Sfax, 3018,Tunisia.

The main interest of this concept is to offer users the Crude oil produced from wells is treated in a separation unit possibility to modify, to insert and to suppress the database then stored in tanks from which it is sent to the terminal via objects. pipeline. This part of facility is vital for the economy and environment; it should be inspected regularly within a The developed tool offers the ability to superimpose framework preventive program. different layers of information having the same referential system of coordinates and integrate them into Geographic The pipeline must be protected externally and internally: Information System ready for Notebook use, which would help field workers in their surveys and analyses. Externally by the cathodic protection;

Keywords: Database, Notebook, GIS, Field Work, Object Oriented Internally by the chemical injection.

Despite the protective means, corrosion occurs all the time Exploitation of the Radar Images Geometric Deformations to in different points. The quantification of dips and 3d modeling Emmanuel Pajot1,2, Jean Paul Rudant1 and Damien Dhont2 If we do not comply with the preventive maintenance 1 Laboratoire Geomatériaux et Géologie de l’Ingénieur, program, a catastrophe may occur. So, to avoid this situation, Université Paris-Est Marne la Vallée, Institut the use of the Intelligent Pig, mainly after using the pipe for 10 Francilien des Sciences Appliquées, 5, bd Descartes, Champs years, is a prime necessity in order to get an accurate state of sur Marne, 77454 Marne-la-Vallée France the line enabling the management team to take the right [email protected] decisions before being under the necessity of a total shut- 2 Laboratoire Modélisation et Imagerie en Géosciences Pau, down of the production site and having to face environmental Université de Pau et des Pays de l’Adour, Av. de matters such as depollution, penalties, authorities. l’université BP 576 64012 Pau Cedex France Although pipelines are considered as the safest means of Geometric deformations generated during the acquisition bulk transportation for hydrocarbons when compared with by spaceborne RADAR (Radio Ranging And Detection) sensor others (rail, road, barge), some failures do occur resulting in are directly linked to the properties of acquisition : elevation of spillages (pollution). the sensor, direction of the pulse, angle of incidence and topography. Those geometric deformations emphasize the

54 The principal causes of failure are: mechanical failure, mapping the surface of the Earth over large areas. However, operational error, corrosion, natural hazard and third party the low spectral resolution of multispectral sensors obstructs activity. geological and mineralogical applications. Many minerals and rocks have unique spectral signatures with characteristic Pipeline Inspection and Monitoring Methods: absorption features that are 10 to 20 nm wide. Imaging Prevention of external corrosion starts with the design and spectrometry or hyperspectral remote sensing allows depicting installation of the appropriate pipeline coating and cathodic these narrow features and thus mapping surface mineralogy protection system. based on spectral image characterization. The significance of hyperspectral remote sensing relies in its capability to acquire If there is a risk of internal Corrosion, this can be combated a full reflectance spectrum for each pixel in the imagery. The by some appropriate operational methods, e.g. regular pigging reflectance spectrum in the 400-2500 nm region can be of the pipe-line by sending spheres or pigs through the line to utilized to identify a large variety of surface cover materials, prevent the settling of water at low points along the route, which is not possible with broadband sensor technology. and/or in certain cases the use of some appropriate corrosion Moreover, digital image classification is a technique that is inhibitors. widely used to classify each individual pixel in an image based on the spectral information in order to create lithological or The occurrence of internal/external corrosion may be geological maps. Various classification algorithms have been determined by means of special corrosion inspection tools used in the past decades in a variety of applications for sent through the pipeline with the medium acting as a mapping. The main disadvantage of these algorithms is that propelling agent. each pixel in the image is compared to the training site We start talking about the “Intelligent Pig” as a special signatures identified by the analyst and labelled as the class it corrosion inspection tool. most closely “resembles” digitally. Linear spectral mixture analysis (LMSA) is different from these standard classification Tool description: methods. The fundamental assumption of LSMA is that - Target: It is built to detect each loss of material (internal generally each pixel on the Earth surface is a physical mixture and/or external), to locate accurately the position and the of several constituents weighted by surface abundance. The degree of it using the GPS’s capabilities. NASA has used the LSMA successfully for geological mapping - Principle: The tool is equipped with 16 Magnets powered and for identifying potential mineral exploration sites with the by a set of batteries. Over-magnetisation induces a Magnetic use of the “USGS Spectral Library” as reference spectrum. Flux within the pipe walls between the poles. An anomaly leads to a magnetic dispersion. This research reports on the geological and mineralogical mapping of central Jebilet near to Marrakech in Morocco using Each anomaly is well located (X, Y, Z, ?° ), and stored, after hyperspectral Hyperion (EO-1) imagery and LSMA. This study the end of survey, a complete data treatment allows the area is located in the Paleozoic terrain of central Jebilet, which engineer to get an accurate and clear general idea about the is characterized by a lithological diversity, semi-desert pipe state. environment, significant mineral potential and consistent geological setting. The Hyperion data were acquired on May Mineral Exploration in Semi-arid Environment Using Hyperion 23, 2005 over the study area. The data were corrected for a (EO-1) Hyperspectral data spatial shift between the VNIR and SWIR detectors, striping, A. Bannari 1, K. Staenz 2, S. Brunet 3, A. Saquaque 3, A. dead column, noise, and gain and offset errors. Then, Zegan 3, A. Radnaoui 3 and R. Hitchcock 4 atmospherically corrected using the MODTRAN 4.2 code, and 1 Remote Sensing and Geomatics of Environment Laboratory, transformed to surface reflectance, corrected for sensor smile Department of Geography, University of Ottawa, (1-3 nm shift in VNIR and SWIR), and post-processed to Ottawa (Ontario) K1N 6N5, Canada remove residual errors. Finally, geometric distortions and relief Phone (613) 562-5800 (Ext. 1042), Fax (613) 562-5145; displacement effects were corrected using a digital elevation 2 Alberta Terrestrial Imaging Centre, model. In order to extract the rocks and minerals fractions, the 817- 4ht Avenue South, Lethbridge (Alberta) T1J 0P3, Canada image was unmixed using a constrained linear spectral 3 Reminex, Groupe de l’ONA, Marrakech, Morocco unmixing algorithm considering the entire spectral range (427- 4 Prologic Systems Limited, Ottawa (Ontario) K1P 5E7, Canada. 2355 nm). Endmember spectra were collected in the field on December 2004 from different rock samples using an Multispectral remote sensing has been widely used in the Analytical Spectral Devices (ASD) Spectroradiometer operating past decades to discriminate different rocks and minerals in the visible and the infrared (325 to 2500 nm). The average of based on the dissimilarity that exist among their spectral twenty spectra was convolved with Gaussian response profiles properties. Geological applications could greatly take to match the bandwidths and the band centres of the Hyperion advantage of this technology because it allows observing and EO-1 sensor. Fractions for each sample point were extracted

The First MAPG International Convention, Conference & Exhibition 55 Marrakech Convention Center, October 28 - 31, 2007 from unmixing results and compared to the reference On the south side of the Eastern Central High Atlas, in measurements in the field. The results will be presented, North of Errachidia, the transition between the shallow plate- discussed and validated to the ground truth. form to the subsident basin is marked by a permanent flexuration zone, along the Tizi n’Firest Fault. At the top of Methodology using remonte sensing and GIS for mapping lower Sinemurian, a system of bioconstruction represented by areas at risk of water-erosion: Atlas of Beni Mellal as a case sponge mounds was established along this zone. The Tizi Bent study (high Atlas of Morocco) Hazim Sponge Mound, studied for the first time, is a part of this system. This cone-shaped building overlies the Idikel dolomites Bahija Bachaoui1, El Mostafa Bachaoui*1, Abderrazak El and massif limestone formation and marks the transition Harti1, Abderrazak Bannari2 et Abderrahmène El Ghmari1 between the lower and upper Sinemurian. It is characterized by 1 Equipe de Télédétection et de SIG appliqués aux the abundance of well conserved forms of spongiaires which Géosciences et à l’Environnement, Faculté des Sciences et are associated with branched corals and big lamellibranchs Techniques, BP 523, Béni Mellal, Maroc. dispersed in a greyish micritic mud with pelletoidal pockets. Its 2 Département de Géographie, Université d’Ottawa, Canada. sequential organisation shows apparently two successive Soil erosion by water is the most important degradation modes of evolution: 1) the keep-up mode during an eustatic problem world wide. in order to protect the soil resource, it is rising and the high sea-level, corresponding successively to therefore essential to apprehend erosion risk. Water erosion is ante-mound deposits and to the mound deposits; 2) the Give- controlled by climatic characteristics, topography, soil up mode which announces resignation of spongiaires mound properties, vegetation, and land management. by drowning.

The aim of this study is to develop a methodology using The accretion by retrograding model, which is based on a remote sensing and geographic information system (GIS) to sedimentary study linked to a sequential analysis, shows the map zones at risk of erosion by water in Beni Mellal Atlas (high interaction between eustatic level and tectonic processes. This Atlas of Morocco) and to produce a risk map that can be used later is linked to a both gradients; tectonical gradient assuring as a reference document for planners. The presented the opening of the south atlas margin by a system of tilted methodology consists in endowing GIS with three factors that blocks northward overbalanced and WNW-ESE transverse control erosion: slope, friability, and ground occupation. The faults, limit these blocks and assure their eastward or derived erosion risk map shows four zones of vulnerability to westward tilting. This model allows explaining the erosion: weak, medium, powerful, and very powerful. The paleogeographic disposition of the equivalent build-up: powerful and very powerful zones cover more than 50% of the Tagounts and Bou Arhous reefal system. mountain zone uphill from Beni Mellal city and correspond very Key words. – Morocco, High Atlas, Liassic, Sponge mound, Sequence well to field observations. This methodology used seems to be stratigraphy. applicable to other areas of high Atlas, were erosion risk constitute a serious threat to agglomerations. The calciturbidites of the Lower Aaleno-Bajocien in the Key-words : water-Erosion ; high Atlas of Morocco ; methodology ; Northeastern Middle Atlas: Sedimentary organization and remote sensing ; GIS. geodynamic context M. Nassili, M. Laadila, M. Ahmamou, A. El Kochri & M. Hadri SS 02 : 3rd Meeting of the Moroccan Jurassic Faculty of the Sciences, University Mohammed V-Agdal, Ave System Atlantic and tethyan Margins : Ibn Battouta, B.P. 1014, Rabat Geodynamics during the Jurassic time Chair : A. Souhel, M. Ettachfini In the northeastern Middle Atlas (“ride anticline of the Jbels Haloua-Richa – Kebibicha”) during lower Aalenian-Bajocien, The Tizi-Bent-Hazim spongE Mound (Late Sinemurian, south morpho-structural differentiation in “rides” and “depocentres” versant of Centrale Eastern High Atlas, Morocco): are clearly expressed by a calciturbiditic sedimentation, Identification and mode of edification characterized by the generalization of the gravitating deposits A. Kaoukaya1, M. Laadila2 A. Hilali1 L. Baidder1 A. El Kochri2 of slope and bottom of slope, materializing the repetitive et A. Benbouziane3 phases of progradation in relation to the periods of marine 1 Département de géologie, faculté des sciences, Université fluctuation. Hassan II B.P. 5366 Mâarif- Casablanca Ain-Chock In the basal Aalenian-Bajocian (“Calcaires à 2 Département de géologie, faculté des sciences Agdal, Cancellophycus”), the predominance of this chaotic Université Mohammed V Rabat, [email protected] sedimentation (“calciturbidites”) giving breccias (debris flow) [email protected] and slumps where the last ones of biodetritic, oolitic and 3 Département de géologie, faculté des sciences Casablanca encrinitic accumulations are intercalated, with broken and used Ben M’sik elements. These resedimented deposits, mark filling partial of

56 the mediums, and testify to shallow platform with emerged and direction). The anticlines are often tight and faulted and the eroded feeding the furrows in allochthonous material, which synclinal broad and at flat bottom. The directions attributed to explains the mixture of littoral facies and basin. Allochthonous this event are NE-SW and N-S. fauna is consisted a mixture of benthic and pelagic forms. The alpine phase: Started in the Miocene with two The sedimentary organization reveals a succession of three directions NW-SE and E-W .The structures of this system line sequences of deposits (SDAa1, SDAa2 and SDAa3) a succession of concentric arcs with convexity towards the composed by dissymmetric parasequences showing slumps South. The folds are of cased style, regular; the anticlines and and nodular limestone, characterizing the shelf margin system the synclinal have comparable dimensions. tract (SMST); the transgressive system tract (TST) is Keywords: Guercif Basin, seismic lines, Jurassic, Atlasic, Alpine, constituted by marls and marl-limestones to ammonites, and Miocene the highstand system tract (HST) constituted by a black limestones in Cancellophycus (Zoophycos). The role of old paleogeography and paleotectonic in In lower Bajocian (“Marnes de Boulemane”), the gravitating differentiation of terrigenous jurassic in Western- deposits, constitute an exceptional indicator of the phases of Maghrebian Tethyian margin. marine fluctuation, especially in overall transgressive period. Aïssa Masrour1, Mohamed El Maâtaoui1, El Maati El Faleh1 et They define atypical sediments which materialize of the Siham Assaoud2 changes or a “blocking” of the sedimentary processes, 1 UFR “Geology of fossil energies”, Department of Geology, probably of a climatic or tectono-eustatic nature. Cyclicity of Faculty of Science of Meknes. these allochthonous sediments “prograding” coming to 2 Department of Geology, Faculty of Science of Fes. interfere the “retrograding” sediments autochthnous. Their identification, defines a remarkable sequential setting (SDBj 1, The terrigenous Jurassic differentiation of Western- SDBj2 and SDBj3) in the formation of the “Marnes à Maghrebian Tethyian margin is mainly controlled by posidonomies”. paleogegraphic and tectonic structures of underlying basement. The Middle Jurassic synsedimentary tectonic is Key Words: Middle Atlas - Aalenian- Bajocian - Calciturbidites - expressed on two levels. The first, of provincial dimension, is Sequences deposits. linked to transform fault, betwen European and African continental margins, which reworks the great Hercynian The Jurassic evolution of Guercif Basin fractures and defines the main geometry of sedimentary Reconstructed from seismic line interpretation basins. The second, of regional dimension, is linked to jerk H. Attar1, A. Chalouan2 and M. Alji3 differential subsidence expressed by tilled blocks which defines 1 Departement of geology, University Mohamed V, Faculty of several paleogeographic zones. The sedimentary landscapes sciences Rabat Agdal show lateral transition of subcontinental area (Atlas saharan) to 2 Departement of geology, University Mohamed V, Faculty of deep marine area (Riffian domain). sciences Rabat Agdal 3 ONHYM, 34 Avenue Al Fadila, 10050-Rabat Key words: Dogger-Malm / terrigenous deposit / paleotectonic / paleogeography / western Maghrebian Tethys The Guercif Basin is a depression of the African margin of This work is carried out within the framework of PROTARS III - D15/26: Théthys, made of Jurassic grounds filled by a discordantly “Knowledge and valorization of the oil potential of Prérif and the south- tertiary series. It is included in the Taza-Oujda corridor and is Riffian furrow” located in the prolongation towards the North-East of the Middle Atlas and the High Plateaux. The phases and the tectonic evolution recognized in the Middle Atlas, also exist in Sedimentary evolution and palaeogeography of Upper Lias- the Guercif basin, because the structures of this last are Dogger deposits of the Central High Atlas, Morocco septentrional prolongations of those of the Middle Atlas. Abdellah Aitaddi Université Cadi Ayyad, Faculté des Sciences et Techniques, The present study is based on the interpretation of 8 Dépt. des Sciences de la Terre BP: 549-Guéliz, Marrakech- seismic lines 03 ML (300 km) acquired by the ONHYM in 2003, MAROC ; e-mail : like some several old lines to show the structural evolution of this basin during the Jurassic and consist to prove that this In the central part of Moroccan central High Atlas, Upper basin is the result of two compressional events: Atlasic and Lias-Dogger series are represented by two formations of clay, Alpine. Opening and filling of the basin preceded each event. marl and carbonate deposits (Agoudim and Tazigzaout formations). On the margins the equivalents of these two The atlasic phase: Started in the Cretaceous and show formations are carbonates and presented lithological and folds of direction ranging between N30 and N50 (atlasic environmental characteristics of Bin El Ouidane Group. This

The First MAPG International Convention, Conference & Exhibition 57 Marrakech Convention Center, October 28 - 31, 2007 Group is overlying by clays and limestone of Tillouguite Structural aspects and reservoir rocks of Prerifan Ridges formation and by silts, sandstones and conglomerates of (Prerif, Morocco) Anemzi formation. Ali Charroud1, Driss Nachite1 , Kacem Souid2 , Bouazza Fedan3, Mohamed Mokhchane4 From Toarcian to early Bajocian (Agoudim members I and Département de géologie, Faculté des Sciences, B.P. 2121, II) a contrasted palaeogeographic evolution is marked by a Université Abdelmalek Saadi, Tétouan ; relatively deep central basin bordered by shallow marine Département de géologie, Faculté des Sciences et techniques carbonates. The Aalenian-Lower Bajocian interval (Agoudim Fès-Saïs, Université Sidi Mohammed Ben Abdellah , Fès ; member II) shows the arrival of channels of biodetritic Institut Scientifique, Avenue Ibn Batouta,B.P. 703, Agdal, limestone within hemipelagic deposits. These facies resulted Université Mohamed V, Rabat ; from recurrent faulting activity which was at the origin of the Ecole Normale Supérieure, Tétouan, Ministère de la formation individualisation of a series of ridges and depocenters within des Cadres, Martil. the High Atlas trough. The geology of Morocco reflects its position at the During the Bajocian (Agoudim member IV) the Northwest extrimities of the alpine orogen of North west african palaeogeography was homogenised on all the central High margin. A great investigations have been concentrated on Atlas and correspond to a carbonate ramp with coral patch mesozoic and cenozoic stratigraphy and structural evolution of reefs. The Upper Bajocian (Tazigzaout basal member) shows a the Atlas system of Morocco and the Rif mountains. The alpine new palaeogeography with reappearance of deep zones in the cycle falls into two successives phases : the first phase is the central depocenters. During the Upper Bajocian-Bathonian pp. tethys conquest and the later is the central atlantic openning in (Tazigzaout upper member) again a very homogeneous the mesozoic . In the early cenozoic times, the tethys is closed carbonate ramp was established. These uniform and started the convegence between Africa and Europe. palaeogeographic situation corresponds undoubtedly to a stable tectonic regime announcing the end of the Jurassic The prerifan ridges in Morocco represented an example of sedimentary cycle. evolution in the boudary between the Atlas and the Rif mountains. In the prerif area, the specific geotraverse from Sidi Structural relation between the High and the Middle Atlas Kacem- Moulay Driss Zerhoun is located in a central position Mountains (Morocco) during the Jurassic-Cretaceous between Gharb basin, Sais basin and the Rif mountain. transition The basin basement is represented by various paleozoic Ralf Löwner1, Abdellatif Souhel, Joseph Canérot, Wilhelm series witch were folded and metamorphozed during the late Dominik stages of the hercynian orogeny. The unconformable mesozoic 1 GeoForschungsZentrum Potsdam, Telegrafenberg A3, series are composed of many successives sequences : the 14473 Potsdam, Germany oldest, of late triassic and earliest liassic age is made of clastics A geological map (1/50.000) of a key-region of the sediments, sandstones and argilites infilled basins ; the Northwest border of the Atlas Ranges of Morocco has been younguest, mainly dolomites, limestones, red marls and realized by using observation and measurement data from the silicoclastics (rich oil reservoir) in the early liassic platform. The field as well as remote sensing data and the rare already Domerian is characterized by carbonate platforms with the existing cartographic works. The region of Aghbala-Naour is internal limestones, the Toarcian is represented by deltaic situated at the articulation of The Middle and High Atlas and mudstones and calcareous repere strata. The Dogger is the Haute Moulouya plane. In comparison with the Beni Mellal characterized by deposition of varied facies, mudstones, region in the Southwest, it enables the discussion of the limeostones and oolitics sandstones (hot porosity). sedimentologic and tectonic evolution of the western slope of The structural and seismic datas in prerif ridges, have show the Atlas ranges. development of an assymerical and complex structures in After the permo-triassic red-bed sedimentation, which differents axes : covered the whole region and presented a typical rifting state the axe of J. Boudra, J. Outita, Si Moulay Yacoub to J. of an intracontinental basin, marine transgressions introduced Boulaas with complex active faults (N20-N30) ; the differentiated distribution of sedimentary basins, as the High and Middle Atlas troughs. Complexes transtensional in the west zone, the Sidi Fili axe with active senestral systems of extension and local compression movements since strike-slip faults (N00-N30), deformed the jurassic series and the Lower and Middle Jurassic dominated the sedimentation the internal sandstones ( reservoirs producing oil) ; during Mesozoic times. The transition from a Tethys supported sedimentation to an Atlantic regime is recorded in the Upper in the east zone, the famous axe between J. Selfat , Guennouffa Jurassic and Lower Cretaceous mostly red bed sediments. and Zerhoun ridges (N10-N150), implicate the successively imbricate ramps within an active depth flower structure ;

58 the axe between J. Kafs, My. Driss, Tekerma to Gannouffa Keywords: Mirror; Moroccan continental margin; Crustal Structure; with the acive faults (N90-N120) and it’s prolonged to the other axe in the North of J. Nesrani, J. Smed and Dhar Nssour, this Mesozoic kinematic evolution of the Central Atlantic axe is similar and complex as the last one. C. Labails1,2, J.-L. Olivet2, D. Aslanian2, B. Sichler2, W. Roest2, M. Evain2 and P. Unternehr3 The reactivation of all depth faults has be defined various 1 NGU, Norway, structures and deformations in the middle jurassic attractive 2 Ifremer, France, reservoirs in this area implying dismigration of oil stocks 3 Total France between each faults. The activity of all axes is not synchron, but the major characteristics implicate a very intersting results The magnetic anomaly signature of Central Atlantic by ONHYM Explorations in anticline structures like this margins is well defined by the gridded data published by geotraverse of prerifan ridges with good production in the Verhoef et al. (1996) on the North American region. However, a North west onshore zone. gridded dataset for the West African margin (South of the Canary Islands) was lacking. We have used magnetic data Keywords : Morocco, Prerif , Ridges, stuctural, reservoir from the Geodas database, an Ifremer dataset and personal Acknowledgement : Thanks of all 3th C3jma congress comite(El communication from H. A. Roeser and W.J.M. Van der Linden Jadida) and Misters A. Morabet et H. Jabour of.ONHYM in order to produce a gridded magnetic data of the Dakhla margin and to better constrain the kinematics of Central Mirror (The deep Moroccan margin as imaged by Reflection Atlantic early opening. and Refraction seismic data : Ocean continent transition of a Our model adopts the breakup timing of 195 Ma as Rifted margin) a project to study the crustal structure of the proposed by Sahabi et al. (2004) - 20 myr earlier than what Moroccan continental margin was generally proposed in previous models. According to our -D. Aslanian1, F. Klingelhoefer1, J.-L. Olivet1, M. Sahabi2, J. interpretation of the newly compiled magnetic data, the early Perrot3, D. Graindorge3, P. Leroy3, M. Rabineau3, M.-A. opening of Central Atlantic was characterized by three distinct Gutscher3 phases. In contrast to other models, we propose that for the 1 Ifremer, France, first 30 myr (195-165 Ma, Lias-Dogger) the oceanic accretion 2 University. El Jadida, was extremely slow (~0.8 cm/y). At the Blake Spur time, 3 Faculté des Sciences (around 165 Ma, Callovian basis), a drastic change occurred, 4 Univ. Brest both in the relative plate motions (initially NNW-SSE, it becomes NO-SE) and spreading rate (that increases up to ~ The NW African margin of Morocco formed during the 4.8 cm/y). The BSMA (Blake Spur Magnetic Anomaly) is related lower Jurassic and is one of the oldest in the world. Together to a great basement topographic change. From magnetic with the conjugate Canadian margin it represents a key to chron M22 (150 Ma, Tithonian basis) onwards, the spreading understanding the formation and evolution of passive rate slowed down to about 2.6 cm/y and remained constant continental margins. until magnetic chron M0 (125 Ma, Barremian-Aptian limit). Ifremer, the universities of El Jadida, Brest, Lisbon, and Total have jointly conducted two deep seismic cruises on the Keywords: Mersozoic; Kinematic; Central Atlantic; Lias-Dogger northern and southern morocan continental margin. Results from these cruises are presented in this meeting. A third On the intracarixian unconformity into initial carbonates survey, planned for 2008 (project - MIRROR), will include wide- platform of the Ouarsenis Block (Tellian Domain, Algria) : angle and reflection seismic data acquisition in order to image Siginfication and consequence the deep structure of the morocan continental margin along Miloud Benhamou and Mohamed bendella the conjugate of a deep profile (SMART-2) off Nova Scotia. 3- D data will be acquired in two regions of particular interest: Université d’Oran, Faculté des Sciences de la Terre, de Geographie et magnetic anomaly S1 (the conjugate of the East Coast d’Aménagement du Territoire, Département des Sciences de la Terre, Magnetic Anomaly, and close to the ocean-continent Laboratoire de Magmatisme et Synthèses Géodynamiques des Bassins Algériens transition) and the edge of the continental platform (10-12°W and 32-33° N). Imaging these structures will allow testing of The Ouarsenis area is localised on southern border of hypotheses regarding the origin of magnetic anomalies (the external tellian domain. Here, the tectonic has provoked a local expression of massive basalt flows - SDR?s ?) and testing of evolution of the Liassic initial platform. rifting models which commonly propose low-angle detachments allowing mantle exhumation during continental The carbonate in the Ouarsenis (Algeria) was deposited at breakup. the beginning of the Jurassic period by the “Carbonate of Kef Sidi Amar” probably during the Late Sinemurian-Early

The First MAPG International Convention, Conference & Exhibition 59 Marrakech Convention Center, October 28 - 31, 2007 Pliensbachian (Early Carixian) belonging to the Alpine belt. success- fully establishing reservoir architecture and fluid-flow Three lithostratigraphical members superposed : lower trends. Data from Gamma Ray, Neutron, Density, Sonic dolomites, calcareous or dolomitic tidalites and massive and Resistively logs was utilized for petrophysical analysis to oolithic limestones corre- late layers in this reservoir characterization study. Petrophysical evaluation of the Shale Sand gas reservoir The Late Carixian (Ante-Demonense zone) is interrupted by (TAGS) of the Rhourde Hamra field, using conventional well log a forced regression documented by a type 1 unconformity. The interpreted techniques and relating the results to core data, sedimentologic data are numerous varied and, often, shows that the reservoir is of very good quality. spectacular. They include several types of emersion markers : tidalites, loferites of teepees, desiccation breccias, vadose- Triasic rupture and Liasic marine invasion in the Lusitanian pisolites. These figures document erosion (incisions) and karst basin (Portugal) – a shift from tectonic to thermal (widening of desiccation or tectonic fissures) episodes associated with magmatism. It has been followed by a sea- subsidence level fall documented by several meters incisions filled by a R.P. Pena dos Reis1, N.L.V. Pimentel2 and A.J.V. Garcia3 fluvial sequence (conglomerate, sandstone, argileous and 1 Dep.Ciências Terra, C.Geociências FCT, U.Coimbra. Lg. Mq. pedogenetic clay with glaebules). After this episode, the Pombal, 3049 Coimbra. platform became uneven and shoals differentiated from more 2 Dep. e Centro Geologia, FCUL. Campo Grande C-6. 1749- subsiding small umbilics. In this sitting, the “Djorf Touka 016 Lisboa. carbonate Formation” (Middle and Lower Carixian) has been 3 Núcl.Est.Rec.Nat./D.E.A., Univ. Federal de Sergipe, Aracaju- accumulated. The detritical material proves that the platform SE. has partially emerged and formed, at the same time, a sort a The Lusitanian Basin is a peri-atlantic basin, related to the nearby palaeogeographic cordillera which has received a opening of the Northern Atlantic. The first rifting phase is strong erosion. This sedimentation suggest, also, a large related to the beginning of crustal stretching and Pangaea latitudinal extension of the warm climate and strong contrast of break, initiated on Upper Triassic (Carnian) along late-variscan humidity. basement fractures, oriented mainly NNE-SSW. Several listric The initial platform environment marks the beginning of the fault movements defined multiple grabens and semi-grabens individualisation of the basins inside of the western Tethys. filled up by alluvial clastics, laterally digitating with clayey and evaporitic deposits. Key words : Unconformity, Karstification, Emersion, Incision, Carixian, Carbonates, Ouarsenis The first triasic sequence is composed of coarse deposits of fans and ephemeral rivers, grading to silts and clays Petrophysical analysis in reservoir characterization – deposited at shallow lacustrine and evaporitic environments, application in the triassic Hamra Gas Field, Algeria. defining a retrograding succession. The second sequence is Eladj said et Rafik baouche composed of coarse to fine sands, deposited by braided rivers University of boumerdes Algeria in a broad alluvial plain, grading upwards to pelitic and thin dolomitic facies, wich present an overall onlap geometry. Petrophysical evaluation of the Upper and Lower shale gas Thickness variations of these two sequences suggest lateral sand reservoirs of the Sahara field, using conventional well log shifting of depocentirc areas and geometries of basement interpretation techniques and relating the results to core data, onlaping by the triassic deposits. shows that the Upper reservoir is of very good quality and ap- apparently better than the Lower reservoir. Evaluation of the A third sequence is initiated by a thin flux of siliciclastics, petrophysical parameters from the wells in the field show rapidly passing to clays with evaporitic layers and dolomitic porosities ranging from 12 to 20% and perm abilities of about limestones with an Hetangian poor fauna. In some depocentric 500 mD, which are similar to regional values of 12 to 20%. sectors of this basin, with shallow lagoons and peri-tidal sabkhas, hundreds of meters thick evaporitic deposits with Porosity and 1000 mD permeability. A cross plot-based gypsum, halite and clays were accumulated. litho- logical study shows that the matrix is dominantly quartz, with calcitic and dolomitic cements, a high percentage of These deposits have been covered by tens of meters of montmorillonite clays, and a smaller percentage of illite and dolomitic limestones with marly intercalations and a rich marine micas. A study of lateral variations of petrophysical parameters fauna of Sinemurian age, associated to the beginning of the shows that porosities increase from NE to SW, similar to the post-rift subsidence. A low-energy carbonate ramp has been saturations. This study shows the role of wire line petrophysical installed thereafter, rapidly opening to a deep marin influence in analysis as a tool in reservoir characterization of shale sands in the Pliensbaquian, as a result of significant thermal subsidence the Sahara field. This paper examines the use of log analysis throughout the Lower Jurassic. and means petrophysical reservoir parameters as a tool in

60 All this evolution has taken place at the Lusitanian Basin in basins (e.g. Peniche and North Newfoundland). around 30 Ma, showing a good example of rapid shifting from Key words: North-Atlantic, Portugal, Lusitanian Basin, Mesozoic, tectonic to thermal subsidence in a peri-atlantic basin. Basinal Events Key words: Triasic, Liassic, Portugal, Subsidence Tithonian extension by double flat listric faults in the Sierra The Lusitanian Basin (Portugal) and its north-american de Crevillente (Betic, SE Spain) counterparts - a comparative approach J. E. Tent-Manclús, J. E. Caracuel, A. Estévez, A.Yébenes N.L.V. Pimentel1, R.P. Pena dos Reis2 and A.J.V. Garcia3 Dpto. Ciencias de la Tierra, Univ. Alicante. Apdo. 99, 03080 1 Dep. Geologia e Centro Geologia, FCUL. Campo Grande C- San Vicente del Raspeig, Alicante - Spain. 6. 1749-016 Lisboa. The “Congost” outcrop located to the southern side of the 2 Dep.Ciências Terra FCTUC, C.Geociências UC. Crevillente Sierra (Alicante Province, SE Spain) shows a Rosso Lg.Mq.Pombal,3049 Coimbra. Ammonitico facies (RA) of Late Jurassic in age faulted, eroded, 3 Núcl.Est.Rec.Nat./D.E.A., Univ. Federal de Sergipe, Aracaju- and unconformably overlied by the Late Albian grey marls and SE. marly limestones. The RA lies over a regional unconformity The Lusitanian Basin (LB) is a peri-atlantic basin, related (hardground with ferruginous crust) developed during the Late with the Triasic crustal stretching and Jurassic opening of the Bathonian to Early Oxfordian. The ammonite assemblages in Northern Atlantic. On the eastern margin of the Atlantic, the LB the RA facies favoured a zone-level biostratigraphic control. is bordered by the Essaouira Basin (to the S) and the Galicia The Late Jurassic succession is composed by 10 m of marly Basin (to the North), whereas on the western margin, just RA (Middle-Late Oxfordian), then 15 m of dm-thick alternating opposite to the LB, the Grand Banks, with the Jeanne D’Arc marly/calcareous RA (Kimmeridgian-Early Tithonian pp.), and (JAB) and Flemish Pass (FPB) Basins are bordered by the finally, 35 to 60 m of dm-thick beds of RA limestones (Early Orphan and Wales Basins. Tithonian to the earliest Berriasian). In this Upper Jurassic succession, a set of listric faults can be recognized producing Assymetrical development between these non-volcanic a thickness variation in the Tithonian-Berriasian interval, opposite continental margins and its basins, involves aspects starting from the Verruciferum biozone (Early Tithonian). The such as crustal and litospheric rupture, and consequently the resulting listric faults converge down to the lower part of the tectono-sedimentary evolution of the related basins. This marly AR (oxfordian) becoming parallel to the stratatification, presentation deals with the comparison between the and thus forming a flat ramp which forms the upper sedimentary filling and events of the Lusitanian Basin and the detachment level of the listric faults. The recognized separation Grand Banks Basins. between listric faults is 50 m and their slips range from 20 to 30 m. Since the major detachment level in the Betic Cordillera The simple comparison between litostratigraphic and is the top of the Late Triassic Keuper facies, the studied faults events chart from the JAB/FPB and LB, points to a broadly are considered the upwards “horse-tail like” faults of one parallel evolution: master two-flats listic fault system. • Rift 1) Carnian – Sinemurian Rift, with Pliensbaquian - Key words: Listric faults, Betic Cordillera, Jurassic. Callovian Post-Rift;

• Rift 2) Oxfordian-Berriasian Rift, with Berriasian - Aptian New data from the Early Pliensbachian Tethyan ammonite in Post-Rift; the Central High Atlas (Morocco) Sarih Soumia1, El Hariri Khadija2, Dommergues Jean-Louis1, •Rift 3) Upper Aptian – Albian Rift, with Cenomanian - Chafiki Driss2, Garcia Jean-Pierre3 and Quiquerez Amélie1 Maastrichtian Post-Rift. 1. Centre des Sciences de la Terre de l’Université de However, some differences are to be noticed: i) at the LB, Bourgogne, Biogeosciences Dijon (UMR CNRS 5561), 6 both the 1st post-Rift unconformity (related to the drastic Boulevard Gabriel, F-21000, Dijon, France. opening to marine tethysean influences) and the 2nd Rift 2. Faculté des Sciences et Techniques, Département des unconformity (related to increased uplift and basin subsidence) Sciences de la Terre, laboratoire de Géosciences et are slightly older at the Lusitanian basin; ii) the 3rd Rift Environnement BP. 549, Boulevard Abdelkrim Khattabi, 40000, unconformity (related to the Grand Banks – Iberian break-up) is Marrakech, Maroc also older at the Lusitanian Basin. 3. Centre des Sciences de la Terre de l’Université de Bourgogne, (UMR CNRS 5594), 6 Boulevard Gabriel, F-21000, These timing delays may be due to the specific Dijon, France. geodynamic evolution of these asymmetric and opposite margins, as well as to the influence of other deeper off-shore A fauna recently discovered in the Central-Eastern High Atlas of Morocco allows the re-examination of the taxonomic,

The First MAPG International Convention, Conference & Exhibition 61 Marrakech Convention Center, October 28 - 31, 2007 stratigraphic and paleogeographical frameworks of with ONHYM, have led to a re-evaluation of the petroleum Pseudoskirroceras mastodon (Fucini, 1935), an Early system. Pliensbachian (Polymorphus - Brevispina sub-chronozones) Tethyan taxon probably restricted to the southern part of the The Zag Basin is one of three large, intra-cratonic basins western (Mediterranean) Tethys. (Reggane, Taoudeni, Zag) developed on the West African craton. These basins are filled with sediments ranging in age This taxa, which is the type-species of the genus from Infra-Cambrian to Late Palaeozoic. The Zag basin has an Pseudoskirroceras, have been for the first time collected in a almost complete sedimentary section from Infra-Cambrian to well-known stratigraphical context. Late Carboniferous (Stephanian), overlain by a thin veneer of Cretaceous sediments. Three biohorizons are known for the lower part of the Early Pliensbachian in the central High Atlas, successively the There is good evidence to indicate the presence of a viable Miltoceras taguendoufi biohorizon (El Hariri et al., 1996), the hydrocarbon system; over 60% of wells drilled reported shows Pseudoskirroceras mastodon biohorizon (proposed in the of oil or gas, and several recovered hydrocarbons from open- present study) and the Metaderoceras apertum biohorizon (El hole tests. Silurian and Late Devonian shales occur at outcrop Hariri et al., 1996). According to the biochronological in the northern part of the basin and have proven source rock interpretation proposed by El Hariri et al. (1996), this set of potential. At least four potential reservoir intervals occur within three biohorizons roughly corresponds to the Polymorphus the Ordovician, Devonian and the Carboniferous; these are and Brevispina sub-chronozones of the chonostratigraphic capped by regionally extensive shale seals. A number of large, standard scale and to the Mediterranean Miltoceras sellae long-wavelength, low-amplitude folds have been identified at biozone. outcrop. These structures have the potential to yield large volumes of hydrocarbons. These observations significantly reduce the usual meaning of Pseudoskirroceras which is actually a rare taxa, probably Recent studies undertaken by Petro-Canada and ONHYM strictly localized in the western Mediterranean Tethys and not a show that the Zag Basin has a complex burial and thermal pantropical genus. history, in common with the other western basins of North Africa (Ahnet, Timimoun and Reggane). Detailed basin Thus, the revised scope of Pseudoskirroceras is consistent modelling indicates that this basin has the potential for with the idea of a western Tethyan (Mediterranean) significant reserves of both gas and light oil. palaeobiodiversity which included many rare and localised taxa. Reservoir Rocks developments in the Moroccan Atlantic These results confirm that the Mediterranean (West Margin Tethyan) ammonite paleobiodiversity includes more rare and A. Ait Salem and M. El Mostaine: localized species that for example in NW Europe. ONHYM, Morocco

Key words: Ammonites, Early Jurassic, Western Tethys, Careful analyses of the existing onshore well data, outcrop Biostratigraphy, central High Atlas. sections and seismic data lead to identification of several potential reservoir intervals that have likely widespread Country Session: Morocco distribution in the offshore of the Atlantic margin of Morocco Chair: El Mostaine, A. Zain within the Mesozoic and the Cenozoic sections.

Petroleum Systems of the Zag Basin, Morocco Pre-Cambrian and Hercynian granites and meta-sediments L. Gillhespy1 and J. Exton2 in the Moroccan meseta, the Anti Atlas, the Tindouf and Adrar 1 Petro-Canada, 1 London Bridge, London, SE1 9BG. UK Soutouf, provide the main source of silico-clastic sediments. 2 Barrowden Consultants Ltd, 77 Clifford Road, Barnet, Herts The most favorable geological time laps identified so far are EN5 5NZ. UK in the Lower Jurassic, the Middle Jurassic, Lower Cretaceous Covering an area of more than 200,000 km? and and tertiary. Investigations on other potential intervals of the occupying parts of Algeria, Morocco and Mauritania the Zag Upper Cretaceous are still ongoing. Basin remains one of the largest prospective frontier basins in Following the Jurassic marine incursion in the central North Africa. Exploration drilling took place between 1959 and Atlantic, carbonate and shale sedimentation prevailed in 1971, based upon surface geology and a few lines of single various Atlantic margin basins. However, relative falls of sea fold seismic data. Drilling density in the basin is extremely low level in the Lower Lias and Lower Mid Jurassic lead to with an average of only one well in 13,000 km?. Extensive installation of fluvial and deltaic systems on the shelf and geological field work, the application of modern technologies turbidite complexes in the basin. and innovative exploration by Petro-Canada, in partnership

62 More than 100m and 300m of fluvio-deltaic conglomerates development) is the conjugate of the Mohawk Graben and sandstones of Upper Lias Amsittene and Middle Jurassic Complex. The Tafelney Plateau separates the Safi and Agadir Amskroud formations respectively crop out in the western High basins. Many aspects of the geology of the facing region of Atlas. coastal Morocco are analogous to those of Nova Scotia. Atlas Mountain tectonism complicates correlations in the Agadir and Areas with narrow shelf, north of the western meseta and Souss regions, though the localised events there are creating south of the High Atlas, constituted privileged entries of silico- new play opportunities. Overall, five play phases are clastic sediments into the basin and therefore even Upper recognised. From the base upwards, these involve: 1) the Pre- Jurassic carbonate sediments, are either rare or absent. Some drift (Hercynian and older) succession, 2) the initial rift (mainly 700m of Jurassic sands silts and shale are preserved on Triassic) succession), 3) the initial drift succession (Jurassic Fuerventura Island, indicating that clastics were transported carbonate dominated), 4) the main drift succession over the shelf and out into the deep environment. (Cretaceous and older Tertiary clastics) and 5) the End of Jurassic is marked by a sea level fall and short lived compressionally influenced succession (younger Tertiary). sub-aerial exposure of the carbonate shelf, leading to intense Existing production and development are associated with play karstification. Relatively rapid transgression of lower most phases 1), 2) and 3). New understanding driven by the pursuit Cretaceous was followed by prominent fall of sea level witch of basin dynamics through time is identifying the risks resulted in the development of mega deltaic systems across associated with the two youngest and also minimally explored the shelf. play phases. Considerable potential is emerging. Combination of this growing insight with the established play controls of the Laterally westwards, seismic shows evidences of channel Scotian Basin will further progress Moroccan understanding. In systems in the slope and basin floor fans development in the turn, Nova Scotia will gain from access to Moroccan ‘state-of- paleo-deep water. Further west, Lower Cretaceous distal the-art’ knowledge. sandy turbidites are exposed in outcrops on the Fuerventura Island and have been penetrated by DSDP wells. The Prérif domain and its forelands, Northern Morocco: Geology and petroleum play concepts The Tan Tan and Boujdour fans are tow of the many deltaic bodies that developed on the Moroccan Atlantic Margin during M. Dakki, M. Hssain, M. El Alji1 and R. El Abib, ONHYM the Lower Cretaceous. Yet further to the south in Mauritania The Prérif area, located in northern Morocco, constitutes and Senegal, lies tow other Lower Cretaceous deltas. the most external structural units of the Rif Alpine domain Base Tertiary is marked by an erosional unconformity. Uplift which includes essentially Mesozoic and Tertiary folded of adjacent hinterlands resulted in rejuvenation and the sediments overlaying the Palaeozoic basement. The Gharb, deposition of coarse clastics, probably of Eocene age. It is Saiss and Guercif basins constitute the main foreland basin of likely that the shelf areas were sub-aerially exposed and the Rif folded belt. sediments had by-passed the shelf in broad river systems and Sedimentary deposits, consisting of about 6000 m of deposited directly into mini basins on the slope and the basin. Mesozoic and Cenozoic sediments, covered by the complex of In the mid-Oligocene re-newed uplift, probably associated nappes overlain by Upper Miocene clastic sediments, resulted with the uplift of the Moroccan mesetas and inversion of the essentially, from the relative sea level changes during the Atlas Gulf, to form the Atlas mountain chain, led to tremendous complex successive tectonic phases of continental collision influx of silico-clastic sediments that were transported and plate divergence inducing the deposition of various westward, to form a depositional thick in the deep water area. sedimentary series ranging from continental and lagoonal carbonate and clastics to open marine deposits.

The petroleum geology of the Moroccan basins facing Nova From tectonic point of view, normal faults initiated during Scotia the rifting period were reactivated into high to medium angle Nick Cameron1, Haddou Jabour2 and Driss Bouhaddioui2 reverse faults, during Late Cretaceous to Early Tertiary times, 1 GB Petroleum plc inducing the development of various thrusts, folds and 2 ONHYM imbricates.

Some 850 km of Morocco’s Atlantic margin between Cap Petroleum exploration started as early as 1910 around Beddouza (Safi) and Cap Juby (Tarfaya) face Nova Scotia. surface oil seeps and surface anticlines, using mostly surface From north to south, the offshore Safi and onshore Essaouira geology, electrical profiles and poor single fold seismic data. basins (total discovered reserves 82 BCF and 5.5 MMBO/C) lie Exploration programs were concentrated within the southern opposite the producing Sable Island portion of the Scotian edge of the Prérif leading to the discovery of small oil and gas Basin, the offshore Agadir and onshore Souss basins tie with fields in Ain Hamra, along Sidi Fili fault and in the Prérif Ridges the Emerald Basin and the Tarfaya Basin (heavy oil (Haricha, Tselfat and Boudraa). The increase of Exploration

The First MAPG International Convention, Conference & Exhibition 63 Marrakech Convention Center, October 28 - 31, 2007 activities between the early 1960’s and the early 1970’s faulting and related growth faults generated subsidence resulted in the discovery of biogenic gas fields in the Gharb controlling sedimentation. In the onshore Rharb Basin, the basin. onset of the extensional collapse is recorded by deposition of coarse sandstone turbidites on the bottom of extensional mini- Successive integrated studies using new seismic basins. programmes and new reprocessing such as PSTM and AVO show that more oil and gas to be discovered in prospects Several bright amplitude anomalies were identified on 2D similar to the producing ones and in plays which have not been and 3D seismic data sets. Reservoir presence is the key tested such as Triassic salt structures, sub thrusts and Tertiary geologic risk as no sand was penetrated by the only well drilled folded sandstones. in the offshore basin (Larache-1). Two independent but complementary techniques were applied to assess this risk. From geochemistry point of view, many mature source We discuss the results of this analysis of one prospect. rocks exist within the Prérif area as proven by hydrocarbon productions, shows and oil seeps. First, seismic stratigraphy geometry indicates channelised turbidites and lobe turbidites. Onlaps and depositional relief are The Lower Jurassic marls and shale (Domerian-Toarcian) interpreted as indicators of sand turbidites onlapping the and the Upper Cretaceous shale seam to be the main source- margins of active mini-basins. Transition from incisions and rocks in the area. TOC values taken from wells data are up to “cut and fill” geometry to continuous lobate reflection 2 % for the Lower Jurassic source rock. The outcropping packages indicate channel to lobe turbidite depositional Upper Cretaceous formations have TOC values up to 15%. environments, respectively.

Maturation of Lower Jurassic source rock may have started Second, rock property modeling of onshore wells shows as early as end of Jurassic-Lower Cretaceous in deeper zones that acoustic impedance and shear impedance can be used to (troughs). On the other hand, maturity modelling indicates that discriminate sands from shale. We conclude that very low maturation and generation of hydrocarbons in the Prérif area, acoustic impedance and high shear impedance indicates gas started after the emplacement of the complex of nappes. sand. The 3D seismic volume was inverted and tied to the Maturation of the Upper Cretaceous source-rock has Larache-1 well. The seismic anomalies described above exhibit occurred recently during the Mio-Pliocene time. both low acoustic and high shear impedance.

Wells drilled up to now and field studies in the Prérif, the Mapped geometries of the anomalies from the inverted Gharb and Guercif basins have shown formations with good cubes are similar to the geometries interpreted from the petrophysical characteristics and favourable for hydrocarbon seismic stratigraphic approach on the final migration data. accumulation. Recorded porosities are good to excellent Combining independent but complementary analyses reaching 35% in the Miocene sands. supports the interpretation of gas-filled turbidite sands at our prospect. This will be tested soon by the drilling of an The defined play concepts consist of Subsalt alluvial and exploratory well. fluvial Triassic sandstones, Jurassic sub thrusts sandstones and carbonates, Jurassic and Tertiary folded sandstones and Hydrocarbon Opportunities Offshore Atlantic Morocco: carbonates and Upper Miocene Low stand system tracks Agadir-Ifni segment sands (LST) in Gharb and Guercif basins. A. Benarchid, M. El Mostaine and H. Jabour ONHYM Morocco Neogene Turbidites in Tanger-Larache Blocks (offshore Morrocco): From Seismic Interpretation to Sand Prediction Hydrocarbons occur in many Basins of Morocco J. Gérard, B. Blake, N. Antich, M. Escalante, X. Legrand and throughout the sedimentary sequence, from Paleozoic to R. Ferrando. Neogene. These hydrocarbons are represented by a variety of Repsol YPF, Paseo de la Catellana 280, 28043 Madrid, Spain gas and liquid petroleum, in addition to a variety of seeps, and gas and oil shows. However, the insufficient exploration drilling Repsol Exploracion SA, gasNatural, Dana & ONHYM are has not yet established commercial accumulations in other exploring the Tanger-Larache blocks in offshore Rharb Basin basins which are hydrocarbon generating. on the Atlantic margin of northwestern Morocco. In the Atlantic Offshore of Morocco, hydrocarbon exploration Tectonism was active in the Moroccan margin and started in the early sixties and was focalised on the Jurassic controlled both facies and architecture of Neogene turbidites. platform and the upper slope. Twenty nine wells were drilled so far, Extensional mini-basins formed at the late stages of the Rif- and the main results of this drilling campaign were the discovery of Betic orogeny due to collapse of the accretionary wedge at a non commercial heavy oil accumulation and oil and gas shows at Tortonian-Messinian times. Supra-nappe gravitational normal different Meso - Cenozoic stratigraphic levels.

64 In this respect, Modern 2D and 3D seismic were acquired of the Late Triassic-Jurassic doleritic dikes and sills on the in the Atlantic Offshore, leading to the definition of new play hydrocarbon generation and expulsion. concepts and the identification of new prospective zones. A brief look at potential hydrocarbon source rocks and their Agadir basin is one of the most promising areas in the maturity, offshore Mauritania Offshore Atlantic of Morocco. This area offers three blocks A, B, and C covered by about 14637 Km of a 2D good quality John Downey seismic, and a total of about 8000 Km2 of 3D seismic. Dana Petroleum PLC, 17 Carden Place, Aberdeen, AB10 1UR, UK The play concepts developed are related to Cretaceous, Oligocene and Miocene turbidites related to salt tectonic. Exploration drilling offshore Mauritania since 2000 has confirmed the existence, in addition to the presence of Country Session: Tunisia biogenic gas, of two working thermogenic hydrocarbon source Chair: El Mostaine, A. Zain systems and the existence of other potential source intervals developed at a number of stratigraphic levels. However, Hydrocarbon potential of Tunisia there is insufficient data at present to allow an understanding of the spatial distribution of even the proven source rock Country Session: Mauritania intervals. Predicting their thermal maturity also presents a Chair: John Downey number of challenges. Fluid inclusion data also indicate that the history of basin evolution is far from straightforward. Neoproterozoic Petroluem System of the Taoudenni Basin, Mauritania Insights into hydrocarbon source systems offshore Jordi Franquès-Faixa, and Ricardo Veiga Mauritania Repsol YPF, Regional Study Group, Paseo Castellana 280, Stephen Kenyon-Roberts1; Andrew Beckly2; Andrew Carr3; 28046 Madrid, Spain Gareth Harriman4; John Downey1 1 Dana Petroleum PLC, 17 Carden Place, Aberdeen, AB10 The underexplored Taoudenni Basin (Mauritania, Mali and 1UR, UK Algeria) is part of the Eastern African Craton which contains 2 Senergy Ltd, 15/16 Bon Accord Crescent, Aberdeen, AB11 over 6,000 meters of Neoproterozoic to Paleozoic section, with 6DE, UK a thin Jurassic and Holocene sediment cover. The Abolag-1 3 Advanced Geochemical Systems Ltd, 1 Towles Fields, (Mauritanian) and Yarba-1 (Mali) wells found gas accumulations Burton on the Wolds, LE12 5TD, UK in the stromatolitic Neoproterozoic Hank Gr. These 4 GH Geochem Ltd, 24 Higher Bebington Road, Bebington, hydrocarbon accumulations are sourced from a time CH63 2PP, UK equivalent black shales section. Outcrop samples from this black shale indicate the high hydrocarbon potential and early Exploration drilling off NW Africa since 2000 has confirmed mature conditions (23.3% TOC, HI=530, Tmax 435ºC, type I). the existence, in addition to the presence of biogenic gas, of Equivalent age and facies constitute a proliferous source rock two working thermogenic hydrocarbon source systems and worldwide (i.e. Oman, Siberia). the existence of other potential source intervals developed at a number of stratigraphic levels. This paper presents evidence The performed multi-dimensional basin modelling from recent Dana Petroleum wells offshore Mauritania that produced from seismic based structural maps indicates that demonstrates the presence of the two thermogenic source the maximum burial of the Hank Group was achieved previous systems. However, there is insufficient data at present to to the Hercinian orogeny with a minor impact of this erosional allow an understanding of the spatial distribution of even these event in the resulting source rock maturity. The SR reached the proven source rock intervals. Predicting their thermal maturity gas window in Late Cambrian-Devonian times with higher also presents a number of challenges, particularly in light of maturity reached in the eastern and western depocenters. fluid inclusion data that indicates that the history of basin evolution is far from straightforward. Oil generation and expulsion took place mainly during the Late Proterozoic and the gas extended until the Carboniferous. The earliest oil accumulations in Neoproterozoic reservoirs were produced during the Upper Proterozoic and were replaced by gas from the Cambrian until the Silurian- Ordovician.

Fission Track analyses indicates that the latest thermal event took place in pre-Devonian times reducing the influence

The First MAPG International Convention, Conference & Exhibition 65 Marrakech Convention Center, October 28 - 31, 2007 Country Session: Guinea Major oil companies, based on the successful recent track Chair: Kalidou Diallo record and current studies, are reporting about 100-125 TCF yet to be found resource potential in addition to the 72.3 TCF La politique pétrolière en république de Guinée : Défis et proved resource by end of October 2007 , compares to 36.4 Perspectives : Quelques éléments structuraux de l’Offshore TCF proved reserve calculated in july 1999. Guinéen New exploration approach in the downthrown side of Gulf of Kalidou Diallo Suez emphasizing, Belayim marine field Abstract Not received Ahmed A. Fattah and Said Shalby Gulf of Suez represents the most interesting oil provinces in Bref aperçu sur le potentiel minier de la République de Egypt, it is divided into three tectonic zones separated by Guinée : Le Birimien Guinéen a-t-il fini par livrer tous ses accommodation and transfer zones. Most of them are secrets interesting as oil exploration and production. The main play traditional concept is represented by structurally high horst and Alkaly Yamoussa Bangoura tilted fault blocks.

Abstract Not received Belayim marine field is located in east central part of the Gulf of Suez which resemble the central fields in their models, Country session: Egypt tectonics and petroleum system. Big numbers of exploratory Chair: Hani Nassar and development wells were drilled through long history of production and tested this conventional play concept. Exploration activities , opportunities of investment and Future Hydrocarbon Potentiality In the last few years application of new non-traditional play concept aided in new discoveries in the down thrown side of Tamam Mohamed Tamam1 and Ashraf Farag2 the Gulf. Some of these discoveries are of Tanka fields down 1 EGPC thrown side of October field of Gupco where the reservoir in 2 Egypt Ministry of Petroleum the down thrown side has the same hydrodynamic as the up Egypt has many Sub-basins which consider having proper thrown side . conditions for accumulation of oil and gas some have been In Belayim Marine field this new reservoirs represent down explored, the other not yet discovered and still consider frontier thrown of the structure high in the form of stratigraphic alluvial and under explored areas (Upper Egypt, Red Sea, and some and sub marine fan and the reservoir behaviors depend on the areas in Western Desert). juxtaposition between the up thrown and down thrown. Egypt has a good exploration experience since 1886 that Another interesting feature in the northern part of Belayim reflect the high rate of success in the exploration field. The Marine field is representing by on lapping of the Miocene units variation in the exploration concept for different companies over the Pre-Miocene scarp created a pure stratigraphic trap added a great values for expecting of hydrocarbon potentiality. which has sand stone in the lower part of Upper Rudeis and The chance of investment in Egypt is a challenge because of the the lower Rudeis with O.D.T lower than the main field by good environment from political and economical point of view. 185m. and till now no water reached in the drilled wells.

The studies and re-evaluation of exploration and This open chances for new approach of exploration in the development leases areas led to discover a new layers main fields in the Gulf of Suez and further exploration in containing hydrocarbon such as Lower Cretaceous and Belayim Marine field and in the other fields in the Gulf of Suez. Jurassic in the Western desert and Nubia Sandstone in the 1) Nallpetco 2) Petrobel Gulf of Suez. In addition to significant oil discoveries in the Mediterranean Sea which encourage the Companies and Jurassic Hydrocarbon Potentiality In Northern Western create a challenge for oil industry in Egypt. Desert of Egypt Emphasizing Khalda Areas Dolson J.C in year 2000, reviewing Egypt hydrocarbon Ahmed Abd El Aleem Ali El Awdan potential and yet-to find based on missing field size Khalda Petroleum Company, Cairo, Egypt distribution, stated that Egypt has potential to add more than 15.7 BBOE resources in the next decades with major The main objective of this paper is to integrate structural discoveries expected yet to be made. These predictions are and stratigraphic studies to assess the main themes of basin now starting to become reality. evolution, structural framework, regional stratigraphy and its effects on Jurassic reservoir distribution and size, their

66 formation and destruction, source nature and distribution, The Pre-Miocene source rocks found at outcrops indicate exploration potential. added great values to expected hydrocarbon potentiality of area. An increasing proportion of the Egyptian hydrocarbon production comes from the Western Desert. The oil production Hydrocarbon Exploration activities in the Eastern in the Western Desert accounted for about 21 % of Egypt’s Mediterranean Basins: Challenges and Opportunities total oil production a day (32.0 mm Ton/ year). The gas fields in the area produced 26% of the total gas production in the Mohamed Nashaat country (38.4 mm Ton/ year). Exploration Department, Rashid Petroleum Company, Egypt, New Maadi, 293 Street, Building 18, Cairo, Egypt, Phone: 202- Most of the successful gas discoveries in the Western 012310-7968. Fax 202-5180580 Desert are coming4 from deferent stratigriphic units within the Jurassic section. The Nile Delta offshore basin comprises a world-class hydrocarbon province between the deep and long existing The Jurassic section represents the ideal example for the Levant Basin to the east and the Herodotus abyssal plain to hydrocarbon system (Source, Reservoir, and Seal & Trap) in the the west. The variety of tectonic styles and depositional northern part of the Western Desert of Egypt. patterns in the eastern Mediterranean basins provide favorable trapping conditions for hydrocarbon generations and An early rifting phase in the Jurassic and Early Cretaceous accumulations. The shallow gas discoveries in the Pliocene formed several half graben-like basins with intervening sands and the high-grade oils in the Oligo-Miocene and platforms having basin and range geometry. Thick wedges of Mesozoic reservoirs indicate the presence of multiple source Jurassic and Lower Cretaceous sections were deposited in rocks and an appropriate conditions for hydrocarbon these basins and include potential source rocks. Rift-bounding accumulations in both biogenic and thermogenic petroleum faults are oriented E-W, ENE-WSW, and WNW-ESE. NNE- systems. These systems were active in the whole Mesozoic SSW oriented faults locally bounded some basins as well. and Cenozoic sedimentary sequences of Levantine, Nile Delta The Western Desert of Egypt still has a significant and Herodotus basins. hydrocarbon potential as recent oil and gas discoveries Trap filling in the Nile Delta and even the western part of indicate (for example in the Khalda Concession, Khatatba Levant basin can be considered as a dynamic process to Formation). Results of new wells, combined with 3D seismic maintain constant pressure magnitude and subsequently and additional geological interpretation, demonstrate that fields constant hydrocarbon columns. Leakage of natural gas from may be larger than previously thought. traps in the Tertiary rocks resulted in gas chimneys mostly related to the deep-seated faults in the Nile Delta. Sealing Hydrocarbon Potentiality in the Egyptian part of Red sea rocks are generally sufficient to hold significant hydrocarbon Adel Omar, Hesham Fawzy Mansour and Mosaad Elleboudy column, except where structural collapses occurs at crests. Ganope El Wadi Holding Petroleum Company Hence, fault re-activation can be generally ruled-out as an additional reason for hydrocarbon entrapment failures in the Egyptian Red Sea region is still a frontier and under Nile Delta and Levant basins. Meanwhile, the majority of such explored area. The most effective prospective curtail element, unsuccessful exploration wells show evidences of residual or the active mature source rock, is recognized which is the base paleo-hydrocarbon columns. to evaluate the hydrocarbon potential of the area. So, Miocene and Pre-Miocene source rocks were found to possess high organic content and generating capability to generate gas and Egypt recent exploration success and future hydrocarbon oil. The high temperature regime at the basins is adequate for potentiality - yet to find high maturation level of sources to generate hydrocarbons. Ashraf Farag Time of hydrocarbons migration and expulsion is post dates General Manager – Agreement and Exploration the rifting of the Red Sea. This cause a high preservation for Egypt Ministry of Petroleum the accumulated hydrocarbons The objective of this paper is to focus on the petroleum The highly prospective Miocene basins at Saudi Arabian future potential of Egypt, based on the recent past-years offshore fields on the eastern side, and Egyptian offshore achievements and industry future expectations. depocenters and old oil field at Hurghuda and Sudanese Suakin and Bashaire condensates and gas fields on the Dolson J.C in year 2000, reviewing Egypt hydrocarbon western side are investigated and correlated. As Miocene potential and yet-to find based on missing field size clastics and evaporites deposits from a suitable source, distribution, stated that Egypt has potential to add more than reservoirs as well as seal, Egyption Red Sea reservoirs are 15.7 BBOE resources in the next decades with major expected to contain considerable condensates and gases discoveries expected yet to be made. These predictions are accumulations. now starting to become reality.

The First MAPG International Convention, Conference & Exhibition 67 Marrakech Convention Center, October 28 - 31, 2007 Starting from fiscal year 1999/2000 till 2006/2007, 308 Pars field. Regarding internal demand a half of this production new oil and gas discoveries have been found, out of these can be assigned to exports, inter regionally or worldwide. discoveries there are different categories from giant to small discoveries, and about 16.2 BBOE of resources have been Iran was the first country in the area to export Natural Gas added. to the ex. USSR through a 42 inches pipeline with a length of 1100 Km. The flow was 10 BCM/Y. Significant success in the Mediterranean region include : gas discovered in Ultra deep-water (more than 2000 m water Pipeline to Turkey has completed and gas flow to this depth), very deeply buried and high pressure gas discoveries country has started from 3 BCM/Y. Also Armenia will have with a reservoir depth more than 5000 meters, plus oil soon been able to receive Natural Gas from Iran. Importing gas discovered in the western side in the Nile basin. In the Western from Turkmenistan implies that Iran is an interregional gas Desert, further success, where the largest gas field ever dealer. discovered was found in 2003. In addition to significant oil The strategic role of Persian Gulf and the huge amount of discoveries were achieved in the Gulf of Suez. Note to worth gas reserves in this area has provided a very good opportunity one of the most important oil discovery during 2007 in Upper for Iran to export gas to demanding countries through pipeline Egypt is Baraka discovery. or in the form of LNG.

All of these indicators are very positive with expanding In energy sector the policy is substitution of oil products by exploration activities to new areas and targets. This has Natural Gas .That is why gas consumption shows such as a encouraged major international oil companies into more high growth over the last decade. investment and the acquisition of more concessions. Transmission pipelines with a length of 20000 Km takes Major oil companies, based on the successful recent track gas from various sources to destinations in the whole country. record and current studies, are reporting about 100-125 TCF Lines with diameter of 56, 48 and 42 inches have been yet to be found resource potential in addition to the 72.3 TCF employed to carry more than 500 millions cubic meters per day proved resource by end of October 2007 , compares to 36.4 of Natural Gas. TCF proved reserve calculated in july 1999. In 21st century gas industry liberalization has been main program for government. Treatment units, distribution and service facilities are more introduced to private investors. Country session: Iran Chair: Soleimani For overcoming the high seasonal difference of consumption installation of underground Natural Gas storage Natural Gas Industry in Iran have been recognized as the best choice. Hedayat Omidvar Three underground storage are understudy with some National Iranian Gas Company No.77-Southern Aban St. - degree of progress to ensure Natural Gas supply to internal Karimkhan Ave.-Tehran users and export destinations. Gas industry in Iran now contributing in supplying energy by 60 percent share in fossil fuel basket has entered the Calcareous Nannofossil Biostratigraphy of the Gurpi developing stage after 40 years of Natural Gas emerging in Formation in The Dare-Shahr Section – Zagros Basin – NW energy sector. Iran Fatemeh Hadavi and Mohhamad Mehdi Rasaezadi: The growing demand for Natural Gas in residential and Dept. of Geology faculty of Science, Ferdowsi University of industry section and supply pushing for covering this demand, Mashhad Iran. are the reasons for such statement. The Zagros basin which is the biggest oilfields in the word, For responding to this phase of Natural Gas life, Iran needs situated in southwest Iran. The northwestern limit of the region investment especially in upstream development, technology coincide with a well know tectonic zone called the ‘’ main transfer and facilitating in exports and imports. According to Zagros Trust’’. The southwestern limit coincides with the the annual report in long term Middle East will be the second southwestern boundary. exporter region and Iran which is the first holder of reserves and first producer and consumer in this area is a potential The Gurpi Formation is exposed along the northeastern exporter for next decades. flank of the Kabirkuh anticline of the Zagros Mountains in southwestern Iran. The dare-shahr section is located between The Islamic Republic of Iran is able to produce more than the towns of dare- shahr and Abdanan in the Ilam province 400 millions cubic meters per day of Natural Gas from giant

68 (Lurestan oilfield). In this area it consists 234 meters thickness. Texture, Diagenesis and Stratigraphy Correlation of the The lower part of the formation consists of white (milky) Asmari Reservoir Evaporitic Caprock, Kupal Oil Field, Zagros, limestone and marly limestone.The upper part consists of soft Iran dark grey shale shale alternating whit marly shale. This Soleimani, B.1 Mohammadi, Y.2 Amiri Bakhtiar, H.3 and Jafari, formation is widely exposed in Zagros increasing in thickness A.4 from Lurestan (NW) to interior Fars (SW). 1 Department of Geology, Shahid Chamran University, Ahvaz, The purpose of this study is to the determine the Iran calcareous nannofossil of this formation and compose with 2 Department of Geology, Shahid Chamran University, Ahvaz, assemblages of the other localities. Afew studies on Gurpi Iran calcareous nannofossils have been carried out mostly, by 3 Department of geology, Shahid Beheshti University, Tehran, Hadavi, & Hadavi et al., 2007. Iran 4 Area Operation Geology, National Iranian South Fields Oil Co In the present study a total of 107 samples were take for (NISOC) the for the examination and studied using light microscope. Nannofossil assemblages were not rich in the lower part of the Kupal oil field located at Dezful embayment, Zagros, SW of section, but well preserved and high in abundance and Iran. Member one of Gachsaran Formation considered as the diversity in the upper part. in this study 55 species belonging caprock of Asmari oil reservoir. It consisted mainly of Anhydrite, marl, limestone, bituminous shale. Halite also detected as to23Genera, have been recorded. Based on the first and/or minor part. The caprock was evaluated using Sonic and GR last occurrence of the calcareous nannofossils the age of Gurpi Logs, petrography, SEM and carbon isotopic analyses. Based formation is Campanian –Danian in dare-shahr section. The on petrophysical well logs and lithological studies, the caprock present of Biantholitus sparsus, Cruciplacolitus primus , divided into 6 key beds: A (Anhydrite), B (Bitumineous shale), Micula prinsii, indicate that the K/T boundary is put in the C (Upper limestone), D (Lower limeston), E (Limestone), and F uppermost of the Gurpi formation. It is evident that (Clay Limestone). sedimentation across the boundary is gradual whit no break. Any one of key beds has spacial markers and distinguished Keyword: Cretaceous-Tertiary Boundary; Biostratigraphy; Calcareous during the drilling of oil wells. In the Iranian oil fields, detection nannofossils of key bebs for the cassing and reduce drilling risk is very important. In the Kupal oil field, key beds D and E are the Reference: suitabel points for the casing. Hadavi, F. (2007) Calcareous nannofossil biostratigraphy of the Gurpi Formation in the type section. Anhydrite represents burial textures such as nodular, The 6th International Symposium of Eastern Mediterranean spherolit, and replacement. SEM observations of halite crystals Geology. present hopper and chevron textures. These textures are Hadavi, F. Khosrotehrani, kh. Senemari, S. (2007) Calcareous nannofossil biostratigraphy of the Gurpi indicators of sabkha environment, but nodular and massive Formation of North Gachsaran, Scientific Quarterly journal anhydrite denoted high burial conditions. Geosciences. Tehran, Iran. Hadavi, F. Khosrotehrani, kh. Senemari, S. (2007) Calcareous Sulphate sediments in the area understudy were nannofossil biostratigraphy of the Gurpi undergone different diagenetic processes includes: Formation of west Shiraz. Azad University journal of Tehran, Iran anhydritization, cementation, compaction, deformation, Hadavi, F. (unpublished) Calcareous nannofossil biostratigraphy of the recrystalization, replacement and calcitization. Gurpi Formation in Tange Maghar (Khuzestan Province). Thickness of cap rock increaasing from the SE to NW of the Kupal field and reach max in 18 well No. Min thickness observed in 34 well No.

Isotopic analysis of selected anhydrite and limestone samples revealed that ?13C of limestone (keybed/C) is -12.1, ?34S of anhydrite samples present a value of 18.3 and ?18O is -0.2 to -0.4. These data along with lithological studies provided a sabkha environment to deposit Gachsaran Formation (Member 1).

Keywords: Oil field, Diagenetic processes, Asmari reservoir, Caprock, Isotope analysis

The First MAPG International Convention, Conference & Exhibition 69 Marrakech Convention Center, October 28 - 31, 2007 Stratigraphy, petrography and diagenesis of Sulphate Country session: Cote d’Ivoire deposits in Cap rock of Agha Jari oilfied, SW Iran Chair: N’Zalasse Bleoue Soleimani, B.1, Gholizadeh, Gh.2, Amiri Bakhtiar, H.3 and Jafari, A4 Geology and Petroleum System of the Cote d’Ivoire 1 Department of Geology, Shahid Chamran University, Ahwaz, Iran Sedimentary Basin 2 Department of Geology, Shahid Chamran University, Ahwaz, Iran N’Zalasse Bleoue 3 Department of Geology, Shahid Beheshti University, Tehran, Iran 4 Area Oprational Geology, National Iranian South Fields Oil The Sedimentary Basin of Côte d’Ivoire is a passive margin Company (NISOC) located in the Western part of the Gulf of Guinea. Create with the favour of Ocean Atlantique opening at the Lower Member 1 of Gachsaran Formation is the cap rock of Cretaceous (106 million years) this basin is limited to the North Asmari reservoir in all Zagros oilfields, SW Iran. The present by the transforming faults of St Paul and Romanche to the study evaluates different aspects of sulphate deposits in Agha South. Jari oilfield’s cap rock. This oilfield is one of the gaint Zagros oilfields in Dezful Embayment. The cap rock composed mainly The basin includes two parts, one terrestrial (Onshore) and of anhydrite, marl, limestone and bituminous shale. another marine (Offshore). Petrographycal and petrophysical data accompanied with The “Onshore” part accounts for only 2.5% of the one that geochemical and isotopic analysis for the following study. lies on the territory the area of which is 8000 km?.

Based on petrophysical and lithological studies, the The “Offshore “ part represents the major part of the basin caprock was divided into 6 Key Beds which from top to bottom and displays on more than 100 km broad. It is subdivided in include: A (anhydrite), B (bituminous shale), C (fossiliferous two margins: the Margin of Abidjan to the East where we have limestone), D (limestone), E (mudstone), and F (fossiliferous important activities of exploration and production, and the mudstone and wackstone). Also 7-8 anhydrite units with Margin of San Pedro to the West where the geology is not different thickness were recognized in the cap rock. These known enough. anhydrite deposits represent wide textural variation such as nodular, enterolitic, lath, decussate and blocky which applied The opening of the basin was carried out in several phases to evaluate the sedimentary environment and also their which correspond to series of specific deposits: alteration during burial. Deposits of Albo-Aptian thick series of continental type Sulphate sediments of cap rock have been undergone (rifting phase); different diagenetic processes include: anhydritization, cementation, compaction, recrystalization, replacement and Deposits of important sand-shale (turbiditic type?) in calcitization. subaqueous environment, more or less eroded sequences, for upper Albian (marine phase); The geochemical and isotopic analyses of bituminous shale, dispersed in anhydrite units in upper part of cap rock, “Deposit/erosion” under marine due to the uplifting, for have been used for determinig the depositional setting of these Cenomanian to lower Senonian, marked by three major deposits. The resultant geochemical indicators and the ?13C discordances: the post albian discordance, the discordance at values in extracted saturate and aromatic parts of bitumin (- the top of Cenomanian to Turonian and the discordance at the 28.5‰ and -27.5‰ respectively) demonstrate terrestrial- top of lower Senonian (phase of oceanisation).The sandy marine environment for these sediments. Carbon isotope value deposits associated with this phase are often impregnated with (?13C) of carbonate samples is -20.4‰. The value ?34S of hydrocarbons; anhydrite samples vary from 17.8 to 18.0‰. These data, Deposits of thick shale series for Maestrichtian to Miocene accompanied with lithological and petrographical studies used as cover to the anterior formation. suggest a sabkha-lagoonal environment for sulphate deposits of Gachsaran Formation (Member 1). The Albian traps are structural type or pseudo structural and the post Albian traps are generally stratigraphic The Keywords: Oilfield, Diagenetic processes, Sulphate deposits, Cap reservoirs are sandy (post Albian traps) and fine sandstones rock, Isotope analysis (Albian traps) with limestone streaks cement pseudo-bedded with shale.

The sedimentary sequences from the Albian to the Senonian have generated hydrocarbons which often migrated along antithetic faults in an East-West direction before being trapped. Oil met in the basin seems to have three origins:

70 Marine (the Espoir, Panthère and Baobab Fields; the Basin Evolution and Tectonics of the Northern Alboran Sea Bubale prospect); during the Plio-Quaternary (Western Mediterranean) Marine with lacustrine influences (the Belier and Kudu Fields); Lacustrine (the Lion Field). Juan I. Soto1, María del Carmen Comas1, Asrar Talukder2, Rick A. Mountfield3 and Yves M.R. Chevalier3 Key words: Basin of the Côte d’Ivoire - passive margin - stratigraphic 1 Instituto Andaluz de Ciencias de la Tierra (CSIC-Universidad traps - structural traps – lagoon fault – Discordance. de Granada) and Departamento de Geodinámica, Campus Fuentenueva s/n, 18002-Granada, Spain GS 10: Salt Tectonic & Sedimentation 2 IFM-GEOMAR, Wischhofstrasse 1-3, 24148 Kiel, Germany, Chair: Tari Gabor and Haddou Jabour 3 ConocoPhillips, Ltd. P.O. Box 2197, Houston, TX 77252- 2197, USA. Salt Tectonics in Atlantic-type Sedimentary Basins: Brazilian and West African Perspectives Applied to the Iberian and NW The West Alboran Basin (WAB) was surveyed by ConocoPhillips in 2000 and 2001, which performed a African Margins regularly-spaced grid of 2D seismics, seabed coring, and a Webster Ueipass Mohriak complete multibeam-swath bathymetry mosaic. In conjunction Petrobras - E&P-CORP/UN-EXP/GP-SSE with other data from different scientific cruises carried out in the The South Atlantic divergent continental margin extends area, it is confirmed the existence of a broad field of fluid from East Brazil towards the continental margin off Argentina venting structures in the basin floor, like mud volcanoes and and from Rio Muni towards Namibia along the West African pockmarks. These features appear in relation to major shale side. This segment is limited both to the north and south by diapirs in the WAB, being developed either from their flanks or transcurrent movements associated with oceanic fracture at their culminations. zones, and by the subduction zone north of Antartica. The The most-recent evolution of the northern margin of the evaporite basin is associated with siliciclastic and carbonate WAB has been studied using the multichannel seismic dataset sediments deposited above a regional unconformity (breakup of ConocoPhillips, completed with commercial and scientific unconformity) that heralds the continental drift phase, which is seismics. Seismic interpretation has been tied with boreholes followed by a thick sag basin and by Aptian evaporite at the Spanish shelf, in particular with ODP-Leg 161 data (Site sedimentation. The evaporitic conditions seem to extend up to 976). We have distinguished four major, seismostratigraphic Early Albian in some regions, as evidenced by extremely thick units in the Plio-Quaternary series of the WAB. These units are layers of stratified evaporites, indicating several depositional bounded by regional discontinuities which have been mapped cycles. The presence of a highly mobile evaporite layer resulted through, thus completing a pseudo-3D seismic model (~1650 in the development of a characteristic tectonic style marked by km2) for the post-Messinian sediments (<5 Ma). salt diapirs and extensional and compressional structures affecting the post-salt sedimentary successions. The inferred sedimentation rates for this period reflect a strong sedimentary input from the Spanish margin (>0.3 mm/y) The regional deep seismic profiles acquired in the South with lower sedimentation rates at the deeper portions of the Atlantic provide a unique dataset that allows identification of basin and at the top of shale diapirs (<0.2 mm/y). The ascent salt tectonics domains from the platform towards the oceanic of shale diapirirs and their collapse (developing symmetrical crust boundary. These prolific salt basins constitute a grabens) condition the broad geometry of the seismic units, framework for the interpretation of the less developed salt although important global sea-level fluctuations during the basin in the North Atlantic continental margins, particularly early Pliocene and early Quaternary seem to determine the along the Iberian and Northwest African continental margins. formation of major turbidite systems. Turbidite canyon courses, Examples of analogue autochthonous and allochthonous salt sedimentation rates, and the internal geometry of the structures, and their geodynamic evolution, have important sedimentary units are in summary clearly controlled in the WAB implications for petroleum exploration in the deep water frontier by deep-seated processes, mainly by the shale diapirism. regions.

The First MAPG International Convention, Conference & Exhibition 71 Marrakech Convention Center, October 28 - 31, 2007 Halokinesis-controlled mud volcanism in the Gulf of Cadiz Triassic Allochthonous Evaporites emplaced during Christian Berndt1, Matthias Haeckel2, Christian Hensen2, Cretaceous Passive Margin Stage in the Betic Cordillera. Are Katja Heeschen1, Dirk Klaeschen2, Doug Masson1, Anja they extensive to the Rif and Tell Cordilleras? Reitz2, Heleen Vanneste1, Davy Depreiter3, Sverre Planke4 Joan Flinch and Hassen El Euchi and Andrey Akhmethzanov1 Repsol Exploración S. A. Repsol YPF Madrid (Spain) 1 National Oceanography Centre, Southampton, United Kingdom Well log and seismic data in the Guadalquivir Valley and 2 IfM-Geomar, Leibniz Institut für Meereswissenschaften, Kiel, field data from the External Betic Cordillera of Spain suggests Germany that Allochthonous Triassic evaporites, mostly gypsum and salt 3 Renard Centre for Marine Geology, University of Ghent, were emplaced during the passive margin stage within the Belgium deep-water Cretaceous and Paleogene section. Triassic 4 Volcanic Basin Petroleum Research AS, Oslo, Norway evaporites that range from centimetric to kilometric scale blocks or as thrust sheets are interbedded with pelagic The Gulf of Cadiz is characterized by pervasive mud Cretaceous to Paleocene deep-water deposits, mostly marls. volcanism. At least thirty mud volcanoes have been identified Similar examples of that are present in the Rif. Even though so far, and it is commonly believed that they result from part of the emplacement that we see today took place during sediment dewatering enhanced by tectonic forces within the Late Neogene compressional phase associated with the accretionary prism. However, the geological processes that westward escape of the Alboran block, previous emplacement control the location of individual mud volcanoes are poorly during passive margin stage is necessary to explain the understood, mainly because of the lack of high-quality seismic structure. The restored Betic margin (mostly the so-called Sub- data in the area. Recently acquired high-resolution 3D seismic Betic Unit) was probably very similar to some areas of the data and geochemical sediment cores indicate that halokinesis present day Gulf of Mexico or Offshore Angola. The Betic controls the location of some mud volcanoes. The 3D seismic margin was facing the Magrebian margin that today is part of data at the Mercator Mud Volcano indicate localized the Meso-Rif of Morocco and the “Zone des Domes” of Algeria development of a slightly asymmetrical anticline that was and Tunisia in the Tell Cordillera. This southern part, specially of continuously active for the past 800 ka assuming average Algeria and Tunisia with extensive salt glaciers represents sedimentation rates of 0.5 m/ka. The 3D seismic data show perhaps a more proximal part of the margin with less that the apex of the anticline is characterised by a rocky sea allochthony that in the Betic Cordillera. bed outcrop of unknown lithology, which is underlain by a chaotic seismic facies. The most plausible explanations for Salt tectonics in the Atlantic margin of Morocco: an overview these observations is the presence of a salt diapir. This is Gabor Tari1 and Jabour Haddou2 corroborated by geochemical cores from the Mercator Mud 1 AllyGabor Geoscience, Bellaire, Texas 77401, USA Volcano which show very high chlorinity values of 4.5 mol/l and 2 ONHYM, Rabat, Morocco Na/Cl ratios of 1.0 indicating dissolution of evaporites (halite). Gypsum clasts within the mud volcano sediments are The Moroccan salt basin on average is ~50-150 km, but probably xenoliths transported to the surface from a deep stretches for at least 1,000 km between the leading edge of source. Linear chlorinity gradients within hemipelagic the offshore pre-Rifean nappe in the north and the Canary sediments 220 m away and 50 m above the nearest mud flows Islands in the south. The significant along-strike variations in indicate a salt source within 100 m suggesting that those the cross-sectional and map-view distribution of the Late particular mud flows have a high salt concentration. Together Triassic to Early Jurassic salt reflect its uneven original the seismic and geochemical observations imply that distribution. The seismically mapped individual salt structures halokinesis is controlling the location of the Mercator Mud such as tongues, sheets and canopies might have originated Volcano and that its fluid flow system is heavily influenced by from an autochthonous, “patchy” salt layer deposited in the presence of ascending salt. Our observations imply that somewhat isolated half-grabens. Therefore, updip extension salt distribution on the northwest African margin extends at may not be the ultimate driving force for the commonly least 500 km further northward than previously known, and observed contractional salt deformation downdip. that petroleum plays for this area have to include the influence Nonetheless, a fairly steep margin like the Safi segment of of salt. They also imply that halokinesis has to be considered offshore Morocco shows surprisingly similar structures to its as a driving force for other mud volcanoes in the area. post-salt counterparts, e.g. in the Lower Congo basin, such as rafts and turtles on the slope and allochthonous salt tongues at the toe of the slope.

The offshore Essaouira Basin (Tafelney Plateau) segment of the salt basin, displays different salt tectonic styles with more advanced allochthonous salt structures. The spectacular mid-

72 Tertiary reactivation of salt tectonics in this segment is primarily Role of Salt Tectonics in the Evolution of the Safi-Agadir attributed to the inversion associated with the Atlas mountain Segments of the Moroccan Atlantic Margin and its Onshore building onshore. The ongoing compressional deformation, as Basins the result of the Africa/Europe convergence, enhanced the Mohamad Hafid1 and Gabor Tari2 steepness of the slope and is largely responsible for the 1 Unité de Géophysique de l’Exploration et Environnement; ongoing salt movements. However, the basinward edge of the Département de Géologie; Faculté des Sciences, BP 133, salt basin has dormant toe-thrust antilclines. Kénitra, Morocco In the Agadir segment, the rapid influx of Tertiary sediments 2 AllyGabor Geoscience, 6719 Avenue B, Bellaire, Texas appears to be the dominant factor in the style of salt tectonics 77401, USA producing a wide diapiric domain underneath the slope. Integration of geological and geophysical data from the However, in this segment, the downdip edge of the salt basin Safi-Agadir segment of the Moroccan Atlantic margin and its is also clearly allochthonous. In general, the westernmost, corresponding onshore basins indicates that the Triassic rift leading edge of the salt deformational front with a well architecture and the post-sedimentary mobility of massive salt developed mid-Tertiary toe-thrust zone along most parts of the associated with rifting continuously influenced sedimentation Moroccan salt basin offers world-class structural traps for and tectonics of this area from early Mesozoic to the present hydrocarbon exploration. Besides the toe-thrust anticlines, time. This particular area is differentiated from the rest of the numerous salt-related play types were defined in the Atlantic Moroccan salt basin by the fact that the salt in this deepwater and remain largely untested to date. segment extends onshore. Numerous salt diapirs were Most of the published plate tectonic reconstructions a mapped here using 2D reflection seismic data. Due to the large single salt basin during the Late Triassic between, for example, number of wells in the onshore Essaouira salt basin, the Nova Scotia and Morocco. Based on the regional analysis of temporal evolution of the salt deformation is better constrained the Moroccan salt basin, the separation of these syn-rift salt here than in the offshore areas. Based on this study, the overall basins by a subaerial volcanic ridge is much more likely. gravity-driven salt tectonics was strongly influenced by the upper Cretaceous to Tertiary compressive events associated with the High Atlas orogeny. The impact of these compressive Salt tectonics in a synrift and strongly tilted salt basin, Safi Atlasic events on the salt tectonic style diminishes rapidly to Haute Mer basin the south and to the north of the Essaouira basin. T. M. Egebjerg, X. Fort, L.W. Kuilman and A. Groth Hydro ASA N-0236 Oslo, Norway A great variety of halokinetic structures were identified including gentle salt-cored folds and pillows, compressional The Safi basin, located offshore Morocco, is a narrow diapirs, salt withdrawal synclines and completely basin, about 100-150 km wide, characterized by Upper allochthonous large salt sheets and canopies. These structures Triassic/Lower Jurassic synrift salt. Its conjugate basin, before show an areal/temporal distribution that is progressively more breakup of the Atlantic occurred, is the hydrocarbon proven complex basinward from the onshore basins towards the area, offshore Nova Scotia in Canada. deepwater basin, defining specific salt tectonic domains The structural study is based on 2D transects and 3D characterized by different halokinetic features. This complexity seismic data in water depth of 200–3000m. This induces an offers a great variety of favourable settings for potential average tilt of the seabed surface higher than 5°. In reality, the hydrocarbon traps, including subsalt and pre-salt plays. near-shore part is undergoing an even abrupt tilting. Regional transects display a salt tectonics zoning, which is extensional Subsalt exploration potential of the Moroccan salt basin upslope and contractional downslope. Such a classical Jabour Haddou1 and Gabor Tari2 segmentation of the margin is in direct agreement with gravity- driven deformation such as in the Angolan African margin. 1 ONHYM, Rabat, Morocco However, salt is here deposited during the rifting and is not 2 AllyGabor Geoscience, Bellaire, Texas 77401, USA necessarily continuous along the basin or nevertheless The central segment of the Moroccan offshore salt basin presented dramatic variations in initial thicknesses as it was between Agadir and Safi is characterized by numerous very deposited in Pre-Mesozoic rifted blocks. The presence to the advanced allochthonous salt structures such as tongues, north of the Mazacan plateau is also a parameter that may have some impacts on the development of the salt structures sheets and canopies. Whereas there are no examples of as it is downslope-curved. subsalt well penetrations offshore Morocco to date, the observed salt tectonic features highlight the possibility of We attempt to link these 3 parameters, strong tilt, subsalt exploration as known in the mature northern Gulf of segmented initial salt basin and basin contour inherited from Mexico salt basin. the rifting, to explain the salt structure formation in a gravity- driven deformation setting.

The First MAPG International Convention, Conference & Exhibition 73 Marrakech Convention Center, October 28 - 31, 2007 The most promising subsalt traps are located in the Ras carbonate sedimentation is marked high energy carbonates Tafelney area, offshore Essaouira Basin, defined by 2D which are expressed on seismic profiles as prograding reflection seismic data. Some of the modern seismic profiles in reflectors. These progradations correspond to sand shoal this area were pre-stack depth migrated specifically to better oolitic carbonate beds which were deposited during the high image subsalt traps. Using the latest subsalt archetype stands. During the Lias and Dogger, these sand shoal oolitic classification scheme developed in the northern Gulf of deposit were prograding and aggrading. Mexico, most of the Moroccan subsalt traps are classified as having a singular salt cover in a single-tiered allochthonous salt The carbonate platform evolved from ramp type platform in terrane. As to the root type, all the traps are related to the Lower and Middle Jurassic to shelf margin platform in the autochthonous roots and therefore offer several common trap upper Jurassic. This evolution is associated with rapid rise of geometries, such as a) anticlinal folds, b) downward flexing sea level and the carbonate platform was catching up in the sigmoid folds, c) low-relief ribbon truncations and d) truncated upper Jurassic. upward flexures. However, and locally salt tectonic prolongated the ramp The classification of the subsalt traps defined in the type to up to upper Jurassic. offshore Essaouira Basin as autochthon rooted subsalt traps The salt uplift compensated for the rapid sea level rise and has important implications for future hydrocarbon exploration prevented the carbonate platform to evolve to self margin in the area. This particular subsalt play family is considered as carbonate platform. the most promising one based on Gulf of Mexico exploration experience. Therefore a qualitative ranking of the subsalt traps The influence of salt tectonics on sedimentation and basin in the Ras Tafelney area is proposed based on the systematic development in Block Safi Haute Mer, offshore Morocco interpretation of the currently available 2D reflection seismic data. Most of these subsalt leads could be matured to C. Weisenburger1, G. Tari2 and L. Wood1 prospects by acquiring 3D seismic data over the most 1 Quantitative Clastics Laboratory, Bureau of Economic promising areas. Geology, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas 78738, USA

The Tectono-Sedimentary Framework of the Jurassic An extensive 3-D seismic survey covering an area of 1,064 Carbonate Platform in the Atlantic Passive Margin of km2 has been used to analyze the morphology of salt and Morocco determine the emplacement history of allochthonous salt Mahmoud Zizi and Mohamed Nahim structures, and to examine the temporal changes in the Office National Des Hydrocarbures et des Mines interaction of structure and sedimentation in offshore Morocco. 34, Av Al Fadila, Rabat, Morocco The survey area is located roughly 150 km west of the Moroccan coast, in Block Safi Haute Mer, in a water depth This paper will focus on the tectono-sedimentary features between about 2,500-1,500 meters. The western half of the of the carbonate Atlantic continental passive margin of survey lies just outside of the salt basin and is marked by Morocco. As it provides a better understanding of the Atlantic relatively flat-lying strata. The eastern half of the survey lies passive margin. The geological interpretation of the passive within the salt basin and is characterized by sedimentation in margin is based principally on the data acquired from and around salt structures and salt deformation of older strata. petroleum industry including seismic reflection surveys and wells. At the distal edge of the salt basin, a thin salt sheet has been driven by sediment loading to extrude some 15 km Prior to the opening of the Atlantic Ocean, a continental beyond the original depositional edge of the salt basin. A series rifting during the Upper Triassic – Lower Lias was marked by of isochron maps show changes in sediment thickness the deposition of continental red beds which grade upward to through time that allow examination of spatial and temporal evaporates. The break up unconformity associated with the changes in depocenters and assessment of the influence of transition from synrift phase to drifting is believed to be salt mobilization on basin fill pattern. Toarcian in age. In the study area, Late-Triassic to Early-Jurassic age salt is Carbonate sedimentation prevailed in the Jurassic time. believed to have began moving in the middle Jurassic resulting Very thick, 4000 m carbonate sequences were deposited on in a number of different types of halokinetic structures including the shelf. Highly platform subsidence is associated with the salt diapirs, sheets, salt-cored anticlines, and turtle structures. post rift and cooling of the lithosphere. Up to 4000 ms of sediment have been deposited in basins created by salt evacuation and around paleo-highs since Early Laterally the Jurassic becomes thinner towards the slope Jurassic time. DSDP data from the deep offshore shows the and the abyssal plain reflecting starved sedimentation with Early-Jurassic to Early-Cretaceous strata to be carbonates, most of the carbonate being deposited in the shelfal areas. The

74 while the strata younger than Early Cretaceous are dominantly Seafloor Morphology and Processes active in offshore: siliciclastic. A detailed seismic geomorphologic study of the Anthropogenic implications of mass failure processes basin fill supports this interpretation. Lorena Moscardelli, Lesli .J. Wood and Dallas Dunlap Quantitative Clastics Laboratory, Bureau of Economic Geology, Mass Transport Deposits in Offshore Morocco, Safi Haute Mer Jackson School of Geosciences, University of Texas at Austin, Area Austin, Texas, USA Dallas Dunlap1, Chad Weisenburger1, Lesli Wood1 and David The modern seafloor off the western coast of Morocco Valasek2 shows a myriad of morphologies developed through a 1 Quantitative Clastics Laboratory, Bureau of Economic combination of consistent deep marine sedimentation Geology, Jackson School of Geosciences, University of Texas processes, regional tectonic instabilities, ongoing movement of at Austin, Austin, Texas 78738 mobile substrates and local currents. A 3-D seismic data 2 Vanco Energy Company Houston, Texas 77046 volume (~1064 sq km in size) provided for analysis of shallow Recent detailed mapping in a 1,064 km2 3D seismic survey hazards and seafloor morphology reveal a complex evolution acquired in offshore Morocco has revealed the presence of at involving large-scale mass transport deposits, unique confined least three regional mass transport complexes (MTCs) within mini-basin development, anticlinal scoring and smaller scale the Cretaceous interval of the Safi Haute Mer area, in addition slumps and slides. to a number of smaller and younger MTCs. Their extent (up to A seafloor dip map shows extreme rugosity of bathymetry 100 km2) and thickness (350 ms) is strongly influenced by in eastern portions of the study area caused by the strong surrounding structural features associated with regional expression of deep-seated salt mobilization. In the west, tectonics and salt mobilization. The MTCs arecharacterized by thrusting caused by regional tectonics generates uplift at the chaotic, mounded seismic facies; however seismic attribute seafloor that is “scored” by steep ridges oriented perpendicular analysis has revealed some degree of internal organization. to the anticlinal axis. These deep canyons are consistent Depositional architectures identified within these units include pathways for sediments cascading from slumps and slides (1) large-magnitude lateral erosional edges, (2) internal syn- developed over the crest of this structure. Slides mapped at depositional thrusts, and (3) kilometer-scale transported mega- the seafloor range in size from small 10’s of kilometer square blocks. Detailed analysis of the internal architecture of the features to 100’s of square kilometers in size. mega-blocks has reveal the presence of discrete low sinuosity, single thread channels that are 90 m wide in average. The clear Submarine slides and slumps are a common mechanism expression of stacked channel complexes within the mega- for triggering tsunamis, with the wave generation dependent blocks indicates that they have preserved their original primarily upon the volume of material moved, the depth of stratigraphy and were likely rafted from upslope, possible 100’s submergence, and the speed of the sliding or slumping event. of kms distance from their source area. In addition to the The potential maximum tsunami run-up height above the slide regional MTCs, an important number of smaller and younger event can be easily calculated using the thickness of the slide MTCs have been identified in the study area, essentially and the water depth at which the failure occurs (assuming a composed of localized slumps and slides. Based on limited Froude number of less than 1 and a slide velocity not to exceed data, these deposits are suggested to be late Cretaceous or 50 m/s). Simple calculations from paleo-slides within the study earliest Tertiary in age. area suggest that a wave in 1600 meters of water, failing a thickness of 110 meters of material could have generated Two working hypotheses address the issue of possible tsunami wave height above the failure up to 5 meters. The triggering mechanisms for these MTCs. The first one suggests tsunami heights would increases as they approach shore to 10 that the causes of the mass failures are associated to the step m, depending on water depths and the local configuration of relief along a narrow shelf, the presence of salt tectonics and the coast line. In addition, the frequency of events and the the frequent occurrence of large earthquakes in the area. continual nature of this activity since Cretaceous times suggest However, the long-distance transport of kilometer-scale, well- significant hazards for occurrence of large failures in the near lithified mega-blocks supports an alternative catastrophic future. model. The alternative hypothesis is that the failures were generated by mega-tsunamigenic forces associated with the K-T impact in the Yucatan Peninsula. Both hypotheses are currently under consideration.

The First MAPG International Convention, Conference & Exhibition 75 Marrakech Convention Center, October 28 - 31, 2007 SS 05: Continental shelf, International Boundary Sovereign rights to Africa’s maritime space – the practical disputes, JDZ JDA & Unitisation pathway for coastal states to secure exploration and Chair: Lindsay Parson, M. El Mostaine exploitation rights for marine resources. Lindsay Parson The final frontier? National Oceanography Centre, Southampton, United Dividing the Outer Continental Shelf Kingdom Robin Cleverly1, Lindsay Parson2, and David Roberts2,3 1 Law of the Sea Division, United Kingdom Hydrographic All but 2 of the 33 nations forming the coastline to the Office, Admiralty Way, Taunton Robin African continent already enjoys rights and responsibilities for 2 Southampton Oceanography Centre, European Way, the governance of various parts of their maritime sovereign Southampton SO14 3ZH. space under the United Nations Convention on the Law of the 3 Rockall Geoscience, Sea (UNCLOS). Territorial Seas extend to 12 nautical miles from coastal baseline, and the Exclusive Economic Zone This paper addresses the potential for access to and continue out to 200 nautical miles. Furthermore, a coastal exploitation of offshore hydrocarbon resources beyond 200M state’s continental shelf can in certain geological from the coast – outside current national jurisdiction. circumstances be located as far as 350 nautical miles from baselines, or 100 nautical miles beyond a water depth of 2500 From Morocco to South Africa, 24 coastal states can metres, whichever is the greater distance. In all of these areas between them claim exploitation rights over a total of more coastal states have sovereign rights over exploration and than 3.9 million square kilometres of Exclusive Economic Zone exploitation for non-living marine resources on and below the (normally 200 nautical miles). Oil and gas licensing and seabed. However, due to the geological and geomorphological exploration and production programmes are well advanced in evolution of the continental margin, many prospective areas many of these regions, and indications are that in general deep are located so as to be potential prolongations of one or more water and ultra-deep water prospects are very promising. coastal states, or have been the target of commercial According to the 1982 United Nations Convention on the development prior to development of mutually agreed maritime Law of the Sea, sovereign rights to development of resources boundaries. Such areas of commercial interest inevitably occur in continental shelf areas beyond the 200M limit could cover a both within and beyond 200 nautical miles. Couplied with the further 650,000 square kilometres of exploitable seafloor. current lack of full knowledge as to the extent to which Some estimates suggest that at the current rate of technological advance, these statutory “extended” continental conventional hydrocarbons such as oil and gas (as well as gas shelf areas will be in production within the next decade. hydrates) continue into ultra deep waters offshore Africa, and the recognition of rapid technological advances in train to Each coastal state is required to submit a claim to the address the difficulties of infrastructure and operations in these United Nations within a strict timescale in order to secure these areas, this paper lays out a number of scenarios for coastal territories, which are naturally both in the deepest waters and states to develop deepwater offshore regimes in coordinated by definition the furthest from land. In many instances around programmes. Examples ranging from recent Joint submissions the world, oil companies (both NOCs and majors) have been of continental shelf cases to the UN, as well as dispute instrumental in developing supporting cases to these claims. resolution via Joint Development Initiatives will be explored for Successful claims will be submitted using a combination of their advantages, implementation issues and degrees of geophysical and geological data, following a precise formula success. The resource potential , and existing bi- and combining an evaluation of sediment thickness and seafloor multilateral maritime boundaries around Africa will be morphology, thus contributing to a regional understanding of discussed in terms of opportunities for coordination in delivery the prospectivity, and in some cases, slope stability, of these of practical solutions for deep water maritime space. ‘frontier’ areas.

This paper examines the probable areal extent of these Moroccan Continental Shelf and Maritime Boundaries deepwater areas for West Africa and conjugate margins of Delimitation South America, evaluates their hydrocarbon prospectivity and M. El Mostaine and A. Lahlou outlines a strategy by which their limits can be defined and ONHYM Morocco established under international law. Morocco has just ratified the 1982 United Nations Keywords: continental shelf, exclusive economic zone, deepwater, Convention of the Law of the Sea (UNCLOS) and, as a coastal exploration state, is required to deposit, within ten years, with the Secretary General of he United Nations charts showing straight baselines as well as the outer limits of the Territorial Sea (TS), the Exclusive Economic Zone (ZEE) and the Continental Shelf (CS) extension.

76 Furthermore and consequently to the development of the HP industry-standard solutions for oil and gas can help you petroleum exploration in the deep offshore, Morocco needs to deploy infrastructures that span the entire workflow to increase define its Maritime boundaries with Spain in the Mediterranean production yields and steadily grow revenues and margins. Sea, the facing Atlantic islands (Madera, Canary and Cape These solutions enable your organization to: Verde) and the adjacent countries. Collaborate better across a broader set of constituents The challenge is to develop a strategy in defining desk-top study, gather and acquire the supporting scientific, technical Execute more effectively to achieve operational efficiencies and legal data, undertake the necessary geological and Innovate to optimize business outcomes geophysical studies and establish the required documents and information for the submission of the Moroccan maritime Solutions Multifonctions HP territorial claims to the UNCLOS. This strategy will also allow Jai Hokimi Ahmed Reda1 and Bruno Torterat2 Morocco to adequately negotiate maritime boundaries with the 1 MFP Product Manager – Africa & DomTom facing and adjacent countries. 2 Imaging & Printing Group General Manager - Africa

JDZ and JDA, Solution to Pending Maritime Disputes Traditionally businesses have relied upon a variety of A. Lahlou and M. El Mostaine hardcopy tools, including printers, fax machines, and copiers. ONHYM Morocco However, adequately addressing users’ changing hardcopy needs can substantially reduce costs, increase productivity, Since the adoption of the Montegobay convention of the and improve workflow. law of the sea, the new maritime cartography requires negotiations, recourse to international justice arbitration which HP MFPs let you manage fewer consumables, reducing is expensive and lengthy. your total cost of ownership, storage requirements, service interruptions, streamline communications with digital sending The most convenient solution is JDZ, JDA between two services and advanced document management solutions, parties or more targeting to joint exploitation of overlapping simplify supplies management with HP MFPs that offer smart areas which are conflicting zones. printing systems, toner level sensors, online supplies ordering, Morocco is not in favour of unilateralism in the field of and no-shake cartridges. maritime delimitation between adjacent or facing countries or Islands. GS 32: Carbonates and Diagenesis Chair: F. Neuweiller and S. Agar He is in favour of the JDZ transitory arrangement in accordance with article 83 § 3 of the UN convention. Flexible Carbon in the Witwatersrand goldfields: its nature and origin solution which keeps valid the claims of each state regarding David J. Mossman the final delimitation. The successful cases are Thailand, Department of Geography Mount Allison University New Malaysia, Nigeria, Sao Tome Principe, Guinea Bissau and Brunswick E4L 1A7 CANADA Senegal etc… The nature and origin of the so-called ‘carbon’ in the Morocco and Spain might consider this solution in their Witwatersrand goldfields has long been an important and pending delimitations cases. controversial question because an estimated 40% of the gold is intimately associated with the carbon. Concerning this HP Session: HP Solutions for the Oil and Gas question it is first of all essential to distinguish between bitumen Industry and kerogen, two of the most prevalent forms of reduced Chair: F. Jellal and Bruno Torterat carbon on the planet. Kerogen is the remains of former living organisms. Specifically, it is a polymer-like organic substance HP West Central Africa and the Oil&Gas Industry which has remained in situ since deposition. In contrast, Fouad Jellal bitumen is a macromolecular organic compound which was HP Morocco-Tunisia-Libya-French West Central Africa and once mobile as a viscous fluid but which has since solidified. In West Indies common organic solvents, kerogen is insoluble, whereas most bitumens are soluble. Neither bitumen nor kerogen consists You’re constantly faced with fluctuating margins, solely of carbon though of course both are converted to challenging political environments, regulatory constraints and graphite under high-grade metamorphic conditions. capacity pressures. To thrive in this environment you need solutions that help you meet the world’s ever increasing A wealth of field evidence bearing on the nature and origin demands for energy. of Witwatersrand carbon indicates that apparently the carbon

The First MAPG International Convention, Conference & Exhibition 77 Marrakech Convention Center, October 28 - 31, 2007 seams are primary sedimentary features, and therefore colloids attach onto a proteinacous network (sorption) that indigenous to the host siliciclastics. For example, the carbon developed due to the dismantling of the collagen tissue. seams are in numerous instances abruptly truncated by Bacteria and other microorganisms support sponge tissue paleoerosion channels. However, veinlets of carbon also occur, degradation, but neither act as a substrate for mineral and microscopic fractures in quartz clasts are in some precipitation or are present in significant numbers at instances filled with carbon. Isotopic analysis of Witwatersrand calcification sites. This process of early calcification may carbon reportedly reveals a range in delta 13C from ~-23.6 to explain the origin of the fossil calcified siliceous sponges, -39.2 ‰ for the insoluble portion of the carbon. Associated thereby attributing a mineral-producing taphonomy as the soluble organic matter reveals small differences (to ~ ± 2.4%). primary control for the development of Early Jurassic sponge The genetic link generally agreed upon is confirmed by results carbonate mounds. of organic petrographic work which shows that both kerogen and bitumen commonly occur together in Witwatersrand The Pliensbachian hemipelagites of Ait Moussa (Middle carbon seams. The kerogen components include inertinite-like Atlas, Morocco): Petrogenesis of an effective source rock (incipient or broken cell structures like semifusinite) macerals, Rachidi Merouane1, Fritz Neuweiler1, Donna Kirkwood2 and vitrinite-like gelified remains of humic tissues. That several 1 Département de Géologie et Génie géologique, Université different macerals (a term which describes the shape, texture, Laval, Québec-City, Canada, G1K 7P4, E-mail: and optical nature of petrographically identifiable entities in 2 Commission géologique de Canada, 490 rue de la kerogen) are observed, as for example, in Vaal Reef carbon, is Couronne, Québec-City G1K 9A9 precisely a characteristic of oil source rocks in that no one maceral (and certainly not bitumen) occurs to the exclusion of Lower Jurassic (Pliensbachian) hemipelagites of Ait all others. Thus in the Witwatersrand, as in some Phanerozoic Moussa (Middle Atlas, Morocco) consist of an alternation of source rocks (less commonly perhaps in Precambrian radiolarian-bearing wackestones and black mudstones. The sediments), solid bitumen occurs where evidently either it has outcrop expells bitumen at intersections between late been generated, or where it has been arrested during migration diagenetic fractures and veins. This study intends to establish through the rock. As such, it is a derivative of kerogen from the fluid pathways of this source rock by applying thin-section shales and /or from carbon seams within the Witwatersrand petrography, fluorescence microscopy, and gas basin. chromatography techniques. The sedimentary matrix of the hemipelagites displays an amorphous-type fluorescence. Biodiagenesis of modern siliceous sponges (The Bahamas) Features of early diagenesis encompass bioturbation, and the origin of Early Jurassic sponge mounds (central High aragonite dissolution, calcification of skeletal opal, authigenesis Atlas, Morocco) of framboidal pyrite, and a 1st generation of subvertical veinlets that were affected by physical compaction. Burial diagenesis Fritz Neuweiler and Isabelle Daoust includes 5 generations of veins (calcite, Fe-calcite), Département de Géologie et Génie géologique, Université accompanied by (all replacive) euhedral pyrite, matrix dolomite Laval, Québec (Québec), Canada, G1K 7P4, (fluorescent), chalcedony (fluorescent), saddle dolomite (partly Phanerozoic shelf carbonate sediments display vast fluorescent), ankerite, and quartz. The onset of primary amounts of calcified siliceous sponges. From textural analyses migration correlates with the reactivation of the vertical dykelet of these spongiolithic rocks it is evident that siliceous sponge system during the 3rd generation of vein formation. The vein calcification must be related to a sponge-specific pathway of filling calcite is fluorescent and rich in impurities. Subsequent (bio-)diagenesis. Calcification occurred syn-vivo to early post- veins display Fe-calcite and are crosscut by tectonic stylolites. mortem and preserved a number of details of the soft tissue Uplift is represented by three generations of calcite veins, organisation of sponges. Understanding the calcification of locally there is dedolomitization of the saddle dolomite siliceous sponges is fundamental in order to assess the (meteoric-phreatic zone), and calcite dissolution (microkarst). accretionary and diagenetic mechanisms of ancient sponge Gas-chromatograms from samples of the host sediment and carbonate mounds. This paper presents a comparison of a the expelled bitumen show similar patterns in terms of a modern calcifying siliceous sponge (Spheciospongia monomodal n-alkane distribution in the range C12–C24 with a vesparium, Great Bahama Bank) with ancient calcified sponge maximum at C19/C20. Pristane/phytane ratios are around materials that are present in Early Jurassic (Late Sinemurian) unity. These features indicate one autochthonous, marine sponge mounds of the central High Atlas, Morocco. We source of the organic substance. The chromatograms differ consider organic colloids to be involved in the calcification with respect to their unresolved complex mixture (UCM hump), (aragonite) of the modern sponge. Calcification goes along i.e., their degree of biodegradation. with sponge tissue degradation under shallow burial conditions within the sediment. Electron microscopy and in-situ fluorescence microspectometry studies indicate that organic

78 Constraints for carbonate mound formation: sediment buffered by the carbon signature of the precursor limestone. architecture, facies patterns, and early diagenesis (Jurassic, The 87Sr/86Sr ratios are slightly but constantly more Atlas Mountains, Morocco radiogenic than Cambrian or Carboniferous seawater values. Stéphanie Larmagnat and Fritz Neuweiler The minor element composition (Sr, Na, Fe, Mn) is consistent Département de Géologie et Génie géologique, Université with a burial origin of the dolomite. Fluid inclusion studies give Laval, Québec (Québec), Canada, G1K 7P4, more insight into the composition of the dolomitizing fluids. The low melting temperature of ice in fluid inclusions points to Carbonate mounds are a perennial, sedimentary to early highly saline brines characterized by the presence of different diagenetic motif of Early to Mid-Jurassic successions of the cation species. Low temperature Raman spectroscopy Middle and High Atlas Mountains, Morocco. Although these confirmed the presence of hydrohalite and al least one other carbonate buildups have in common their mound-shape and a salt-hydrate phase. The halogen ratios are consistent with relatively fine-grained sediment composition, the mechanisms basinal brines derived from evaporated seawater, which has of their formation appear fundamentally different. This paper been modified through water/rock interaction. A regional, long- presents the results of field observations and petrographic lasting fluid flow can be hypothesized, affecting the Cantabrian analysis of three examples of Jurassic carbonate mounds. At Zone. The dolomites probably formed in Early Permian time localities Foum Zidet and Foum Tillicht (Early Jurassic, High during post-thrusting orocline formation in an extensional Atlas) mounds are up to 20 meters thick and rich in calcified setting. Lithospheric delamination enabled increased heat flow siliceous sponges. Here, primary bedding may pass through and thermal convection of the fluids. the mounds and lateral changes of facies are subtle or absent. Keywords: Hydrothermal dolomites, reservoir analogs, Paleozoic, Other sponge mounds are more massive in their core with Spain features of a skeletal framework due to overgrowths by polychaetes and bryozoans. Thus, the major factors for mound Integrated basin analysis of the Atlantic margin, Tarfaya formation are early diagenesis combined with biotic encrustation. At locality Jebel Assameur (Mid-Jurassic, High basin, Morocco Atlas) mounds are 3 to 10 meters thick and relatively rich in Axel Emmerich1, Manfred Böckmann, Hans-Hermann Ecke corals and coral debris. The cores of the mounds develop from and Jürgen Schober lateral thickening of one or two beds. Lateral changes of facies RWE Dea AG, Überseering 40, 22297 Hamburg, Germany are subtle, i.e., the traditional reef mound concept does not Introduction apply, and there is no direct, textural evidence for the mechanisms of their formation. The technique of numerical stratigraphic modelling has been introduced with the refinement of sequence stratigraphic Massive hydrothermal dolomites in the Cantabrian Zone (NW concepts and the advent of powerful computer technology. Spain) and their relation to the Late Variscan geodynamic Since approx. 15 years, this technology is now widely setting distributed in both academia and industry. It is especially suited Thilo Bechstädt1, Maria Boni2, 1, Marta Gasparrini1 and Fabio for assessing and ranking exploration targets and is illustrated Lapponi1 with a case study from a mixed carbonate/siliciclastic 1 Geologisch-Paläontologisches Institut, Universitaet sedimentary environment–the Cenozoic Atlantic margin in the Heidelberg, INF 234, D 69120 Heidelberg, Germany; Aaiun-Tarfaya basin sector. [email protected] The Moroccan margin exhibits a complex structural 2 Dipartimento Scienze della Terra, Univ. Napoli, Via evolution that can be schematically subdivided in three major Mezzocannone 8, 80134 Napoli, Italy episodes: pre-rift, synrift, post-rift. During the post-rift period Large-scale, massive burial dolomitization affected the (Jurassic to recent) several abrupt changes in drift direction Carboniferous and Cambrian carbonate succession of the affected African plate’s motion. To the south of Tarfaya, Cantabrian Zone (Asturia, Cantabria and Leon Provinces, NW geodynamic evolution of the continental margin appears Spain). These dolomites are excellently exposed and represent homogeneous and represents the typical rifted Atlantic passive an important outcrop analogue for hydrocarbon reservoirs continental margin. Northwards, the creation of the basin elsewhere. The dolomitization is discontinuous and irregular between the Canary Islands and the African continent was but has a remarkable spatial distribution in different tectonic subsequently overprinted by effects of the Tertiary alpine units of the area. Dolomitization has no relation to local early orogeny, antithetic rotation of tectonic blocks at the continental diagenetic dolomitization. Replacive and void-filling dolomites margin induced by rifting motion along the master detachment formed and were often post-dated by calcite cementation. fault, and episodic salt-induced movements which made Each dolomite type is characterized by an ample range in geometry and structural patterns of this passive margin very ?18O, on a regional scale, and by more constant ?13C, complex.

The First MAPG International Convention, Conference & Exhibition 79 Marrakech Convention Center, October 28 - 31, 2007 In the onshore part of the Aaiun-Tarfaya basin, thicknesses local development of hardground features, the margin is of Lower Cenozoic lithological units vary significantly (0- characterised by: 1100m;). In most cases, they unconformably overlie Upper Cretaceous strata. A major input in clastic sediments during progradation of shaly sediments into the basin over this the Eocene indicates either a sea-level fall, an increased presumed hardground surface, sediment flux from the hinterland or the combination of both. influx of sand and abundant mass transport complexes The basal Oligocene transgression is recorded by limestones during an Eocene to Oligocene interval and of a coastal playa lake, followed by red siltstones characteristic of a playa plain. This succession is overlain by a regionally progradation of shaly sediments with significant carbonate known Lower Oligocene angular unconformity. Sedimentation and sand content from Upper Miocene onwards triggered by continues with a siliciclastic fining-upward megasequence, climatic factors (erosion history of hinterland), tectonic factors comprising of alluvial fan to playa plain facies. Major (uplift of shelf and hinterland) and SL change (SL fall, global depositional breaks (Oligocene to Lower Miocene) can be lowstand during Plio-, Pleisto- and Holocene). traced towards the shelf. Especially in the northern coastal basin, the Oligocene is missing due to widespread erosion Session: The tectonics of vertical movements, during this interval. Miocene deposits thicken considerably mountain building and subsidence -Europe and the towards the south and west, they are mostly transgressive and world characterised by sandy lime- or claystones. The Upper Miocene is characterised by a regressive phase (5.3 Ma, Late Neoproterozoic convergence between the West African Messinian event) and represented in the offshore basin by a craton and the Pan-African terranes: metacratonic evolution, strongly bedded acoustic unit. post-collisional magmatism and Cenozoic volcanism in the Numerical modelling Tuareg shield and the Anti-Atlas Jean-Paul Liégeois The particular feature of sequence stratigraphic forward Isotope Geology, Royal Museum for Central Africa, B-3080 modelling is the simulation of sedimentary facies patterns Tervuren, Belgium depending on the creation/destruction of accommodation space. This accommodation development of the Tarfaya The West African craton (WAC), this huge body stable for 2 sector of the Atlantic margin was determined beforehand billions years, has collided with a series of terranes in West during an inverse modelling procedure taking into account Africa at the end of the Neoproterozoic (Pan-African orogeny). lithological and crustal parameters. Calibration of the modelled It is generally considered that little occurred in the WAC while section was realised by visual comparison with seismic and the other West African terranes have been modelled during this well data. Several models with different sets of input major collision, forming the Pan-African mobile belt. The parameters were run simultaneously in order to achieve a best contrast is indeed clear but it must be precised: WAC margins fit and min-max scenarios. have been affected, sometimes as strongly as they have been considered as part of the mobile belt and parts of the mobile Results belt were sufficiently cratonic to largely preserve their pre-Pan- African features and to strongly influence the development of The sedimentary and stratigraphic framework of the the Pan-African structures. This metacratonic evolution (“meta” Tarfaya margin is characterised by its complex structural in the sense of what is coming after, in this case the cratonic history and also by global eustatic sea-level change. The stage) is marked by an absence of major crustal or lithospheric Middle and Upper Cretaceous shelf deposits are marked by a thickening, by transcurrent tectonics and post-collisional general transgression and sea-level highstand. During the magmatism as major effects and by the preservation of old entire Cenozoic the shelf is characterised by tectonic instability features and of early orogenic ophiolitic and island arc and high-amplitude glacio-eustatic sea-level fluctuations which assemblages accreted early towards these regions. started in the Oligocene. This interaction is represented by numerous unconformities within the sedimentary deposits on With their rigid but fractured structure and their position by the shelf as well as by erosion surfaces and lack of Tertiary definition at rheological discontinuities, metacratonic regions sediments on land. are highly susceptible to be repeatedly reactivated. They are thus often the locus of major mineralizations and of intraplate The course of sequence stratigraphic forward modelling volcanic provinces. made clear that a basal unconformity (i.e. basal Cenozoic U/C) existed at shallower levels than the seabottom is observed The Tuareg shield, on the eastern side of the WAC and the today and this basal Cenozoic unconformity lay bare in distal Anti-Atlas, on its northern side are taken as examples: the areas for several millions of years. After this period of Tuareg shield comprises several Archaean/Palaeoproterozoic submarine exposure combined with non-deposition and the terranes variably metacratonized during the Pan-African and is

80 the locus of a Cenozoic volcanic province as it is also the case relative tectonic quiescence during Oligocene-Lower Miocene for the Anti-Atlas which is considered here as the northern with development of extensional tectonic structures with metacratonic boundary of the WAC itself. slightly tilted panels, grabens and locally the development of listric normal faults linked to reactivation of the “décollement” Lithospheric structure of Maghreb and Western surfaces. Mediterranean Comparison of the seismic and field data collected along Hermann Zeyen1, Javier Fullea2 and Manel Fernàndez2 the Atlas, in the Tellian domain as well as in the Eastern Tunisia 1. UMR 8148 IDES, Université Paris-Sud – CNRS ; foreland, allows us to propose a coherent tectonic scenario at Département des Sciences de la Terre, Bât. 504, 91405 Orsay the scale of Tunisia. In particular, we emphasise the role of the Cedex, France so-called “Atlas event” (Middle-Late Eocene), which was 2. Intitut Jaume Almera, C.S.I.C., C/Lluís Salé i Sabarís s/n, initially defined in Algeria but remains poorly known and defined 08028 Barcelona, Spain in Tunisia. We will show that that the tectonic agenda defined Topography and geoid anomalies have been inverted in the in Tunisia is consistent with the one proposed elsewhere in the Western Mediterranean in order to obtain a large-scale image Maghreb allowing us to propose an unified view of the of crustal thickness and depth of the lithosphere- geodynamic evolution of the whole Atlas system. asthenosphere boundary (LAB). The basic assumptions for the So, the Cenozoic tectonic history of the whole Maghreb inversion are local isostatic equilibrium, smooth (long- seems to be dominated by two periods of uplifts (Middle-Late wavelength) anomalies and thermal steady state, which have Eocene and Plio-Quaternary) separated by a period of as effect to smoothen out the resulting depth variations. As has subsidence during the Oligo-Miocene. The Oligo-Miocene is to be expected from seismic and other observations, thinnest the period during which the convergence between Europe and lithosphere is obtained under the Tyrrhenian Sea. West of the Africa is accommodated by subduction, with slab roll-back and Corsica-Sardinia block, a linear NE-SW trend of strongly back-arc spreading, in the west Mediterranean. So the thinned lithosphere is modelled that starts in the Ligurian Sea, subsidence observed at the same time in the Africa plate can continues under the eastern Alboran Sea and crosses the be linked to its flexuration in front of the moving Tell-Rif internal Mediterranean margin of Africa underneath eastern Morocco, zones. where it continues under the Middle and High Atlas until near the Atlantic Moroccan Margin. This trend is independent of Key words: Maghreb geodynamics, Paleogene, structural inversions, actual plate boundaries and the principal tectonic strike in Tunisia, subsurface data, field data, Tellian domain, Atlas, foreland northern Africa. It may be explained by the remnant effects of a retreating slab or active upwelling of the asthenosphere in Offshore evidence for contractional tectonic reactivation of this area. the north Africa margin, Western Mediterranean Sea, and geodynamic implications The Paleogene structural inversion and the Oligo-Miocene Jacques Déverchère1, Abdelkarim Yelles2, and the subsidence in Tunisia: toward an unified tectonic MARADJA-MARADJA2 Scentific Parties interpretation of the Maghrebian Atlas system 1. UBO-IUEM (Université de Bretagne Occidentale, Institut Sami Khomsi1*, Dominque Frizon de Lamotte2, Mourad Universitaire Européen de la Mer), UMR 6538 CNRS Domaines Bédir1, Mohamed Ghazi Ben Jemia3, Mohamed Soussi4 and Océaniques, Place Nicolas Copernic, 29280 Plouzané, France Kmar Ben Ismaîl-Lattrache4 2. C.R.A.A.G. (Centre de Recherche en Astronomie, 1. Laboratoire géoressources, Centre des recherches et technologie Astrophysique et Géophysique), BP 63, Bouzaréah, 16340 des eaux. Technopôlr de Borj Cédria, Tunis, Tunisie Algiers, Algeria 2. Université Cergy Pontoise, Dép artement des Sciences de la Since the closure of the Tethyan ocean and the collision of Terre et de l’Environnement (CNRS, UMR 7072), Neuville/Oise, the Internal Zones with the African passive margin by 15 Ma, 95 031 Cergy-Pontoise Cedex, France the slow convergence between Africa and Europe is 3. Kuwait foreign petroleum company, Tunisia Limited accommodated in a different way, implying a tectonic (KUFPEC), Berges du Lac, Tunis, Tunisie reorganization of the plate limit. From a set of ~10 000 km of 4. Université de Tunis El Manar, Faculté des Sciences de Tunis, Tunisie swath bathymetry and seismic lines aquired in 2003 and 2005, * Adresse de correspondance : 57 rue 7301 par avenue, Tahar we reveal the development of young, active fault-related folds Ben Ammar Menzah 9 B, 1013, Tunis, Tunisie at the foot of the Algerian margin and describe its general Structural interpretation of surface and subsurface data in pattern. The active faults identified depict similarities in length, Tunisia, allows us to recognize inversion structures expressed tectonic style, position on the margin, and geometry (south- and recorded in the Paleogene sedimentary pile of the Atlas dipping segments). This young tectonic system is well domain. This compressive episode is followed by a period of preserved in the sedimentary record and further supports the hypothesis of subduction inception, with a progressive transfer

The First MAPG International Convention, Conference & Exhibition 81 Marrakech Convention Center, October 28 - 31, 2007 of stress at the boundary between continental and oceanic The Betic-Gibraltar-Rif system: a squeezed plate boundary crust, i.e. near the foot of the margin. We show how the Jaume Vergés and Manel Fernàndez development and style of this system from West to East Group of Dynamics of the Lithosphere (GDL), Institute of Earth depend on structural inheritance and the Africa-Europe plate Sciences “Jaume Almera”, CSIC, Lluis Solé i Sabarís s/n, velocity field, and compare this evolution to the recent strain 08028 Barcelona, Spain pattern observed in the southern Alboran and Tyrrhenian Seas. We try to show how this new step of deformation is related to The Alkapeca (Alboran-Kabylies-Peloritan-Calabria) the Miocene collision of AlKaPeCA blocks, to slab detachment tectonic domain model has been conventionally used when of the Tethyan ocean, and to shortening in the Tell and Atlas trying to interpret the geodynamics of the arcuated orogenic domains. belt constituted by the Betics, Arc of Gibraltar and Rif as well as the enclosed Alboran Basin. This model suggest the A synchronous Alpine and Corsica-Sardinia rotation existence of a relatively large continental block attached to the NE Iberian margin during the early Oligocene that F. Speranza1, M. Maffione1, C. Faccenna2, A. Cascella3, G. dismembered in smaller pieces that formed the present day Vignaroli2 and L. Sagnotti1 allochthonous terranes cropping out along the western 1 INGV, Roma, Italy Mediterranean region. In this model the Alboran block would 2 Università di Roma 3, Italy have travelled a large distance to the SW and then W to finally 3 INGV, Pisa, Italy collide with the SE margin of Iberia and NW margin of Africa. We report on the paleomagnetism of 34 sites from lower Questions like the original shape of the Alboran block, its Oligocene-middle Miocene sediments exposed in the Tertiary detailed path of motion, how this motion fits with the general Piedmont Basin (TPB, northern Italy). The TPB is formed by a evolution of the western Mediterranean, what is the structure thick (~4000 m) and virtually undeformed sedimentary behind the fast moving Alboran Block, what is the geodynamic succession unconformably lying upon Alpine nappes mechanism that triggered the rapid westwards motion of the decapitated by extensional exhumation, which in turn are block are difficult to answer and are currently ignored. tectonically stacked over the Adriatic foreland. Paleomagnetic We present a new evolution model for the arcuated Betics- directions from 23 (mostly Oligocene) sites yielding a primary Arc of Gibraltar-Rif orogenic belt and its Alboran back arc basin magnetization were chronologically framed using new that tries to fit the bunch of published geological and biostratigraphic evidence from calcareous nannoplankton. Our geophysical results that are difficult to interpret with previously data, along with previous paleomagnetic results, show that the proposed models. Our interpretation is supported by surface TPB rotated ca. 50° counterclockwise with respect to Africa in geology and especially by the map distribution of the Aquitanian-Serravallian times. The rotation was likely driven by basement rocks in both the SE margin of Iberia and the NW underneath nappe stacking, and was synchronous with margin of Africa, the timing of the complex tectonic, magmatic, (further) bending of the Alpine chain. Both the rotation and metamorphic evolution in both the Betics-Arc of Gibraltar- magnitude and its timing are alike to those recently Rif orogenic belt and its back arc Alboran basin, the present documented for the Corsica-Sardinia microplate. This reveals a highly irregular geometry of the two margins, the present day common dynamics determining the formation of the western crustal and lithospheric structure and the proposed plate-scale Alpine arc (or at least part of its curvature), back-arc spreading reconstructions of the Iberia-Africa boundary, especially at the of the Liguro-Provençal Basin, and drift of the Corsica-Sardinia onset of African northern convergence in Late Cretaceous block. Paleomagnetic data also document that the Adriatic times. plate has undergone no paleomagnetic rotation since mid-late Miocene times. Anisotropy of magnetic susceptibility results We discuss the evolution model based on four main from the paleomagnetic specimens suggest that the TPB, an geodynamic scenarios: a) Late Cretaceous at the onset of N to enigmatic basin arising from a controversial tectonic setting, NNW African convergence; b) Oligocene when first limited formed in an extensional regime characterized by a stretching foreland basins formed in front of advancing thrusting in the direction ca. orthogonal to the main trend of the underlying Betics; c) early Miocene to late Miocene during the westwards chain. motion of the Arc of Gibraltar and allochthonous tectonic units in the Gulf of Cadiz; and d) from late Miocene to present to show the change in tectonic regime in the entire area as well as the present deformation taking place along the Iberia-Africa boundary.

82 The Gulf of Cadiz accretionary prism: the active offshore link Further upslope, there are two-sub-arcs which appear to between the Rif and Betic mountain belts bound a gravitationally sliding upper portion of the wedge Marc-André Gutscher1, Stephane Dominguez2, Graham (roughly above 2000 m water depth). Locally steep slopes (10- Westbrook3 Pascal Gente4 Nathalie Babonneau4, Thierry 15°) indicate strongly focused, active deformation and present Mulder5, Eliane Gonthier5, Raphael Bartolome6, Joaquim potential gravitational instabilities. The unusual surface Luis7 and Filipe Rosas8 morphology of the upper accretionary wedge includes “rafting- 1. IUEM, Univ. Brest, UMR 6538, Plouzané, France tectonics” type fissures and abundant sub-circular 2. Univ. Montpellier depressions. The possible contribution of dissolution and/or 3. Univ. Birmingham diapiric processes to the formation of this morphology is 3. IUEM, Univ. Brest, UMR 6538, Plouzané, France discussed. Mesozoic salt is present on both the 4. Univ. Bordeaux Portugese/Spanish as well as the NW Moroccan continental 5. CMIMA, Barcelona margins. The role of salt and/or mud diapirism in the wedge 6. Univ. Algarve and the relation to the tectonic style observed is discussed. 7. Univ. Lisbon Structural style of inversion of rifts and passive margins: The offshore continuation of the arcuate Rif and Betic Feedback between mountain building and surface mountain belts lies within the Gulf of Cadiz. Here, the plate processes. Application to the Pyrenean-Cantabrian boundary between Africa and Eurasia is diffuse, with Mountains deformation spread over a 200 km wide (N-S) zone. The complex plate kinematics suggest the presence of Ritske Huismans1,2, Christopher Beaumont2 and David Pedreira3 independent blocks with strong internal deformation. The 1. Department of Earth Science, Bergen University, Bergen, Norway study of the historical seismicity in this area (the Great Lisbon 2. Department of Oceanography, Dalhousie University, Halifax, Canada earthquake of 1755, M8.7) and assessment of the modern-day 3. Department of Earth Science, Oviedo University, Oviedo, Spain tsunami hazard, has stimulated an international effort to map Inversion of sedimentary basins and passive margins at the seafloor and active faults in this region. We report on the various stages of their evolution is modeled with thermo- results of recent bathymetric swathmapping and multi-channel mechanical viscous-plastic finite element techniques. We seismic surveys carried out here, primarily the Delila cruise (R/V focus on two aspects of the inversion and collision process: 1) Dom Carlos Oct. 2004) and DelSis cruise (R/V Suroit April the role of the strength of the lower crust on the style of 2005), but also the Cadisar 1 and 2 surveys (R/V Suroit Aug. inversion, and 2) feedback relations of surface processes with 2001, Sept. 2004). the tectonic deformation and their control on the style of The seafloor is marked by contrasting morphological lithosphere inversion. The model involves a crustal layer of 35 provinces, spanning the SW Iberian and NW Moroccan km thick and a lithosphere of 125 km. All materials follow continental margins, abyssal plains and an elongate, frictional-plastic strain softening, or thermally activated viscous horseshoe shaped, accretionary wedge. The accretionary flow laws. The model is thermally coupled and the thermal wedge, with abundant curvi-linear ridges and troughs, evolution is calculated. presents evidence of recent deformation at its boundaries. It During a first phase the model is extended to form a rift appears to be the active offshore link between the Rif and Betic basin. The rift basin or passive margin geometry is then used mountain belts. The older Miocene external Betic allocthons as as initial condition for a phase of lithosphere scale inversion well as the external Rif nappes (“nappe pre-rifaine“) are both and collision. Using a prior rift or passive margin formation currently inactive and buried beneath several km of sediment. phase allows examining the role of pre-existing heterogeneity However, a new tectonic boundary has formed further south, on the style of inversion and continental collision. We examine and north, respectively (in a more “internal“ position) the effect of very simple end member surface process models abandoning the older tectonic front. on the style of mountain building: 1) No erosion and no Bathymetric data and high-resolution seismic profiles sedimentation, 2) No erosion and complete sedimentation, 3) provide evidence for frontal and possibly basal thrusting, Complete erosion and complete sedimentation. Very actively deforming the accretionary wedge. The frontal portion contrasting behavior is observed for these end-member of the accretionary wedge is marked by an undulating variations in surface process model. morphology formed by anticlinal thrust ridges and suggesting The model results indicate that the efficiency of surface deformation is distributed over a very wide region (at least 100 process models to remove and distribute mass in the system km from the deformation front). The very shallow mean surface forms a strong control on the overall style of inversion and and basal slopes of the accretionary wedge (1° each) indicate collision. Without erosion or sedimentation deformation a very weak decollement layer, geometrically similar to the migrates outward into the foreland after an initial phase of Mediterranean Ridge accretionary complex. orogenic growth. In the end-member case where erosion

The First MAPG International Convention, Conference & Exhibition 83 Marrakech Convention Center, October 28 - 31, 2007 removes all topography, deformation is localized in the core of the mass deficit associated to the compensating loads located the orogen with strong asymmetric exhumation. Implications below the mountain range. Assuming that the density deficit for inversion tectonics in the Cantabrian-Pyrenean Mts will be below the Scandes is purely thermal in origin, thermal discussed. modelling allowed for testing the magnitude of the potentially associated temperature anomaly and its impact on surface 3D density and temperature distribution at passive heat flow and lithosphere rheology. Modern heat flow data continental margins –an example from the North Atlantic recently acquired in the framework of the Kontiki (NGU/Statoil) Magdalena Scheck-Wenderoth and Yuryi Maystrenko and HeatBar (NGU/Statoil/Research Council of Norway) GeoForschungsZentrum Potsdam, Sect. 4.3: Organic projects were used in order to validate the results from the geochemistry, Telegrafenberg C423 D-14473 Potsdam, thermal modelling. Germany Subsidence and uplift in the Carboniferous basins of The physical state of passive continental margins is northern England: interplay between asthenospheric controversial concerning the mode and level of isostatic processes and crustal architecture at the Variscan margin of compensation and the configuration of the lithosphere- Laurussia asthenosphere boundary. One of the few passive continental Tim Pharaoh margins where the detailed structure of the crustal part of the British Geological Survey, Keyworth, Nottingham, UK system from the continental onshore, over the continental margin offshore and across the continent ocean transition to The Carboniferous basins of northern England have been the oceanic part is well explored, is the Norwegian margin of intensively studied in recent years. They were initiated by the northern Atlantic. This provides constraints for the 3D lithospheric extension of the Laurussia margin bordering the conductive thermal field and the density distribution across the Rhenohercynian Ocean. In Dinantian time, several elongate margin in the crust and in the lithospheric mantle. To evaluate asymmetric half-graben developed, partly controlled by pre- which configuration of the lithosphere asthenosphere existing crustal structures of Neo- proterozoic to early boundary is consistent with the observed crustal configuration Palaeozoic age. Asthenospheric melting produced extensive and with measured temperatures in the sedimentary part of the basaltic magmatism, emplaced along major crustal margin, we test different scenarios. We use a present-day 3D lineaments. Intra-basinal highs were underpinned by buoyant structural model of the Vøring and Møre segments of the granite-intruded basement blocks. Strong footwall-uplift on rift Norwegian margin which is constrained by seismic, well and flanks resulted in localised erosional unconformities not present gravity data. 3D gravity modelling and isostatic calculations in the basins. revealed that the lithospheric mantle below the ocean is less dense than below the continent. Subsequently, we calculate Silesian strata postdate lithospheric extension, forming the temperature distribution for the 3D structural model of the during a long period of thermal relaxation. The basin axis runs margin and compare the results to measured temperatures in north-south, oblique to the Dinantian depocentres. In deep wells on the margin and in two ODP wells on the oceanic Namurian time, detritus from the reactivated Caledonian crust. Our results indicate higher temperatures in the oceanic mountains in Norway and Scotland was fed to major mantle than in the continental mantle. southward-prograding fluviodeltaic systems developed in eustatically-controlled lowstand and highstand system tracts. Did a mantle thermal anomaly cause uplift of the Scandes? These were constrained by highs in the south (London-Brabant C. Pascal and O. Olesen Massif) and east (Nocton High), underpinned by crustal NGU, Geological Survey of Norway, N-7491 Trondheim, domains which remained buoyant until late Namurian time. Norway Westphalian strata transgressed onto these residual highs. By this time the landscape had evolved into a plain close to sea- The Scandes is a recent and long mountain range level, covered by rivers, lakes and swamps, episodically stretching from southern to Arctic Norway and being invaded by marine incursions. In late Westphalian time, the characterised by a rugged topography and peaks up to 2,5 km region began to suffer compressional deformation in the far- high. The origin of this mountain chain far away from any plate field of the Variscan orogenic system. Inversion was most boundary remains a matter of harsh debates inside the intense along reactivated basement lineaments and in a geoscientific community. Hot mantle “fingers” originating from peripheral bulge to north of the developing orogenic foreland the Iceland Plume and impacting the base of the Scandinavian basin. These newly uplifted regions superceded the northern lithosphere is one of the most accepted hypotheses for provenance in latest Westphalian time and fed sediment to a explaining Cenozoic uplift in Norway. In order to test this new basin template. In latest Carboniferous to early Permian hypothesis we conducted integrated gravity and thermal time, extensive plume-related post-orogenic magmatism led to modelling. We used the dense NGU gravity grid (i.e. one crustal uplift and erosion, setting the scene for Permo-Triassic measurement every ~3 km) and modelled the depth extent and basin development.

84 Tracking mountain belt and foreland basin evolution from Structural evolution and hydrocarbon accumulation in detrital thermochronology and numerical modelling: an Central Iran (Qum region) example from the central Himalaya (Nepal) Jean Letouzey1, Jean Luc Rudkiewicz1, Dariush Baghbani2, P.A. van der Beek1, X. Robert1, J. Braun2 and M. Bernet1 Laurent Cuilhe3 and Kazem Kazemi2 1. Laboratoire de Géodynamique des Chaînes Alpines, 1. IFP Université de Grenoble, France 2. NIOC 2. Géosciences Rennes, Université Rennes I, France 3. Beicip-Franlab

Thermochronological analysis of detrital sediments derived Geological and petroleum exploration in Central Iran from the erosion of mountain belts and contained in the focuses again the Oligo-Miocene Qum Formation, time- sedimentary basins surrounding them allows reconstructing the equivalent of the prolific Asmari limestone in the Zagros. These long-term exhumation history of the sediment source areas. two formations were deposited on both sides of the Zagros- The effective closure temperature of the thermochronological Central Iran continental suture zone. The structural evolution of system analysed determines the spatial and temporal resolution Central Iran during tertiary times will be presented based on of the analysis through the duration of the lag time between recent seismic, gravity, magnetic data as well as geological field closure of the system during exhumation and its deposition in data. This evolution will be put in light of the global changes the sedimentary basin. High closure-temperature systems such since the beginning of the Mesozoic, up to the present time of as mica Ar-Ar or zircon fission-track (ZFT) data allow estimating both Central Iran/Eurasian and Zagros/Arabian plates. long-term exhumation rates using the lag-time concept (cooling Following the Late Cretaceous ophiolite obduction on the age – depositional age) and for analyzing the overall pattern of Zagros platform, the northward migration of the Arabian plate exhumation. The complementary, lower temperature apatite continued up to the continental collision with the fission-track (AFT) system allows testing for shorter-term Eurasian/Iranian Plate at the Oligo/Miocene. The convergence variations in exhumation rates. Because of its relatively low between Arabian and Eurasian plates was absorbed by closure temperature, AFT thermochronology is also sensitive to northern subduction of the remnant ocean bellow the southern the thermal evolution of the foreland basin itself. margin of Central Iran . Extensive calc-alkaline volcanic activity, Stratigraphically higher samples will remain unreset and retain a in shallow marine environment occurred during the Eocene. signal of source-area exhumation. More deeply buried samples Then, during the Oligocene-Early Miocene, volcanism will lose this information when they have been partially reset, in narrowed to a NW-SE trending zone. Rapid facies and contrast, they may provide constraints on the thermal and thickness variations in the Oligocene-early Miocene kinematic history of the foreland basin. continental, marine and brackish formations are locally Detrital mica Ar-Ar, ZFT and AFT data from Miocene to controlled by wrench faulting and volcanic intrusions. The Pliocene Siwalik Group sediments in central and western climax of tectonic activity in the Qum basin occurred during the Nepal allow to track the long-term exhumation history of the middle-upper Miocene molasse deposit (URF, Upper Red central Himalaya, which has been only poorly constrained so Formation), as illustrated by lateral changes from fast subsiding far. The new detrital data provide important new insights in the areas to uplifting areas in adjacent locations. Up to 6 to 9 km long-term exhumation history in the central Himalaya, as well of URF is preserved in the Saveh region, whereas nearby areas as in the thrust propagation sequence and burial-exhumation are uplifted at that time. Growing strata in the URF horizons history of the foreland fold-and-thrust belt. In particular, the show that faulting and folding affected the area at that time. 2D high-temperature (Ar-Ar and ZFT) data indicate a rapid and seismic lines show syn-sedimentary faults with normal and important phase of exhumation at ~15-18 Ma, apparently reverse components, typical of wrenching movements. contemporaneous with major tectonic reorganization of the Hydrocarbon accumulations are probably related to small orogen (transition from extrusion along the Main Central Thrust source ponds located within the Qom formation. The to forward propagation), and followed by more focused maturation and expulsion occurred during URF deposition, steady-state exhumation at ~1.5 km/Myr, whereas the lower generating either oil, condensate or gas traps. temperature AFT system shows spatial variations in recent GPS measurements and seismologic studies show that the exhumation rates not picked up by the higher-temperature north trending Arabian-Eurasian convergence was absorbed systems. We use a 3-D numerical thermo-kinematic model, both in the Zagros folding (NE/SW shortening) and in Central including lateral motion along faults and evolving surface Iran (NW/SE trending, right lateral wrench faulting). We topography, to predict thermochronological ages for different observed that this partitioning of the deformation between pure systems at the surface through time. The probability-density compression with folding in the Zagros and dextral strike slip functions of thermochronological ages are compared to the movements along the southern part of the Central Iran has single-grain detrital age distributions in order to quantitatively existed since the collision in Late Oligocene time. This constrain exhumation scenarios for the central Himalaya that partitioning is due to the obliquity of the former suture zone permit to explain the observed detrital age patterns.

The First MAPG International Convention, Conference & Exhibition 85 Marrakech Convention Center, October 28 - 31, 2007 relative to the N-S relative movement of the plates. We assume from a (far-field) stress transmission from the Arabia-Eurasia that volcanic arc activity during the Oligo-Miocene has created plate boundary. a weak zone within the Central Iran Micro-plate which will Key-words : Arabian margin inversion, Zagros, basement faults favour strike slip deformation during the collision. To test and illustrate the structural observations, sand box models were performed. A great similarity between the faults and Causes and timing of mountain building in the Zagros Fold subsidence locations was observed between sand-box Thrust Belt. models and fault and fold patterns in the field. Pascale Leturmy1, Dominique Frizon de Lamotte1, Jean Letouzey2, Jean-Paul Callot2, Matteo Molinaro3 and Sharam Evidence for early Miocene pre-orogenic margin inversion Sherkati4 /basement faults reactivation and related vertical 1. Université de Cergy-Pontoise, France 2. IFP, France movements in Central Zagros (Iran) 3. Shell Research, Netherlands Olivier Lacombe1, Frédéric Mouthereau1, Faram 4. NIOC, Iran Ahmadhadi2, Jean-Marc Daniel3, Julien Tensi1 and Khalid Amrouch1,3 In the Zagros Fold Thrust Belt (ZFTB) of Iran mountain 1 Université P. et M. Curie - Paris 6, Paris, France building is linked with folding of the cover, basement faulting 2 Norskhydro, Norway and lithospheric thinning. These three processes are 3 Institut Français du Pétrole, Rueil-Malmaison, France superimposed but produce topography at different length scales that can be distinguished. Folding only create local Reactivation of Tethyan and Panafrican basement faults topography and has been intensively studied these last years related to early orogenic inversion of the Arabian margin is while lithospheric thinning (Molinaro et al., 2005) probably evidenced by depositional patterns and facies variations within affect a zone larger than the ZFTB. Basement faulting creates the Lower-Middle Miocene strata of the Zagros foreland basin, topography at intermediate scale. The strongest line of as well as distribution of pre-folding fracture populations within evidence for basement faulting involved in deformation comes folds. from the relatively intense mid-crustal seismic activity In the Fars, isopachs maps reveal an inhomogeneous (Berberian et al, 1995; Maggi et al., 2000; Talebian and pattern of deposition : the northwards increase in thickness of Jackson, 2004). Molinaro et al. (2005) shown that in the the Fars Group reflects flexurally-induced subsidence, while Eastern Zagros Mountains basement control on surface second-order depocenters suggest a more complex structures only occurred at a late stage of the tectonic subsidence pattern in relation with tectonic inheritance in the evolution. In other words, the current thick-skinned style of Arabian margin and basement faulting : along the Persian Gulf, Zagros deformation succeeded a more general thin-skinned the lack of Gashsaran and lower Mishan Formations on the phase of orogeny. This chronology is particularly well illustrated southern limb of the Asaluyeh anticline may indicate early by spectacular interference patterns, in which early movements along the Mountain Front Fault, while variations in detachment folds are cut by late oblique basement faults. This thickness of the Gashsaran and Razak formations support leads up to form sigmoid and butterfly like structures at early reverse movements along the Surmeh-Qir Thrust. surface. Systematic morphological analysis (large scale topography and river network) combined with structural In the Dezful, facies variations and development of sub- analysis allows us constructing a general map of basement basins during the sedimentation of the Asmari Formation also faulting in the Fars arc and a synthesis of basement uplift from support early basement fault reactivation; the evaporitic series Lurestan to eastern Zagros. The faults show an increase in of the Kalhur Member likely resulted from the development segmentation in the eastern limb of the Fars Arc which is during Aquitanian of a long and narrow restricted lagoon coeval with a diminution of basement uplift on each fault. This environment, between two main basement faults. Early change in geometry and deformation partition may be related basement fault reactivation is additionally suggested by pre- to the influence of inherited transverse structures within the folding joint sets in the Asmari Fm which are oblique to Arabian basement, related to the Oman Line transform fault present-day anticlines (and observed even within synclines) system which developed during the Permo-Triassic Neotethys and are not compatible with simple fold-related fracture rifting. models: these sets likely formed within the cover in response to local extensional stresses caused by large-scale flexures/ drape forced folds above reactivated N-S and NW-SE trending basement faults.

This early orogenic compressional deformation reflects early Miocene stress build-up in the Arabian plate resulting

86 Upper Crustal Thermo-Kinematics and Lithosphere’s Thermochronological data and denudation history along a Rheology, inferences on Vertical Motions from the SE transect between Chañaral and Pedernales (≈26º S), north Canadian Cordilleran Foreland Belt Chilean Andes: orogenic implications N.J. Hardebol1,2, J.P. Callot1, G. Bertotti2 and P. Fermor3 Thierry Nalpas1,2, Gérard Hérail2, Constantino Mpodozis3, 1. Institut Français du Pétrole, 1-4 av. de Bois Préau, 92852 Rodrigo Riquelme4, Jorge Clavero5 and Marie-Pierre Dabard1 Rueil Malmaison cedex, France 1. Géosciences Rennes, Université de Rennes1, Campus de 2. Faculty of Earth and Life Science, Vrije Universiteit, De Beaulieu, 35042 Rennes cedex, France Boelelaan 1085 1081 HV Amsterdam The Netherlands 2. IRD-LMTG, Román Díaz 264, Casilla 53390, Correo Central, 3. Devon Canada Corp., Calgary, Canada Santiago, Chile and Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas de la Universidad de Chile. The SE Canadian Foreland-Fold-and-Thrust Belt (FFTB) Santiago, Chile constitutes a regional scale study area to decipher the 3. SIPETROL, Av. Vitacura 2736, Las Condes, Santiago de progressive development of an orogenic wedge, focusing on Chile, Chile fault block thermo-kinematics and burial-exhumation histories. 4. Universidad Católica del Norte, Avenida Angamos 0610, This study further aims at linking upper crustal thermo- Antofagasta, Chile kinematic history to lithospheric scale dynamics. The Canadian 5. SERNAGEOMIN, Av Santa María 0104, Providencia, FFTB provide a valuable combination of structural work, rich Santiago, Chile thermal-proxy catalogues and ample deep seismic sounding studies for determining the deeper litho-astenosphere The Chilean Andes along the southern Atacama Desert structure. The combination of these (near) surface structural (26°-27°S) include into five morphotectonic units: (Coastal and thermal characteristics with extensive geophysical remote Cordillera, Central Valley, Precordillera, Preandean depression sensing studies makes the Canadian Cordillera a qualified and Western Cordillera). Uplift and denudation have produced place for studying the lithosphere behavior at various scales in a large amount of sediments during the Cenozoic but only in terms of thermicity, rheology and vertical motions. the Preandean depression, thick sequences of Tertiary sediments has been preserved, while in the Precordillera and Plate convergence along the North American western Central Depression a thin blanket of Miocene Atacama Gravels margin have caused the distortion of the lithospheric infill paleovalley (Mortimer 1980; Riquelme, 2003; Gabalda et compositional and thermal structure across the southern al., 2005). In this contribution we present a new set of Canadian Cordillera up to the FFTB. Vertical motions in the thermochronologicals data that will allow us to establish the FFTB, operating on wavelengths of individual fault-blocks to ages of main exhumation episodes, which can be tied to the entire belt, are controlled by a mixture of foredeep flexure periods of erosion and Andean uplift along the western slope and deposition, thrustsheet displacement and erosion. Our of the southern Central Andes. That regional exhumation thermal-proxy catalogue allows for the approximation of burial, occurred in three steps along the Chañaral-Pedernales uplift and exhumation patterns in the deformed belt. This transect: Mid-Cretaceous to Paleocene on the Coastal integrated data, analytical, and modeling study reveals that Cordillera, Eocene from the Central Valley to the Pedernales uplift and denudation have not only affected the deformed Basin, and Oligo-Miocene at Cordillera Claudio Gay. Data Canadian Foreland Belt on the small wavelength of individual shows the eastwards propagation of the exhumation that is thrust sheets, but also involved severe tectonic unroofing in the interpreted as propagation of the deformation. Only sediments Cordillera interior and the undeformed distal foreland, which originated during the Eocene Oligocene events seem to have are described at the scale of the belt through time. Ultimately, been preserved in the compressive pre-Andean Pedernales this study allows to link the response of the observed thinning basin. At the same time, withdrawal of material towards the of thermal lithosphere to the rheological stratification and to ocean prevailed along the western Precordillera and Central propose an upper crustal thermo-kinematic history, including Valley. These considerations indicate that topography is not the its uplift and denudation history. major factor controlling the amount of mass transfer during Andean uplift as the adjustments in the volume of mass transferred out of the system seem to track climatic changes towards semiarid-hyper arid conditions during the Miocene. Gabalda G., Nalpas T. and Bonvalot S., 2005. Base of the Atacama Gravels Formation (26°S, Northern Chile): first results from gravity data. ISAG VI, Barcelona. Mortimer, C., 1980, Drainage evolution of the Atacama Desert of northernmost Chile. Revista Geológica de Chile, no. 11, p. 3–28. Riquelme, R., Martinod, J., Hérail, G., Darrozes, J. and Charrier, R., 2003. A geomorphological approach to determining the Neogene to Recent tectonic deformation in the Coastal Cordillera of northern Chile (Atacama). Tectonophysics 361, p. 255-275.

The First MAPG International Convention, Conference & Exhibition 87 Marrakech Convention Center, October 28 - 31, 2007 The Mexican Sierra Madre Oriental Orogeny during Late Andean chain by identifying and quantifying episodes of Cretaceous to Paleogene Time vertical movements, we produced and compiled Fission-Track Jaime Rueda-Gaxiola thermochronological ages from the Eastern Cordillera and ESIA-IPN: Unidad de Ciencias de la Tierra, Calzada Ticomán Sub-Andean Zone. This region was void of such data even No. 600, México, D.F. though varying climatic conditions are there ideal to debate the .relative importance of climate and far-field tectonism in During Pangea formation, the Appalachian-Oachita influencing denudation. Patterns of apatite fission-track Orogeny took place at the North America southeastern margin, apparent ages with elevation as well as compilation from far from Carboniferous to Permian, probably up to Early Triassic. east oil datasets indicate a ten-fold increase in apparent The Appalachian-Oachita mountain belt was intruded by denudation rate between 4 Ma and today. The time frame for batholiths, younger from north to south. At the southern end of this change corresponds to that of global climate cooling since North America were placed the eastern Mexican batholiths. the Pliocene associated with the onset of widespread After Late Triassic Atlantic Ocean origin, during Late Liassic glaciation and the development of El Niño like conditions. a RRR triple junction system was at the origin of the Gulf of There is no information for important modification in tectonics Mexico and its Middle Jurassic expansion formed several of the Andes with the exception of the approaching nail of the fractions of Late Paleozoic batholiths and distributed them buoyant Nazca ridge below the orogen over this interval. This around the Gulf. They became, in the Mexican rim, the most suggests a mostly climatic operator for enhanced erosion in resistant lithospheric pieces that controlled the Jurassic oil the Eastern Andes since the Pliocene. basins origin and later the Sierra Madre Oriental initial deformation (from Late Albian, 100 M.y. to Late Eocene, 40 Keywords: Central Andes, denudation, climate, Pliocene, M.y.), erroneously considered as a part of the Laramide thermochronology Orogeny. Nevertheless, this deformation became younger southeastward, suggesting, during Tertiary, an origin related to GS 12: Ordovician system (Sedimentology, the Chortis Block displacement, before the collision of the East glaciation, Biostratigraphy, Stratigraphy, Pacific Rise and the Northamerican border, during Oligocene paleogeography and magmatism…) time, which is at the beginning of the Transmexican Volcanic Chair: N. Hamoumi Belt, the Sierra Madre Occidental and the Gulf of California evolution. One of the most important tectonic facts was the Characteristics of turbidites in a few ancient deposits development of another triple junction which is bordering the A. H. Bouma Jalisco Block by its Tepic and Colima arms. The widening of the Tepic arm during Oligocene is considered the final factor of The Peira-Cava area north of Nice, SE France, shows an deformation and thrusting of the Sierra Madre Occidental at its active margin. Detailed field studies started the understanding Monterrey- Victoria portion. of the sandstone characteristics and their fixed order. Later someone named it the “Bouma Sequence”. Visits to some A Pliocene climatic proxy for abrupt gain of denudation in other European countries revealed the same characteristics. orogens: example and implications from the Central Andes - The last Deep Sea Drilling Project program was in 1985 in Peru the Gulf of Mexico. Interesting results showed up once we G.M.H. Ruiz compared the cores from different locations. At that time we Neuchâtel, Switzerland were not aware of the differences when dealing with passive The high elevation of the active mountain belts represents margins. The location showed that the relative sand increase a balance between the tectonic processes that create is at the outer fan. topography and erosional surface processes that destroy it. The Permian Karoo just north of Cape Town in South Africa The understanding how internal (tectonic) forces act to shape is the only known ancient passive margin set of two more or the Earth’s surface requires knowledge of long-term changes less similar age depositional groups. One set is nearly vertical whereas few studies have shown convincing correlations while the Tanqua Karoo is presently horizontal. The Tanqua between observable indices of climatic and tectonic processes Karoo has five fans of which the middle one is complete with at the scale of an orogen. The Andean Chain is 8000 kms long its upper fan, middle fan and outer fan. Calculations indicate along the western edge of the South American plate and that the upper fan is comprised of sandstone ridges at right results from the ENE convergence between the subducting angles to the paleocurrent. The middle fan is characterized by oceanic Nazca and South American plates. Between 12 and sand-filled channels and shale-rich overbank deposits. The 15°S the Central Andes are constituted of two different outer fans are interesting. The sheet sands comprise about mountain ranges, the Eastern and Western Cordillera, each 80% of all the sands. having elevation up to 6000 m separated by the 3800m high Altiplano. To better constrain the orogenic growth of the Studies of the Pennsylvanian Jackfork Group in the State of

88 Arkansas have no present horizontal deposits. However, we The Ordovician of Tafilalt-Taouz (Eastern Anti- Atlas Oriental, can apply the Tanqua Karoo deposits and notice similarities. Morocco): Depositionnal systems and control El Maazouz Brahim and Hamoumi Naima The Ordovician of South- Western Anti- Atlas, Morocco: Laboratory “ Oceanology and Geodynamics of Sedimentary Depositionnal systems and control basin”, Department of earth sciences, Faculty of sciences, El Kabous El Houssain1 et Hamoumi Naima2 Mohammed V-Agdal University, Rabat, Morocco 1 Ministry of Mines and Energy, Rabat Sedimentological study of thirteen representatives 2 Laboratory “ Oceanology and Geodynamics of Sedimentary Ordovician (Arenigian-Ashguillian) successions in Tafilalt-Taouz basin”, Department of earth sciences, Faculty of sciences, (eastern Anti Atlas), allow to identify for the first time the Mohammed V-Agdal University, Rabat, Morocco depositional systems and their controls. It also highlighted a The sedimentological study of Ordovician (Trémadocian - complex history of this part of the Moroccan north Gondwanan Ashgillian) successions of South Western Anti -Atlas (Zini and platform. folded Bani) based on sedimentary facies reconstruction, During the Lower and Middle Ordovician, the Tafilalt-Taouz petrographic composition analysis and sequence stratigraphy, domain acted as a silisiclatic epeiric shelf with ENE-WSW allows to identify the depositional systems, the nature of the trending isopachs, that was alimented by siliciclastic sediments sediments and the sources and the factors that control the from the Panafrican shield and it’s old cover and intrabasinal sedimentation. sources (oolitic ironstones and shell fragments). The During the Lower and Middle Ordovician the sedimentation sedimentation took place in storm dominated offshore and occurred in a shallow siliciclastic epeiric sea under the control transition zone, macrotidal estuary and tide dominated subtidal of the subsidence and the sea level fluctuations. The zone under the control of subsidence and eustatism. sediments are mostly silicilastic from the panafrican belt and it’s During the Upper Ordovician, an extensional tectonic event old cover, with minor intercalations of bryozoan mounds, resulted in the individualization of two sub basins the « Khabt- carbonates and oolithic ironstones (intrabasinal sources). They El-Hejar sub basin » and the « Western Tafilalt sub basin », accumulated in various sedimentary environments: where the sedimentation developed under the interplay tide dominated littoral during the Tremadocian, between tectonics and glaciation. The « Khabt-El-Hejar sub basin » created at the Eastern edge of the Tafilalt domain, fluvial currents, waves and storms dominated deltas and correspond to a ramp type basin where took place Bryozoan storms dominated shelf (upper Fezouata Formation) and mounds and a mixed siliciclastic carbonate high energy storms and tides dominated shallow shelf (Zini Formation) peritidal littoral that was alimented by biogenic gravels and during the Arenigian, sand derived from subtidal areas and glacial siliciclastic sediments originated from the Saharan ice sheet. The « storms dominated delta, storms dominated offshore, tide Western Tafilalt sub basin » corresponding to the previous dominated littoral and carbonate platform with Bryozoan silisiclatic epeiric shelf recorded a change in the direction of mounds during the Llanvirnian, isopachs that became NW-SE and was structured in half storms dominated offshore and shoreface and tide graben. The sedimentation occured in storm dominated dominated littoral during the Llandeilo, offshore, estuary, deltas and fan deltas and the sediments are mostly siliciclastic supplies from the Saharan ice sheet and During the Upper Ordovician the sedimentary basin was carbonates originated from the « Khabt-El-Hejar sub basin ». still a subsiding shallow siliciclastic epeiric sea. But the glacial climate induced eustatic sea level fluctuations and controlled Keywords: Ordovician, Tafilalt-Taouz, Paleogeography, Extensional the rate and the nature of the sediment supplies. The tectonics, Glaciation. siliciclastic sediments derived from the panafrican belt and it’s old cover and transported by cold wind and glaciers were Evolution and control of Ordovician sedimentation in the accumulated in: Western and Central High Atlas (Morocco) Chacrone Choukri and Hamoumi Naïma storms dominated offshore and tides dominated shelf and Laboratory “ Oceanology and Geodynamics of Sedimentary littoral during the Caradoc, basin”, Department of earth sciences, Faculty of sciences, macrotidal estuary, tidal flat and deltas during the Ashgill Mohammed V-Agdal University, Rabat, Morocco

Key-words : Ordovician, South Western Anti –Atlas, Depositional The detailed Sedimentological study of Ordovician system, Paleogeography, Upper Ordovician glaciation successions in Western High Atlas (Aït Lahsen, Bas Seksaoua, Adrar Amesnir and Adrar Walma) and Central High Atlas (Tizi- n-Tichka, Imini, Aït Tamlil, and Skoura) leads to several results

The First MAPG International Convention, Conference & Exhibition 89 Marrakech Convention Center, October 28 - 31, 2007 concerning sedimentary environment, depositional sequences, dominated nearshore and shelf environments and tides and/or sedimentation control, transport paths and paleogeographical storm dominated deltas. The sediments are mostly siliclastic reconstruction. They also suggest that the Western High Atlas with minor intercalations of carbonate lenses, glauconitic sand, and the Central High Atlas domains were two independent oolitic ironstones and localised volcanic and pyroclastic rocks epeiric seas separated by an emergant area which in the eastern Anti-Atlas (Jbel Siguenit) and coastal Meseta. corresponds to the present-day location of the Ouzellagh Massif. During the Upper Ordovician, the paleogeography of the two epeiric shelves was widely modified under the interplay of In the Western High Atlas basin, the arenigian the glacial climate and a major extensional event. Various transgression induced shoreface erosion and the development environments occurred: glacial fjords, marine outwash fjords, of a “Basal Transgressive Sand”. The sedimentation occurred mesotidal to macrotidal estuary, high energy waves and/or in a wave and storm dominated delta (Arenigian) a storm storms dominated beach, waves and storms dominated delta, dominated silisilastic offshore (Llanvirnian ) and a storm cold (frost dominated) peritidal mixed siliciclastic/ carbonate dominated silisilastic offshore and shoreface (Llandeilian) under high energy beach, carbonate platform with bryozoan mounds, the control of eustatism and subsidence. During Caradocian- storms dominated continental shelf ice distal (muddy shelf, Ashgillian period, the supplies from the Saharan ice sheet were offshore transition zone, shoreface), tides and storms accumulated in waves, storms, and/or tides dominated dominated temperate shelf, mixed waves and tides temperate nearshore under the interplay of the Upper Ordovician nearshore, storms dominated temperate shoreface, fan delta glaciation and tectonics. and deep sea fan. The sediments are mostly siliciclastic deposits (mainly coarse sand and bouders derived from the In the Central High Atlas basin the arenigian transgression Saharan ice sheet), oolitic ironstones and carbonate from leads to the development of glauconitic deposits and the bryozoan mounds. Llanvirnian commenced with a transgressive/regressive cycle which allow the formation of ferruginous ooids. The Key-words : Ordovician, Morocco, Paleogeography, Upper Ordovician sedimentation occurred in tide dominated deltas (Arenigian) glaciation and tides, waves and fluvial currents influenced deltas with occasional storms (Llanvirnian -Llandeilian), under the control GS 06: Advances in Biostratigraphy and of eustatism and subsidence. During Caradocian-Ashgillian Sedimentology period, the supplies from the Saharan ice sheet were Studies of the Devonian dynamic systems Chair: A. Benbouziane, A. Hilali accumulated by tidal currents in macrotidal estuary and by gravity flow processes in troughs under the interplay of the upper Ordovician glaciation and tectonics. Genesis and Paleoenvironment of the Emsian Kess Kess of Hmar Lakhdad (South East of Erfoud, Tafilalet) Key-words : Ordovician, High Atlas, Depositional system, Atika Hila1i1 and Hassane Lachkhem2 Paleogeography, Upper Ordovician glaciation. 1 Faculty of Sciences Ain Chok, Casablanca 2 Faculty of Sciences Dhar El Mehraz; B.P. 1796 Fez-Atlas Ordovician paleogeography in north Gondwanan Moroccan Margin The Kess Kess of Hmar Lakhdad correspond to about fifty Hamoumi Naima biosedimentary monticules of the Emsian age, situated at the Laboratory “ Oceanology and Geodynamics of Sedimentary south east of Erfoud (Morocco). They rise on a bar of crinoidic basin”, Department of earth sciences, Faculty of sciences, limestone (180 m.) and are constituted of chalk that is more or Mohammed V-Agdal University, Rabat, Morocco less dolomited.

In the north Gondwanan Moroccan margin, the Ordovician The faunistic display is distinguished by the absence of sedimentation occurred in two sedimentary basins: the stromatopores and cyanobacteries, usually present in mictritic “Mesetian basin” including the Moroccan Meseta, the western monticules of the Devonian. High Atlas and the north western Anti-Atlas domains.and the The sharp slope of these Kess Kess suggests the “Atlasic basin” including the south western Anti-Atlas domain, intervention of a stabilization process of the sediment. In the the central and eastern Anti-Atlas domains and the central and absence of encrusting organisms, the cohesion of the eastern High Atlas domains. sediment could be explained by an early cementation of During the lower and middle Ordovician period, they acted, micritic clay; no perforation of the sediment and no lithoclast both of them as epeiric shelves that were dominated by shifting have however been observed. of the subsidence centres (reactivation stage), block faulting The presence, relatively abundant, from the base to the associated some times with basic volcanic flows and eustasy. summit of all the Kess Kess, of ferruginous microscopic The sedimentation took place in tide and /or waves and storms structures, is attributed to microstromatolithes that would have

90 played a determining role in trapping and linking sediments, The structuration on tilted blocs of eastern Tafilalt is allowing in this way the preservation of the slopes of these conbtroled by both faults: Erfoud fault and Tesdrmine fault. edifices whose growth would have then been under biologic Key words. Anti-Atlas, Morocco, Devonian mounds, Tabulate, control. morphostructuration. According to the autocyclic model, only the phases of stabilization-colonization are present in the Kess Kess. It is Contribution to Moroccan Palaeozoic Biostratigraphy by therefore an instance of truncated or aborted growth that we Microfossils Conodonts. Example: Devonian of North- could attribute to the action of storms (Brachet et al, 1992); Western Meseta however, no sedimentologic index that could confirm this El Mostafa Benfrika 1, Mohamed Raji1, Piere Bultynck2 and hypothesis has been observed Ahmed El Hassani3 1 University Hassan II- Mohammedia , Faculty of Sciences Ben The homogeneity of facies of the Kess Kess and the M’Sik Sidi Othmane BP 7955 Casablanca, Morocco. existing ecological communities (only one ecological 2 Institut Royal des Sciences Naturelles de Belgique, rue community composed of corals and crinoids) allows them to Vautiers 29, 1000 Bruxelles, Belgique be situated under the photic zone and at the limit of the action 3 University Mohamed V, Institut Scientifique de Rabat, zone of storm waves, that is at an expanse of water ranging Avenue Ibn Batouta, BP 703 Rabat-Agdta Morocco from -70 to -100 meters. The study of microfossils Conodonts from Devonian strata Key words: Anti-Atlas, Morocco, Emsian mounds, Paleoenvironment. of Northwestern Moroccan Meseta allows to recognize several biostratigraphic species. These microfossils are very Morhostructuration of hmar lakhdad mounds (Anti-Atlas, SE interesting to date with precision and correlate various of Erfoud, Morocco) devonian Formations of three significant areas of Meseta. Atika Hilali1, Lahssen Baïdder,1 Hassan Rhinane 1 Abdehadi 1. Rabat-Tiflet area Kaoukaya 1 and A.Benbouziane 2 1 Faculté des sciences Aïn Chock, département de géologie, The Condonts biostratigraphy studies from some sections B.P5366 Maarif of this area, allows to: 2 Faculté des sciences département de géologie Casablanca - Recognize the presence of Givetian in the Rabat-Tiflet Ben M’sik area (Lower varcus Zone); - Confirm and recognise the age of some Formations The Hmar Lakhdad area, situated within the eastern Anti such as Pragian of Al Khaloua, Emsian (dehiscens and atlas mountain range, some 20 Km Southeast of Erfoud, inversus/laticostatus Zone) and Eifelian (partitus and provides very good exposures of lower and middle devonian ensensis Zone) of the Rabat- Tiflet area. mounds, mostly developped in the Emsian. 2. Oued Cherrat area and its southern extension Four families of tabulate corals are abundant in the Hmar Lakhdad: Auloporids, Dendroporids and Striatoporids are very Late Pragian to early Givetian sections from the Oued frequent in the micritic mounds (named “Kess-Kess”), and Cherrat shear Zone and its southern extension were also Favositids are rather common in the argilaceous limetrobnes systematically sampled for conodonts. Serotinus through lower overlying the mounds. varcus Zone conodonts were recognized and allow an approximate positioning of the base of the Emsian, Eifelian and Statical analysis of the tabulate corals distribution shows an Givetian. evident lateral variation. The western part of the mound range is characterised by o facies with Bainbridgia, the central part by 3. Oulad Abbou and Mechraa Abbou areas a facies with tubular auloporids and ornate dendroporids, and Many sections in these areas have been analyzed for the eastern part by a facies with tubular auloporids. Each conodont biostratigraphy. Two sections are interesting, the first facies corresponds with a part of the range limited by two one (Oulad Abbou area) concerns the Lochkovian to Emsian normal faults. The tabulate corals distribution shows also an (Caudicriodus woschmidti, Ancyrodelloïdes transitans, evident north-south variation. Pelekysgnathus serratus, Icriodids...) of Oued Cheguiga; the The coral distribution is an agreement with the identification second one (Mechraa Ben Abbou area) corresponds to the of the origin of cinerits and a tectonic study. Emsian-Eifelian and the Givetian of Bouchhada quarry (Icriodus corniger ancestralis, Polygnathus costatus, Polygnathus The cartographic cinerits of the north eastern Tafilalt shows linguiformis, Polygnathus varcus, Polygnathus timorensis.) that the biosedimentary mounds of Hmar Lakhdad are Key words: Biostratigraphy, Devonian, Microfossils, Condonts, developped on south side of an emsian volcanic. Palaeozoic, Meseta, Morocco.

The First MAPG International Convention, Conference & Exhibition 91 Marrakech Convention Center, October 28 - 31, 2007 Conodont color alteration (CAI), an thermal maturation index members. Each one contains a pelitic term, an argilo- and its application to Devonian Outcrops of the Western carbonated term, and a carbonated term at the top. The lower Moroccan Meseta member is distinguished by basaltic intercalations (doleritic), Mohammed Raji1, El Mostafa Benfrika2 & Abdelmajid disposed on interstratified basaltic flows, meaning the end of a Benbouziane3 volcanic episode; the Siluro-Lochkovian passage. Université Hassan II-Mohammedia, Faculté des sciences Ben The carbonate sedimentation is developed into a M’sik, BP7955 Sidi Othmane, Casablanca, Morocco monocline platform carbonate of ramp type, and in an adjacent Several authors have described the origin, calibration, and basin. geologic applications of conodont colour alteration, particularly The lower Siluro-Devonian of the Oued Cheguigua shows as related to hydrocarbon and mineral exploration (Epstein et a succession of three sequences of deposit: SD1, SD2, and al., 1977; Harris, 1979; Harris et al., 1980, 1981, 1990; SD3 which are respectively Siluro-Lochkovian, Praguian, and Rejebian et al. 1987; Wardlaw & Harris, 1984; and Grow et al., Emsian ages. Each sequence develops a prograding shelf 1994). All these authors demonstrate that CAI is time and margin, with calciturbiditic sediments, limited by a temperature dependent. transgressive, bioturbate and bioclastic surface. The Devonian limestone (Lochkovian to Fammenian) in Western transgressive system tract is equivalent to the pelitic term. The Moroccan Meseta are analysed by means of conodont colour highstand system tract marks the progressive installation of an alteration index (CAI). A general pattern with CAI values encrinitic shoal, characterizing a high energy environment with increasing from the west to the east of the Western Meseta a local fore-reef fauna. can be observed. The western part of this domain (Coastal The diagenetic analysis allows us to define the multiple Meseta and the west edge of Central Meseta) show low to phases of cementation and recrystallization which affect the moderate CAI values (1,5-2 to 3) suggesting diagenetic granular facies. They led to a total lithification. The early conditions. A stratigraphical control in the distribution of the dolomitization is distributed at the top of the SD2 and SD3 CAI values is inferred, but the tectonic has an indirect influence sequences. It leads to the formation of a crystalline rock on the levels of thermal maturity. The stratigraphical interval resulting from a process of replacement-recrystallization of a (Lochkovian to Givetian) in this part is within hydrocarbon muddy limestone. To these transformations, are added the window. In the Central Meseta CAI value from 4 to 6 are compaction, the tectonic fissuration, and the associated observed, and seems related to anchizone-epizone phases of late dolomitization. metamorphism and/or heat associated with hercynian syn- tectonic igneous activity. Mixed CAI values recorded at Jbel The potentialities of lower Devonian of Oulad Abbou as a Bouchot locality in the Mrirt area (East of Central Morocco) reservoir rock, a preliminary study of its petrophysical could be due to the effects of hydrothermal fluids. Textural properties was carried out according to two approaches: analysis of the conodont elements favour this possibility. - A qualitative petrographic, by defining porous spaces, Key words: Conodont - Devonian - Meseta - Thermal maturation- CAI and their relationships to the diagenetic transformations,

Lower Devonian of Oulad Abbou Area (Coastal Meseta, - A quantitative approach by the measurement of the petrophysical parameters. Morroco): Dynamic of sedimentation, diagenesis and petrophysical Key words: Oulad Abbou, Sequential stratigraphy, Diagenesis, impacts¶ Petrophysical properties. Bouchra Cherradi 1 , , Mohamed Laadila 2, Abdelmajid Benbouziane 3, Abdeslam El Kochri 2, Abdel Hadi Koukaya4 and Atika Hilali 4 1 Office national des Hydrocarbures et des mines (O.N.H.Y.M.). 2 Université Mohammed V, Faculté des sciences, département des sciences de la terre, B.P. 1014, Agdal – Rabat. 3 Université Hassan II – Mohammedia. Faculté des sciences Ben M’Sik, Casablanca, département des sciences de la terre. 4 Université Hassan II, Faculté des sciences de Casablanca- Aïn Chock,.

At Oulad Abbou area, the lower Devonian shows a succession of several carbonated horizons wich intersect with pelitic recurrences. It’s organized in three lithostratigraphic

92 Eustatic sea level changes and dynamic strategy of GS 09: Hight impact of the Mesozoic-Cenozoic stromatoporoïds of Oulad Abbou and DKL1 Well of Middle Palynology in Petroleum Geology Devonian (Western Meseta) Chair: T. Hssaida, J. Riding Abdelmajid Ben Bouziane1, Mohammed Laadila2, Bouchra Cherradi3, AbdelhadiKaoukaya4, Abdeslam El Kochri2 and Biogeography of late albian Dinoflagellate cysts as climatic Atika Hilali4. and stratigraphic proxy 1 : Université Hassan II – Mohammedia. Faculté des sciences Edwige Masure1, Touria Hssaida2 and Bruno Vrielynck 3 Ben M’Sik, Casablanca, département des sciences de la terre. 1 Pierre et Marie Curie-Paris6 Université, UMR-CNRS 5143, 2 : Université Université Mohammed V, Faculté des sciences, case 104, 4 place Jussieu, 75252 Paris Cedex 05, France, département des sciences de la terre, B.P. 1014, Agdal – 2 Université Hassan II,Mohammedia. Faculté des sciences, Rabat. Ben M’Sik, Casablanca. 3: Office national des Hydrocarbures et des mines 3 Pierre et Marie Curie-Paris6 Université, UMR-CNRS 7072, (O.N.H.Y.M.). case 129, 4 place Jussieu, Paris, F-75005 4: Université Hassan II, Faculté des sciences de Casablanca- Aïn Chock,. The mid-Cretaceous is known as an interval of warm, equable climate with weak thermocline and absent or very The analysis of Middle Devonian at the outcrops in Oulad discrete latitudinal bioprovinces. Biogeography and Abbou location and in subsurface at DKL1 well, led to the biostratigraphy cannot be decoupled. Biogeography provides better understanding of the carbonate platform at that time. The morphology of the substratum was favourable to a framework for the maximum precision in biochronologic installation and development of bank and bioherms rich on determination and increases the potential utility of microfossil stromatoporoïds, corals and other organisms; these highs are remains as stratigraphic proxies. associated with the tilted blocs. In modern time, dinoflagellate distribution defines five Carbonates deposits encountered in the DKL1 well and latitudinal constrained bioprovinces from equator to poles. Oulad Abou show the lateral filling sequence in prograding Dinoflagellates are very sensitive to temperature and salinity platform. The carbonate platform evolved from open marine conditions of water masses and useful for reconstructing environment to subtidal environment caracterized by quaternary palaeoceanographical and palaeoenvironmental deposition of biodetrital sediment. In this hydrodynamic conditions as climatic and salinity proxies. context, the erosion of highs was very frequent,eroded In order to define accurately the strategies of life of species bioclastic product were transported and are found at reef front with significant relations with temperatures and salinity in the area. Behind the crinoïds dunes and bioherms, a confined ocean climate system under greenhouse conditions environment (lagoon) was developed and caracterized by distribution maps have been drawn using thirty five Late Albian algea that which is intertidal to supratidal environment in origin. index species. Fifty years of published data have been Based on sedimentological and sequential studies, considered and synthesized using a database coupled with a elementary sequences analysis, organisation and sedimentary GIS “ArcGis ESRI software”. The data, the thousands of evolution at Sidi Abdellah cross section have defined the specimens studied from about one hundred fifty outcrops and environmental changes according to marine sea level deep sea drilling holes (ODP, DSDP), range from 75°N to 10°N. variations. The patch reef show tree periods of carbonate build Biostratigraphy was the main topic of the sixty height up: plant period, colonial period and colonisation- publications encountered. diversification. We recognized four dinoprovinces on the Northern The first period is represented by prograding bank with Hemisphere by spatial distributions of dinocyst associations in transported bioclastic material above limestones rich on their endemic and pandemic taxa. The dinoflagellate provinces pelagic or/and planctonic organisms of open marine boundaries are parallel or near parallel to latitudes. Mixing environment. The second period shows evolution from crinoids belts, which represented major palaeofrontal systems facing facies to build up facies rich on stromatoporoïds. The “warm” and “cooler” assemblages, were located at 40-45°N. installation of these build up is located on bioclastic slope but In despite the flat Late Albian temperature gradient, their evolution was stopped by hydrodynamic and bathymetric dinoflagellate cysts provincialism seems well developed. changes which is related to flowding phases. The last phase corresponds to bioherm rich on stromatoporoïds and corals. The maps also serve as a basis for understanding how and Marine sea level was favourable to maximum production of why the biostratigraphy of dinoflagellate cysts is affected by carbonate. biogeography. All taxa do not occur in all environments simultaneously due to tolerances among species to inshore- Key words: Western Meseta, Middle Devonian, carbonate platform, offshore and latitudinal trends. The four assemblages which sedimentary evolution.

The First MAPG International Convention, Conference & Exhibition 93 Marrakech Convention Center, October 28 - 31, 2007 characterized the provinces increased the potential utility of Dinoflagellate impact in Petroleum Geology dinoflagellate cysts as biostratigraphic proxies. Edwige Masure Université Pierre et Marie Curie-Paris6, UMR-CNRS 5143, Key words : Cretaceous, provinces, dinoflagellates, stratigraphy case 104, 4 place Jussieu, Paris, F-75005,

Applied Multidisciplinary biofacies analysis of the Khafji and Microscopic in size, dinoflagellates are algal unicelles Safaniya Member of the Wasia Formation (Cretaceous) of referred to the division of the plant kingdom. They are Saudi Arabia important constituents of the marine and freshwater biota Merrell Miller1, Wyn Hughes1, Jim Riding2 and Osman Varol3 today and are represented by abundant fossils with 1 Saudi Aramco, Dhahran, Saudi Arabia sporopollenin in Upper Triassic and younger strata. The pre- 2 British Geological Survey, UK Triassic record includes some of the fossils treated as acritach. 3 Varol Research, UK After the pioneering works (1836-1940) and the II world Integral to a sequence stratigraphic study of the late Aptian war, significant studies of fossil dinoflagellates restarted in the to Albian Khafji and Safaniya members of the Wasia Formation early 1950s. The demonstration of the biostratigraphical is a multidisciplinary definition of biofacies. Palynological and potential has been demonstrated at the end of 1950s. nannofossil datums provide a broadly spaced conventional Enhanced processing method and improved microscopic biostratigraphy within the deltaic successions of Khafji and equipment at the same time have facilitated research on the Safaniya but higher resolution correlations can only be detailed structures of polynomorphs. Research on achieved through the use of multidisciplinary biofacies that dinoflagellates expanded at the University of Kiel with W. contribute to the recognition of higher order flooding events Wetzel, at Tubingen with A. Eisenack, at Paris with G. associated with the siliciclastic successions of the world’s Deflandre, at Sheffield with C. Downie, at Cambridge with N. largest offshore oil field reservoirs. Hughes, in Belgium with Pastiels. Their graduate students in both academic and industrial fields described new taxa and The intervals between biostratigraphic datums based on investigated the stratigraphic distribution of dinoflagellates from the appearances of elaterate palynomorphs (late Albian), stratotypes in correlation with ammonites, foraminifera and pollen, dinoflagellate cysts and selected nannofossils control other groups. Then important impetus has been given to the (late Aptian and Albian) are characterized by study of dinoflagellate cysts in petroleum exploration, where diversity/abundance peaks of dinoflagellate cysts, fresh-water their small size, their abundance in many strata deficient in algae, foraminifers and coccolith and ascidian spicule other fossils, and their broad geographic distribution combined nannofossils. with their resistant composition and their rapid evolution made them highly useful in stratigraphic studies. Evitt (1961) worked Recent agglutinating foraminifera assemblages from the in the Jersey Production Research Company when he Sedili River, Malaysia, which were calibrated to ebb and flood demonstrated that the fossil dinoflagellates were cysts and not salinities from the South China Sea to a distance 32 km motile forms and that the great majority of the so-called upstream, provided the uniformitarian template for estuarine “Hystrichospheres” were likewise dinoflagellate cysts. biofacies. These data are the basis for understanding ecological significance of Cretaceous foram genera such as After 1970s, petroleum geology truly expanded into the Trochammina, Ammobaculites and Orbitolina, all morphotypes oceans and palynology with dinoflagellates became a staple present in the Khafji and Safaniya members. means of correlating submarine sediments. Also, wide-range studies resulted from the international Deep Sea Drilling Project Dinoflagellate cysts also show similar trends to those of the (1968-1983) and the Ocean Drilling Program (1983-2003). foraminifera responding to salinity, of which Subtilisphaera Biostratigraphical resolution has increased using origination dominates brackish water environments with assemblages and extinction with the concept of FAD (First Appearance diversifying with increasing salinity. Pteridophyte spores Dating) and LAD (Last Appearance Dating). Information is now dominate the terrestrial successions. The integrated biofacies available concerning the sequences of dinoflagellate cysts in all developed from the palynology and micropaleontology display the world’s oceans. isolated but distinct evidence of marine flooding events of variable extent within a depositionally complex, thick After 1980, both exploration and exploitation programs succession of Khafji and Safaniya deltaic sediments. were greatly enhanced by applying seismic sequence Integration with sedimentology is an ongoing part of this stratigraphic analysis (Vail et al., 1977). Originally founded on project. the sedimentary interpretation of seismic data, it evolved towards a global concept illustrated by the well known eustatic chart. Bioevents of dinoflagellate cysts have been correlated with sequences and the biochronozones of other groups (Haq et al., 1987; Hardenbol et al., 1998).

94 3-D seismic and 3-D modelling were two major GS 07: Gaz seepage, Mud volcanism and related gaz technological breakthroughs for exploration and production. To hydrate and carbonate formations, provide high resolution sequence stratigraphy, projects linked Chair: M. Ivanov, N. Hamoumi scientific requirement to industrial reality, have been developed choosing sites that are adjacent to mature petroleum fields Mound drilling for science and industry from the same strata that were studied in outcrop. Using Jean-Pierre Henriet1, Christian Dullo2, Menchu Comas3, Davy origination and extinction data of fossils has been Depreiter1, Anneleen Foubert1, Naima Hamoumi4, Dierk supplemented at the reservoir scale, by more subjective local Hebbeln5, Judith A. McKenzie6, Silvia Spezzaferri7 and the bioevents in the form of First Down hole Occurrence (FDO), IODP 673 and 689 proposal teams Low Down hole Occurrence (LDO), cyclic events, abundance 1 Renard Centre of Marine Geology (RCMG), Ghent University, fluctuations of individual taxa. Traditional multivariate statistical Belgium methods are used to refine resolution correlation between 2 Leibniz-Institute of Marine Sciences at Kiel University (IFM- wells, wells and outcrops, but sometime without success. GEOMAR), Germany Recently a method “the Statistical Modelling of Ecological 3 Instituto Andaluz de Ciencias de la Terra, CSIC & University Signals” (SMES) has been developed using statistical methods of Granada, Spain that most accurately reflect and quantify the ecological signals 4 Dept. of Earth Sciences, Université Mohammed V Agdal, expressed by the cysts (Dale et al. 2005). Rabat, Morocco 5 MARUM-Center for Marine Environmental Sciences, Demand for higher stratigraphical resolution in field Bremen, Germany development studies has been successful in the utilization of 6 Institute of Geology, ETH-Zentrum, Zurich, Switzerland new approaches within integrated multidisciplinary teams. 7 Department of Geosciences, University of Fribourg, Dale, B. et al. (2005). Statistical modelling of ecological Switzerland signals: a new method for biostratigraphy, in Recent Morocco has a privileged position for the study of Development in Applied biostratigraphy, edited by Powell A. J. carbonate mounds, in particular those found in association and Riding J.B., pp. 179-203, The Micropalaeontological with fluid migration processes. Morocco’s Palaeozoic record in Society. particular features spectacular examples. Recent exploration Haq Bilal, U. et al. (1987). The new chronostratigraphic on the Moroccan continental margin however has revealed a basis of Cenozoic and Mesozoic sea level cycles. Timing and wealth of modern mound provinces, exposed at the seafloor or depositional history of eustatic sequences; constraints on at shallow depth beneath the surface, both on the Atlantic and seismic stratigraphy, Special Publications Cushman the Mediterranean margins. Foundation for Foraminiferal Research, 24, 7-13. An important research momentum develops since 2002 on Hardenbol, J. et al. (1998). Mesozoic and Cenozoic the mound provinces, associated with giant mud volcanoes off sequence chronostratigraphic framework of European basins. Larache, NW Morocco. These mounds and mud volcanoes Mesozoic and Cenozoic sequence stratigraphy of European form the target of two IODP proposals: 673 (Atlantic Mound basins, Special Publication Society for Sedimentary Geology, Drilling II: Morocco Margin) and 689 (Mud Volcanoes as a 60, 3-13. Window into the Deep Biosphere). In preparation of these drilling campaigns, the “MeBoTech” proposal for a Support Vail, P. R. et al. (1977). Seismic stratigraphy and global Action under the 7th Framework Programme has been recently changes of sea level: Part 3, Relative changes of sea level from submitted to the European Union. coastal onlap. Seismic stratigraphy: applications to hydrocarbon exploration, Memoir American Association of The scientific rationale behind MeBoTech builds upon the Petroleum Geologists, 63-81. preliminary results of IODP Expedition 307 on Mound Challenger off Ireland, which has highlighted the importance of Key words: dinoflagellate cysts, biostratigraphy, petroleum geology. early diagenetic processes in the shaping of a carbonate mound reservoir. Modern mounds may be regarded as active hydrogeological bodies and open diagenetic systems. The dynamics of these processes possibly could be analyzed by instrumenting a mound, turning it into a natural laboratory. Analyzing the feasibility of such challenge, utilizing both ROV- deployed sensors and the unique capability of the remotely controlled sea-floor drill rig “MeBo” for instrumenting a sub- seafloor observatory, is a prime technological objective. Such studies however can build a solid ground for an improved

The First MAPG International Convention, Conference & Exhibition 95 Marrakech Convention Center, October 28 - 31, 2007 dialogue and win-win initiatives between the marine science Composition of hydrocarbon fluids from mud volcanoes of community and the industrial world, which share the the Moroccan Margin (Gulf of Cadiz) excitement of the study of carbonate mound reservoirs. V. Blinova1, M. Ivanov1, A. Stadnitskaia2, L. Mazurenko3, E. Kozlova1 Key words: carbonate mounds, mud volcanoes, ocean drilling 1 UNESCO/MSU Centre for Marine Geology and Geophysics, Geological Faculty, Moscow State University, GSP1, Leninskie Mud volcanism at the Alboran Sea: Insingts for oil and gas Gory, 119991, Moscow, Russia, prospecting 2 Royal Netherlands Institute for Sea Research, Texel, the Menchu Comas 1, Michael Ivanov2, Juan-Ignacio Soto1 Netherlands 1 Instituto Andaluz de Ciencias de la Tierra (CSIC and 3 All-Russia Research Institute for Geology and Mineral University of Granada), University of Granada. Spain Resources of the Ocean 1, Angliyskiy ave., St. Petersburg, 2 Research Centre for Marine Geology and Geophysics, 190121, Russia Moscow State University. Russia During the TTR-cruises (1999-2006) on board R/V Mud volcanoes in the Alboran Sea formed upon the west “Professor Logachev” 14 mud volcanoes, located at the Alboran Mud Diapir Province (MDP), from the Spanish to the Moroccan margin on water depth from 200m up to 1200m, Moroccan margins. The MDP occupies a major sedimentary were studied in details. Large set of geophysical and depocenter up to 8 km in thickness, and is formed of over- geochemical methods was applied for these investigations. To pressured shale, including olistostromes from the lowermost base on these data, relatively active and passive mud sedimentary sequences (Burdigalian to Langhian) in the basin. volcanoes were distinguished. At the active volcanoes MCS reflection profiles demonstrate that initiation of the methane concentration reaches 9000mkM/l. Hydrocarbon mud diapirism during the Miocene (between 18 and 9 Ma) gases from most of volcanoes have similar composition. These matches to processes of widespread crustal extension. gases are characterized by relatively high concentration of Younger stages of mud diapirism (Pliocene to Quaternary) methane homologues (up to pentane), and heavy stable occurred in compressive tectonic context, and proceed with carbon isotopic signature of methane (about -39‰PDB). It pierced diapirs and subsequent development of extrusive mud clear points out the thermogenic origin of these fluids and volcanism. MSC lines show volcano feeder-channels possible unified source. Moreover composition of main kations connected to deeper mud-diapir bodies, so that it is proved and anions from pore water of mud breccias proves active that volcanic processes bring up to the seafloor over-pressured migration processes of deep volcanic fluids. Principal material and fluids from more than 5 km deep. compound of free gas from pulsate bubbling site at the crater of the Mercator mud volcano is methane with heavy ?13C Side-scan sonar data imagine mud volcano morphologies, signature (-39,12‰PDB). ?13C of CO2 is light (-29,02‰PDB) and high-resolution seismic profiles provide accurate and shows to the intensive microbial processes of AOM at the information on volcano’s internal structure and host rocks. uppermost sediments. Gas hydrates at the Moroccan margin Different stages of active mud volcanism are punctuated by were recovered only from Ginsburg mud volcano and events of mud-flux activity. The extruded material, in addition to characterized by high concentration of ethane and propane, likely fluids and gases, is formed of a mixture of mud-breccias which suggests gas hydrate precipitation at the structure II. and exotic blocks. Detail study of hydrocarbon gas composition from mud volcanoes shows immature organic matter (terrestrial) at the Mud volcanoes appear within pockmark fields, indicating beginning of oil window, which is in good accordance with that active fluid discharges (methane seepages?) occurred in geochemical data of mud clasts. However molecular and the western Alboran Sea. Association of mud volcanoes and isotopic proportion (C1, C2 and C3) from the Ginsburg, Gemini pockmarks may be a signal of hydrocarbon migration in the and Al Idrissi mud volcanoes suggests that this gas can be basin. So that the Alboran basin, defined as a gas-prone basin, produced due to cracking of oil. seems of high potential for oil and gas prospecting. Future survey in the Alboran mud-volcano field will shed light in the Key words: hydrocarbon gas, mud volcano, thermogenic source nature of fluids and gases producing overpressures at depth that caused the mud volcanism.

Key words: Alboran Sea. Mud-volcanoes. Hydrocarbon potential

96 Organic matter from the rock clasts and matrix in the mud Extensive high resolution, partly 2.5D, seismic volcanoes of Moroccan Continental Margin investigations at the Pen Duick Escarpment (Gulf of Cadiz) and Kozlova E.1, Ivanov M. 1, Blinova V. 1, Hamoumi N. 2 the surrounding area reveal a complex history of compression, 1 UNESCO/MSU Centre for Marine Geology and Geophysics, mud volcanism, diapirism, erosion and deposition in the area. Geological Faculty, Moscow State University, GSP1, Leninskie Cold water corals occurring in this area are likely to be Gory, 119991, Moscow, Russia, influenced by these relatively long term changing 2 Mohammed V-Agdal University, Rabat, Morocco environmental parameters. Short term environmental changes near the sea bed were observed with benthic landers equipped During several international cruises of UNESCO-IOC with an acoustic doppler current profiler, temperature and Programme “Training-Trough-Research” the investigations in salinity sensors, optical backscatter sensors and a sediment the Gulf of Cadiz were focused on hydrocarbon seep areas trap. These measurements reveal a strong tidal component in characterized by widespread underwater mud volcanism. the sediment transport processes. 24-Hour CTD stations show More than 500 samples of rock clasts and matrix from mud the strong influence of the tide throughout the entire water breccia of different mud volcanoes from the Moroccan column. Continental Margin were analysed with use of large set of organic geochemical methods, such as fluorescent analysis, Sea bed imaging indicates that at present cold water corals Rock-Eval pyrolysis, chemical extraction, gas-chromatography show a limited distribution. If present only a few individuals are and others. found. Most of the cold water corals present today are soft corals (for example Isidella). Stony corals (Dendrophyllia, Mud breccia appears as pluricentimetric clasts embedded Lophelia pertusa, Madrepora occulata and others) are hardly in silty clayey matrix. Fragments of rocks from different mud ever found alive while box and piston cores reveal that in the volcanoes of Moroccan Margin in the Gulf of Cadiz are past this type of corals occurred abundantly during certain represented by variety of lithotypes: bioclastic or micritic periods. The present study aims to investigate during which limestones, marlstones, claystones and sandstones. The periods the corals were present, what exactly caused the rise clasts from the mud volcanoes derived from different and fall of the coral populations in time and what is their sedimentary rocks range in age from Cretaceous until relationship to carbonate mud mound formation. Pleistocene. A second important topic is the presence of various types According to geochemical investigation the organic matter of carbonate concretions. These objects seem to be of the rock clasts and matrix belongs to immature and low omnipresent at some mounds while they are hardly found at mature kerogen of the II and III types. Organic carbon content others. Within this study we aim to understand how these is different and depend on environmental conditions during structures are formed and whether they play a role in the sedimentation. Level of maturity and significant range (from formation and stabilisation of the mud mounds. poor to excellent) of oil/gas potential of the samples suggest, that organic matter of the study rocks can produce mostly gas Sedimentological and paleo-oceanographic changed as from upper gas window zone, and quantity of this gas strongly recorded in a Pistoncore of the Pen Duick Escarpment, Gulf depend on total organic carbon content and type of kerogen. of Cadiz Key words: mud volcanic breccia, organic matter, maturity, kerogen. A. Chiguer1, T.C.E. van Weering, F.Mienis, H.C. de Stigter, H. de Haas and N. Hamoumi1 Cold-water corals, carbonate concretions and carbonate 1 Mohammed V University Sciences Faculty Agdal Rabat, mud mounds in the Gulf of Cadiz Morocco, Henk de Haas1, Furu Mienis1, Cees van der land1, Mihkail 2 Royal Netherlands Institute for Sea Research, Texel, The Tokarev2, Nikolay Kuzub2, Tjeerd C.E. van Weering1. Netherlands Vrije Universiteit, Amsterdam, The Netherlands 1 Royal Netherlands Institute for Sea Research (NIOZ) The Pen Duick Escarpment is located 30 nautical miles off P.O. Box 59, 1790 AB, Den Burg, The Netherlands shore the Moroccan coast in the Gulf of Cadiz and is a fault 2 DECO Geophysical, MSU Science Park, estate 1, building formed in a compressional system. 77, office 104, Leninskie Gory, Moscow 119899, Russian Federation The area surrounding the escarpment is characterised by a very complex geological history and many mud volcanoes are Since 2004 NIOZ has organised several cruises with the present, e.g. Gemini mud volcano. Sedimentation at the top of research vessel “Pelagia” to the Gulf of Cadiz (NE Atlantic Pen Duick Escarpment might be affected by the mud volcano Ocean) within the framework of the Moundforce and activity, as well as vertical particle flux. Main aim of this project MiCROSYTEMS projects. These projects are carried out as is to study the sedimentological processes on top of the Pen part of ongoing cold water coral and carbonate mound studies Duick Escarpment and relate them to changes of the last at NIOZ along the European continental margin.

The First MAPG International Convention, Conference & Exhibition 97 Marrakech Convention Center, October 28 - 31, 2007 glacial-interglacial period and to detect the influence of mud However the size of the living corals in this area is relatively volcano activity on the sedimentological processes in the area. small, they vary between less than 7cm to 14cm, larger To study the sedimentary changes in the area, a pistoncore colonies occur rarely. M2005-12 was analysed by the use of X-ray fluorescence (XRF) data, vertical grain size distribution and measurements of The mobile megafauna existing in this area includes tube the stable oxygen isotopes on planctonic foraminifera. Analysis worms, red fish, shrimp, starfish, crab, molluscs and sea of the core shows that the core consists of mainly silty clay with urchins. foraminifera. Several sandy layers were observed in the core at Key words: Cold water corals, Pen Duick Escarpment, Gulf of Cadiz. different depths. In some zones coral fragments occur, which seem to have been transported to the core site. Stable isotope Discovery of carbonate mounds in the Alboran Sea: The analysis of planctonic foraminifera show a repetition of recent Melilla Mound Field Holocene material in the pistoncore. The changes in Menchu Comas 1 and Luis M. Pinheiro 2 composition and mineralogy of the sediment in the core might 1 Instituto Andaluz de Ciencias de la Tierra, CSIC and be related to sedimentological processes like turbidites or the University of Granada. Spain activity of nearby situated mud volcanoes. 2 Department of Geosciences, University of Aveiro. Portugal

Cold water corals and associated biota of the pen duick A cluster of Holocene mounds was discovered during the escarpment (Gulf of Cadiz). recent MARSIBAL I-06 cruise (R/V BIO HESPÉRIDES, Loubna Terhzaz 1, Tjeerd Van Weering 2, 3, Henk de Haas 2, December 2006) east of Melilla in the southeastern margin of Furu Mienis 2 and Naima Hamoumi 1 the Alboran Sea (Morocco margin). The area was investigated 1 Laboratory of Oceanology and Geodynamics of Sedimentary with swath bathymetry, high-resolution sub-bottom profiling basin, Mohammed V-Agdal University, Rabat, Morocco. and seismic reflection. Based on seismic and swath- 2 Department of Marine Chemistry and Geology, Royal bathymetry data, mounds are thought to be largely biogenic Netherlands Institute for sea Research, P.O.Box 59,Texel, The carbonate accumulations. Nevertheless, as it is known from Netherlands. comparable settings, mud mounds or even mud volcanoes 3 Dept. of Paleoecology and Geomorphology, Faculty of Earth may well coexist there. The Melilla Carbonate Mound Field and Life Sciences, VrijeUniversiteit Amsterdam, the Netherland (MCMF) covers an area of circa 15km2 and probably extends off the actual surveyed area. A Statistical evaluation of the presence and distribution of cold water corals and associated biota of the Pen Duick Seabed and buried mounds are elongated and domed Escarpment was carried out within the framework of the families of ridge-like buildups occurring in water depths from Euromargins programme Moundforce. The aim of this study is 200 to 400m. Mounds rotted on high reflective sedimentary to show the distribution of living and dead cold water corals layers, and are surrounded by dark reflective moats caused by and other biota on the Pen Duick Escarpment on the bottom currents. Some mounds have no linear but branched Moroccan margin of the Gulf of Cadiz. shapes. Seabed mounds begin beneath the gentle upper slope (water depth from 200-230m) producing bulges in the Eight video lines were recorded along transects across the seafloor, and give way with depth to larger buildups 100–250m Pen Duick Escarpment during cruise M2005 with R.V.Pelagia wide, 2-6km long, and 20-60m high. At 400m depths a mound and were subjected to a description and statistical study. Dead ridge attains 100m high above seafloor. Three generations of and living corals were determined, counted and presented as successive mound-growth are observed, and some ridged a percentage of the abundance of living and dead colonies, mounds nucleated upon older domes so that buried with an approximation of the size. In addition the sessile and constructions grow up to 150m. mobile megafauna were counted. Other features like biological features and sedimentary structures were noted. On the basis Planned sampling will inform mound nature and origin of these statistical analysis, several maps was constructed (coldwater bioherms, diagenetic knolls?), or if microbial which present the data. mediation accounted for its nucleation and stabilization.

The west of the Pen Duick Escarpment shows the Seismic profiles across the MCMF show that faults exist presence of a medium community of corals with high beneath the mound ridges, so that mounds nucleation may percentage of living ones. have some influence from fluid venting via fractures that may leak thermogenic gas or cold hydrocarbon seepages, in The summits of the mounds at the eastern part of the Pen addition to any likely oceanographic control. Duick Escarpment are covered by a high percentage of living corals, except for the summit of the eastern mud volcano where a high percentage of dead corals is present.

98 A concept for worldwide Gas Hydrate Data Dissemination - Shallow gas hydrate accumulations in the Gulf of Cadiz The Gas Hydrate Markup Language (GHML) and network Ivanov M. 1, Pinheiro L. 2, Hamoumi N2 , Blinova V. 1 applications 1 UNESCO/MSU Centre for Marine Geology and Geophysics, Ralf Löwner1, Willa Wang2, Tom Smith3, Dendy Sloan4 Geological Faculty, Moscow State University, GSP1, Leninskie 1 GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Gory, 119991, Moscow, Russia, Potsdam, D-14473, Germany 2 -Mohammed V-Agdal University, Rabat, Morocco 2 Computer Network Information Center, Chinese Academy of Near bottom gas hydrate accumulations in the Gulf of Science, 4, 4th South Street Zhong guan cun, POBox 349, Cadiz are related to nowadays seepage activity in craters of Beijing 10080 China deep water mud volcanoes. 3 MIT Systems, 565 Plandome Road #294 , Flushing, NY 11367-1597, USA. Email: More than 25 mud volcanoes were studied with seismic, 4 Center for Hydrate Research, Colorado School of Mines, side scan sonar, underwater TV and sampling in the Gulf of Golden, Colorado 80401 USA Cadiz during the Training Through Research cruises of R/V “Professor Logachev” (1999-2006). In general these mud Data and information exchange is crucial for any kind of volcanoes are less active than hydrate bearing structures in the scientific research activities and is becoming more and more Black Sea, Caspian, East Mediterranean and other regions. important. The comparison between different data sets and However, there are number of mud volcanoes where different disciplines creates new data, adds value and finally occurrence of shallow gas hydrate accumulations is very accumulates knowledge. probable or even verified by coring. Furthermore, natural gas hydrates may contain more Gas hydrates were sampled from five mud volcanoes: energy than the combined other fossil fuels, causing hydrates Ginsburg, Bonjardim, Captain Arutyunov, Semenovich and to be a potentially vital aspect of both energy and climate Soloviev. Several other volcanoes: Carlos Ribeiro, Olenin, change. Hence, knowledge in this field of research is Meknes demonstrate very high methane concentrations in the expanding exponentially. mud breccia deposits (up to 7000mkM/l). Pore water Through its multi-disciplinary worldwide network, the composition showed strong depletion in Cl-ion compare to CODATA Gas Hydrate Data Task Group bottom water and reference station. Potentially they also can (http://www.codata.org/taskgroups/TGgashydrates/index.htm contain gas hydrates in sediments. l) recognized the need for Information Technology and is It was revealed that gas hydrate accumulations correspond implementing a virtual data infrastructure for gas hydrate to local highs inside crater area. They characterised by very research. strong backscatter on side scan sonar record and strong Because of the worldwide dispersion of the gas hydrate bottom reflections on seismic and 5,5 kHz profiler. Very often research community, a first step to achieve this goal is the such places associate with dense population of creation of a technical communication language, the Gas chemosynthetic fauna. Hydrate Markup Language (GHML). GHML is a standard Key words: gas hydrate, mud volcano, gas seep. based on the Extensible Markup Language (XML) to enable the transport, modeling and storage of all manner of objects Rifting evolution of the Mesomediterranean Continent related to gas hydrate research. The result of these investigations is a custom-designed application schema, R. Somma1, I. Martín-Rojas2, F. Delgado3, A. Estévez2 and V. which describes the features, elements and their properties, Perrone4 defining all aspects of Gas Hydrates. 1 Dipartimento di Scienze degli Alimenti e dell'Ambiente, Università degli Sudi di Messina, Sant'Agata, 98166 Messina, In the near future, distributed heterogeneous databases will Italy. be connected by specific adapters to the data infrastructure. 2 Dpto. de Ciencias de la Tierra y del Medio Ambiente, These adapters create XML files valid to GHML and translate Universidad de Alicante, Ap. 99 03080 Alicante, Spain. them in proprietary formats used by the local data provider and 3 Dpto. de Estratigrafía y Paleontología, Universidad de vice versa. Services, which are accessible via web-based Granada, Av. Fuentenueva sn, Granada, Spain. interfaces (Portal), permit all desired data transactions and 4 Istituto di Geologia dell'Università “Carlo Bo” di Urbino - functionalities (e.g., data exchange, data storage, data Campus Scientifico Località Crocicchia, 61029 Urbino, Italy. visualization and data mining). In the Mediterranean region, along the Alpine Orogenic Belt Keywords: service-oriented data infrastructure, GHML, Gas Hydrates, which stretches from the Calabrian Arc to the Gibraltar Arc, the exchange formats Internal Zones are terranes derived from a former microcontinent, the Mesomediterranean Microplate. In these

The First MAPG International Convention, Conference & Exhibition 99 Marrakech Convention Center, October 28 - 31, 2007 terranes, the Alpine sedimentary cycle starts with Middle The thrust belt has been realized through several Triassic to Lower Jurassic redbeds. In this research, we deformation steps, as fold associations, in places inducing analyse some outcrops of these early continental deposits foliation and clivage, thrust and compressional faults, which associated with evaporitic rocks and evolving upwards to shortened the belt in flat-ramp, duplex, enveloping and Jurassic carbonate successions. breaching geometries. This deformative phase continued until the Late Miocene, when the activation of low-angle extensional In the southern Calabrian Arc (Peloritani Belt), redbeds faults, related to the taper angle of the tectonic pile, produced belonging to the Alì-Montagnareale Unit (affected by a northward stretching of the belt, through reorientation and anchimetamorphism) are presumably Middle Triassic in age. inversion of previous structures. Subsequently, the bulk of the They consist of a detrital formation made up of a facies Sicilian Maghrebides+Calabrian Arc experienced a severe association ranging from dark red conglomerates to pelites. shear tectonics, connected with the southern Tyrrhenian basin The Mesozoic succession continues with Carnian rhauwackes evolution, consisting in strike-slip and net- or dip-slip (Alì) or Middle-Upper Triassic stromatolitic limestones and extensional fault systems, which allowed the increasing of the dolostones with evaporitic moulders (Montagnareale). In the Alì Calabrian Arc bending and the identification of an hinge-zone area, Triassic deposits are followed by upper Pliensbachian between northern Sicily and southern Tyrrhenian. Several of cherty marly limestones (locally dolomitized) and Dogger to the Plio-Pleistocene brittle structures are still active, and Cretaceous (?) variegated marls and radiolarites intercalated by sometimes responsible of the shallow seismicity in the area. cherty microbreccia. The reconstruction of the sequential order of deformations In the Gibraltar Arc (Betic Cordillera), the Malaguide which affected the northern Sicilian belt, from Oligocene to composite Mesozoic succession starts with Anisian-Ladinian Recent times, emphasizes some not still resolved problems, redbeds (non metamorphic to anchimetamorphic) followed by as: a) how the paleotectonic settlement was ?; b) which the Upper Triassic marls with gypsum. They evolve to Lower regional relationships were between the “internal” sectors of Jurassic dolostones and limestones. The Jurassic succession the belt (Calabria-Peloritani, Kabilie, Rif) ?; c) were the also includes Middle to Upper Jurassic platform limestones, deformation steps diachronic along the chain ?; d) since when overlain by Cretaceous to Neogene deposits. have the southern sector of Calabrian Arc been belonging to From a palaeogeographic standpoint, the Mesozoic the Maghrebides ?; e) how severe has been the shear successions under study developed along a continental margin tectonics ?, and how long has been active ? which recorded the evolution from continental to marine Key words: Deformations, Sicilian Maghrebides, Calabrian Arc. environment.

At the geodynamic scale, the Triassic redbed Serpentinite slivers and MP-LT metamorphism in the External sedimentation occurred during the continental pre-rifting stage Maghrebides: A hint for an intracontinental suture in the of Pangea; the Lower-Middle Jurassic carbonate North African paleomargin (Morocco, Algeria) sedimentation took place during the successive syn-rifting André Michard1, Michel Durand-Delga2, Dominique Frizon de stage, whilst the post-rift stage developed from the Upper Lamotte3, and François Negro4 Jurassic onward. Finally, this process originated in the western 1 Ecole Normale Supérieure, 24 rue Lhomond, F75231 Paris Tethys two oceanic branches delimitating the Cedex 05 Mesomediterranean Microplate. 2 La Pélisserie, F81150 Marssac 3 Département des Sciences de la Terre, Université de Cergy- GS 17 : Geodynamics of mountain belts Pontoise, F95031 Cergy-Pontoise Cedex Chair : A. Chalouan, A. Michard 4 Laboratoire de Géologie, Université de Neuchâtel, CH2007

The main suture zone of the Alpine Maghrebide orogen The reconstruction of the deformational history in Northern extends between the North African paleomargin units and the Sicilian Maghrebides and South-Western Calabrian Arc Alboran-Kabylias terranes, in correspondence with the former Giuseppe Giunta Flysch oceanic domain. We describe here a subsidiary suture Dipartimento di Geologia, Università di Palermo, Via Archirafi zone located within the North African paleomargin itself. This 20-22, 90133 Palermo, Italia intracontinental suture is well documented in the Eastern Rif The west-east running Sicilian Magrebides show an axial between the Intrarif and Mesorif domains. It is first recorded by depression in north-eastern Sicily, where the southern sector of the occurrence of serpentinites slivers of Jurassic-Early the Calabrian Arc overthrust southward the Sicilidi and the Cretaceous probable age in the Nekor Fault zone (Beni Malek external units of the chain. The tectonogenetic history, from the massif), associated with metabasites and recrystallised Oligocene, is related to at least three main phases, serpentinite sands. Second, we assume that the subduction of compressional, extensional and transcurrent. the Temsamane Mesorif beneath the Ketama massif of the

100 Intrarif is evidenced by the moderate pressure, low sediments. temperature (MP-LT) chloritoid-phengite metamorphism recorded in the Ras Afraou, Tres-Forcas and Khebaba units From slab pull to plate convergence, active inversion during the Late Oligocene (40Ar-39Ar dates at 23-20 Ma). A tectonics in the Granada basin, Betics (Western quite similar setting can be observed in the Oran massif, with Mediterranean). serpentinite slivers associated with chloritoid-bearing schists G. Booth-Rea1, V. Pérez-Peña1, F. Torcal2, J.M. Martínez- overlain by the epi-Tellian nappes). This intra-margin suture can Martínez1, 3, J.M. Azañón1, 3. be followed eastward up to the Cheliff massifs at least, i.e. over 1 Departamento de Geodinámica, Universidad de Granada. >500 km E-W. West of the Nekor Fault lateral ramp, the suture 2 Departamento de Sistemas Físicos, Químicos y Naturales. is likely hidden beneath the Intrarif thrust units. We suggest that Facultad de Ciencias Experimentales. Universidad Pablo de the South Ketama-Nekor-Cheliff suture corresponds to the Olavide. inversion of a thinned crust/serpentinite crust zone formed 3 Instituto Andaluz de Ciencias de la Tierra (C.S.I.C.- between the proximal and distal parts of the African Universidad de Granada) paleomargin during the Ligurian-Maghrebian Tethys opening (Upper Jurassic). It now records a thick-skinned shortening Subduction rollback below the Alboran basin and edge tectonics of the internal paleomargin during the Late Oligocene delamination under its margins have driven westward-directed inception of the Maghrebide collision. extension, magmatism and regional uplift from the Middle Miocene until present in the Western Mediterranean. These Key words: Collision, Metamorphism, Suture, Rif, Tell processes have acted coeval to NW-SE plate convergence between Eurasia and Nubia that has produced the main Middle to Late Miocene Thrust and Piggyback Basin Neogene to Quaternary contractive and transpressive Development in the External Betic Chain structures observed in this region. Both processes have Rodríguez-Fernández, J.1, Roldán-García, F. J.2, Azañón- worked coevally in the region, however, while slab-pull has Hernández, J. M3. and Booth Rea, G.3 driven W-SW-directed extensional detachments following a 1 Instituto Andaluz de Ciencias de la Tierra CSIC-Univ. belt of westward-directed thrusts, plate convergence has Granada. mostly shortened the unloaded footwalls of the detachments 2 Instituto Geológico y Minero de España producing ENE/WSW folds and both NW- and SE-directed 3 Universidad de Granada, Departamento de Geodinámica reverse and strike-slip faults.

Several lines of evidence, surface geology, seismic lines At present, a boundary can be drawn between regions and wells, show that the eastern and central external zones extended by westward slab-pull processes situated to the (east of 5º W) of the Betic chain have been affected by a piggy- west of a highly segmented extensional system and uplifted back sequence of thrusts in the later part of Middle Miocene regions where plate convergence dominates producing folds, and early Late Miocene (13-10 Ma). reverse faults and inversion of previous extensional-related faults, in the footwall of the aforementioned active extensional The piggy back thrust sequence affects the previous system. This boundary has migrated westward since the Mesozoic and Cenozoic sedimentary sequences as well as a middle Miocene following the retreating slab and is located at remarkable brecciated sedimentary sequence mainly present in the eastern margin of the Granada basin. Here, Plio- nourished by Triassic, Cretaceous and Tertiary soft Quaternary extension-related structures in the footwall of the sedimentary rocks. This ubiquitous unit has been previously main active normal faults of the basin are mostly inactive, the cited as Guadalquivir olistrostrome, Olistostromic unit, Chaotic related sedimentary infilling is starting to fold and both reverse Subbetic units, etc. More than three thousand samples allow and strike-slip earthquake focal mechanisms compatible with dating this unit as Late Langhian to Early Serravallian (15-13 NW-SE convergence occur. Meanwhile, structures and focal Ma). These units constitute the basement of many piggy back mechanisms in the hanging-wall respond mostly to westward basins formed on the thrust hangingwalls, contemporaneously slab-pull dominated processes, having E-W- to NE-SW- with the northwest movement of them. oriented pressure axes or producing SW-directed extension. Sediment deposited in these piggy back basins, forming the Castro del Rio unit show clear evidences of sinsedimentary and coseismic deformation and in a general way show a fining and thickening upward sequence, from detrital or carbonatic to fine grained marly sediments. Abundant reworked fauna from Cretaceous to Early Tertiary make it difficult to date these sediments, with only a few samples providing a Late Serravallian-Early Tortonian age. The Castro del Rio Unit is also cut by thrusts that are finally sealed by Late Miocene

The First MAPG International Convention, Conference & Exhibition 101 Marrakech Convention Center, October 28 - 31, 2007 Two-stage plate tectonic evolution of the Betic-Rif Orogen Successive development of large-scale recumbent fold and recorded by inclusion trails with regionally coherent trends boudinage structures in extensional shear zones. Examples in the Nevado-Filabride Complex from the Alboran Domain Domingo Aerden1 and Mohammad Sayab2 Miguel Orozco1, 2, Francisco Manuel Alonso-Chaves3 and 1 Departamento de Geodinámica, Universidad de Granada, Carlos Sanz de Galdeano2 Avda. Fuentenueva s/n, 18002 Granada, Spain 1 Departamento de Geodinámica, Universidad de Granada, 2 National Centre of Excellence in Geology, University of Campus de Fuente Nueva, 18071 Granada, Spain Peshawar, 2 Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad Peshawar - 25120, NWFP, PAKISTAN. de Granada, Facultad de Ciencias, 18071 Granada, Spain 3 Departamento de Geodinámica y Paleontología, Fac de The early orogenic history of the Betic-Rif system has Ciencias Experimentales, Universidad de Huelva, Campus de remained poorly known due to the widespread modification El Carmen, 21071 Huelva, Spain and obliteration of corresponding structures during Miocene crustal extension. In an attempt to provide new constraints on The internal structure of a series of dome-like Alpujárride the pre-Miocene tectonic evolution we investigated the carbonate massifs (e.g. Turón and neighbouring “windows” in geometry and orientation of tectonic foliations (i.e. inclusion the eastern Alpujarras, Sierra de Lújar in the western part of the trails) preserved within garnet porphyroblasts of the Nevado- region; the Tejeda mountain in the Granada-Málaga provinces Filabride Complex (NFC), Betic Cordillera. Thirty oriented or the Sierra Blanca-Sierra de Mijas in the western Betics) can samples of garnet bearing schist were collected from different be interpreted as large boudinaged folds which resulted of a structural levels of this high-pressure unit, along a total strike progressive deformation process of competent thick layer length of 120 km. Measurements of the strike of inclusion trails sequences (the Triassic carbonates). These rocks were on oriented horizontal thin sections define a regionally formerly folded and later modified, as a result of stretching. The consistent orientation pattern, which allows these previous folds underwent changes in shape leading to bowing microstructures to be correlated and grouped in two principle of the axial directions, sheath- and, eventually, boudinaged- age sets. Each set comprises multiple homoaxial foliations. folds formation. Inclusion trails belonging to the older set have mainly N-S to NE-SW trends, whereas the younger set predominantly has An early contractional event and associated high-pressure WNW-ESE to NW-SE trends. The relative timing of both sets is metamorphism, which probably occurred about 50Ma ago, indicated by core-rim relationships within idividual garnets. affected Alpujárride rocks. The previously thickened continental crust underwent stretching and thinning which We also compiled over 4000 orientation data for seem to have closely followed crustal thickening. As in other successive fold generations distinguished and measured by regions affected by late orogenic extension, complicated different workers in the NFC. This wealth of field data is shown structural geometries with extensional structures to independently witnesses a superposition of different crustal superimposed on early contractional folds developed. A shortening directions, whose directions match the strikes of particularly intriguing fact is the occurrence of recumbent folds the newly discovered sets of inclusion trails. The two-stage developed in relation with the extensional tectonic event orogenic evolution indicated by this data is tentatively linked to (Vissers et al., 1995; Orozco et al., 1998; Orozco et al., 2004). a transition from orogenesis controlled by NW-SE oriented The folds very probably initiated by vertical shortening in Tethys-Iberia convergence and subduction, prior to 35Ma, steeply inclined competent layers (e.g. quartz levels; quartzite followed by NNE-SSW Iberia-Africa convergence from 35Ma to or carbonate sequences) and the geometry of these folds was 15Ma. This transition appears to have played a crucial role in later severely modified by strong imposed shear strain (e.g. low triggering the sinking or roll-back of lithospheric slabs and dipping ductile and brittle extensional shear zones of lower ensuing WNW-ESE crustal extension in the western Miocene age). Where initial folds had a slightly curving axis the Mediterranean basin. structure become modified, the interlimb angle is strongly reduced and the axial directions become much more Key words: Nevado-Filabride, inclusion trails, porphyroblasts, tectonic considerably bowed than those of the initial folds. Finally, evolution, Betic Cordillera boudinage and intrafolial or boudinaged folds, at different scales, may be formed.

Keywords: Boudinaged folds; Extensional shear zones; Betic-Rifean orogen

102 Tectonic Evolution of an Intra-arc Basin in Central Japan sedimentary basins on the East Chinese Continental Margin based on physical analogue modeling methods and seismic are characterized by (1) the formation of rifting half-graben reflection profiles. basin initiated by asymmetric, extensional faulting on the inner Driss Elouai1’, Yasuhiro Yamada1, Ming Zhang2 continental shelf in Paleocene and Eocene; (2) the formation of 1 Department of Civil and Earth Resources Engineering, extensional and relic backarc basins on the shelf-break in Graduate School of Oligocene; and (3) the formation of foreland together with Engineering, Kyoto University, Kyoto 606-5801 Japan forearc basins on the eastern edge of the continental margin in 1’ Ex Affiliation at Kyoto university Early Pliocene, which were resulted from the interaction of the 2 Research Center for Deep Geological Environments, National Philippine Sea Plate and the Chinese Continental Margin. Institute of Advanced The Early Tertiary rifting basins are typical half-graben filled Industrial Science and Technology (AIST), Tsukuba, Ibaraki with syn-rift Paleocene and Eocene sequences derived 305-8567, Japan principally from Mainland China. The characteristics of the In this work using scaled physical modeling techniques, we basin architecture, lithofacies, burial and thermal history simulated the Northern Fossa Magna (NFM), which is a suggest that the Paleocene and Eocene sequences are Miocene intra-arc in Central Japan. Results from analogue favorable potential targets. models demonstrate for the first time the role of certain normal The foreland basin, which is expanded the greatly parts of faults during the opening and the fill in of the basin. Growth onland Taiwan and is bordered by a westward moving fold- normal faults, which were observed in physical models, and-thrust belt to its east.The foreland basin , greatly validate the structural geology data. This clarified the composed of Later Neocene clastic sequences, was formed sedimentary lack of certain members in the western part that owing to the continuous collision of the Philippine Sea Plate of the study area and the remarkable strata thickening from and Eurasian Plate since Late Miocene. A number of east to the west. It suggests that the NFM basin has been hydrocarbons are found from the faulted anticline traps .The largely controlled by an extensive tectonic regime from Early pre-existing normal fault traps underneath the shallow lower Middle Miocene to Late Miocene period, and relatively during angle thrust belts and the gentle anticline structures associated the Pliocene. During the tectonic inversion, a popup structure with the lower Miocene stratigraphic traps in the foreland basin of the basin was observed. This structure was guided by are the most favorable targets for future hydrocarbon reactivation for shortly of the pre-existed normal faults at the exploration as well. end of the Pliocene then by the new created—in and out of the basin—reverse and thrust faults in Pleistocene, which Key Words: Tectonic Evolution, Hydrocarbon Habits, Rifting, Foreland continued to slip during the Holocene. Some of them are still Basin, Taiwan active nowadays, namely the Itoigawa-Shizuoka Tectonic Line as thrust fault developed within the basin, the West Nagano The triasico-liasic rifting related to the Central Atlantic Basin fault and probably some other reverse and thrust faults opening: geometry at ground and sea developed in the basement, to which the active seismicity Azzouz Kchikach1, Jacques Malod2, Jean -Pierre Réhault3 recorded out the NFM basin is probably related. Mohammed Jaffal1, Mostafa Amrhar4 1 Enseignant chercheur, FST, Université Cadi Ayyad, Keywords: Analogue Modeling, Northern Fossa Magna, Itoigawa- Marrakech; Shizuoka Tectonic Line, Japan. 2 Chercheur, Institut Universitaire Européen de la Mer, Brest, France ; The Basin Architecture ,Tectonic Evolution and Hydrocarbon 3 Professeur, Institut Universitaire Européen de la Mer, Brest, Habits of the Cenozoic Rifting and Foreland Basins, Western France ; Taiwan, Eastern Asia 4 Enseignant chercheur, Faculté des Sciences Semlalia, Wen-Rong Chi Université Cadi Ayyad, Marrakech Exploration and Development Institute, Chinese Petroleum Corporation, Taiwan, The control of the triasico-liasic basins structure in the 1 Ta Yuan, Wen -Shan Road, Miaoli, Taiwan 36010, R.O.C. Atlantic Central and at conjugate margins (East American and Nova Scotian) is necessary to reconstitute the Pangean Five major types of basins including rifting basin, kinematic dislocation. Synthesis studies (Olivier and Al, 1984; extensional basin, relic back arc basin, foreland basin and LeRoy and Piqué, 2001; Sahabi, 2004; Sahabi and Al, 2004) forearc basin on the offshore and onshore Taiwan are show that the Triasico-liasic basins in these margins recognized. correspond to a system of grabens or haf-grabens located at ground or on the deep of Maroccan margin. Basin distribution associated with regional tectonic setting suggests that the tectonic evolutions of the western Taiwan

The First MAPG International Convention, Conference & Exhibition 103 Marrakech Convention Center, October 28 - 31, 2007 Recent works completed by scientists: University of GS 14: Isotopic dating in Morocco : State of the art Bretagne Occidentale (IUEM), CNRS-French (GDR “Marges”), and perspectives IFREMER-French, Geophysical Institute of Lisbon, Universtity Chair : A. Azdimousa , M.l. Bouybaouene of Marrakech and El Jadida (Morocco), aimed at looking further into knowledge of the structural development of the Atlantic Geochemistry and Nd isotopes of the post-collisional margin off NW Morocco. This study related to: margin granitoids formation and segmentation, salt diapiric structure repartition from the Aouzioua - Lac Ifni area, Anti-Atlas (Morocco) in deep basins, continent-ocean crustal transition off Morocco A. Toummite1, M. Ikenne1, J.P. Liegeois2, D. Gasquet3, E.H. and explain the mechanisms of the lithospheric breaking off Beraaouz1 between Moroccan margin and its conjugate Canadian LAGAGE, Faculté des Sciences, B.P. 8106 Agadir – Maroc margin. Isotope Geology, Royal Museum for Central Africa, B-3080 Following this work, Maillard and Al, 2006 proposes a Tervuren, Belgium subdivision and a 2D-model of the conjugate margins of EDYTEM, Université de Savoie, F 73376, Le Bourget du Lac Morocco and Nova Scotia at a rifting pre-rupture stage. A deep Cedex, France penetration seismic survey, carried out during the SISMAR In the “Lac Ifni-Aouzoua” area, located in the western part cruise, allowed us to propose a new subdivision of the NW of the Siroua Mountains, plutons ranging in composition from Moroccan margin. Great faulted structures, extension and granite, diorite and granodiorite intruded at a shallow level the geometry of salt triassic basins are clearly mapped at the subcontemporaneous volcanic and volcanoclastic rocks of the broad of El Jadida. Other structures having the same age, Ouarzazate Group. This volcanic-plutonic event between 580 observed in the Moroccan Meseta and High Atlas, are and 545 Ma represents the largest igneous activity in the Anti- compiled from bibliography and integrated in the data base to Atlas. allow an exhaustive interpretation for the first phases of the Atlantic opening. The Aouzioua – Lac Ifni granitoids and the associated mafic rocks, which can be considered as members of a single suite Acknowledgment: This study was supported by « related by a crystal fractionation process, belong to a high-K integrated action n° MA/75F/03 » and SISMAR project. We calc-alkaline series. Coupled with the transtensive environment acknowledge deeply the invaluable help of all colleagues demonstrated for this period of time in the Anti-Atlas (Gasquet (IUEM) to make our various stays in Brest profitable and et al., 2005), this composition points to a typical post- pleasant. Thanks to friends (ONHYM, Rabat) for collisional setting (Liégeois et al., 1998). The geochemical communicating data of Meseta. subduction-like signatures have to be ascribed to their source References: and are not determining the actual setting. LeRoy P. ; Piqué A., (2001). Triassic-Liassic Western The granitoids and the associated rocks have clearly Moroccan synrift basins in relation to the Central Atlantic positive eNd-570 Ma between +4 and +5 and young NdTDM opening. Marine Geology, 172, pp. 359-381. between 610 and 790 Ma. This signature impose a juvenile Maillard A. ; Malod J. ; Thiébot E. ; Klingelhoefer F.; Réhault source, either a lithospheric mantle metasomatized during the J. P. (2006). Imaging a lithospheric detachement at the preceding Pan-African subduction period (750-660 Ma Siroua continent-ocean crustal transition off Morocco. Earth and – Bou Azzer oceanic complex; Thomas et al., 2001; Samson Planetary Science Letters, 241, pp. 686-698. et al., 2004) or a lower mafic crust derived from the latter. This Olivet J.-L., Bonnin J., Beuzart P., Auzende J.-M., (1984). is new in the Anti-Atlas where other contemporaneous post- Cinématique de l’Atlantique nord et central, CNEXO, Plouzané, collisional high-K calc-alkaline granitoids from Saghro in the 84, 108. eastern Anti-Atlas have negative eNd (Errami et al., 2006; Sahabi M. (2004). Evolution cinématique triasico-jurassique de Ikenne et al. 2007). The location of the Aouzioua – Lac Ifni l’atlantique central : Implications sue l’évolution close to the South Atlas fault, the northern boundary of the géodynamique des marges homologues nord ouest africaine West African craton (Ennih and Liégeois, 2001) allows probably et est américaine, Thèse de doctorat, Univ. Chouaib Doukkali, this juvenile source to be expressed without a WAC 210p. contamination, which is the case in Saghro. Sahabi M., Aslanian D., Olivet J. L. (2004). Un nouveau point de départ pour l’histoire de l’Atlantique central, C. R. Key words: Neoproterozoic, Anti-Atlas, granitoids, post-collisional, Geoscience, 336, pp. 1041–1052. juvenile source.

Key words: deep seismic profiling, Central Atlantic, rifting, geometry

104 40Ar/39Ar dating of white micas in the Temsamane units m.y. This is in contradiction with Hercynian mineral ages (External Rif): new constraints on the tectono-metamorphic derived earlier. In order to assess the geodynamic evolution, it evolution of the Rif. is necessary to understand the relation between Hercynian and Negro F.1,2, Villa I.3, de Sigoyer J.2, Goffé B.2, Saddiqi O.4 Alpine metamorphic events. For this purpose, we measured 1 Institut de Géologie, Université de Neuchâtel, Switzerland monazite, zircon, and thorite from granulite of the Beni 2 Laboratoire de Géologie, Ecole Normale Supérieure, Paris, Bousera. France. P-T evolution is characterized by a high P/high T episode 3 Institute für Geologie, Universität Bern, Switzerland. (M1) followed by medium P/high T partial melting und 4 Département de Géologie, Université Hassan, Casablanca, crystallization (M2). Morocco. Monazite Located at an intermediate position in the External Rif nappe pile, the Temsamane units present an abnormally Chemical U-Th-Pb dating (electron microprobe) was intense metamorphism and a penetrative ductile deformation. applied. The derived ages depend on the position of the Some of the Temsamane units, which could have an internal monazite relative to garnet. Monazites in the matrix as well as origin, underwent medium-pressure low-temperature (MP-LT) in multi-phase inclusions in garnet invariably result in young < conditions (7-9 kbar; 330-430°C). These conditions are similar 50 m.y. ages that can not be further resolved with this method. to the ones recorded in the lower grade Internal Rif units In contrast, single-phase monazite inclusions in garnet are (Alboran Domain). Whereas several geochronological studies distinctly older. The measured data result in ages between have been carried out to constrain the Alboran Domain 173-266 m.y. An intermediate position is taken by monazite metamorphic evolution, data are lacking in the External Rif. We appearing in the rim of garnet: the resulting ages vary from have undertaken 40Ar/39Ar dating, together with microtextural young Alpine to 220 m.y. Obviously, early in the metamorphic and chemical analysis of the dated white micas in order to history (Variscan times?), monazite was formed. Later, it is assess the tectono-metamorphic evolution of the MP-LT overgrown by garnet that subsequently shielded the enclosed Temsamane units. We show that three groups of ages can be monazite. Monazite formed during high T equilibration of the pointed out: (1) 33-23 Ma corresponding to Si-rich relic micas, matrix including partial melting, in contrast, is probably newly (2) 15-12 Ma corresponding to the micas defining the foliation formed in young Alpine times. and (3) 10-6 Ma corresponding to late micas and alteration. We propose that the MP-LT metamorphism in the Temsamane, Zircon probably Oligocene in age, could be related with the Results of SHRIMP dating are concordant ages of 21 m.y subduction of the Sebtides units and the HP-LT event in the in the rim of grains. Highly discordant data points yield a lower Alboran Domain. However our data show that the exhumation intercept of again 21 m.y., whereas the upper intercept of 2011 of the Temsamane took place during the Middle Miocene when m.y. may reflect formation of zircon in the source region. In the Alboran Domain units were already exhumed. The timing of addition, there is a significant amount of weakly discordant the tectonic and metamorphic evolution of the Temsamane is data with apparent ages of 150-450 m.y. No clearly defined set back within the External Rif tectonic time frame and Variscan event is discernable, and the latter data may be compared with the Alboran Domain units of the internal Rif. We related to the contribution of a low/medium grade finally compare our results with the available geochronological metamorphic precursor and/or of a heterogeneous data in the whole Betic-Rif orogen and discuss the implications sedimentary source region. for regional geodynamics. Thorite Keywords: 40Ar/39Ar, Alboran domain, metamorphism, Rif, Inclusion in garnet was chemically dated (U Th Pb) with the electron microprobe. The resulting ages range between 56-78 Temsamane m.y. This age may also be assessed, as in the case of monazite, to a partial rejuvenation of an old mineral during New geochronological dating of zircon, monazite and thorite Alpine time. from the granulite of the Beni Bousera massif (internal Rif). Bouybaouene ML1 ., Theye T2., and Massonne HJ2., and According to the data, only the alpine event 21 m.y. is Alami R1. clearly discernable. Older data are scattered and do not seem 1 Département des sciences de la terre Faculté des sciences to define a single major event. Therefore, it is tentatively BP 1014 Rabat. Maroc assumed that the major rock-forming episode spanning M1 at 2 Institut für Mineralogie und Kristallchemie Universität high P and M2 at medium P is young Alpine. This includes the Stuttgart, Azenbergstr 18, 70174 Stuttgart. Allemagne. formation of most of garnet, partial melting and growth of matrix monazite. Within the last years, the age of metamorphism in the Sebtides (internal Rif) is mostly considered to be Alpine, 19-23 Keywords: monazite/zircon/ thorite, granulite, metamorphism, Internal Rif.

The First MAPG International Convention, Conference & Exhibition 105 Marrakech Convention Center, October 28 - 31, 2007 GS 20: Neogene depositional systems Biostratigraphy of late Miocene of North Eastern Morocco Chair : A. Benmoussa, G. Moratti Contribution of planktonic Foraminifera Nadia Barhoun1, Abdelkhalak Ben Moussa2 et Khalil El Hajjaji2 Relationships between prograding and sharp-based 1 Département de Géologie, Faculté des Sciences Ben M’Sik, depositional sequences Université Hassan II Mohammedia BP 7955 Casablanca. of onshore to offshore Miocene series of eastern Tunisia 2 Département de Géologie, Faculté des Sciences de Tétouen, Ayadi Soumaya1, El Euch Narjess1, Mouhamed Ouaja2, ferry Université Abdelmalek Essaadi. Serge3, The aim of this work is to contribute, starting from Bedir Mourad4, Zargouni Fouad1. planktonic Foraminifera, at the realization of a precise 1 Faculté des Sciences de Tunis, Université El Manar. Campus chronological framework for the marine sediments of late Universitaire - Tunis – 1060. Miocene in the Boudinar and Melillia - Nador basins (North 2 Faculté des Sciences de Gabès, Cité Erriadh 6072 Zrig Eastern, Rif Morocco). By their situation in the Eastern part of Gabès, Tunisie. the southern Rifian corridor, these two basins recorded the 3 Université Claude Bernard Lyon 1, 43, Boulevard du 11 various events having preceded the crisis by Messinian salinity. novembre 1918 69622 Villeurbanne Cedex. The sedimentation of late Miocene is generally detrital in the 4 Centre des Recherches et des Technologies des Eaux, Boudinar basin; only a short phase essentially carbonated Technopôle de Borj Cédria, B.P.273, 8020 Soliman, Tunisie. marked sedimentation during this period. Whereas In Central Tunisia (N-S Axis), outcropping Serravalian and sedimentary filling of the Melillia - Nador basin is composed of Tortonian deposits are made of two formations, Beglia at base a marine series not very deep, evolving laterally to a complex and Saouef at top. The Beglia Fm. is represented by a thick forms carbonated marginal platform. In the two basins, marno- package of tide-dominated sandstone units separated by thin diatomitic alternations represent a principal component of clayey intervals. The thicker Saouef Fm. is mostly argillaceous Messinian sedimentation. with minor sandstone beds usually representing the top of The biostratigraphic study based on planktonic foraminifera wave-dominated prograding sequences. The two Formations allows emphasizing bio-events, which are gauged directly on are easily recognizable. the magnetostratigraphic scale and the astronomical time Eastward, in the wells and scattered outcrops of the Sahel, scale (Hilgen and al., 1995; Krijgsman and al., 1999; Sierro and The two Formations can still be clearly identified. Beglia is still al., 2001), to date with precision the sediments from late overally sandy but Saouef is different. It is made of a complex Miocene and to establish high resolution correlations between alternation of sandstones and clays in which are represented the various Mediterranean and extra-Mediterranean basins. either mostly clayey, wave-dominated, prograding sequences Detailed analysis of the planktonic assemblies of Foraminifera similar to those of the N-S Axis, or thick, tide-dominated permitted to identify the succession of nine bio-events: sandstone units that are laterally continuous in wells. These are Five in late Tortonian and pre-evaporitic Messinian of the sharp-based, and supposed to represent relative lowstand Boudinar bassin; deposits vs. some of the wave-dominated sequences of the N- S Axis. The interstratification of prograding and sharp-based Four in pre-evaporitic Messinian of the Melillia basin - sequences can be explained by complex fluctuations of the Nador. shoreline. These biostratigraphic events had already been recognized In offshore wells, off Mahdia and Monastir ports, the by Sierro and al. (2001) in the section of reference of Messinien distinction between the two formations is hard or impossible to “Abad composite” in Spain. Hence, this succession of bio- make because the Serravalian-Tortonian is represented by a events allows deducing that the series of marno-diatomitic rather homogenous succession of thin sandstone bed and alternations of the Boudinar basin represents the base of clays. That is the reason why the use of the Oum Douil Group Melillia – Nador ones. is preferred although the term of Birsa Fm. is used in place of Beglia Fm. The reason why the succession is so Key words: Biostratigraphy, planktonic Foraminifera, Late Miocene, undifferentiated is because the offshore, storm-beds-bearing Morocco. facies of both types of the sequences evidenced in wells of the Sahel are stacked.

Key words: Miocene, Prograding sequence, Sharp-based sequence, Eastern Tunisia.

106 New High-Resolution seismic data through the Rharb Nature and structures of the filling of the paleo-channels of continental shelf (North-Western MorocCo) : Characterisation the straits of Gibraltar in the threshold of Camarinal New of the recent evolution of the Western termination of the data of drillings (1997/2005) Fixed Link Europe-Africa Project Southern Rif Corridor Fouad Salhi1; Ali Bahmad2; Khalil El Kadiri3; Ahmad Maad Nissrine1, Le Roy Pascal1, Sahabi Mohamed2, Dakki Chalouan4; Abdel Aziz El Mrihi5 Mohamed3, Hssain Mohamed3, Gutscher Marc André1, 1 Faculté des Sciences El Jadida M’Hammdi Nadia4, Mehdi Khaled2, El Archi Karim2, Zourarah First studies of subsurface undertaken jointly by the Bendehhou2 et al. Société Nationale d’Etudes du Détroit (S.N.E.D) and Sociedad 1 UMR Domaines Océaniques, IUEM, Place Nicolas Copernic, Española de Estudios para Comunicación fija del Esterecho of 29280 Plouzané, France Gibraltar (S.E.C.E.G), in the Straits of Gibraltar and more 2 Laboratoire Géosciences Marines, Département des precisely in the threshold Camarinal (short borehole surveys, Sciences de la Terre, Faculté des Sciences d’El Jadida, 24 000 seismic reflexion, side scan sonar, bathymetry, surface El Jadida, Morocco sampling....) allowed to conclude that this threshold Phone : 212 3 34 23 25) corresponded to a high bottom made up of flyschs which 3 ONHYM, Rabat Agdal, Morocco would have resisted to marine erosion, at most covered by 4 Institut Scientifique, Av. Ibn Batouta, BP 703, 10106, Rabat corals constructions. Agdal, Morocco The campaigns of long boreholes offshore carried out in the The recent high-resolution seismic survey Protit2, carried sector reached penetrations going until 325m. Currently it is out during summer 2003 and conducted by the University of well established that it is acted in fact of a false threshold then Brest in France and the Faculté des Sciences d’El Jadida in that it is crossed by two paleo-channels of general directions Morocco recorded 900 km of seismic lines through the Rharb E-W, filled by recent deposits and separated by a relief made continental shelf. The integration of new data with industrial up of grounds of the flyschs type (Tartesos Mount). The seismic lines, bathymetry (Vanney, 1982 ; Gutscher, Delila formation of those paleo-channels are contemporary opening cruise report 2004) and field observations collected along the of the Straits of Gibraltar by collapse during lower pliocene, coastline allows us to identify the formation and the recent shown by an intense marine erosion. evolution of the western termination of the Southern Rif Corridor. This coastal basin corresponds to the foredeep basin The filling of those paleo-channels was carried out in linked to the Rif Cordillera and extends southwards through the several stages which include: (1) a deposit of argillaceous northern Moroccan Meseta that defines the forleand region of breaches by gravity, coming from the still unstable slopes of the Western Rif. Seismic stratigraphy analysis clarifies the main paleo-channels, but also of the close areas; (2) one period steps in the postnappe evolution of the offshore Rharb basin tectonically calms, with a biolithoclastic sand brought back by during Neogene times. marine currents; the absence of these sands in the Northern paleo-channel can be explained either by a non deposit or by The Tortonian/Lower Pliocene step corresponds to the their erosion or then were not cross-pieces by the surveys; (3) foredeep stage induced by loading of the Rif thrust sheets. a deposit of lithic and bioclastic conglomerate limited in the Results show evidence of flexural extension of the Adjacent Rif space which would be due to a fall of the marine level and foreland during these stage. It consists of reactivation of finally (4) the unit is crowned by a bioclastic limestone Hercynian N150°E trending faults corresponding to the lithohèrmes cover supported by an important biological offshore extension of the Cherrat Horst. The basin records a productivity and a water resource of weak energy. new uplift of its southern margin during Upper Pliocene and Pleistocene times. Seismic profiles display the segmentation of The absolute age of the various layers remains are the continental self controlled by the clear individualisation of unknown, except for the calcareous cover dated on corals by the present-day topographic front of the Prerifaine Nappe. the method U-Th of 150-180 thousand years. The lithological Tectonics remains active until Upper Pleistocene as shown by column has a higher thickness to 325m, penetration reached faulting of the coastal deposits. This segmentation constrains by the major survey carried out in the paleo-channels ones the distribution of the Sebou deposits through the continental without touching the substratum flysch. shelf. Preliminary results show that deformation occurs from Tortonian to Quaternary times and controls the evolution of Rharb foreland basin system. keywords : Rharb Basin, continental shelf, seismic.

The First MAPG International Convention, Conference & Exhibition 107 Marrakech Convention Center, October 28 - 31, 2007 Tectonic and sedimentation in the Southern Alboran Sea that was formed in the early Miocene south of the Balearic Ammar A.1, Mauffret A.2 and Gorini, C.3 Islands in a fore arc position the primitive arc being located 1 Département de Géologie, Université Mohamed V Faculté north of the Balearic Islands. Two rifiting episodes can be des Sciences, Avenue Ibn Batouta, BP 1014, Rabat, Maroc. identified. The first one, late Oligocene to early Miocene is 2 Lab Tectonique, UMR 7072, Case 129, Univ. P. et M. Curie, coeval to the opening ofthe Provençal basin and the rotation of 4 Place Jussieu, 75252, Paris Cedex 05. the Corso sard block. During this extensionnel event the deeply 3 Lab. Sedimentologie et Géodynamique, Univ. Lille 1-SN5 F- metamorphosed Alpujarride and Sebitides terranes have been 59655, Villeneuve d’Asq, France. exhumed and formed the basement of the West Alboran Basin. The second rifiting event occurred during the middle (16 The Alboran Sea is divided into two pars ; a eastern part Ma) to the late Miocene (8-6 Ma) during the drift towards the where the acoustic basement is mainly formed by late Miocene west of the volcanic arc. The seismic profiles show clearly volcanic rocks and a western part where a more than 10 km these two rifitng and a tilting related to an recentuplift of the thick basin is infilled by early Miocene to Quaternay sediments. adjacent land along the western Mediterranean coast of The eastern province belongs to a volcanic arc that forms a Morocco. large stripe from the Cabo de Gata in Spain to the Trois Fourches Cape and Ras Tarf in Morocco. This arc, that trends GS 18 : Recent evolution of the Betic-Rif chain NE-SW, traveled from the East and collided with the Africa and Eurasia plates during the Late Miocene (Late Tortonian and Chair : M. Benmakhlouf, J. Galindo-Zaldivar Messinian). During its motion the arc was separated from the northern and southern plates by strike-slip tear faults. Th New gravity and magnetic data of the Al Hoceima Bay and southern boudary is limited by left-lateral E-W to NE-SW faults. Boudinar Basins One deep late Miocene fault, trending E-W is probably located Farida Anahnah1, Jesús Galindo-Zaldívar1, Ahmed beneath the Gourougou-Chafarines volcanic struture as shown Chalouan2, Patricia Ruano3, Latifa Ameza4, Antonio by a prominent E-W magnetic anomaly. The Nekor F. Z. is the Pedrera1, Mohamed Benmakhlouf5, Omar Azzouz4, Carlos superficial expression of the southern left-lateral boundary. Marín6, M’fedal Ahmamou2, Angel Carlos Lopez-Garrido7, The Nekor F. Z. is a crustal structure with a probable flower Ana Ruiz- Constan1 shape. and it is not a linear and straight fault but fomed by 1 Departamento de Geodinámica, Universidad de Granada, several short segments. In the offshore region of the Trois 18071, Granada, Spain Fourches Cape three basins that trend NE-SW show a dextral 2 Département des Sciences de la Terre, Faculté des offset and the main faults are normal and have opposite throw Sciences, Université Mohammed V-Agdal, Rabat, Morocco from one basin to another. The onshore geology shows that 3 Departament de Geologia Dinàmica i Geofísica. Universitat the Boudinar basin has been formed along the Nekor fault first de Barcelona, 08071, Spain in a strike-slip setting during the lower Tortonian then with a 4 Département de Géologie, Faculté des Sciences, Université normal component during the late Tortonian and the early Mohammed premier-Oujda. Morocco Messinian. The same geological history is illustrated by the 5 Faculté des Sciences. Université Abdelmalek Esaadi. Tetuán, seismic profiles in the two others basins. The seismicity Morocco demonstrates that the Nekor F. Z. is not active at the Present. 6 Instituto Geológico y Minero de España. and the eastern region is now governed by the right-lateral 7 Instituto Andaluz de Ciencias de la Tierra, CSIC. Universidad transpressional motion of the Eurasia Plate relative to the Nubia de Granada, Spain (Africa) Plate. The Yusuf Fault and its pull-apart basin is the main expression of this motion. The deep fault beneath the Al Hoceima bay and Boudinar basins, are located in the Gourougou-Chafarines volcanic structure may change its north sector of central Rif, westwards of Nekor fault. They are motion from left-lateral to right-lateral and an intra-Pliocene sill separated by the Intrarif and the volcanic rocks of Ras Tarf. of large extension has been identified off Chafaines Island. All During the Neogene and Quaternary, the local tectonic regime the region west off the Trois Fourches Cape is affected by a changed with a first episode of southwestwards motion prominent tilting that suggests an uplift of the aqdjacent followed by the relief uplift producing a complex overprinting of continent that can be evaluated to 800-1000 m. Off Ras Tarf structures. –Al Hoceima the Al Idrissi F. Z. forms the western boundary of The combined geophysical researches, using together new the eastern province. This deep fracture has several superficial gravity and magnetic data, allow to identify and precise the structural expression. Several nomal fauls are identified in the features of the deep structure, thickness of sediments, and the Al Hoceima region where a prominent seismicity is related to main contacts with the basement rocks. The large faults this normal faulting. The Tofino and the Xauen banks are folded determining the development of the basins, sometimes and offset from the Alborazn Ridge that a complex covered, constitute the main active seismogenic structures of transpressional feature with a volcanic core. The western part the region. In addition, these new data allow to determine the of the Alboran Sea is occupied by the Western Alboran Basin

108 position of magnetic anomalous bodies that corresponds to formed during the Miocene southwestwards motion of the basic igneous rocks. Internal Zones, seem to be inactive at present.

In Al Hoceima bay we realised two profiles. Gravity and Seismological data including earthquake focal mechanisms magnetic models determine the location of two normal fault and hipocenters indicate that major present-day sets at both sides of the basin. Covered faults produce internal seismogenetic faults are located at shallow depths (14 km for steps mainly in the western part of the basin, tha may therefore the February 24, 2004 earthquake), have NNE-SSW be considered as a graben, filled by Neogene and Quaternary orientation and strike-slip kinematics. However, field sediments. The Bouguer anomaly profiles show that the basin researches do not allow to confirm that these large crustal is asymmetric and the depocenter is located in its eastern side. faults reach the surface. The present-day abrupt relief of the These results are similar in both models. region and the presence of marine terraces clearly point the elevation of the coast, confirming that Rif Cordillera continue to In Boudinar basin we acquired the gravity and magnetic be uprising. A set of N-S oriented normal faults, with eastwards data along two profiles. The northern one is measured near the and westwards dipping senses show evidences of recent and volcanic rocks. The anomaly model show two normal fault sets present-day activity, and determine the development of near the surface, determining graben and horst structures. The sedimentary basins, like the Al Hoceima Bay and the Boudinar other one is acquired around Oued Amekran. The profile is also basins, separated by horst structures like Ras Tarf. asymmetrical, as the determined in Al Hoceima bay, but the graben depocenter is located at its western side suggesting This setting allow to propose the activity at present of large that the Ras Tarf represent a main horst that is undergoing crustal detachment faults that separates the uppermost crust active uplift. and the seismogenetic faults located at middle crustal levels. These detachment structures may be similar to the Miocene Key words: Geophysical methods, asymmetric basins, faults, volcanic detachments that are exposed in the Betic-Rif Cordilleras. rocks, Al Hoceima region. Key words: Al Hoceima, crustal active faults, detachment, seismic Recent and active tectonics related to the large seismicity in activity. Al Hoceima Region (Rif Cordilleras) Jesús Galindo-Zaldívar1, Ahmed Chalouan2, Omar Azzouz3, Fault and fold development, crustal structure and seismic Latifa Ameza2, Patricia Ruano4, Carlos Sanz de Galdeano5, activity in the Almanzora Depression (Eastern Betic Carlos Marín-Lechado6, Antonio Pedrera1, Angel Carlos Cordillera) López-Garrido5, Farida Anahnah1, Ana Ruiz-Constán1, Antonio Pedrera1, Jesús Galindo-Zaldívar1, Ana Ruíz- Mohamed Benmakhlouf7, M’fedal Ahmamou 2 Constan1, Carlos Duque-Calvache1, Ángel Carlos López- 1 Departamento de Geodinámica, Universidad de Granada. Garrido2 Carlos Marín-Lechado3, Carlos Sanz de Galdeano2 Spain and Inmaculada Serrano4. 2 Département des Sciences de la Terre, Faculté des 1 Departamento de Geodinámica, Universidad de Granada, Sciences, Université Mohammed V- Agdal. Morocco. 18071 Granada, Spain. 3 Département de Géologie, Faculté des Sciences, Université 2 Instituto Andaluz de Ciencias de la Tierra, (CSIC-Univ. Mohammed premier- Oujda. Morocco. Granada), Facultad de Ciencias, Univ. Granada, 18071 4 Departament de Geologia Dinàmica i Geofísica. Universitat Granada, Spain. de Barcelona, Spain. 3 Instituto Geológico y Minero de España. Urb. Alcázar del 5 IACT, CSIC-Universidad de Granada. España. Genil, 4. 18006 Granada, Spain. 6 Instituto Geológico y Minero de España. 4 Instituto Andaluz de Geofísica, Universidad de Granada, 7 Faculté des Sciences. Université Abdelmalek Esaadi. Tetuán. 18071 Granada, Spain. Marruecos. The relief of the Betic Cordillera, situated along the western The Al Hoceima región, located in the Rif Cordillera near the part of the Europe-Africa convergent plate boundary, is Alboran Sea, is one of the sectors of the westernmost produced by the interaction of folds and faults that Mediterranean that show most intense seismicity. The two large accommodate the N-S to NW-SE convergence between the recent events (February 24, 2004, M=6,3 and 26 May, 1994, Eurasian and African plates since Tortonian. The Almanzora M=5,5) are integrated in the frame of a continuous seismic activity. Corridor, located in their Internal Zones, constitutes an example of E-W elongated asymmetrical narrow basin This region is located at the boundary between Internal generated by the interaction of fold and fault sets. Zones, outcropping at the Bokoya Massif and the External Zones of the Rif, mainly formed by the Ketama unit, separated A detailed structural study (including mapping and by well represented Flysch units. However, the major kinematics analysis of meso/micro-structures) and the structures, like thrust contacts and the sinistral Nekor fault, combination of geophysical data (magnetotelluric, gravity and

The First MAPG International Convention, Conference & Exhibition 109 Marrakech Convention Center, October 28 - 31, 2007 seismicity) allow to characterize: (a) the evolution of the Sierra coexisting with the compression and practically perpendicular de Los Filabres- Almanzora- Sierra de Las Estancias folds to it. In this case it is necessary that the position of ?1 change trend that interact with the faults conditioning the to a vertical position. In fact, sometimes in the Betic Cordillera sedimentation since Serravallian-Lower Tortonian, (b) the the extension is more important than the compression. presence of a main large active detachment with associated seismicity that allow the growth of these kilometric folds in its One possible interpretation of the position of the hanging wall, (c) the structures with associated seismicity that earthquakes of Gergal, in the north part of the basin, is that the does not extends up to the surface, where NW-SE and WNW- NNW-SSE faults are propagating northwards from the south ESE outcropping normal faults (as the Baza fault) and ENE- where formed previously, although the existence of young WSW reverse faults deform the Quaternary sediments and (d) morphologic features linked to them indicates that they are the paleostress evolution from the Serravallian-Lower Tortonian active in all their range. to the present mainly characterized by a N-S to NW-SE Key words: Betic Cordillera, Neotectonics, Active Tectonics, Active compression with an orthogonal associated extension. faults.

The above regional observations give rise to the Recent tectonics and crustal rheology in the Gibraltar Arc development of kilometric folds related to large crustal heterogeneities that play an important role during basin Fernández-Ibáñez, F.1, Soto, J.I.1, and Morales, J.2 evolution. In addition, the instrumental seismicity associated to 1 Dpto. Geodinámica e Instituto Andaluz de Ciencias de la blind structures point the need of the geophysical crustal Tierra (CSIC-Granada University), Facultad de Ciencias, studies to characterize the seismic hazard. Campus Fuentenueva s/n, Universidad de Granada. 18002 Granada (Spain) Key Words: Crustal detachment, synformal basin development, fault 2 Instituto Andaluz de Geofísica y Prevención de Desastres overprinting, relief uplift, crustal thickening. Sísmicos, Granada University, Campus Universitario de Cartuja s/n, 18071 Granada (Spain). Neotectonic and active tectonic deformations in the Tabernas Desert (Almeria, Betic Cordillera, Spain) The Gibraltar Arc region constitutes a broad area of active deformation and scatter seismicity in the western Sanz de Galdeano C.1, Galindo-Zaldívar J. 2, Shanov S. 3, Mediterranean, reflecting that current oblique convergence Radulov A. 3 and Nikolov G. 3. between the Eurasian and African plates is accomplished 1 Instituto Andaluz de Ciencias de la Tierra. CSIC-Univ. within a diffuse plate-boundary. To characterize the current Granada. Fac. Ciencias. 18071Granada. geodynamics of the Gibraltar Arc region we have integrated 2 Dpto. Geodinámica, Fac. Ciencias, Univ. Granada, 18071 different data sources. Firstly, we have built up a robust Granada. seismicity data set, selecting those seismic events developed 3 Geological Institute, Bulgarian Academy of Sciences. Acad. within the crust, removing those seismic events with no G.Bonchev Street, building 24. 1113 Sophia, Bulgaria. accurate location or with low magnitude (period 1992-2005 The Tabernas Desert is an upper Neogene basin situated in and md<2.5). the eastern prolongation of the Alpujarran Corridor (south of To interpret both vertical and horizontal distribution of sierras Nevada and Filabres, SE of Spain). There, the Betic seismicity in the region we have conducted an interactive Internal Zone, formed by metamorphic rocks, constitutes the geophysical modelling that reproduce the most suitable basement where were unconformably deposited Tortonian to lithosphere configuration that explain surface elevation, based Quaternary sediments infilling the basin. Important dextral E-W on the regional heat flow pattern and assuming local isostasy. faults cross it and limit great antiforms mainly formed in the With this lithospheric model we have developed a thermal and basement. Moreover, there are NNW-SSE and NNE-SSE rheological model, characterizing crustal yield strength and the faults. All these faults affect Pliocene and Quaternary depth of the brittle-to-ductile transition (BDT) within the crust. sediments. The Gergal earthquake (04-02-2002) and its We have found that long-term rheology matches focal depth aftershocks are probably related to the NNW-SSE faults. distribution of the crustal seismicity since >60% of the shallow The E-W faults cut longitudinally the Internal Zone helping seismicity is placed within the upper brittle crust, decaying to its progressive westward displacements. They are the older exponentially below the BDT zone. faults of the area, although also present young displacements. A comprehensive map with the location of quaternary faults The E-W folds are something oblique to the present ellipsoid of throughout the Gibraltar Arc compared with the present-day stress but probably they are forced by the previous existence stress field, demonstrates that active deformation in the arc is of the E-W faults. For this reason we interpret that they driven by a major left-lateral (transpressional) strike-slip fault respond to the same state of compression of NW-SE to N-S system that run NE-SW from eastern Betics to the Rif, in the direction. The formation of the NNW-SSE and NNE-SSW faults Alhoceima region. This fault system, together with a conjugate, is consequence of the approximately ENE-WSW extension,

110 WNW-ESE trending, right-lateral (transtensional) strike-slip thrusts. The two banks are offset by a right-lateral fault.. The fault system, determines the current escape of the Gibraltar Xauen Bank is mainly formed by sedimentry folded layers and Arc to the west and the simultaneous extension in those areas the Jebha well show that these layers have been originally with a thicker crust (e.g., central Betics). deposited in the early Miocene Western Alboran Basin and an uplift of 3.5 km is esrtimated since the Messinian. The Al Idrissi Key words: active tectonics, strike-slip faults, seismicity, rheology, F. Z. is a major crustal structure that trends NE-SW and shows Gibraltar Arc. a 30 km left-lateral displacement of the Alboran Ridge. A similar 30 km offset is observed between the Ibn Batouta Al Idrissi active Fracture Zone seamount and the Djibouti Bank . The aeromagnetic map Mauffret1; A; Ammar2, A ; Gorini3, C. shows clearly the annalogy between the two features. Two 1 Mauffret, A. Lab Tectonique, UMR 7072, Case 129, Univ. P. hypotheses are discussed . In one case the Al Idrissi F. Z is et M. Curie, 4 Place Jussieu, 75252, Paris Cedex 05. related to the Carboneras Fault and this fault zone crosses the 2 Ammar, A. Département de Géologie, Université Mohamed V Alboran Sea. In the second case the Al Idrissi F. Z. is limited to Faculté des Sciences, Avenue Ibn Batouta, BP 1014, Rabat, the Alboran Ridge and this frcture maybe the boundary of a Rif Maroc. block moving towards the southwest as suggested by some 3 Gorini, C. Lab. Sedimentologie et Géodynamique, Univ. Lille GPS studies. 1-SN5 F-59655, Villeneuve d’Asq, France.

In the center of the Alboran Sea the Alboran Ridge is a Recent wrench tectonics at the Alboran-Ridge and Yusuf complex struture with late Miocene and Pliocene sedimentary Fault Zones: Unraveling evidences from seismic images layers uplifted along the two flanks and folded. In the core of Pedro Martínez-García, Menchu Comas, and Juan-Ignacio the anticline late Miocene (9 Ma) volcanic rocks outcrop and Soto form the small island of Alboran. These calk-alcaline volcanic Instituto Andaluz de Ciencias de la Tierra (CSIC and University rocks belongs to the volcanic arc that extends in a NE-SW of Granada). Campus Fuentenueva, University of Granada, direction from Spain (Cabo de Gata Cape) to Morocco (Mellila Spain Peninsula and Ras Tarf). The Messinian erosional surface that has an anticlinal shape is a good marker to estimate the The recent tectonic evolution of the Gibraltar Arc System, deformation and the shortening is evaluated to 11.7 km. To the the Betic-Rif chains and the enclosed Alboran Basin, is clearly southwest the Alboran Ridge becomes narrow then depicted in the basin’ realm. Regional MCS profiles (re- disappears as a continuous feature. A small bank is offset to processed until 7 s.t.w.t.) provide a comprehensive view on the the south and separated from the Alboran Ridge by a sill. This structural framework in the Alboran Basin. The actual crustal bank is limited to the northwest and southeast by reverse faults structure in Alboran results from the aftermath of extension and with an opposite vergence. The shortening is estimated to 4 compression in basin evolution: Extensional tectonics, resulting km. To the southwest of the bank the Al Idrissi High that in block-faulting and low-angle normal detachments, occurred trends NE-SW is in strike with the Ras Tarf volcanic feature. from early Miocene (about 18 Ma) to late Miocene (about 9- Several normal faults suggest that the Al Idrissi High is a 8Ma); and subsequent contractive tectonics, producing horst.with a left–lateral component The area where the normal folding, high-angle faults and basin inversion, happened from faulting is evidenced is offshore of Al Hoceima where the late-Miocene till now days. seismicty is very important.. The focal mechanisms suggest Recent deformation is mainly conditioned by post- normal faults and strike-slip faults with normal Messinian wrench tectonics. Conjugated, NE-SW and NW-SE component..Most of the faults trends NE-SW and this directed, strike-slip fault systems and associated folding orientation is compatible with a left-lateral motion. However the deform Pliocene to Holocene sequences. radar interferometry has shown that the 24/02/2004 earthquake occurred on a conjugate fault with a NW-SE The major bathymetric high along the basin, the Alboran orientation and dextral motion.Only one earthquake has a Ridge-Xauen Bank lineament, represent a giant complex thrust mechanism at the southern end of the Alboran Ridge antiform bounded by strike-slip to reverse fault zones. This and the other part of the ridge is aseismic.. The others structure, from the sinitral NE-SW fault system, encompasses earthquake show normal and strike-slip focal mechanisms significant uplift and basin inversions. even in the areas where the compression is evident like the Tofino Bank. whereas the Xauen Bank is aseismic. The Tofino The Yusuf Fault Zone, fitting in the dextral NE-SW fault Bank is 30 km offset relative to the Alboran Ridge. The system, includes two master faults that condition local shortening of this structure is 7 km whereas the shortening on transtension given way to the Yusuf pull-part basin. the Xauen Bank is only 3.7 km. The two banks formed by two Multibeam side-scan sonar and ultra-high resolution main E-W folds that have been1.2 km eroded at the flat top seismic data of both the Alboran Ridge and the Yusuf Fault- of the bankstop and are limited to the north by prominent Zone, show how the wrench tectonics affects the seafloor.

The First MAPG International Convention, Conference & Exhibition 111 Marrakech Convention Center, October 28 - 31, 2007 Active tectonics there is proved by slumps and mass wasting bearing accumulations post-migration where the higher structures, probably derived from the earthquakes reported at horizons are relatively rich paraffinic condensates with light these lineaments. products and the bottom (near to the contact with the aquifer) being rich in highly asphaltic heavy oils. The thermodiffusional Seismic images from the Alboran Basin are expressive of migration consequences on the evolution of the water-oil significant crustal deformation in the Gibraltar Arc System interface will be also approached. drove by post-Messinian tectonics, which in turn is responsible of the actual roughly-meridian shortening and substantial Key words : thermal diffusion, migration, hydrocarbons, WSW-ENE elongation of the basin. porous media

Key words: Alboran Basin. Wrench tectonics. Seismic profiles. Travail réalisé dans le cadre du PROTARS III D15/26 GS 31 : Organic geochemistry applied to petroleum exploration Organic sedimentation in Sud-Rifain Jurassic Basin Chair : H. Er-raioui, H. Belayouni Siham Assaoud1, Mohamed El Maataoui2, Ahmed Chalouan3, Habib Belayouni4 and Mohamed Rouai 2 Importance of the thermal gradient on the stratification of 1 Université Sidi Mohamed Ben Abdallah, Faculté des Sciences Dhar El Mehraz. Département de Géologie, Fès the oil fluids in the rocks reservoirs 2 Université Moulay Ismail. Département de Géologie, UFR Mohamed El Maataoui 1 , Siham Assaoud 2, Abdelilah Dekayir Géologie des Energies Fossiles, BP 11201 Zitoune, Meknès 1. El Mati El Faleh 1 et Aissa Masrour 1 3 Université Mohamed V, Faculté des Sciences. Département 1 Université Moulay Ismail. Département de Géologie, UFR de géologie, Rabat Géologie des Energies Fossiles, BP 11201 Zitoune, Meknès 4 Université de Tunis, Faculté des Sciences, Département de 2 Université Sidi Mohamed Ben Abdallah, Faculté des géologie, Tunis Sciences Dhar El Mehraz. Département de Géologie, Fès The organic sedimentation in the Sud-Rifain Jurassic basin The presence of a oil-bearing accumulation is dependent of was very heterogeneous. The organic sedimentation process the succession of elementary events (from the organic was controlled by several factors. The principal ones are the productivity to the formation of a layer) which must be tectonic, paleogeographic and physico-chemical factors. distributed in space and ordered in time and which form an These parameters allowed the installation within the basin of integral part of the geological history of the area; each one of two distinguished organic sedimentation areas. these events has a probability of occurrence more or less weak but never negligible. An area (A), located at the western part of the basin, with terrigenous detrital mineral content. The deposited organic The stratification of the oil fluids in the layers is an event matter is a lignite with a percentage of organic carbon not which requires to be recognized, analyzed and correctly exceeding 1%, associated with low values of oil potential and interpreted. S2/S3 ratio However, the index of production (IP) is high Oil-bearing accumulations of the post-migration can be testifying the presence to important accumulation of seen as rest areas in which the hydrocarbons remained for hydrocarbons. These geological and geochemical criteria long time in order to provide a stationary distribution of the make the area (A) as hydrocarbon rock reservoir. species as a function of the gravity action and the geothermical * An area (B), located at the eastern part of the basin, gradient. characterized meanly by fine sedimentary shale deposits. The The natural lithospherical configurations surrounding the oil geochemical study of fossilized organic carbon shows the layers sites are, in general, compatible with the existence of presence of a well preserved organic carbon with a percentage thermoconvectives circulations which, at least in the past could which exceeds 2.5%, associated with high values of S2/S3 be active for significant geological time. So we can not ratio, petroleum potential (PP) and hydrogen index which exclude, at least for these active periods, the presence of a reaches 716mg HC/G of COT. These geochemical results differential enrichment of hydrocarbons by thermodiffusional testify of better conditions of organic sedimentation in an process and more particularly by thermogravitational diffusion anoxic medium leading to the existence in this area (B) of a (1) in porous media. good petroleum source rock.

The gool of this study is to show by experimentation the The juxtaposition of the area (A) as petroleum rock reservoir effect of the thermal gradient on the differential migration of and the area (B) as petroleum source rock in the same basin is crude oils hydrocarbons (2) impregnating porous media. an exceptional phenomenon that attracts the attention of prospectors and places the Sud-Rifain basin among the most The result stratifications are similar with those of many oil- promising petroleum Moroccan systems. In fact, more the

112 source rock is close to the hosting reservoir, more the Key words : Hercynian geodynamic, foreland basin, thermic evolution, probabilities of having important accumulations are higher due organic matter, hydrocarbons. to the complicated hydrocarbon migration processes.

Keywords: organic matter, Sud-Rifain basin, petroleum potential, GS 40 : Geothermics petroleum source rock, rock reservoir. Chair : A. Rimi, F. Lucazeau

Gases in thermal waters of North of Tunisia Geodynamic and thermal evolution of the organic matter: Sadki O. 1, Benaabidate L.2 & Charef A.3 Example of the Qasbat-Tadla Basin (Central Morocco) 1 ONHYM, Rabat, Morocco Hassan Er-Raioui H. 1, Mohammed Bouabdelli M.2, Habib 2 Department of Geology, F.S.T.- Fez, Morocco Bélayouni H 3. 3 INRST, Borj Cedria, Tunisia and Hassan Chellai H.2 1 Faculté des Sciences et Techniques de Tanger, laboratoire de Several thermal springs in North Tunisia present emissions Géochimie organique, B.P. 416, Maroc. of gas as impulse which varies in time and from a source to an 2 Faculté des Sciences Semlalia-Marrakech, laboratoire de other. Gases associated to thermal waters in this part of Tunisia Géodynamique, U.F.R . « Dynamique de la lithosphère. present different origins. Their contents vary according to their Structure et géoressources », B.P. S.15, Maroc. localities. Gases can bring informations on their origin, as well 3 Faculté des Sciences de Tunis, département de Géologie, as on physico-chemical processes that can occur to during the laboratoire de Géochimie organique, 1060 Belvédère, Tunisie. ascension of these thermal waters

The exam of the analysis’ results and interpretation of the The oxygen is of an atmospheric origin for the majority of lithological logs, seismic profiles and isochron maps of the studied thermal springs. Nitrogen would have an atmospheric Qasbat-Tadla basin reveals the stratigraphic hiatuses and the origin, for the majority of studied springs, however, a deep lateral variations of thickness. It’s a results of a block toppled origin could be evoked for springs of H. Sollah, H. Nefzas and system having taken birth in a transtension regime. The H. Ket Ettout. Methane would have for origin, especially for depocenters, so created, present some oblique directions in thermal springs of diapirs zone, the bacterial fermentation of relation to the major structural lineaments and correspond to a organic matter. strike-slips basins. These depocenters, probably of pull-apart Carbon dioxide would be bound in all studied springs, to type, are affected by a weak subsidence rate. They two different origins, a juvenile and another organic. corresponded to the sheltered zones characterized by an important degree of preservation and permited the Carbon monoxide would be the result of the reaction accumulation of important quantities of organic matter, which between the CO2 and the CH4 in depth. For helium, we is typically marine plankton. especially admit a deep origin mainly for springs of Biadha, Ali Dhaoui, H. Bourguiba, H. Sollah and H. Kef Ettout. From the upper Visean to the final Paleozoïc, the basin is affected by a compressive tectonic that is going to generate The composition in gas of these thermal waters in North of an orogenic basin in convergence “ forland basin “, Tunisia permits to differentiate between the Nappes zone and characterized by the imbricate structures, schistosées and Diapirs zone. In Diapirs zone, rates of CO2 and CH4 are very chopped by a very dense fault bundle. raised, while N2 shows weak rates.

The global tectono-sedimentary system is constituted by For Nappes zone, rates of nitrogen are important with the uplifted anticline, gutter syncline and gutter « piggy back » elevated contents of helium. However, the CO2 and the CH4 representing the three compartments of the basin which remain relatively weak. distinct by their geodynamic characters. Key words: North Tunisia, Thermal springs Gaz. The compressive strain, associated to the hot circulations, took place in the thermal conditions corresponding to an anchizonal to épizonal métamorphism. The complementary effects of these parameters let to defer in source rock maturity levels, from the oil production to graphitisation domain.

These differences in the organic matter thermal evolution correspond also to a diachronisme in the generation of hydrocarbons. The reconstitution of the basin thermal burial history established by Genex model confirms this hypothesis and indicate that the generation of hydrocarbons occurs in two phases.

The First MAPG International Convention, Conference & Exhibition 113 Marrakech Convention Center, October 28 - 31, 2007 High geothermal prospect in north-eastern Morocco Ain Allah… Thermal water, with temperature of emergence is Correia, A.1*, Carneiro, J.1, Rimi, A.2, Zarhloule, Y.3, EL up to 54°C, that constitutes indeed, the expression in surface Rharnathi N.3, Boughriba, M.3, EL Houadi, B.4 of a hydro – geothermal reservoir, permitted an evaluation of 1: Geophysical Centre of Evora, University of Evora, Rua water temperature in the deep reservoir (i.e. Liasic reservoir). Romao Ramalho 59, Geothermometric investigation reveals that studied waters are 7000-671 EVORA, Portugal all in equilibrium with quartz, thus, quartz geothermometer can 2: Scientific Institute, Dept. Physics of the Globe, B.P. 703, be used for the estimation of temperature at deep reservoir. Rabat, Morocco Key words: temperature, geothermal gradient, thermal water. 3: Laboratory of Hydrogeology-Environment, Faculty of Sciences, Oujda, Morocco GS 39 : Geophysical modelling 4: Hydraulic Basin Agency of Moulouya, Oujda, Morocco Chair : D. Elazzab, S. Lallemant New temperature data obtained in 2007 in a hydrogeological borehole (1100 m deep) near Berkane has Three dimensional modelling of magnetic structures in the revealed an average geothermal gradient of about 126 ºC/km Amjar-Saidia region (Morocco) at depths greater than 300 m. This result confirms the average D. El Azzab1, A. Koulali Idrissi2, L. Seddaoui3 geothermal gradient estimated in a mining borehole located 1 FST Department of Geology, BP 2202, Fez - Morocco about 30 km west of the Berkane borehole, in which water with 2 FS Department of Geology, Kenitra Morocco temperatures about 96 ºC was reached at a depth of about 3 FSDM Department of Geology, Fez - , Morocco 700 m. The new geothermal gradient, exceeding by far the ones already determined for this Moroccan area allows thinking The magnetic anomaly of North-eastern of Morocco shows about the possibility of programs for using high temperature the individualization of three picks. The eastern one of the pole waters in north-eastern Morocco. reduced map is well correlated to the outcropping of Chaffarines Islands. Whereas, the anomaly located at Kariate Introduction to hydro – geothermal exploration of the Couloir Arkeman, remains without surface evidence. Moreover the anomaly’s pick in the west, still shifted forward, in the South sud Rifain, Morocco direction with respect to the volcanic complex of Gourougou. Benaabidate L.1, Sadki O.2 & Zian A.1 1- Department of Geology, F.S.T.- Fez, Morocco, 2- Direction of exploration, National Office of Hydrocarbon and The magnetic anomalies map, make clearer that the three Mining, Rabat, Morocco picks, described below, may be correspond to volcanic edifices buried in depth. We can also show that the three picks Geothermal characterization of the Couloir sud Rifain has are overlaid to a big size anomaly, which testifies the existence been led by an integrated approach using petroleum well, of unique base for the three edifices. This later can be shallow geothermal prospecting and the study of thermal considered as a fossil magmatic room which would have springs emerging in the Couloir. The compilation and the supplied the outcropping volcanic apparatuses. treatment of those data permit to determining the underground temperature that constitutes the main parameter of basis for all In order to quantify the materials having caused the geothermal prospecting. observed anomaly, we carried out a three dimensional The investigation of temperature deep obtained from modeling of these magnetic structures, using Talwani method petroleum well permitted to have a middle geothermal gradient based on simulating the geological objects by polygonal of about of 23.6 °C/kms. Besides, the analysis of the shallow sections. The shapes of magnetic objects were inspired from depth temperatures gotten from the geothermal prospecting the map reduced to the pole. The measured total companion in the superficial slice of soil, showed that these magnetization varies from 1 to 4.2 A/m. We calculated our temperatures are influenced by local, climatic and streamlined model after a certain number of trail error computing tests. The conditions and that this influence seems to dim from the depth volcanic material responsible for the observed anomalies in of 5 m. The calculation of thermal indexes gave relatively addition to its outcropping would have a depth of 1.9 km and elevated indications (> 25°C) notably in the northern part of the a thickness of 1.3 km. The common base would be length 80 Couloir, to the west of Fez city. With these relatively elevated Km and with of 20 Km. indications, this area seems to be confirmed like a zone where geothermal applications are foreseeable, at least for the The comparison between computed and observed fields medium and low enthalpies. indicates a satisfactory fitting. These elements stress the importance of magmatic phenomena occurred in North-East of Couloir sud Rifain region is recognized by the presence of Morocco. several thermal springs such Moulay Yacoub, Sidi harazem,

114 Key words: Magnetic, magmatic room, magnetization, Talwani, Contribution of geophysics to the characterization of the magnetic modelling basaltic formations Application to the Rommani area, Morocco Contribution of geophysics to structural recognition and Anasse Benslimane1, Hassane Sahbi2, ElMostafa Mili3, prospecting groundwater in the Guelmim plain, Bas draa Ahmed Benamara4 1 Faculté des Sciences Dhar El Mehrez, Université Sidi basin, morocco Mohamed Ben Abdellah, Fès. Mustapha Boualoul, 2 Laboratoire de Géophysique et d’Ingénierie Géologique Geophysics and geotechnics team, My Ismail University, (L.G.I.G), BP 11201 Zitoune Faculté des Sciences, Université Meknes, Morocco. Moulay Ismail, Meknés. In the Guelmim plain (Bas Draa Basin, Morocco), several 3 Faculté des Sciences, Université Mohamed Premier Oujda. geophysical surveys has been undertaken. The results of the 4 Faculté des Sciences et Techniques, Université Moulay Ismail analysis and the synthesis of these studies led to some Meknès. structural and hydrogeological conclusions. These conclusions In the Rommani volcanic area, the rainwater infiltrates until allows to best orient the hydrogeological prospecting, and to a their retching to the impermeable level which generally good management of the local water resources. corresponds to the crystalline basement. The role of the In the structural plan basaltic formations in the field of hydrogeology is much diversified; indeed, when they are in contact with a very to The gravimetric prospecting allows highlighting some impermeable substratum they are used as drains, and when anomalies and lineaments which correspond to structural they are directly on the permeable formations, they do not lineaments such in Taïdalt plain in the south eastern of the contain any water traces because of their strong permeability. study area and in the Seyad-Noun plain, south-western of the The better geophysical method used in the hydrogeology of Guelmim city. These regions showed a much more the volcanic grounds is the electric prospecting which provides fracturation. The high resolution seismic shows that the deep vertical cuts of the electrical resistances. It is then possible to structure of the Guelmim basin is a syncline with an axis quantify the hydrous potentialities of the basaltic formations, to oriented ENE-WSW, the thickness of the Cambrian formation determine the geometry of these aquifers, and the variation is more than 1500m and the top of the Adoudounien limestone basaltic thicknesses. Our study comprises 15 electric surveys formation under Guelmim city is more than 2000m deep. and two surveys of calibration. The electric surveys carried out Between Jbel Tayert and Jbel Taïssa, the limestone is much in the area, allowed the recognition of the geological formations fractured and some thrust slices are seen towards the south. and the determination of the space geometry of the aquifer. The results of interpretation have leads on the one hand to the The electrical prospecting allows to mapping the geometry electric definition of the various formations; it is about the top of the resistant bed-rock attributed to the unfractured shales downwards of altered basalts ?=170Ωm compact basalts which constitute an impermeable floor. ?=560 Ωm, and of the schistous basement ?=110 Ωm. The 1D In the hydrogeological plan modelling lead us to characterize the different layers and to the establishment of an interpretative map. The electrical study shows that the plio-quaternary cover is very heterogeneous and well developed at the centre of the Key words: Rommani, Basalts sub-levelling, hydrogeology, geoelectric prospecting, resistivities plain and at the western part of the study area, but this region is characterised by low resistivity indicating a bad water quality. The high resolution seismic shows that the limestone formation is very deep in the almost part of the Guelmim plain so that the hydrogeological prospecting must obviously be oriented near the limestone outcrops especially at Jbel Taïssa.

Key words: geophysical prospecting, hydrogeology, structural, Guelmim plain, Morocco.

The First MAPG International Convention, Conference & Exhibition 115 Marrakech Convention Center, October 28 - 31, 2007 GS 47 : Advanced hydrogeology and information Water flow, a propagation agent of pollutants from and systems towards the groundwater, is governed by the knowledge of the Chair : B. El Mansouri, L. Bouchaou two functions of transfer and retention. These two parameters Use of GIS in groundwater modelling: Advantages in fitting which are hydraulic conductivity and characteristic moisture processes are functions of the water content. El Mansouri B., Chao J. and Kili M. University Ibn Tofail Knowledge of the soil water retention curve, expressing the Faculty of sciences, Earth sciences department relation between water pressure h (cm) and water content Lab. Applied Geosciences & Technology of Water Resources (cm3/cm3), is of prime importance in many field studies dealing BP. 144, 14000 Kenitra, Morocco. with irrigation and drainage management.

The water resources are subject of several modern Optimization of the parameters describing the soil hydraulic methods, in particular: the computational techniques which functions and in which is the volumetric water content, h is based on mathematical methods. the soil water pressure head, and K is the unsaturated hydraulic conductivity, in a transient-flow is a promising It’s not anymore to disassemble the role that the method to derive soil hydraulic information. mathematical and numeric models play in the water resources management. The most important phase in the process of Some authors tried to determine these functions modelling of the phenomena of the groundwater is the fitting of concerning measures as well as analytical determination. the model and it’s validation. The fitting is done to restore the Laboratory measurements of the retention curve based on physical parameters (generally the Transmissivity and the desorption of initially saturated soil samples are often not Storage coefficient in the case of the flows or the Kinematic applicable under field conditions. Hence, in situ measurements Porosity and the Dispersivity coefficients in case of simulation based on simultaneous monitoring of soil water content and of the pollution) is complicated in the case of the resolution of water pressure are preferable. the direct problem by try and errors method. Numerous data must be injected and possibly controlled to be introduced in The object of this paper is to show a determining method the model. of these parameters, which is a combination of particle size distribution method, in situ method and classical laboratory At the time of the fitting of the Gharb aquifer complex method. model, we had to manipulate an important data bases necessary to this model: data relative to boundary conditions, This method was applied to the unsaturated part of the reference piezometry, type of geological materiel given by the Bruxellien aquifer at the right of the lake of Louvain la Neuve in boreholes, land use, irrigation water quantity, others uses of Belgium and has given satisfactory results. (The error of water,…. The integration of the GIS in this phase for the adjustment by the model of Van Genuchten is about the management the visualization and the spatial distribution of percent). these data proved to be of a big utility to accelerate the phase of fitting and to verify the adequacy of the results discounted Key word: Unsaturated zone, hydraulic parameters, artificial recharge, Louvain-La-Neuve, Bruxellien. with the physical data of the area. This study chows that the GIS techniques will give assistance to numerical model in particular to identify the hydrodynamics parameters by the Interactions between surface waters and groudwater of the resolution of direct problem. Oued Mekkis Basin Key Words: GIS, Hydrodynamic modelling, fitting, Gharb aquifer. K. Belhassan1, M.A. Hessane1, O. Fassi Fihri2, S. El Rhaouti3 1 UFR: Geology applied to hydrogeological researches, Faculty of Sciences Dhar Mehraz, Fès. A combined method for the determination of the transfer and 2 Water service. Meknès. retention parameters in unsaturated zones 3 Agency of the Hydraulic Basin of Sebou. M.A. Hessane1, H. Karrat L.1. W. De Backer2 The oued Mikkes basin presents by its three structural sets 1 Departement of Geology, faculty of Sciences, Dhar Mehraz, (Pre-Rif, South Rifain Sillon and the Mid Atlantic Causse) an Fes example of groundwater-river interaction. 2 Agricultural Engineering Unit, the Catholic University of Louvain The study of the yearly volume of water in this basin shows the influence of geology on infiltration and surface runoff in The aquifer unsaturated zone constitutes an obliged each basin sector. Indeed, in the Pre-Rif, where the drainage passage of any superficial pollution. It also constitutes the key density is high and the geological formations are impermeable of any quantification of the feeding of the groundwater. and erodable, the surface runoff is rough whereas the

116 infiltration is poor. In Saiss, where the drainage density is mean increase the mineralization of the Oued Innaouen waters and where the soil is rather permeable, the flow as well as the flowing toward the Idriss I Dam; (ii) the low salinity of water infiltration is mean. Finally, in the atlassic mid causse, observed in the biggest part of the south portion of the constituted primarily of lias limestone and dolomitic limestone, watershed is due to dilution by waters from the both southern- and where fracturing is important, the surface runoff is almost side tributaries and Liassic limestone springs which derived nonexistent and the infiltration is at its maximum. from snowmelt and the leaching of the high Palaeozoic massif.

The analysis of the monthly mean flow between 1968 and The high concentration of strontium in water can be 2005 shows a rough oceanic system, with a baseflow explained mainly by the dissolution of Celestine (SrSO4) which maintained by springs. The average yearly flows of the river is bound to the gypsum. The variation of Strontium contents in present a temporal variety which is globally decreasing. The groundwater confirms the evaporitic origin of the anomalies in yearly hydraulicity has shown a succession of two periods, the the north part of the basin. Furthermore, this element first is prior to 1980 and is moist, the second one is later than contributes to well distinguish between the different 1980 and is dry. contributions (Middle-Atlas Miocene, Prerif Miocene, Middle- Atlas Palaeozoic and Middle Atlas Liassic and Triassic). The positive correlation between the river flow and the piezometric level, outside the flood periods, let us think of a Key word: Innaouen oued, evaporitic, water quality. feeding - drainage relationship between the aquifer and the river, according to the competition between the piezometric GIS application in the study of Liasic Aquifere of Saïs. level and the topographic level of the river. The recharge is, F. Amraoui1, L. Bouchaou2, H. Rhinane1 and F. Sami1 however, optimal during the stable period, outside the cold 1 Laboratoire Géosciences, équipe Hydrosciences, Université periods. The important drop of the level since 1980 is the result Hassan II Ain Chock, Faculté des Sciences, BP 5366 Maarif, of a combination of dryness and overfarming. Casablanca, Maroc. E.mail 2 Laboratoire de Géologie et de Géo-environnement, Faculté Key words: Groundwater–river relation ship; fracturing; drainage des Sciences Ibn Zohr, BP 28/5, 80000 Agadir, Maroc density; surface runoff. The karstic aquifers constitute in the Mediterranean basin an essential water resource for domestic drinking and/or Lithologic effects on the quality of water in the Oued irrigation. The object of this study is to approach the very Innaouen Watershed (Upstream of the Idrissi Dam, NE of complex hydrodynamic of the carbonate aquifer of Liass, in Morocco) order to more understand the global functioning of the system. S. Boutaleb1, M. Hajji1, L. Bouchaou?, Z. Lgourna2, N. This knowledge is an essential importance for a quantitative Edoullati1 and L. Laarej1. and qualitative of water resources management which 1 Energy, natural resources and modelling laboratory, Sidi becomes urgency in a context of prolonged dryness and arid Mohamed Ben Abdallah University, Polydisciplinary Faculty of climate. Taza. Morocco. 2 Applied Geology and Geo-Environment Laboratory, Ibnou- The hydrodynamic of the liassic aquifer of Saïs is analyzed Zohr University, Faculty of Sciences, BP 28/S, 80000 Agadir, using the hydrogeological data base, in particular the data of Morocco. several deep boreholes drilled in the studied area. A geographical information system (SIG) was carried out for this In order to define the anomaly of salinity in the Oued aquifer of 2100 km2 geographical extension playing an Innaouen watershed (upstream from the Idriss First dam), the important role drinking water supply of the two big cities of hydrochemical approach is used and three areas are identified Meknès and Fès (2 million inhabitants). The SIG seems and described. According to spatial variations of some performante tool to provide informations on geometry and hydrochemical parameters in these identified areas, we noted structure of the aquifer. The all data allows to establish the their close relation to the geologic features and to the climatic multiple hydrodynamic maps which can improve considerably cycle’s variations. High sulphate contents are located in the knowledge on functioning of this aquifer system and can help north part of the basin. The high chloride concentrations are the decision-makers to more mange the water resources in this measured during flood periods. The marl outcrops of Miocene area. the Middle-Atlas situated in the south west parts of the basin are leached by streams draining the dense hydrographical Key words : Plain of Saïs, Liasic aquifer, GIS, Hydrodynamics. network. These variations of hydrochemical parameters depend also on the relative abundance of tributaries on both sides of the Innaouen oued. Their respective chemical contributions are very different: (i) northern-side tributaries, which mainly leach gypsum rocks of the Miocene period which

The First MAPG International Convention, Conference & Exhibition 117 Marrakech Convention Center, October 28 - 31, 2007 Piezometric impact of recharging waters on the Bruxellien areas located respectively in central Meseta and middle Atlas. Aquifer at the Lake Detroit of Louvain–La–Neuve Monitored period was spread over three years from November M.A. Hessane1, L. W. De Backer2 2000 to April 2003. 1 Departement of Geology, faculty of Sciences, Dhar Mehraz, Fes Large variations in both ?18O and ?2H, as well as in 2 Agricultural Engineering Unit, the Catholic University of deuterium excess were recorded at the three stations during Louvain this time period. Correlations between stable heavy isotopes On the site of Louvain-la-neuve (Belgium), the aquifer of and meteorological parameters are not reliable while ?18O / Bruxellien is an unconfined aquifer fed primarily by precipitation ?2H plots give important information about the precipitating air water. Since the ponding of the storm basin in 1985, an masses origins. At the Atlantic station (Rabat); the majority of additional feeding comes from the recharging induced by the samples presents d-excess around +10 ‰ revealing Atlantic infiltration of waters of this storm basin. Near the plan of water, Ocean origin of the precipitating air masses. At the continental the variations observed of the water level in the piezometers stations, isotopic signature of the water vapour coming from the are related to water ponding and to climatic conditions. Water Mediterranean Sea is more registered with weighted mean ponding has caused a rise of the water level in piezometers values for d-excess around +14 ‰ of samples collected at Beni around the plan of water of about 1 m. Mellal and +17 ‰ recorded at Bab Bou Idir. Also, at this later station, the East Mediterranean origin was pronounced by d- On the other hand, since 1989, the piezometer level has excess values up to +22 ‰ and confirmed by weather maps. decrased. It was noticed that this discharge is not uniform in all the aquifer, but is more accentuated as we move away from Combinations between different origins and trajectories of the lake. This means that the influence of the lake is not to be air masses which attain Morocco using weather maps defined neglected, at least nearby. three groups. The first one is characterized by air masses coming from central Atlantic reaching Morocco by it Atlantic A question may be asked: what’s the artificial recharging coast. The second group is associated with air masses coming part in comparison with the general behaviour of the aquifer. from North Atlantic and crossing the western part of the Mediterranean Sea. The third group is characterized by air We propose her to calculate the artificial recharge coming masses coming from East Mediterranean and traveling over from water ponding taking into account the evolution of the North Africa and West Mediterranean Sea. groundwater surface in the different piezometers and basing also ourselves on the principle of flow superposition during Key words: precipitation, isotopes, air masses, Morocco. transient state.

The found value little differs from the one found while using Contamination of groundwater in irrigated areas under arid hydric assessment and represents an average between 1990 climat (Souss-Massa Aquifer, Morocco). and 1993. It is not excluded that the quantity of reload varies Tarik Tagma1*, Youssef Hsissou1, Lhoussaine Bouchaou1, from one year to the next (see a seasonal variation even). Latifa Bouragba2 This technique may constitute a first tool for evaluation the 1 Laboratoire de Géologie Appliquée et Géo-Environnement, artificial recharge efficiency and the prediction of its impact on Faculté des Sciences, groundwater. Université Ibn Zohr, BP. 8106, 80150 Agadir, Morocco. 2 Research Team EA 2642 “Géoscience : Déformation, Key words: artificial recharge, louvain–la–neuve, Bruxellien écoulement, Transfert”, Faculté des Sciences, Université de Franche-Comté, 16 route de Gray, 25030 Besançon cedex, 18O & 2H compositions of the Precipitation at three France. moroccan stations: Influenced by oceanic and mediterranean The Souss-Massa basin is one of Morocco’s most air masses important economic regions. It has significant agricutural B. Ouda, A. Elhamdaoui, H. Marah, M. Ibn Majah activities based mainly on early fruits and vegetables Centre Nationale de l’Energie et des Sciences Nucléaires productions and contributes about 60 % of national exports. (CNESTEN). B.P.1382, R.P, Rabat 10001 During the three last decades, the region showed the important changes in agricultural production systems. Several Oxygen-18 and deuterium compositions were monitored in hectares are developed for irrigation, fertilizers replaced largely several rain events on daily and monthly time scales at three animal manure as a source of nitrogen and monocultures meteorological stations in Morocco. One of them is located at substituted often diversified cropping systems. These drastic Rabat which is an Atlantic coastal city. The two others are improvements had an impact on the environment aspects, situated at Beni Mellal and Bab Bou Idir that are a continental specifically on groundwater quality.

118 Thus, the objective of this study is to show the current storativity coefficients. The analyse of the groundwater status of alluvial water tables in the Souss-Massa basin, where equilibrium budget show he balance showed entries of water the nitrate contamination of groundwater is increasing. Also, it of sea and the Oum Er Rbia river. is to identify the potential sources of pollution. This model also permitted to simulate some situations of Inverse Distance Weighting (IDW) interpolation method was management, especially to make move back the saline intrusion used to map the areal distribution of nitrate contents in 295 by artificial recharge. In fact, the simulation of an artificial waterholes. recharge of 0.5m3/s , which come from the Oum Er Rbia river chows that the saline intrusion move back 5 m from the coastal High contents of nitrate occur mainly in the central and line and the piezometric level can reaches 11 to 13 m. southwestern parts of the study area. Chtouka-Massa water table seems to be most affected by nitrate pollution. Indeed, Key words: Coastal Chaouia aquifer, MODFLOW, saline intrusion. more than 40% of the sampled waterholes exceed 50 mg L- 1 which constitutes the maximum limit value for nitrate GS53: New Developments in Exploration and contents in drinking water Moroccan standards set on World Health Organization (WHO) standards. The Souss aquifer is Production Technologies Chair: W. Klopf , M. Zerhboub relatively less polluted. Only 7 % of the waterholes exceed this level. Chirp and Bathymetric Data: a new Approach of the South The widespread distribution of high nitrate contents agrees Morocco Continental Margin, offshore Dakhla with the distribution of irrigated zones which explain the major A.Baltzer1, D. Aslanian2 , M. Rabineau3, F. Germond4, B. origin from agricultural fertilizers. However, the sporadic nitrate Loubrieu2 anomalies near some agglomerations may be explained by 1 CNRS-UMR 6143, Laboratoire de Morphodynamique liquid and solid waste disposals and the effect of gravewards. Continentale et Côtière, Université de Caen, 24 rue des Tilleuls, 14000 Caen Key words: Contamination, Groundwater, Fertilizers, Irrigated areas, Souss-Massa. 2 DRO/GM, IFREMER, BP 70, 29 280 Brest 3 DUMR6538, Domaines Océaniques, IUEM Univ Brest, CNRS 4 INTECHMER, Plage de Collignon, 50 000 Cherbourg Approach the saline intrusion in Chaouia Costal Aquifer by This paper presents geophysical data acquired on a groundwater budget analysis. portion of the west african margin, offshore Dakhla, in the Benfarji F.Z.1, Filali-Moutei J.2, Kacimi I3. and El Mansouri B1 south Moroccan shelf around 23°N. The Dakhla cruise (2002) 1 University Ibn Tofail, Faculty of Sciences, Lab. Applied allowed to acquire very high resolution seismic data (CHIRP) Geosciences, together with swath bathymetry (EM300). These 2 Hydraulic Administration, Rabat, complementary data give a vertical and horizontal view of the 3 University Mohamed V, Faculty of Sciences, Rabat. surficial sediment with a similar resolution. This approach The unconfined aquifer of the coastal Chaouia area, enables to define the extension and geometry of the superficial between Casablanca and Azemmour, is formed essentially of structures. Results show that superficial processes probably the primary fractured shales, the calcareous marl of the reflect deeper structures. Cenomanian and the calcareous sandstone of the Plio- The studied area, just north of the Canyon Barbas and Quaternary. This aquifer is characterized by shallow south of the Saharian slide scar , is situated in a relative groundwater level: about 8 and 30 m, what encouraged the unknown portion of this margin, at the junction between two implantation of wells to agricultural ends and the development systems . Profiles from around 23° N show a constructional of the market cultures along the sea, generating an section of the margin and evidence of shelf and slope overexploitation of the aquifer. progradation (Vonrad and Wiessmann, 1982). On the other Since 1980, an anarchical exploitation of the groundwater hand, profiles from around 25° N and northwards, show accompanied by periods of successive drought generated the destructional section of the margin with numerous slumps and decrease water level of 0,5 m/an. This causes dewatering in slides cutting the slope surface. part and a marine intrusion very marked and that spreading on Although the area prospected during the Dakhla Cruise 2 km the long the coast. What reduced the degree of should correspond to the constructional section of the margin, exploitation and the abandonment of several pumping wells. it reveals numerous different instability processes. More over, An hydrodynamic 2D model has been achieved by the use on land, there is no drainage system because of the desertic of the MODFLOW code. The fitting of this model in steady and saharian climate, and turbidity currents pathways are only transient state permitted to calculate the permeability and the inferred (Wynn et al., 2000).

The First MAPG International Convention, Conference & Exhibition 119 Marrakech Convention Center, October 28 - 31, 2007 A new method to estimate paleotemperatures in deep Seabed logging - changing the dynamics of exploration - petroleum basin: The use of RSCM Geothermometer New information enabling new discoveries - Abdeltif Lahfid1, 2, Olivier Beyssac1, Eric Deville2 and Bruno Patrick Hamou1 and Dave Ridyard Goffe1 1 EMGS (ElectroMagnetic GeoServices AS) International Sales 1 Laboratoire de Géologie, Ecole Normale Supérieure, CNRS Manager UMR 8538, Paris, France 2 Division géologie-géochimie, Institut français du pétrole, As exploration moves into ever more challenging deep 92852 Rueil-Malmaison Cedex - France water environments, drilling costs have spiraled and exploration risk has become a major factor for operators. A good estimate of the thermal history is critical for the Seabed logging has proven its ability to reduce risk by evaluation of the petroleum system. But for the exploration of measuring subsurface resistivity prior to drilling, and evaluating deep targets, temperatures estimate in sedimentary basins the presence of hydrocarbons in structures identified from which have undergone high diagenesis or low-grade seismic. Although this technology has shown significant value metamorphism conditions is difficult using routine methods already, it may be that the greatest value in applying seabed such as illite cristallinity, mineralogy, isotopes, fluids inclusions, logging may be much earlier in the exploration workflow. What vitrinite reflectance and Rock-Eval. if we applied seabed logging on a regional basis to identify the most prospective areas early in the workflow ? This approach, The aim of this study is to extend the applicability of the known as scanning, would allow seismic, drilling and other Raman Spectroscopy of Carbonaceous Materials (RSCM) resources to be focused on areas that actually contain geothermometer in the range 200-350°C. This hydrocarbons, resulting in reduced time to first oil and reduced geothermometer based on structural evolution of organic finding cost. matter OM was calibrated in the range 330-650°C by Beyssac et al. (2002) and tested in different contexts. Furthermore, many unconventional trap types, such as stratigraphic traps which may have little or no amplitude The samples used for this new calibration come from two expression on seismic data are either not detected on seismic, different contexts, the Helvetic nappes in Western Switzerland or, when detected, they remain undrilled. The scanning (Glarus Alps) with normal gradient and the Franciscan complex technique offers the promise of detecting these traps, and in central California (Diablo Range) with a high pressure generating new commercial prospects. gradient. The peak temperatures were estimated by several independent methods (Rahn et al., 19995; Dalla torre and al., In this paper we will use real data examples to review the 1996). principles of seabed logging, and discuss how technology and workflows can be adapted to enable rapid scanning of frontier Our preliminary results show that systematic trends are areas. Efficient operational methods, using modern fully three observed in the evolution of some Raman parameters with dimensional wide azimuth acquisition and processing increasing maturity grade along both the Swiss and Californian techniques are making seabed logging scanning a powerful transects. The spectra bands present a variation with and significant exploration tool, especially in deep water. temperature increase. Some bands appear (D3 and D4) and Electromagnetic scanning data is a powerful complement to evolve with temperature in the range (200-350°C), the classical seismic data, that, when properly integrated and interpreted, bands of OM spectra D1 and G evolve too. can dramatically change the dynamics of risk and reward in exploration.

To quantify this evolution of Raman spectra, we are The use of cable-less multi-component seismic acquisition currently working on a fitting procedure to identify the reliable systems for improved reservoir characterisation. parameters. Our calibration is tested in various contexts (e.g. Taïwan and Alps) by confronting our results with other methods Brian Donnelly (low T thermal chronology). Input/Output Inc. We discuss how recent developments in seismic recording Key words: Carbonaceous material, RSCM method, Thermal history, techniques can be used to dramatically improve operational deep basin and petroleum system. efficiency and geophysical data quality in land seismic acquisition. Key aspects of the techniques are GPS satellite surveying and LIDAR laser altimetry; readily-deployable portable field acquisition units; cellular radio communications: wide-azimuth survey configurations; and single-point multi- component MEMS sensors.

Employing wireless technology allows for unrestricted fully-

120 configurable survey geometries, making super-high fold map. However, borehole seismic (VSP) survey can be recording a practical proposition. This technique has significant designed/processed and interpreted for high resolution implications in terms of operational efficiency and enhanced imaging, providing delineation of subsurface structure and QHSE exposure. Further, the wireless recording system is characterization of the physical properties of the reservoir married with the use of high fidelity single-point multi- surrounding the well. It can help provide answers to questions component MEMS sensors. These record all components of and interpretation challenges which are critical and important in the seismic wave-field, enabling accurate determination of exploration or development phase of a field: anisotropic and AVO characteristics of the reservoir. Recording shear wave data allows for direct calculation of reservoir • What is the location of the well with respect to nearby properties, for instance Vp/Vs and fracture orientation. faults? • What are the orientations and types of faults (normal or The optimised orthogonal survey spread lends itself to the reverse)? use of cross-spreads concepts and Offset Vector Tiling • At what depth should the next casing string to set? methods for geometry regularisation and enhanced seismic • What the best direction and reach is of sidetrack or next data processing. This means that ‘true’ 3D seismic processing well? techniques can be used for noise attenuation and image • Is the reservoir fractured, and what is the fracture enhancement. orientation? • What is the optimum placement for the next well? New geometry of a 3D design Advanced and new borehole seismic acquisition tools and Ladmek Abdeldjebar processing techniques have been deployed in Algeria for better Sonatrach Division Forage, Hassi Messaoud Algeria understanding and revealing complex structural picture in the In seismic 3D acquisition, the geometry design is one of the vicinity of the well. This paper discusses the case studies big concern, because of the difficulties in handling the (reported in Sonatrach-Schlumberger Well Evaluation problems caused by Conference Algeria 2007 book) where high fidelity VSP data • the lack of fold acquired with multi-levels 3-components VSI (Versatile Seismic • bad azimuth distribution Imager) tool and, processed using advanced 3C processing • irregularities in offset distribution techniques delineates confident structural imaging of faults and • footprint characterization of natural fractures. • bad spatial continuity • no contribution of source in spatial filtering Oilfield technologies for characterization of fractured clastics The scope of this new 3D design geometry is to enhance Smaine Zeroug the weaknesses related to other methods by laying out Schlumberger North Africa Geomarket, Algeria regularly and continuously the receivers lines in both direction in easy way in the field. Cost-effective production of oil and gas from fractured clastic reservoirs requires comprehensive characterization of This method have these advantages: the structural and petrophysical properties of these reservoirs • increasing the fold significantly and, in particular, of the static and dynamic attributes of the • reducing by half the shot density fracture networks. • allow a good distribution of azimuths • reduce the holes in offsets distribution • reduction of acquisition footprint Structural imaging with surface and borehole seismic • symmetrical sampling technologies help detect swarms of fractures and delineate • good spatial filtering faults at the scale of the reservoir. In the vicinity of the well and at a scale of the meter down to the centimeter, sonic logging Structural delineation with VSPs as well as resistivity and acoustic borehole imaging complement the large scale seismic imaging. Data processing Muhammad Idrees1 and Zahia Djebbar2 and interpretation methods have been developed to help 1 Schlumberger North Africa Geomarket, Algeria discriminate open from closed fractures and estimate their 2 Sonatrach, Algeria alignment with respect to the local stress field. Dynamic Structural features such as faults and pinchout play an attributes of the fracture networks and petrophysical properties important role in evaluating and understanding the extent of a of the matrix can be estimated through a host of technologies; reservoir and the further development of the field. Due to in particular through transient (well) testing at the reservoir various factors related to resolution limitation on surface scale and through pressure measurements and fluid sampling, seismic, these features may not necessarily clear enough to as well as NMR measurements in the vicinity of the well. These

The First MAPG International Convention, Conference & Exhibition 121 Marrakech Convention Center, October 28 - 31, 2007 technologies have seen remarkable advances over the past demonstrates how borehole imaging can play an important few years whether in the hardware, in terms of enhanced signal role in better understanding of complex reservoir structures. acquisition, resolution, and repeatability, and processing and interpretation methodologies that take into account more Combined electrical and acoustic imaging for fracture and realistic measurement environments such as mechanical fault characterization: Cases studies from Cambro- damage or fluid invasion in the near wellbore. Using examples Ordovician tight sands of Algeria. from case studies performed in fractured reservoirs of Algeria Nouredine Bounoua, Arnaud Etchecopar and Philippe and reported in the latest Sonatrach-Schlumberger Well Montaggioni Evaluation Conference Algeria 2007 book, this paper will 1 Sonatrach DP highlight the advances and benefits obtained in the 2 Schlumberger applications of these technologies. The paper will also highlight 3 Schlumberger the necessity to consider the acquired data and processed and interpreted results within an integrated reservoir modeling Fractures play a major role in the hydrocarbon production framework that facilitates design of optimal strategies for of the tight sandstone reservoirs of Cambro-Ordovician age in reservoir development and production. Algeria. These unconventional reservoirs, with matrix permeabilities usually less than 10md and porosities between Integration of borehole image log and surface seismic data 3-10PU, do not produce commercially without the presence of for improved characterisation of complex fault zones fractures. As a consequence the main objective for drilling J.A. Van Doorn wells in these reservoirs is to maximize the number of open Schlumberger Bucharest fractures intersected by the wellbore, whether these are natural fractures or fractures created with stimulation techniques. Since the 1980s borehole image logging has provided geoscientists with an excellent means to visualise the However, the fact that a fracture will flow or not depends on subsurface. Micro-electrical and later also acoustic and numerous factors, the main ones being the fracture aperture, nuclear measurement principles have been used to build tools its lateral and vertical extension, its orientation with respect to that can provide high-resolution image logs over long rock the maximum in-situ horizontal stress and connectivity with sequences. The possibility to detect, orient and classify another other sets of fractures. Another challenge in these different sedimentary and tectonic features in borehole image formations is the risk of water breakthrough from open faults or logs has played an important role in improving our capability to fractures reaching the underlying water table. build reliable geological models and in unraveling complex Acoustic borehole imaging has become part of the reservoir structures. standard logging suite in these reservoirs drilled with oil based In many parts of the world hydrocarbon exploration is mud since the early 90’s mostly because of their application to shifting towards more difficult reservoirs. Several exploration fracture characterization. Recent changes of drilling practices companies in Europe have moved their attention towards in the Hassi Messaoud field, from vertical wells to slim short relatively small, complex structures in the vicinity of major radius horizontal wells often drilled under balance, have tectonic structures, such as thrust faults in the Alps and highlighted some of the difficulties of acquiring good quality Pyrenees. data with the UBI imaging tool.

Structural interpretation in general can benefit greatly from The combination of UBI acoustic images with electrical a combination of seismic sections with borehole image logs. images from the OBMI* Oil-Base MicroImager addresses most Bedding dips can be displayed in the form of apparent dip of the inherent limitations of acoustic imaging and provides sticks along the well trajectory to check structural dip complementary geological information in these wells. interpreted from surface and/or borehole seismics. Besides Examples shown in this paper highlight the benefits of OBMI- apparent dip sticks we use powerful software to generate UBI image combination for the characterization of the fracture structural models from bedding dips and interpreted faults and and fault network in these reservoirs: fractures, although we need to make certain assumptions - differentiation of open from closed fractures and about the dominant structural style. determination of the direction of the in-situ horizontal stress Accurate descriptions of fracture and fault systems on with the UBI data. borehole images has helped to better understand the delicate - improved detection of faults and their type (sealing vs non interplay between eustatic sea level changes, sedimentation sealing), identification of fractures and structural dip in poor and tectonics. quality borehole sections and permeability indication from the This paper, which describes examples from a/o the Alpine OBMI data. thrust fault systems with associated drag folding,

122 When combined with dynamic measurements and Hydraulic Fracturing at the Root of the Field Development production data the fractures identified from the UBI and OBMI Plan data provide critical input for the characterization of the best G.C. Dozier productive intervals and the zones of possible water entry in these challenging reservoirs. In conventional reservoirs of high to moderate permeability and sufficient flow capacity (k*h) to produce hydrocarbon * Mark of Shlumberger naturally, hydraulic fracturing is a secondary technique used to improve productivity of wellbore. In this instance, fracturing is How tight are tight reservoirs: The answer comes from NMR sometimes left to a point where skin damage reduces the measurements actual performance where the well potential is much higher. W. Klopf However, this is not the case for complicated, low-permeable 1 Schlumberger S.p.A,Via Dell’ Unione Europea, 6/A-Torre Alfa “tight” reservoirs. In these reservoirs, it is highly unlikely the (Figures courtesy EAGE) reservoir will flow hydrocarbon without significant stimulation due to the low flow capacity. Nuclear Magnetic Resonance well logs (NMR) have become standard measurements for petrophysical evaluations The flow profile in hydraulic fractured well exhibits periods in the oil industry. In addition to determining porosity and its of bilinear, linear, and pseudo-radial flow. In tight reservoirs, the bound and free-fluid components , NMR logs have been periods of bilinear and linear flow tend to dominate the applied to distinguish pore fluids such a gas, condensate, and producing profile for a fracture of significant length and high or low viscosity oils. The influence of hydrocarbon type conductivity. This lengthy bilinear and linear flow profile results may dominate the behaviour of the T2 relaxation times and in a well drainage pattern that differs from the circular pattern unfortunately may interfere with the ability to obtain pore size often planned for in field development planning. Moreover, distributions or permeabilities. since well drainage pattern is key to success and efficient well planning, the field development plan is dependent on the At the same time in the oil industry the research for fracturing program to be implemented in the field. This hydrocarbon is pushed from conventional to unconventional presentation looks at the forecasted production profiles of both hydrocarbon reservoirs, ranging from deep basin gas hydraulically fractured and unfractured tight gas reservoirs and reservoirs to continous oil reservoirs. The main characteristic is, the impact it has on the drainage pattern within the field. that the areal dimensions can be huge, the hydrocarbon Furthermore, it allows for an economic comparison, justifying content the need to incorporate potential post completion stimulation (eg porosity) is very low and the natural producibility ( eg (fracturing) into early stages of the field development concept permebility) is extremely low or not existent. to ensure maximum value is obtained.

Studying these reservoirs is quite difficult, since a lot of GS 44: Giant Hydrocarbon reservoirs: African and conventional methods used in the formation evaluation are not Middle East applicable. Chair: B. Duvall

On the other hand to successfully produce unconventional Time-dependent Flow Partitioning in Weakly Deformed, Giant reservoirs (eg tight gas reservoirs) stimulation processes have to be applied which need as their input parameters like stress Carbonate Reservoirs regimes, fracture orientation and aperture, but also Susan M. Agar1, Ravi Shekhar2, Michael Tsenn1 and Paul conventional parameters like lithology (mineralogy) , porosity Benkendorfer1 and permeability. 1 ExxonMobil Upstream Research Company, Houston, TX, USA. To push NMR measurements to its limits, ANDRA, France’s 2 Dept. of Geology & Geophysics, Texas A&M University, agency for radioactive waste management , studying low College Station, TX, USA. permeability argillites The flow behavior of carbonate rocks in the shallow crust is (clay rich sedimentary rocks) as potential host formations influenced by the combined impacts of primary and diagenetic for radioactive waste, used NMR measurements to measure textures and deformation overprints. These processes create permeability and pore-size distributions in basically non and destroy permeability, influencing time-dependent flow permeable rock. paths on both exploration and production timescales. As production from several giant carbonate reservoirs over several These examples are able to show, that also in the oil decades has shown, the heterogeneous permeability structure industry these measurements can be used in extreme of carbonate rocks can have a significant and changing impact conditions. on production as reservoir conditions change. A key aspect of

The First MAPG International Convention, Conference & Exhibition 123 Marrakech Convention Center, October 28 - 31, 2007 effective, long-term strategies to sustain production in giant Middle East. The high-impact wells reviewed will focus on play carbonate fields requires early recognition of the potential flow openers and those over 250 MMboe in size. systems that could evolve during their lifespan. With the world quickly running out of places to find new By combining insights from field analogs in Oman, elephants this talk will highlight the provinces in Africa and the published industry data and flow simulations we discuss Middle East that the industry hopes will stem the decline in different types of flow systems that might evolve and their discoveries of over 250 MMboe. potential impact on recovery. Features that tend to focus flow or introduce strong permeability anisotropy are clearly of Gas Worldwide Reserves, Resources and Production interest. For example, fracture corridors, low-displacement Yves Mathieu faults, and regional fracture arrays are commonly difficult to IFP Rueil Malmaison, France resolve in seismic data but can extend vertically and laterally for hundreds of meters-to-kilometers as permeable conduits. The presentation shows a general overview of reserves, Laterally persistent zones of intense pressure solution resources, productions, constraints and scenarios for the influenced by stratigraphic textures can influence flow future. anisotropy. Hierarchical fracture systems can provide the Firstly, reserves and resources definitions and their critical links among fracture sets otherwise confined to single significances are well defined and discussed. beds. Preliminary experiments that explore the impacts of fracture corridors on flow predictions are used to illustrate both Secondly reserves are presented per country and per the sensitivity of flow predictions to structural geometries and capita and also for main geographical and economical areas. the impact of reservoir conditions on flow system development. While the results of these studies rely on Thirdly the different factors affecting future production are assumptions inherent to the modeling software, they indicate listed and analyzed according to future reserves remaining to the need to develop a deeper understanding of the detailed be discovered. geological controls on flow partitioning on production Finally, two possible worldwide production scenarios are timescales. presented, one without any constraints, the second taking into Keywords: Carbonate, Flow, Giant, Reservoir Characterization account the different current and future ones.

At least, conclusions show the main trends for gas A Review of Global Elephant with a Focus on Africa and the exploration and production for the next decades. Middle East; 2006-2010 Ian Cross Exploring Giants : some Thoughts on Success Drivers Business Intelligence – IHS, Houston. Bernard C. Duval

Since 1860 over 1540 discoveries exceeding 250 million By virtue of the lognormal distribution of field reserves in a barrels of oil equivalent (MMboe) have been found outside of basin, the number of large fields found and to be found is lower North America. These discoveries are comprised of 433 of than the number of small-to-medium size fields. Finding and over 1 billion, 53 over 10 billion and three over 100 billion. developing large fields is critical to a company’s upstream However, in recent years the number of 250 MMboe growth, and particularly so for frontier exploration like in discoveries made each year, which peaked at 50 in 1969, is deepwater, high pressure-high temperature or fold-belt worryingly down to a trickle. In 2006, at time of writing, conditions, where size matters much economically. preliminary data suggest 12 were made while the year has Some thoughts about giant fields and related exploration seen only two of over 500 MMboe and none over 1 billion. are illustrated with examples from West and North Africa, Deepwater discoveries dominate, although somewhat down South America and South-East Asia. on the peak of 15 of over 250 MMboe made in 2000, with the NW Shelf of Australia and US portion of the Gulf of Mexico Firstly a much better predictivity of prospect expected providing much of the excitement. In addition significant new reserves is made possible through a combination of advanced plays have been opened in Angola, India and China while Iran technology and practice of risk analysis. A giant discovery has recorded some large oil and gas discoveries. does not come as a surprise as much as it happened in the past. This talk will first look at historic trends, including a review of the past two years, which will help give us an idea of what Secondly, size is not an absolute criteria. A “non-giant” (as we can expect in the future. The presentation will then discuss defined by the conventional classification), can be very some of the high-impact wells which are likely to be drilled profitable if developed as a satellite of a “true” giant. during the next three years with a focus on Africa and the

124 Thirdly, beyond the rationality of risk analysis, based on components exhibit interesting source features, which are established models usually considered for a given area, some instead distorted. room must be left for an optimized vision, which means thinking that maybe things will turn out better than expected, This methodology was first applied to synthetic data and for instance with deeper hydrocarbon-bearing reservoirs, or a then to a real case where it helps to reveal details of the new trapping mechanism. subsurface geometry of faults and basin architecture which are not evident in the subsurface geology. A fourth remark is that one never ceases exploring a field (giant or not) well after its discovery and appraisal. Reservoir Seepage-induced magnetic anomalies associated with Oil characterization is a long process, for instance when and Gas Fields: Onshore and Offshore examples considering field re-engineering at a stage of maturity, to make Robert S. Foote1 and Dietmar Schumacher2 sure that the related program fits well with fluid and reservoir 1 Geoscience and Technology, Euless, TX, USA conditions. 2 Terralliance Technologies, Newport Beach, CA, USA

Last but not least, geological thinking respectful of the laws The presence of magnetic anomalies over oil and gas fields of nature and the reality of rock analogs, and a spirit of has been noted for several decades, but it is only in recent innovation are and will be needed to continue exploring years that the phenomenon has been critically examined. successfully. Studies of geologically and geographically diverse regions document that (1) authigenic magnetic minerals occur in near- GS36: Non-Seismic Exploration. Methods and surface sediments over many petroleum accumulations, (2) exploration case Histories this hydrocarbon-induced mineralization is detectable in high Chair: D. Schumacher resolution, broad bandwidth magnetic data acquired at low altitude and with closely-spaced flight lines, and in ground Terrain derivative computation in potential field magnetic surveys, (3) the magnetic susceptibility analysis of interpretation drill cuttings and near-surface sediments confirms the F. Italiano1, M. Fedi2, P. Bernardelli1, I. GIORI1 and M. existence of the aeromagnetic anomalies, (4) sediments with Antonelli1 anomalous magnetic susceptibility frequently contain 1 ENI S.P.A. – Exploration & Production Division – Via Emilia, 1 ferromagnetic minerals such as greigite, maghemite, – 20097 San Donato Milanese (MI) – Italy magnetite, and pyrrhotite, and (5) approximately 80% of oil and 2 Università degli Studi di Napoli « Federico II » - Dip. Scienze gas discoveries are associated with hydrocarbon-induced della Terra magnetic anomalies.

Methods based on Gravity Gradient Tensor (GGT), and on The association between hydrocarbon seepage and the its related quantities, such as horizontal gradient or Euler formation of authigenic magnetic minerals in the near-surface deconvolution are in great development. Their interpretation has important applications in hydrocarbon exploration. allows a high resolution and non-invasive investigation of the Application of this methodology can quickly identify the areas Earth’s subsurface. GGT components may be either measured or prospects with the greatest petroleum potential. Although or numerically calculated from Bouguer anomaly data. the discovery of shallow sedimentary magnetic anomalies does Numerical algorithms to compute the GGT components are not guarantee the discovery of hydrocarbon accumulations, it straightforward if gravity data are acquired over an does identify areas requiring more detailed evaluation, thereby approximately flat topography. When the data are instead focusing attention and resources on a relatively small number acquired over a rugged terrain, false GGT anomalies may be of high potential sites. Proper integration of near-surface created, due to the topography. This because such algorithms magnetic data with geologic and seismic data can improve are based on the assumption that the measurements are exploration success and reduce development costs. This referred to a flat level. To avoid those problems we propose a presentation will be illustrated with examples from North strategy called “Terrain Derivative Computation” (TDC). America (including the deep-water Gulf of Mexico) and Morocco. It consists of: a) upward continuing the data to a flat level, Key Words: Hydrocarbon Seepage, Magnetic Anomalies b) compute gradients there c) downward continuing the gradient to the topography surface.

The Terrain Derivatives Computation (TDC) would allow more accuracy computation, avoiding most of errors due to topography. In particular horizontal gradient or gravity gradient

The First MAPG International Convention, Conference & Exhibition 125 Marrakech Convention Center, October 28 - 31, 2007 Surface geochemical exploration in deserts of North Africa Detection of hydrocarbon reservoirs using controlled source and the Middle East: Strategies for success electromagnetic imaging. Dietmar Schumacher David Andréis and Lucy MacGregor, Terralliance Technologies, Newport Beach, CA, USA OHM Ltd Aberdeen

Luigi Clavareau and Daniel Hitzman, The Controlled Source EM imaging (CSEMI) method is rapidly gaining acceptance as an exploration tool. Originally Geo-Microbial Technologies, Inc, Ochelata, OK, USA developed in the late 1970s, the CSEMI method uses a high Surface geochemical exploration for petroleum is the powered horizontal electric dipole to transmit a low frequency search for surface or near-surface occurrences of electromagnetic signal through the seafloor to an array of multi- hydrocarbons and their alteration products. Most oil and gas component electromagnetic receivers. By studying the accumulations leak, this leakage is predominantly vertical, it is received signal as the source is towed through the array of dynamic, and this leakage can be detected using surface and receivers, the bulk electrical resistivity of the seafloor can be remote sensing methods. Hydrocarbon microseepage surveys determined at scales of a few tens of meters to depths of in deserts require careful planning and implementation. several kilometres. Transmission frequencies are typically Microseepage data are inherently noisy and require adequate between 0.01 Hz and 10Hz. At such low frequency, the sample density to distinguish between anomalous and behaviour of electromagnetic fields in the earth is governed by background areas. To optimize the recognition of a seepage the diffusion equation. anomaly, the sampling pattern and sample density must reflect Typical water saturated sediments have a resistivity in the survey objectives, expected size and shape of the target, range 1-5 Ωm. Replacing the sea water with resistive expected variation in surface measurements. Defining hydrocarbon can result in an increase in the bulk resistivity of background values adequately is an essential part of anomaly the formation by 1-2 orders of magnitude. CSEMI sounding recognition and delineation. Undersampling and/or the use of exploits this dramatic change in physical properties to improper analytical techniques is a major cause of ambiguity distinguish water bearing formations from those containing and interpretation failures. hydrocarbons. The presence of resistive structures in the Results of microbial and soil gas surveys in North Africa background section (for example salt, tight carbonate or and the Middle East are presented her, and .illustrate the value shallow gas and hydrates) increases the complexity of CSEMI of hydrocarbon microseepage data for high-grading basins, surveys. Despite this, with careful survey design, data plays, and prospects. Surveys in Algeria and Tunisia document acquisition and data analysis positive results have been hydrocarbon microseepage to the surface in spite of the obtained in a variety of settings. presence of thick halite seals above Triassic reservoirs, and the While there is a requirement of fossil fuels there is a need to composition of the migrating hydrocarbons correctly predicted reduce both the cost and environmental impact of exploration the composition of the reservoired hydrocarbons. In Oman, and extraction. CSEMI is a non-invasive technology able to samples were collected from 3000 line kilometers of seismic minimise the risk of drilling unsuccessful exploration wells by lines to high-grade seismic leads and prospects, and identify confirming (or otherwise) the presence of hydrocarbons prior areas that warrant further evaluation. The Yemen survey to drilling. It can also provide a cost effective way of proving illustrates the use of geochemical ground-truthing of possible many more prospects within a portfolio, preventing economic seep-induced remote sensing anomalies. Results from surveys reserves of hydrocarbon from being missed. in Egypt, Yemen, Oman, and Algeria successfully discriminated prospects on basis of hydrocarbon charge. Geochemical GS49 Environment and earth Sciences exploration surveys such as these require close sample Chair: J. Hernandez spacing and are most effective when results are integrated with subsurface data. Explosive Remnants of War Risk Assessment Key words: Geochemical Exploration, North Africa Deserts Peter Alm

Over the past 70 years there has been wide spread military activity in a significant number of countries. Coincidentally much of the area fought over has mineral, oil and LNG deposits. In order to access these deposits the threat posed by the Explosive Remnants of War (ERW) needs to be addressed both on land and underwater. For example prior to any oil field development programme it necessary to carry out an exploration programme to identify the potential reserves or

126 oil/LNG. North Africa was the scene of intense military activity Predicting Groundwater Vulnerability to Climate Change by involving British, Italian and German forces as a direct result of Using a Coupled Catchment Hydrologic Model: Preliminary which large tracts of land remain contaminated with land Results for Sidi Taibi Subbasin, Maamora, Morocco. service ammunition, including anti personnel and anti tank Brahim Ben Kabbour1 and Claudio Paniconi2 mines as well as air dropped bombs and sub munitions. Prior 1 Université Cadi Ayyad, Faculté des Sciences et Techniques to any scouting or seismic survey activity it is incumbent upon Béni Mellal, B.P. 523, the contractor to carry out a risk assessment and implement appropriate risk mitigation measures to eliminate the threat 2 Institut National de la Recherche Scientifique, Centre Eau-Terre- Environnement, Quebec Ville, Quebec, Canada posed by ERW. Although the ordnance has been in or on the ground for many years it is still capable of functioning causing death or damage to personnel and/or equipment. Appropriate In order to demonstrate the impact of climatic change on Risk Mitigation measure include General Impact Survey (Level the hydraulic heads and budget of groundwater in Morocco, 1) to identify as accurately as possible the location and nature the present study uses a numerical hydrologic model for Sidi of the ordnance threat this would normally be followed up by a Taibi unconfined aquifer located in western Maâmora, Gharb technical survey (level 2) were there is positive indication of a Basin. Precisely, this aquifer is located in the North of the threat. This may lead to a full clearance operation to provide capital of Morocco Rabat. It covers an area of approximately the necessary access for survey and exploration purposes. 400 Km? and it is the only one water supply for drinking water for almost 3 million inhabitants on the cities of the Western This presentation will address the threat, the risk and North of Morocco. appropriate mitigation measures that can be applied to sure the safety of personnel and equipment on former battle areas The code used is a CATchment Hydrologic Model named or area subjected to military activity. CATHY which allows the simulation of coupled three dimensional groundwater flow in porous media with variable saturation (FLOW3D) and water surface flow in the form of Mathematical model of the salt water intrusion in Rhis Nekor hillslopes, reserves, lakes and channels (SURF-ROUTE). Coastal Aquifer (El Hoceima Region, Morrocco) Nisrine Iouzzi1 and Abdelkader Larabi2 A steady state simulation made it possible to find a 1 Laboratory of Identification and Natural Environment hydraulic head distribution similar to the years eighties one modelling(LIMEN) when drought and pumping had less impact on the aquifer 2 Department of Mineral Engineering - Mohammedia School of watertable. The use of this piezometric head as initial condition Engineers, Mohammed V University. of a series of transient state simulation made it possible to predict the decrease in hydraulic head and groundwater The plain of Rhis-Nekor, located at the north of Morocco, reserves as a result of 4% decrease in rainfall predicted recent has an important agricultural potential for the Al Hoceima studies using climatic model MAGICC/SCENGEN and the province. It stores on all its area a groundwater considered as scenario IS92a of emission provided by the IPCC as well as the one of the most important aquifers of the Rif belt. state of hydraulic head spatial distribution of the year 2020. The thickness of the aquifer witch is made by plio- quartarnay alluvia was identified by the geological, geophysical Key words: Modelling, Climate Change, Groundwater and groundwater studies. It’ is roughly about 240 meters.

The chemical study of the aquifer shows a strong An Open-Access Archive on Historical Seismology mineralization of its water due to the high concentration of Paola Albini and Massimiliano Stucchi chlorides and sulphates. This salt enrichment is related to the INGV-Istituto Nazionale di Geofisica e Vulcanologia, irrigation practices of the Rhis-Nekor perimeter by Department of Milano, via E. Bassini 15, 20133 Milano, Italy strengthening of pumping wells, whereas in the coastal part, the salt concentration at the bottom is allotted to the salt water The important contribution of historical earthquake data to intrusion witch was confirmed by geophysical studies. seismological studies, in particular to seismic hazard assessment and related topics, is increasingly acknowledged by the Indeed, this work supplements the recent groundwater international scientific community. Historical earthquake data studies, by integrating the modelling of the salt water intrusion stems from the written records of seismic effects of the past, as (which was not approached before). Using the current model we specified and corrected the hydraulic assessment of the provided by the historical sources; as such, they supply the most aquifer, the quantities of salt intruding the aquifer, the extension important - if not the unique - evidence of earthquake activity of salted level, and the optimum abstraction without a large risk before the early instrumental period. Historical Seismology has of salt water intrusion in the aquifer. now established itself as a discipline with internationally recognized, rigorous procedures, for both retrieving historical

Key words: Groundwater, model, marine intrusion data and interpreting them in seismological terms.

The First MAPG International Convention, Conference & Exhibition 127 Marrakech Convention Center, October 28 - 31, 2007 Around the world, historical earthquake data are collected Session: Vertical movements in sedimentary basins: by many organizations with varying criteria and degrees of stratigraphic systems, thermal history and petroleum commitment. A few countries only have a set of historical aspects earthquake data accessible online; in many more countries scattered data are available on paper only. These materials Thermo-mechanical models for basin (de)formation often miss the international dissemination, also because of S. Cloetingh1, J.D. van Wees1,2 and F. Beekman1 language problems, and wait to be made available to the 1. Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, scientific community. The Netherlands An Open-Access Archive is being implemented in the 2. TNO, Postbus 80015, 3508 TA Utrecht, The Netherlands framework of a IASPEI WG, designed to inventory and be Polyphase extensional and compressional reactivation of capable of storing the studies (published or not) that provide basins is a common feature in basin evolution. To differentiate historical earthquake data. A link is established between each between the different modes of basin formation and study through an in-progress list of worldwide earthquakes. reactivation of passive margins and extensional basins, the The Open-Access Archive is supported by a Hardcopy Archive development of innovative combinations of numerical and from which the original studies are scanned and converted into analogue modeling techniques is key. In this paper we present searchable electronic documents; items in languages other an overview of our advancement developing and applying than English will have a translated title. A demo version of the analogue and numerical thermo-mechanical models to Archive is here presented, to discuss how it could be further quantitatively asses the interplay of lithosphere dynamics and developed and improved in the next years. basin (de)formation.

Large-scale Monitoring of Gully Erosion in Semi-Arid Field studies of kinematic indicators and numerical Landscapes (Morocco) modeling of present-day and paleo-stress fields in selected Annika Wachsmuth areas have yielded new constraints on the causes and the Stadt München, Referat für Umwelt und Gesundheit, expression of intraplate stress fields in the lithosphere, driving Daiserstraße 6, 81371 München, Germany, basin (de)formation. Temporal and spatial variation in the level and magnitude of intraplate stress have a strong impact on the Gullies are typical erosion forms in semi-arid and arid record of vertical motions in sedimentary basins. Over the last landscapes all over the world where high morphological activity few years increasing attention has been directed to this topic and dynamics can be observed. Semi-arid climate conditions advancing our understanding of the relationship between and precipitation regimes combined with widespread land use changes in plate motions, plate-interaction and the evolution of changes of traditional agriculture towards more extensive use rifted basins. – often as sheep pasture – induce reduced soil infiltration capacity of the ground and increased runoff, aggravating the The actual basin response to intraplate stress is strongly risk of linear erosion downslope. The contribution of gullies to affected by the rheological structure of the underlying total soil loss by erosion is, however, much debated by erosion researchers: While some speak of spectacular but lithosphere, the basin geometry, fault dynamics and interplay overestimated erosion forms, others describe gullies as the with surface processes. most important sediments sources in drylands and emphasize the massive offsite impairment (e.g. reservoir siltation) caused Integrated basin studies show that rheological layering and by gullying. strength of the lithosphere plays an important role in the spatial and temporal distribution of stress-induced vertical motions, One study areas is situated in an arid region in South- varying from subtle faulting to basin reactivation and large Morocco near Foum el Hassane. Research methods to wavelength patterns of lithospheric folding, demonstrating that investigate gully erosion in this area include large-scale aerial sedimentary basins are sensitive recorders to the intraplate photographic surveys, pedological and geomorphological surveys of the regional surroundings and experimental stress field. The long lasting memory of the lithosphere, in measurements of surface runoff and infiltration capacity. A core terms of lithospheric scale weak zones, appears to play a far method is the large-scale aerial photographic monitoring with more important role in basin formation and reactivation than hot-air blimps and kites for detailed documentation of the gully hitherto assumed. A better understanding of the 3-D linkage systems with very high spatial and temporal resolution. Gully between basin formation and basin reactivation is, therefore, growth and loss of soil material are precisely measured with an essential step in research that aims at linking lithospheric geographic information systems and digital photogrammetric forcing and upper mantle dynamics to crustal vertical motions, analysis, thus allowing the quantification of gully development and their effect on sedimentary systems and heat flow. in different climatic zones under various conditions of relief, runoff, substrate and land use. Vertical motions in basins can become strongly enhanced, Key words: Gully erosion, pedological and geomorphological surveys, through coupled processes of surface erosion/sedimentation land use and lower crustal flow. Furthermore patterns of active thermal

128 attenuation by mantle plumes can cause a significant spatial continental topography is different from past one, mainly Upper and modal redistribution of intraplate deformation, as a result Jurassic – Lower Cretaceous time, where large intracontinental of changing patterns in lithospheric strength and rheological basins (intracratonic basins, large passive margins, rifts…) with layering. low relief, occurred. New measurements of the relative and absolute sea level have been carried out using the Amazon Novel insights from numerical and analogue modeling aid in present-day hypsometry, which could be the best analogue of quantitative assessment of basin history and shed new light on the Upper Jurassic-Lower Cretaceous time. At Tethys-scale, tectonic interpretation, providing helpful constraints for basin the amplitude of the highest sea level (Cenomanian) would be exploration, including understanding and predicting vertical +250 m above present-day sea level. At world-scale, the motions (eroded sedimentation record), source fill amplitude of the highest sea level (Cenomanian – relationships, and heat flow. Maastrichtian) would be +100 m above present-day sea level. In conclusion, the most realistic value for the highest sea level Gas Worldwide reserves, resources and production (Upper Cretaceous) should be more around 100 m than 250 m Yves Mathieu as suggested by numerous studies (e.g. [3]). IFP, Rueil Malmaison, France [1] Dercourt, J., Gaetani, M., Vrielynck, B., Barrier, E., Biju-Duval, B., The presentation shows a general overview of reserves, Brunet, M.F., Cadet, J.P., Crasquin, S. & Sandulescu, M. (2000). Atlas resources, productions, constraints and scenarios for the péri-Téthys. Paleogeographical maps. Commission for the Geological future. Map fo the World, Paris, 24 pl.

Firstly, reserves and resources definitions and their [2] Vrielynck, B. & Bouysse, P. (2001). Le visage changeant de la Terre. significances are well defined and discussed. Secondly L’éclatement de la Pangée et la mobilité des continents au cours des reserves are presented per country and per capita and also for derniers 250 millions d’années en 10 cartes. Commission de la Carte main geographical and economical areas. Thirdly the different Géologique du Monde (Commission for the Geological Map fo the factors affecting future production are listed and analyzed World), Paris, 30 p. + 1 CD according to future reserves remaining to be discovered. Finally, two possible worldwide production scenarios are [3] Haq, B.U., Hardenbol, J. & Vail, P.R. (1987). Chronology of presented, one without any constraints, the second taking into fluctuating sea levels since the Triassic. Science, 235: 1156-1167. account the different current and future ones.

At least, conclusions show the main trends for gas Long lasting interactions between tectonic loading, exploration and production for the next decades. unroofing, post-rift thermal subsidence and sedimentary transfers along the western margin of the Gulf of Mexico: Very low term (250 Myr) quantification of the eustasy during some insights from integrated quantitative studies Mesozoic – Cenozoic time based on coastal onlap François Roure1, Humberto Alzaga 1,2,5, Jean-Paul Callot1, measurement at the Tethys and world-scale Helga Ferket1,2, Didier Granjeon1, Esmeralda Gonzalez1,3, C. Robin1, F. Guillocheau1 and B. Vrielynck2 Nicole Guilhaumou4, Michel Lopez5, Pascal Mougin1, 1. Géosciences Rennes, UMR6118 CNRS-University of Salvador Ortuno2 and Michel Seranne5 Rennes, Campus Beaulieu, Rennes, 35042, France 1. IFP-Rueil 2. Tectonique ,UMR 7072, Université Pierre et Marie Curie 2. IMP-Mexico (Paris 6), 75252 Paris Cedex 05, France 3. PEMEX-Veracruz, 4. MNHN-Paris, The fathoming of the eustasy is still debated. This study is 5. Géosciences-Montpellier focused on the very long-term variations (250-350 Ma) during the Meso-Cenozoic with two main questions: at what time is After Jurassic rifting, numerous carbonate platforms (i.e., the highest sea level and what is its amplitude? Relative sea- the Cordoba and Tuxpan platforms) developed during the level variations (continent-scale) or absolute sea-level variations Lower and Middle Cretaceous episode of thermal subsidence (world-scale) are defined by the intersection of the coastal along the western passive margin of the Gulf of Mexico, with onlap at the studied period on the present-day hypsometry intervening basinal domains (i.e., the Tampico-Misantla, (altitude distribution of one or all continents). This method has Zongolica, Veracruz and Deep Gulf of Mexico -DGM- basins). been applied to a new paleogeographical dataset for the Meso-Cenozoic: one at the Tethys-scale (project PeriTethys, During the Late Cretaceous-Paleocene, the east-verging [1]), a second at a global-scale (IUGS/GMW project “Changing Sierra Madre Oriental-Cordoba thrustbelt developed, resulting Earth Face”, [2]). First results are based on the present-day in tectonic uplift and unroofing of the allochthonous units (i.e. continental hypsometry. The main question is: did the present- Orizaba Platform and Zongolica Basin series). This new day altitude distribution represent the past? The present-day topography provided also an important source of clastics to

The First MAPG International Convention, Conference & Exhibition 129 Marrakech Convention Center, October 28 - 31, 2007 feed the adjacent foredeep, where coeval tectonic loading Freund, R., 1965. A model of the structural development of Israel and accounted for the bending of the foreland lithosphere. adjacent areas since Upper Cretaceous times. Geol. Mag., 102: 189- However, shallow water facies or even emersion persisted until 205. the Eocene in the forebulge area (at the present location of the Quennell, A.M., 1959. Tectonics of the Dead Sea Rift. 20th Int’l. Geol. Golden Lane), preventing the clastics to reach the DGM. This Cong., Mexico, 1956, Assoc. Serv. Geol. Afr., 385-405. topographic barrier was ultimately bypassed by the clastics only during the Oligocene and Neogene, once (1) the Zak, I. and Freund, R., 1981. Asymmetry and basin migration in the Dead Sea rift. Tectonophysics, 80:27-38. prograding clastic wedge had exceeded accomodation, and (2) the long lasting thermal subsidence of the passive margin could overpass the effect of the bending and force the former An unsual sedimentary and stratigraphic system: the 1st bulge to sink. Bani Group (Middle Ordovician, Anti-atlas, Morocco) - Lower Paleozoic vs. present-day platforms? Numerous paleothermometers (Fluid inclusions, Tmax, Ro), Adrien Marante1, Philippe Razin1, Cécile Robin2, François PVT and coupled forward kinematic and thermal modelling Guillocheau2 and Jean Loup Rubino3 have been used to calibrate and date the progressive unroofing 1. EGID-Bordeaux 3, France of the thrustbelt. Coupled tectonic and sedimentologic 2. GEOSCIENCES-Rennes 1, UMR 6118 CNRS - Université modelling was applied in the foreland to predict the distribution de Rennes 1, France of sand versus shale ratios in the Oligocene to Plio-Quaternary 3. TOTAL-Pau, France clastic sedimentary wedge of the passive margin, where gravitational gliding of post-Eocene series occurred during the During the Ordovician, very large siliciclastic platforms Neogene along major listric faults. (1000-3000 km wide) characterised the northern side of the “great” continent Gondwana. Those “giant” platforms have no Basin migration and asymmetry in the Dead Sea rift equivalent in present-day and meso-cenozoic sedimentary Israel Zak basins. The Middle Ordovician sediments (1st Bani Group) of Institute of Earth Sciences, The Hebrew University, 91904 Moroccan Anti-Atlas (Akka and Zagora areas) are one of the Jerusalem, Israel. best outcrops for those types of platforms. • The sedimentary system of the Zagora area corresponds The Dead Sea rift is a transform fault which extends from to a large marine deltaic complex, evolving during a the Red Sea spreading center to the Taurus-Zagros stratigraphic cycle from flood-dominated to storm-dominated subduction zone, and separates the Levantine (Sinai-Israel) systems. Compared to the present-day systems, the Zagora and Arabian plates. The offset of pre-Senonian (Upper deltaic complex displays several differences. Cretaceous) sedimentary, igneous and structural features •The progradational trend of the cycles is characterised by indicates a 100-110 km left-lateral slip, with an anticlockwise low energy sheet floods deposits (current ripples beddings). rotation. No mouth bar deposits, similar to the present-day environments, have been identified. The Dead Sea depression sensu stricto, forms the deepest The retrogradational trend or transgressive systems tract continental part of the Dear Sea rift, with up tp 10,000 m of (TST) is characterised by high energy storm deposits. The Late Neogene to Recent evaporites and clastics. It is occupied Zagora system shows untypical erosional structures, by three distinct sedimentary bodies, deposited in basins exclusively fill up by storm deposits. They correspond to whose depocenters are displaced northward with time. The multiple superimposed large incisions (few hundreds of metres are: the continental red beds of the Hazeva Formation to one kilometre large) with a finite vertical amplitude reaching (Miocene), the Bira-Lido-Gesher marls and the exceptionally 70 m. thick rocksalt of the Sedom Formation (Pliocene-Early Pleistocene), and the successive Amora, Lisan and Dead Sea If most of the deltas are dominated by flood-deposits evaporites and clastics (Early Pleistocene – Recent). during progradation, the occurrence of storm deposits during Lengthwise and crosswise asymmetries of these sedimentary retrogradation is unusual. The complex storm erosional basins and their respective depocenters are due to: left-lateral surface, located at base progradation, corresponds to the shear combined with anticlockwise rotation of the Arabian ravinement surface. In this case, and this is original compare to (eastern) plate; steeper faulting of the crustal eastern margin all other published case examples, this surface records the than of the western sedimentary margin, and modification of storm wave-base and not the fair-weather one. the depositional pattern by twice filling up of basins, by Hazeva red beds during Late Miocene pause of shear and by Sedom Those specificities have to be explained taking into account rocksalt during Pliocene marine ingression (Quennell, 1959; the flat (?) topography of the system. But other parameters Freund, 1965; Zak and Freund, 1981). such as the high paleolatitude of the system or unusual relative sea-level amplitudes at third order scale can be other ways of

130 research. Basins, both simple and complex, may be classified by analyzing their geologic history in the context of plate Turbidite modelling: importance for North Africa tectonics. The major elements of this history are (1) basin- Dave Waltham1, Deirdre Duggan2 and Stuart Mclean2 forming tectonics, (2) depositional cycles or sequences, and (3) 1. Royal Holloway, University of London basin-modifying tectonics. 2. Midland Valley Exploration, Glasgow The model presented here is designed to link common Current understanding of the transport and deposition of elements of petroleum systems and plays to natural stages in turbidite sediments is typically limited by the information basin evolution. It shows that basins with similar subsidence contained in borehole, outcrop and well data, which do not history in the same tectonic region have experienced the same provide accurate criteria for the predictive modelling of turbidite modifying tectonics and have similar trap types. sedimentation. A new approach uses forward modelling to With the support of numerical modeling we can also make predict the deposition patterns of turbidity currents on a predictions on maturation of the hydrocarbons in the basin. reconstructed geological palaeosurface. Keywords: petroleum systems, plays The benefits of using this approach are manifold. Grain-size distributions, palaeotopography and chosen sediment input A new calibration of Raman Spectroscopy of Carbonaceous locations allow the direction of flow of the turbidity current to Materials RSCM: Application in the Helvetic nappes be calculated and the resulting deposit mapped. Flows can be repeated to build up a picture of the stacking of turbidite (Switzerland) and Big Franciscan complex (California) deposits over time. This can be easily compared to and A. Lahfid1,2, O. Beyssac1, E. Deville2 and B. Goffe1. correlated with known deposits, and incorporated into 1. Laboratoire de Géologie, Ecole Normale Supérieure, CNRS geological modelling to investigate the effects of subsequent UMR 8538, Paris, France deformation on the integrity of the deposit. 2. Division géologie-géochimie, Institut Français du pétrole, 92852 Rueil-Malmaison Cedex, France This approach has many applications. It can be used in the identification and modelling of aquifers, hydrocarbon reservoirs The Raman Spectroscopy of Carbonaceous Materials and alluvial ore deposits. When used in conjunction with flow (RSCM) geothermometer was developed by Beyssac et al. and fracture modelling, the optimum locations for wells can be 2002 to estimate maximum paleotemperature in the range narrowed down. It can also be applied to hazard assessment 330-650°C for organic bearing rocks. Later we calibrate this for mining. tool in the range of temperatures 200-350°C.

Keywords: sediment modelling, turbidites, deposition To test the new calibration of RSCM, we applied the new method to samples from different contexts. the study of several Classification of sedimentary basins according to their cross-sections in various tectonic contexts is important to structural genesis, evolutionary history and calculated discuss the roles of the rock lithology, CM precursor, deformation history and geological timing rate. We focused our hydrocarbon maturation zones: study area Pannonian basin studies on two cross-sections: Morcle cross-section (Helvetics system nappes of Switzerland) and Sur area cross-section (Franciscan Maarten Corver1, Harry Doust1, Jan-Diederik van Wees1, complex, central California). In the selected areas, the thermal Gabor Bada2 and Sierd Cloetingh1 history of the rocks is well described thanks to the systematic 1. Dept. of Tectonics, Faculty of Earth and Life Sciences Vrije combination of various techniques which are probably not Universiteit, Amsterdam perfectly reliable taken individually, but provides a robust 2. Institute of Geology, University of Budapest estimate when they all converge. These methods are fluid We develop the concept that sedimentary basins can be inclusion thermometry, vitrinite reflectance, index mineralogy, classified according to their structural genesis and evolutionary illite cristallinity and low-T thermochronology. history. Data of RSCM show variations with temperature increase. Basins can be classified according to the so called “basin In both cross sections, RSCM temperatures evolve from building blocks” they contain. This building block approach diagenesis to epizone conditions. helps us to understand the basin evolution and allow a RSCM results of Morcle area concord with data provided comparison of basins. The basic unit is the basin cycle, which by other methods used by Burkhard and Goy-Eggenberger consists of the sediments deposited during one tectonic (2001). We note the same observation in Big Sur area after episode. Simple basins have only one sedimentary or tectonic confronting RSCM data and classical methods information. cycle. Most basins, however, contain more than one tectonic/sedimentary cycle, and are called polyhistory basins. The carbonaceous material was analysed under

The First MAPG International Convention, Conference & Exhibition 131 Marrakech Convention Center, October 28 - 31, 2007 transparent minerals such as quartz or carbonates (sometimes Canadian Shield, where no Phanerozoic sedimentary record is in the same sample we find quartz and carbonates). We did not preserved. This leads us to hypothesize a potential link notice any influence of the lithology on structural evolution of between accelerated epicratonic basin subsidence and “far- CM with temperature increase. field” plate margin interactions. We infer, for Williston Basin at least, a primary Cambro-Ordovician subsidence with RSCM geothermometer is a reliable method to constrain characteristics suggestive of a thermal contraction temperatures in the range 200-350°C. It constitutes a useful mechanism, possibly accompanying the cooling of thick sills. tool for a better estimate of the thermal history of rocks and to Subsequently, the contiental lithosphere is dynamically thinned, calibrate basin modelling studies. probably as a result of far-field Antler and Laramide orogenic interactions such that the region underlain by the early Thermal History and Epicratonic Basin-forming Mechanisms: Paleozoic intrusions responds differently than the Precambrian Williston Basin Shield, although both regions see the anomalous heating K.G. Osadetz1, B. P. Kohn2, S.Feinstein3 events. This suggests that the lithological composition and 1. Geological Survey of Canada, 3303 33rd St. NW, Calgary, position of the early Paleozoic intrusive bodies exherts a Alberta T2L 2A7, CANADA protracted effect on the mechanical behaviour of the 2. School of Earth Sciences, University of Melbourne, Victoria continental lithosphere that distinguishes the Epicratonic basin 3010, AUSTRALIA region from the surrounding Precambrian craton. The search 3. Geological and Environmental Sciences, Ben Gurion for and elaboration of these mechanisms has potentially University of the Negev, P.O. Box 653, 84 120 Beer Sheva, important economic consequences for both petroleum system ISRAEL. history and diagenesis (hydrothermal dolomitization and MVT deposits). Epicratonic basin origin and evolution remains a significant geodynamic problem. Several, begin in the early Paleozoic, GS 02 : Formations Clastiques potentiellement including the Williston Basin. They exhibit geographically pétrolifères du Maroc et des régions limitrophes persistent, symmetrical subsidence that preserves thin Chair : M. Oujidi, M. Soussi successions. Some have proposed a single persistent subsidence mechanism. However, other features, including Evolution of Stratal Anatomy and Depositional Patterns in a protracted and episodically accelerated subsidence, combined with links to larger tectonic elements suggest mutiple, perhaps, Lower Jurassic Isolated Carbonate Platform Captured by GIS distinctive mechanisms. Data against which plausible tectonic (Djebel Bou Dahar, Southern High Atlas, Morocco) models can be evaluated relied previously on geohistory Oscar Merino-Tomé1, Giovanna Della Porta1, Jeroen A. M. without other thermal and mechanical constraints. Thermal Kenter2, and Klaas Verwer3, Mitch Harris4, Erwin Adams5, history constraints are also important because for diagenesis Diego Corrochano6 and Noel Canto Toimil7 and petroleum generation processes. 1 School of Earth, Ocean and Planetary Sciences, Cardiff University, Park Place, Cardiff, CF10 3YE, UK, Apatite fission track (AFT) thermochronology constrains 2 Chevron Energy and Technology Company, Appelgaarde 4, shallow crustal behavior. The method provides a thermal 2272 TK Voorburg, The Netherlands, history record below ~110°C. Using AFT thermochronology we [email protected] derive Precambrian basement thermal history underlying both 3 Faculty of Earth and Life Sciences, Vrije Universiteit, De Williston Basin and the adjacent Canadian Shield. The Boelelaan 1085, 1081HV, Amsterdam, The Netherlands, combination of these thermal history models with organic 4 Chevron Energy and Technology Company, 6001 Bollinger maturity data significantly modifies geodynamic history and its Canyon Road, San Ramon, CA 94583-2324, USA, link to petroleum systems. 5 Shell International E&P, Kessler Park 1, Rijswijk, 2288GS, Netherlands, Most important is the inferred link between the middle 6 Departamento de Geología, Facultad de Ciencias, Devonian onset of accelerated Kaskaskia sequence deposition Universidad de Salamanca, 37007 Salamanca, Spain, and a late Paleozoic thermal anomaly, which reaches the top [email protected] of the crystalline crust ~75 m.y. after the onset of accelerated 7 HUNOSA, Spain, subsidence. This interval is consistent with a lithospheric thermal anomaly originating from a rapid and dynamic thinning The quantification of spatial distribution of lithofacies and of the continental lithosphere. A similar, but smaller, their physical properties is fundamental for depositional Cretaceous and Tertiary thermal anomaly is observed during models, geostatistical analyses, sequence stratigraphy, subsidence of the Laramide Interior seaway, which evolved prediction from seismic reflection data, and flow models for contemporaneous with the Cordilleran orogeny. Thermal hydrocarbon reservoirs. This paper presents such spatial (GIS, anomalies similar in age and magnitude to those observed in LIDAR and photogrammetry) data acquired from an the epicratonic basin are also observed on the flanking

132 exceptionally well-exposed, high-relief platform, the Djebel Bou Studies integrating high-resolution 3D lithofacies Dahar (DBD), in the southern High Atlas, Morocco. This distributions and stratal geometries in carbonate platforms are platform developed in a rift basin and evolved from an uncommon because of scarcity of 3D continuous outcrops. A extensive shallow platform/ramp system (nucleated above seismic-scale and continuous carbonate-platform outcrop continental and volcanic deposits of Triassic age) into a high- (Early Jurassic Djebel Bou Dahar, High Atlas, Morocco) relief and narrower platform during the Sinemurian and provided those conditions and was analyzed using DGPS and Pliensbachian (Early Jurassic), up to the termination due to LIDAR imaging. The DBD nucleated and developed in a rift drowning in the lowermost Toarcian. Synsedimentary setting during the Sinemurian and Pliensbachian, and drowned extensional tectonics played a major role in controlling the in the lowermost Toarcian. It measures roughly 35 by 4-5 km evolution of the platform geometry and architecture that has and is fully exposed as exhumed topography. been into six major stages: The Pliensbachian margin has a typical backstepped Stages I and II consist of widespread development of anatomy and is completely exposed along a platform, margin, shallow marine intertidal and supratidal environments on a to basin profile; this slope window measures 2.5 km in length, several tens of km’s wide carbonate system (ramp to shelf) 1 km in width and provides access to a margin to toe-of-slope developed under slow and uniform thermal subsidence after succession, which eventually evolved to a height of 450 Triassic rifting phase. Renewal of extensional tectonics during meters. The margin is self eroding and shows repetitive Sinemurian led to the break up of the previously deposited backstepping. It consists of a 1) deeper dark gray peloidal rich successions with formation of fault-controlled blocks. The wackestone-mudstone with abundant fossil remains of sponge irregular distribution of the tectonically-created like organisms and stromatactoid-like cavities lined by accommodation space (due to subsided, rotated, tilted and abundant rims of marine cements; and 2) shallower coral uplifted blocks) resulted in the development of a progressive framestone with dominant pink to light gray micrite or grain- narrower carbonate system (stages III to IV). In the final stages rich fabrics surrounding the coral branches. Updip of this (V and VI), a high relief (up to 450 m high from the adjacent boundstone belt, grain-dominated outer platform deposits with basin floor) geometry developed through successive stages of large coral patch reefs and dipping several degrees (up to 15o) lithofacies retrogradation and platform margin backstepping. prevail. Downdip, the steep (up to 40o degrees) slope is Gravitational collapse modified the depositional margin leading dominated by (mega)breccias and grain flow deposits derived to the accumulation of large debris aprons of carbonate debris from the margin alternating with thin-bedded turbidites and near the toe of slope. The drowning of the carbonate system in marls reflecting a highly discontinuous sedimentation pattern. the Toarcian is recorded by a typical drowning succession capped by deep basinal shales. The spatial information on sedimentary bodies and stratal anatomy will be used to populate a full 3D depositional model Keywords: Jurassic, carbonate platform, extensional tectonics, digital of a backstepping margin. Such information is essential to outcrop model improve our concepts of geostatistical modeling using outcrops, sequence stratigraphy, prediction from seismic reflection data, and flow models for hydrocarbon reservoirs. High Resolution Spatial Models of a Carbonate Platform Margin (Early Jurassic, Djebel Bou Dahar, Southern High Keywords: Jurassic, carbonate platform, digital field geology, digital Atlas, Morocco) outcrop model Klaas Verwer1, Oscar Merino-Tomé2, Giovanna Della Porta2, Jeroen A. M. Kenter3, Ted Playton4, Erwin Adams5 and Mitch Petroleum potential of the Jurassic of central Tunisia as Harris6 deduced from outcrops and boreholes. 1 Faculty of Earth and Life Sciences, Vrije Universiteit, De Mohamed Soussi Boelelaan 1085, 1081HV, Amsterdam, The Netherlands, Université de Tunis El Manar, Faculté des Sciences de Tunis, 2 School of Earth, Ocean and Planetary Sciences, Cardiff département de Géologie, C.P. 2092, Tunis, Tunise. University, Park Place, Cardiff, CF10 3YE, UK, 3 Chevron Energy and Technology Company, Appelgaarde 4, The Jurassic sequences of central Tunisia include all the 2272 TK Voorburg, The Netherlands, necessary ingredients for the conception of a petroleum 4 Jackson School of Geosciences, University of Texas at system. This is apparent through: Austin, PO Box B, University Station, Austin, TX 78713-8902, (1)- the evidence of source rocks within the Middle Nara USA Formation (outcrop and borehole sequences). 5 Shell International E&P, Kessler Park 1, Rijswijk, 2288GS, (2)- the evidence of several carbonate reservoirs mainly Netherlands, dolomitic or oolithic within the Lower, Middle, and Upper Nara 6 Chevron Energy and Technology Company, 6001 Bollinger Formation. Canyon Road, San Ramon, CA 94583-2324, USA, (3)- the evidence of shaly and tight pelagic limestone seals

The First MAPG International Convention, Conference & Exhibition 133 Marrakech Convention Center, October 28 - 31, 2007 within the Middle Nara and the Lower Cretaceous. The compilation of the available enabled us to reconstruct (4)- the Jurassic faulted blocks and associated source and the Miocene spatial distribution deposits (facies and thickness reservoir rocks are covered by a thick shaly Formation (Sidi Khalif). variations) and to highlight the role of the tectonics and sea level changes in controlling the geometry and relationships Therefore the Jurassic rocks constitute a petroleum target between the different sequences and associated facies. and the chance for a good Jurassic play remain mainly related to the structures which were not intensively affected by the last High resolution surface to subsurface correlations major tectonic Atlasic phase. The most important traps are constrained by stratigraphic well data and log analysis, those located within the platform margins adjacent to the permitted to outline the lateral extension and the architecture Jurassic troughs. Such prospects should exist either on the of the sandstone bodies of the five sequences. western or the eastern side of the NOSA. It is worth to mention that the oil kitchen is practically proven, especially on the Sedimentary characteristics and sequential organization eastern side. However, the western area also shows a good suggest that the sandstone bars correspond to quite different indication of natural migration corroborated by the presence of depositional environments of deltaic to siliciclastic shelf numerous oil-impregnated levels located: (1) at the top of the system. The sandy bodies of the lowstand deposits are the Lower Nara Formation within the NOSA area and (2) within the most important intervals in terms of reservoir characteristics sands and limestones of the Sidi Khlif Formation at Jebel and interest. The latter have been identified at the base of Melloussi. SDM2 (Birsa formation) as well as within SDM3 of Saouef formation. The so far, lack of discovery, especially towards the East of the NOSA and probably also towards its West, is only due to The presence within the Langhian-Tortonian deposits of the small number of drilled exploration wells within the platform several separated clastic reservoir intervals sealed by thick domains, their raised rims, and at the platform-basin transition shaley units illustrates a multi-layers reservoir type that has to zones adjacent to the troughs. be more investigated.

GS 11 : Advances in Biostratigraphy and Clastic reservoir facies and sequence stratigraphic analysis Sedimentology studies of the Cretaceous dynamic OF Eastern Tunisia Miocene Deposits systems Gharsalli Ramzi1,2, Chebbi Mohamed Riadh1,2 , Soussi Chair : K. Taj-eddine, J. Rey Mohamed2, Bedir Mourad1 and Khomsi Sami1 1 Laboratoire de Géoressources, Centre de Recherches et The echinoid faunas of the lower cretaceous in the atlantic Technologies des eaux (CERTE), Technopole de Borj Cedria, BP 273-Soliman 8020, Tunisie. high atlas region (Morocco) : Paleontological and 2 Département de Géologie, Faculté des Sciences de Tunis, stratigraphical interest C.P, 1092, Tunisie. Moussa Masrour1, Mohamed Aoutem1 and François Atrops2 1 Université Ibn Zohr, Faculté des Sciences, Département de During Miocene, Pelagian block of Eastern Tunisia, which is Géologie, BP 8106, Agadir (Maroc) located in the Maghrebian Alpine foreland, has acted as flexural 2 Université Lyon 1, UFR Géologie, UMR 5125, 2, rue Dubois, subsident basin filled by important continental deposits, 69622 Villeurbanne cedex (France) essentially of fluvio-deltaic to shelf environments. Some sandy bodies of these series constitute a proven hydrocarbon The echinoid fauna from the Lower Cretaceous of the High reservoir in the Gulf of Hammamet Oil fields. Atlantic Atlas is one of the richest in the southern Tethyian area. The echinoids are widely represented on thick and continous The study of the Miocene series of Central-oriental Tunisia sections without important gaps. So, it is easy to follow, in (Sahel of Kairouan) and North Eastern Tunisia (Cap Bon detail, the evolution of this group, from Berriasian to Aptian with Peninsula and Hammamet Gulf) has been carried out following a good biostratigraphical control by ammonites which are also an integrated approach including sedimentology, sequence abundant in the same levels. stratigraphy, seismic reflection and wire line logging. The rich echinoid fauna from the Lower Cretaceous of the Sequence analysis of Miocene deposits outcropping in Agadir, Haha and Essaouira basins has been revised Jebel Abderrahmane and Saouaf syncline has led to identify taxonomically, based on new and abundant collections. Forty- five third-order depositional sequences (SDM1-SDM5) within seven species have been identified, of which 20 are reported the Langhian-Tortonian time interval. The subsurface for the first time from this region and a further three represent analogues of these sequences have been characterised by new species left in open nomenclature. Their stratigraphical seismic stratigraphic analyses of several calibrated seismic ranges have been determined accurately by reference to the lines in Gulf of Hammamet and the Kairouan zones. regional ammonite zonation. So, it is possible to use a local

134 biostratigraphical scale based on the echinoid succession, in levels defined by the first Turonian ammonites. when ammonites are rare. The Toxasteridae, which are very abundunt and underwent rapid evolution, are the most useful This isotopic signal, calibrated on various paleontological biostratigraphically. The genus Toxaster appears in the Lower groups, is synchronous at the global oceanic scale. This event Berriasian and continues until Gargasian passing through the is identified as a “global oceanic geochemical event”. following succession: T. africanus, T. granosus, T. kiliani, T. Thereby, it can be used as a proxy in setting of the lorioli, T. obtusus, T. exilis, T. retusus, T. maurus, T. peroni, T. Cenomanian-Turonian boundary interval on outcrops where collegnoi. biostratigraphic records or markers are rare or absent.

Moreover, the presence of Eoholaster, Macraster, Key Words: Biostratigraphy, Isotope Geochemistry, Cenomanian- Douvillaster, Palhemiaster, Heteraster and Pygopyrina is Turonian Boundary, Morocco. signaled for the first time in the Atlantic High Atlas region.

The impact of the sedimentary conditions on the settlement Student Session and morphology of primitive Spatangoid by analysis of Chair: El Hassan Chellai, Haddou Jabour Toxaster isochronous populations is in progress.

Keywords: Echinoids, Spatangoida, Lower Cretaceous, High-Atlas, Important details on depositional Fine-Grained deposits. Morocco. Center for shale studies: plans A. H. Bouma This study was carried out with the financial support of the French- Moroccan Committee, AI n° MA/06/149. Present studies and experiments on passive margin sediment transport provide a few unknown discoveries that will d 13C Isotope geochemistry, a Tool to place the Cenomanian- be of interest to those working on outer fan deposits. The Turonian Boundary in Morocco head at the front of currents rotates counter clockwise while the major part of the current is not too organized, except that Ettachfini El Mostafa1 and Andreu Bernard2 it still moves fine grained sediment upward. Gradually the very 1 University of Chouaïb Doukkali, Faculty of Sciences, Lab. fine sediment forms a second fluid layer that thickens downdip Geosc & Techniques of Environment, B.P. 20, 24000, El during transport, while the sand-rich current thins and Jadida, Morocco disappears at the end of sand deposition. Both currents 2 LMTG, University of Toulouse, CNRS, IRD, OMP, 14, av. E. transport silica-rich sediment. Seismically there may be very Belin F-31 400 Toulouse, Frensh. little to no difference between the deposits of both types of fluid Paleoenvironmental disturbances of the global ocean are with sediment transport: sand-rich and very fine-grained identified by numerous studies at the Cenomanian-Turonian sediments. boundary. The development of a Center for Shale Studies will become In the Moroccan Atlas, this boundary is characterized by a important to most companies. At the present several research carbonate sedimentation characterized by bioclastic and groups conduct detailed studies without keeping the complete lumachellic massive limestones overlapped by chalky, white system under control. That results in massive bypassing. and platy limestones. This lithologic unit is regarded as the The Center for Shale Studies will have a broad set of specialists regional manifestation of the OAE2 linked with a global eustatic from the USA and Canada for starting and soon thereafter rise. A geochemical correlation, coherent with biostratigraphic world wide. Industry will support the research groups. We data, is proposed to precise the Cenomanian-Turonian hope that we can start late in 2008. One Center is required to boundary in the Moroccan Atlas. avoid irregularities while they have to take care that all involved companies receive all information timely and well organized. From a paleontological point of view, this boundary is placed in a “precision interval” defined by the last occurrence of the planktic foraminifer Asterohedbergella asterospinosa at the base, and the first occurrence of the planktic foraminifer Helvetoglobotruncana helvetica, coeval with the ammonite Watinoceras sp., at the top of this interval.

From a geochemical point of view, a positive anomaly of the d13C is displayed, which take place close to this “precison interval”. It is located either in the lower part of this interval defined by the last occurrence of Asterohedbergella asterospinosa in the Upper Cenomanian, or above this interval,

The First MAPG International Convention, Conference & Exhibition 135 Marrakech Convention Center, October 28 - 31, 2007 Physical and mechanical properties of the late littoral Deformation style, sedimentology and Petrology of the Flysch quaternary deposits of the Casablanca-Mohammedia coast of Tisirène Nappe and Internal “Dorsale Calcaire” in the (Morocco) Jebha area (Jebha Sheet 1/50000, Central Rif) : a preliminary S. Hichour1, A. Hourimeche1 and H. Ejjaouani2 survey. 1 LGSE, Department of Geology, Faculty of Science Ben Msik, T. Ben Ali1, J.S. Armstrong-Altrin2, A. Di Staso3, P. B.P. 7955, Casablanca, Morocco. Mazzoleni4, Perrone V5, M.N. Zaghloul1, H. Mhamdi1 and G. 2 LPEE, Experimental Center of the Soils (C.E.S.), Route d’El Barbera4 Jadida, Casablanca, Morocco. 1-Geology department, Abdelmalek Essaadi University, FST- Tanger, Morocco The sedimentological and geotechnical studies of the late 2-Instituto de Ciencias Básicas e Ingenier?a, Centro de quaternary littoral deposits of the Casablanca-Mohammedia Investigaciones en Cciencas de la Tierra, University of Hidalgo, coast made it possible to characterize the sediments and to Mexico specify the factors controlling their physical and mechanical 3-Dipartimento di Scienze della Terra, University Federico II of properties. Napoli, Italy ; The microfacies study of tidal and dune deposits showed a 4-Dipartimento di Scienze Geologiche, University of Catania, Italy ; predominance of remains of shells, entirely or partially 5-Istituto di Geologia dell’Università “Carlo Bo” of Urbino, Italy ; recristallized out of sparite. The terrigenous fraction is The Tisirène nappe belongs to the Mauretanian Sub-domain. It represented by grains of quartz, feldspars and some heavy starts with Middle Jurassic limestones to filaments, followed by minerals. The phase of cementation corresponds to radiolarites, locally associated with Upper Jurassic remnant microsparite, localised at the points of contact between basaltic and doleritic rocks. Upwards, succession shows elements and characterizes a continental vadose environment. Thitonic-Berriasian marly–limestone alternations, jaspes, calcareous microbreccias and fine-grained limestones. The The geotechnical study showed a strong porosity which succession continues with about 2500 m thick Berriasian- represents one the third of the rock. The density indicates a Lower Aptian turbiditic sandstones with intercalations of low compactness to average. The unit weight is very close to calcareous sandstones and marly limestones. This work is the densities of the principal components of these littoral aimed to evidence the structural analysis at micro- and deposits (calcite, quartz and feldspars). The indices of quality macroscale, coupled with a detailed cartography at 1/10.000 and resistance mean that these tidal and dune deposits is of in scale in order to highlight geometrical relations and bad with average quality and low resistance. The index of sand geochronology of the observable structures. equivalent shows a spectrum ranging between clayey sands and very clean sands. The complexity of deformation style suggests a preliminary scheme with a polyphasic superposition of compressive and The correlation of the results of the sedimentological and distensive deformation phases, observed within Lower geotechnical studies revealed that the physical and mechanical Cretaceous deposits of Tisirène nappe and also within Upper properties of these littoral deposits are largely influenced by the Oligocene-Aquitanian deposits of the Internal “Dorsale sedimentological characteristics and especially by the Calcaire” of Jebha area. Both show south and locally diagenetic processes. Economically, the use of these tidal and northward verging structures. Some southward verging dune deposits remains very limited because of its poor structures display ramp and flat geometry, associated to fairly geotechnics properties. Generally they are used in work of civil E-W oriented thrust planes; some decimetre-sized open and engineering and construction. reversed folds indicating fairly N-S compression trend are also present. This deformation is overprinted by a distensive phase(s), represented by low and high angle normal faults, that seem to be parallel and orthogonal to the Mediterranean coast of the Central Rif belt.

The stratigraphic, paleogeographic, and educational interest of the standard paleozoic section in Rabat Area. S. Aoufiq, A. Mansouri, A. Touzani, I. El Basta & Y. El Kabbaj Geology department, Faculty of Sciences, Mohammed V University, Avenue Ibn Batouta, PO Box 1014, Rabat, Morocco

The Akrech area, located at 12km southern of Rabat city, shows a geological sequence from the Ordovician to the Devonian levels. The section along the Bou-Regreg river is the

136 most complete one, containing very interesting olds events in framework a very particular bond of affection being interested case of sedimentary, tectonic, magmatic and paleoclimatic in the safeguard of this geological heritage. order. Contamination in traces metals of superficial sediments at This area is the mean refer to the Caledonian and the exitoire of Tensift river-Souira Qdima (Marocan Atlantic Hercynian tectonic movements indicated by the presence of the Caledonian granite and magmatic rocks. Those events are margin) identified by the presence of basaltic flow, pillow lava and Bouasria S.1, Sadki O.2, Benaabidate L.3, and Hamoumi N.4 sedimentary levels proving the opening of an extension basin 1 Mining and Energy Ministry, National Laboratory Division, during the Ordovician. The presence of very rich and Casablanca, Morocco interesting palaeontological and palynological content, as the 2 Mining and Hydrocarbure National Office, Rabat, Morocco. Acritarchs, the chitinozoaires and the spores permitted to have 3 Geology Department, Faculty of Sciences and Technologies, a very precise datation to the succession of the Ordovician to Fez, Morocco Devonian sequence. 4 Geology Department, Faculty of Sciences, Rabat, Morocco

The study area made the correlation easier in the national This work aims essentially to approach the degree of and international scale. This section is also very important chemical contamination of superficial sediments. Indeed, because it is the only place in Morocco where the emerging surface sediments have been sampled and analyzed at about granite prove the presence of Caledonian orogenic events in five kilometers downstream Tensift river as well as at its exitoire Rabat area. at Souira Qdima located at about twenties kilometers to the South of Safi city on the Moroccan Atlantic margin. The illustration of this succession of events in the time and Sedimentary dynamics in this part of Tensift River shows an in the space revealing the palaeogeographic evolution of this unusual evolution of granulometry from upstream to zone, and gives to this standard Paleozoic section of Rabat a downstream which increases and decreases in relation with stratigraphic interest and also educational role what’s can anthropic activity (overlaying of watersheds by construction make this region a recognized and valorized geological site. and demolition wastes such as bricks, cements, glasses, etc.). The organic matter is present with relatively elevated contents The Stratotype section of the Neogene in the BOU REGREG in positive interrelationship with fine sedimentation. The six Valley. Geological and Patrimonial interests heavy metals analyzed in the superficial sediments show S. Amal , N. Ait Idir, F. Atrassi, N. El Fahchouch and A. relatively strong and variable concentrations: Zn

At Neogene age, the paleo-oceanographical model of the Sedimentary dynamic in the Triassis series of Imini and time, supposes that Morocco was crossed by a gutter, the Ighrem n’ougdal area (Hight Atlas of Marrakech, Moroocco) Rifian corridor which ensured a messinien passage between H. Aiche, S. Azzami, R. Essamoud and E.H. El Arabi the Atlantic and the Mediterranean. Geology department, Faculty of Sciences Ben M’sik, , PO Box Indeed the micropaleontologic of benthic Foraminifera and 7955, Casablanca. micropalynologic study of the sediments of Neogene of the The area of Imini and Ighrem n’ougdal is located section of Akrech, area located at 7km in the SE of Rabat, approximately at 80km to the north of Ourazazate in a sector revealed the presence of a rich paleobiological assembly which belongs to the southern subatlasic zone of the High- dating the period extending from Messinien to Tortonien. Let us Atlas of Marrakech. add, in particular, that this standard section clearly indicates the limit between these two stages characterized by a brutal The Triassic series of this area, is represented by facies with impoverishment of the microflora and microfauna and who detrital predominance, made up primarily of conglomerates, allowed also the correlation between the two marine fields. coarse to fine sandstones, clays and siltstones, with an intercalation of gypsum levels then basaltic lava on the top of It thus constitutes, of share its continuity and its the series. paleontological contents a stratotype of quality of great teaching interest but as a richness patrimonial as the scientific A detailed sedimentological study allows to subdivid the company must put forward in order to contribute to the series in four formations : sensitizing of the citizens and this must be concretized while contributing to create between the population and its natural The E1 formation, thick of 20m, consists of a succession

The First MAPG International Convention, Conference & Exhibition 137 Marrakech Convention Center, October 28 - 31, 2007 of purplished conglomerates and microconglomerats with L’Utilisation des Images Satellites et du SIG pour la centimetric to pluricentimetric elements of schist and rhyolite Caractérisation Lithologique et Géomorphologique de la from the substratum with dominated through cross bedding. It région d’Ighrem “l’Anti-Atlas, Maroc” is overlaid by coarse sandstones with planar cross bedding Tajdi.A1; Erraji.A2; Ouajhain.B1; Alami.O2. and horizontal bedding, with also mud cracks and burrows in 1 Faculté des sciences El Jadida the top. 2 Centre Royal de Télédétection Spatiale

These facies correspond respectively to deposits of Ce travail a été réalisé dans le cadre de l’initiative TIGER, channel lag with scour and fill movements, the deposits of lancée par l’ESA (Agence Spatiale Européenne) avec le soutien transverse bars whose sedimentary bodies settle for the de l’UNESCO pour la mise en application du plan d’action du periods of raising of the water level and in the shallow places Sommet Mondial sur le Développement Durable (WSSD). Le of the channel. The current was enough strong to allow CRTS en partenariat avec l’Agence du Bassin Hydraulique de avalanches deposits. The caliche palaeo-soils are present in Souss-Massa a proposé le Projet TIGRES « Télédétection et the conglomeratic levels and are pilot of a carbonated Information spatiale pour la Gestion intégrée des Ressources epigenesis. The sequences are plurimetric, thining and fining en Eau dans le bassin hydraulique de Souss-Massa. En vue de upwards. This formation is typically continental showing the promouvoir l’utilisation des images satellites dans le processus installation of a relatively proximal braided system. de gestion des ressources en eau dans la région.

The E2 formation, thick of about thirty meters, consists of Les résultats obtenus au cours de cette étude, montrent unorganized conglomerates, rich in silty matrix, corresponding que la télédétection multi source et les Systèmes to debris flows, becoming chenalized upwards. These d’Information Géographique sont des moyens puissants pour conglomerates are overlaid by siltstones and red clays with les études géomorphologiques et hydrologiques. vegetable remains and mud cracks at the top. It is about a deposit by vertical accretion in the calm zone of the floodplain, En effet, l’intégration des produits élaborés à partir des with a fast lowering of the water section towards the end of the images satellites dans un Système d’Information rising. These fine deposits temporarily receive sandy clastic Géographique, nous a permis de définir on les caractères rocks at the time of the brutal phases of flood: overbank géomorphologiques de la région d’Ighrem ainsi que ces flooding. These facies contain some sandy channels. The top caractères hydrologiques. Ce-ci nous laisse confirmer que la of the formation is characterized by the appearance of zone d’étude appartient à la ligne de partage des eaux ce du stromatolitic levels pilot of a algae epigenesis in a floodplain. bassin Souss formant ainsi qui la charnière du bombement de The sequences are plurimetric in majority, thining and fining l’Anti-Atlas. upwards. This formation thus shows the deposit in proximal braided system passing to a more distal one. La classification des images multi sources permet l’obtention de produits très satisfaisants en matière de la the E3 formation thick of about twinty meters is silty sandy classification lithologique. Les résultas obtenus comparés à la where the horizontal bedding with parting lineation pilot of a carte géologique d’Ighrem montrent plus de détails, upper flow regim are dominate. These facies correspond to notamment en ce qui concerne le pouvoir de discrimination frequent sand flat deposits in the sandy fluviatile systems. entre les unités lithologiques de la boutonnière et celles de la couverture. The E4 formation, thick of a hundred meters, is sandy at the base and silty to clayey at the top. It is characterized by Il est par ailleurs important de signaler que les produit the presence of evaporites in the form of fibrous laminate but dérives des traitements des images satellites ainsi que produits discontinuous gypsum. The sequences are metric, thining and dérivés du MNT s’avèrent utile pour l’extraction des grandes fining upwards. The presence of the gypsum is the index of the structures linéamentaires, Cependant, une vérification terrain containment of the generating basin of local sursalures. s’impose afin de valider et compléter les résultats obtenus par cette étude en vue d’élaborer une cartographie détaillée des The Triassic formations of the buttonhole of Imini thus discontinuités et des unités géologiques à l’intérieur des correspond to continental deposits at the base which were secteurs supposés être comme potentiellement favorables à la done by sometimes brutal discharges on a paleozoic proposition hydrogéologique. substratum where there were still reliefs, then by more regular currents. Containment is specified at the top with the levels with evaporates.

138 GS 52 : Moroccan geological patrimony Vertebrates fossils from Morocco, Prosperity or a Chair : M. Masrour, Y. Ennadifi decadence? N. Jalil, N. Feddi, A. Nahid, A. Qajoun and S. Sebbane Dinosaur footprints in Central High-Atlas: Ichnodiversity, “Vertebrate’s Evolution and Palaeoenvironnments”, restoration and valorization. Department of Geology, Faculty of Sciences Semlalia, Felix Perez-Lorenté1, Mohamed Boutakiou2, Youssef Marrakesh, PoBox 2390 - Morocco Ennadifi3, Susana Caro1, Majid Hadri2 and Jaouad Nouri2 1 Universidad de La Rioja, Logron˜ o, Espana,, Fundacio´ n Fossils from Morocco can illustrate most of the history of Patrimonio Paleontolo´ gico de La Rioja, Espana. vertebrate evolution, from the earliest known fishes of the end- 2 Departmentdes Sciences de la Terre, Universite´ Mohamed Devonian (Fammenian:-365Ma) to the prolific Mio-Plio- V,Faculté des Sciencse, Rabat, BP 1014,Maroc. Pleistocene sequences of Atlantic coast, which cover the last 3 Holcim, rue An-Nakhil, Hay Riad, Maroc 6 millions years of vertebrate’s history, throughout the oldest known terrestrial vertebrates of North Africa and the oldest The majority of the traces of dinosaurs explored in our known modern mammals and birds in Africa. Mesozoic fossils sector of interest and generally in all of Morocco suffer from illustrate the rise and diversification of saurischian dinosaurs continuous degradation and contemporary faunas, including marine reptiles. The four global biotic crises that affect vertebrate’s evolution could be State of conservation: The state of conservation of the rock outcrop of Ibaqalliwn (Tabant) is good, the calcareous flagstone documented by Moroccan fossils. of the impressions is well consolidated and the footprints of the Considering this wealth of palaeontological data, one could dinosaurs are well preserved. expect that Morocco possesses important Museums and the The traces of dinausaur footprints in Iouaridène (Demnate) most complete collections on vertebrate fossils. Nothing of the are in a bad state of conservation, they are imprinted on kind! Much worse, these fossils are left to the covetousness of argillaceous flagstones with mud cracks. The polygonal dealers. Vertebrate fossils are commercially attractive and raise dessicated sections are readily subject to deterioration and are much private demand. Therefore entire regions are plundered detachable. These layers are thus vulnerable, their restoration and cleared of their fossils. Commercial dealers argue that they and protection is urgently needed. help peasant who make a living from selling fossils. In fact, they take advantage of them and sell fossils to the highest bidder. Restoration: The rocks and flagstones carrying the traces Moreover, the scientific significance of fossils is lost as soon as dinosaurs must be cleaned and restored. The restoration work they are removed from their geological context. completed in the commune of Rioja in Spain is a model of inspiration and is adaptable to the Moroccan layers. The Fossils offer significant educational opportunity. They are procedure involves a certain number of techniques including rare or unique and non-renewable. They must be protected cleansing, filling by silicones, resins containing microfine of and valorised as a source of sustainable development. No alumine, azurine or glass beads. miraculous solution is available, but until efficient laws are Protection: The majority of the traces of dinosaurs of the proposed for stopping uncontrolled excavations, the creation central High-Atlas are printed in natural carbonated or of on-site museums, interpretation centres and collections of argillaceous flagstones with mud cracks. The protection of reference, as seen in all industrialised countries, should limit the these layers is must be urgently attended to. Fences would damage of this systematic pillage. Scientists who often share make it possible to appreciate the sites and meadows without the responsibility for public ignorance of fossils should provide trampling the traces ,or causing their deterioration. Shelters more information to the public and thereby help in preserving would make it possible to protect the layers from the sunshine this priceless heritage. and erosion due to the run-off Key words: Palaeontology; Vertebrate; Heritage; pillage; Protection The dinosaur layers constitute a national and international geological heritage. The state of advanced degradation is alarming, requiring study, restoration, protection and development. Valorization is carried out within the framework of the M’Goun geopark: a regional tool for valorization of the geological heritage, both natural and architectural, in order to generate beneficial socio-economic development projects involving the local population (geo- and eco-tourism attractions generating service sector employment: guides, restaurants, lodgings, hotel trades, soils products…).

Key words: Dinosaurs, Inheritance, Restoration, Valorization, High- Atlas

The First MAPG International Convention, Conference & Exhibition 139 Marrakech Convention Center, October 28 - 31, 2007 Inventory and valorization of the geotopes in the High Atlas Géologie, BP 8106, Agadir (Maroc) (Morocco) 3 Laboratoire Biogéosciences, Université de Bourgogne, Moussa Masrour1, François Atrops2, Mohamed Aoutem1, CNRS, 6 bd Gabriel, 21000 Dijon, (France) Abel Prieur2 et Jérôme Thomas3 Morocco is a country rich in remarkable fossiliferous sites 1 Université Ibn Zohr, Faculté des Sciences, Département de and this in all the levels of the Phanérozoïque one. The only Géologie, BP 8106, Agadir (Maroc) collection, which deserves this name, is currently preserved at 2 Université Lyon 1, UFR Géologie, UMR 5125, 2, rue Dubois, the Ministry for the Energy and the Mines of Rabat. In the 69622 Villeurbanne cedex (France) Moroccan university towns, it would be desirable to constitute 3 UMR CNRS 5561 Biogéosciences, 6 bd Gabriel, F-21000 museums of collections of natural History which would gather Dijon, France. the local collections of geology for teaching, research, the The inventories constitute an indispensable tool for the dissemination of knowledge, and the conservation of an management of the geological heritage. They make it possible inheritance. The authors currently work on a project in the area to identify and classify with precision the Geotopes which must of Agadir concerning Mesozoïc of the Atlantic High-Atlas and be protected. of Paleozoic of the Western Anti-Atlas where the grounds are very well represented, exposed and very fossiliferous. It is thus Within the framework of co-operation program set up by a considered, in Agadir and in its area, to create at the same time French-Moroccan multi-field team (Universities of Lyon, Dijon, natural reserves to preserve the paleontological material “in Agadir and Rabat), an inventory of the geological sites to situ” and a museum to preserve and develop the inheritance protect started in the Moroccan High Atlas. “ex situ” coming from scientific studies on quite localised levels resulting from particular layers. These two types of collections Beside the geotopes, the inventory includes the geological are perfectly complementary and are indissociable one of the works published as well as the Moroccan and French other. They will then constitute tanks for future scientific collections coming from the High Atlas. research in the area, and the vectors for the formation of the The inventory is carried out according to a methodology future generations of geologists, for the diffusion of knowledge which consists: and sensitizing of school and of general public and for the To identify the geological sites. protection of the inheritance. To gather their characteristics in a data base. Keywords: collections “ex situ”, collections “in situ”, Preservation, To classify the sites with patrimonial vocation. Valorization, Morocco. To evaluate their vulnerability and needs for protection. This study was carried out with the financial support of the French- We present here some Geotopes from the High Atlas Moroccan Committee, AI n° MA/06/149. (Examples: El Ma, Tamzergout, Assaka, Imsouane, Addar…) which offers a very diversified rich fauna, mainly represented by ammonites, echinoids, brachiopods and bivalvia. The good Aïn Maarouf prehistoric site of El Hajeb region, (Moroccan outcrop conditions of these sites give them a great interest in Middle-Atlas): a scientific patrimony almost desapeared the comprehension of the moroccan geological history. Sophia Bouzid Department of Geology, Faculty of Science, Ibn Zohr University, It should be noted that some geotopes can be integrated Po Box : 8106, Agadir 80000, Morocco. in biotopes which already profited from a protection, as it is done for Argan tree reserves, classified by UNESCO since In the Elhajeb area, (Meknes destrict), an important 1999 within the world heritage. prehistoric site delivered a very varied fauna of vertebrates mainly composed by Perissodactyla, Artiodactyla, carnivores, Keywords: Inventory, geotope, High Atlas, data base. hominids, probosidians, reptiles etc...They are old excavations This study was carried out with the financial support of the French- (J Margat, 1950). Collected pieces are part of fossils vertebras Moroccan Committee, AI n° MA/06/149. collection of the Faculty of Science of Reduction.

Our work was focused more particularly on Equidae fossils “Why it is necessary to constitute collections “ex situ” and whose specimens were firstly indexed and itemized by us “in situ” of Geology in Morocco” (teeth and metapodes). These perissodactylas allowed us to Abel Prieur1, François Atrops1, Moussa Masrour2, Mohamed underline the old character of this deposit, which dates from Aoutem2 et Jérôme Thomas3 the whole beginning of average Pleistocene (Bouzid, 1991), i.e. 1 CNRS – UMR 5125 PEPS Paléoenvironnements et an age as primitive as that of the famous algerian deposit of Paléobiosphère, Université C. Bernard Lyon1, Bâtiment Tighennif. Géode, 2 Rue Dubois F 69622 Villeurbanne Cedex 2 Université Ibn Zohr, Faculté des Sciences, Département de

140 Later works (Geraads, Amani, and Hublin, 1992; Geraads containing exceptionally preserved fossils, at the end of the and Amani, 1997) confirmed our conclusions, using hominids 1990s. Of particular interest in this respect are several recently and the others remainder vertebrates. discovered sites situated to the north of Zagora. Stratigraphically, these sites belong to the Lower and Upper The man of Aïn Mâarouf is a Homo erectus archaic, Fezouata Formations and range in age from the latest probably the oldest human fossil known in our country (0.7- Tremadoc to the middle Arenig. In addition to rich classical 0.8 M.A.). shelly faunas, these localities also yielded various articulated Thus, Aïn Maarouf is, as far as we know, the most sponges, palaeoscolecids and other soft-bodied vermiform important prehistoric site by its ancient age, and its fossiliferous organisms, exceptionally complete machaeridians, a whole content, existing inside the moroccan lands and even in the range of unmineralised arthropods and trilobites with hole North Africa. Unfortunately, this site is today completely preserved appendages and spectacularly complete damaged because of the lack of de sensitizing toward local echinoderm material. Apart from the scientific importance population and authorities. So, its patrimonial value is lost for common to Konservat-Lagerstätten in general, the new ever and only the remainder fossils collected before, will Moroccan sites have added significance because of their Early remember us his existence. Ordovician age. They are the first exceptional fossil sites from this time interval, critically documenting the onset of the Great The same risks are threatening several other Moroccan Ordovician Biodiversification Event, one of the two greatest prehistoric sites. They must be recognized as a national and most significant evolutionary radiations in the Phanerozoic scientific patrimony, emphasized and be protected from natural history of life. In consequence, the new Moroccan localities and anthropogenic degradation. have the potential to provide profound new insights into the mechanisms of the Ordovican radiation and the first stages of Key words: Morocco, average Pleistocene, Vertebrate, Perissodactyla, the resulting faunal turnover, a topic which until now has almost prehistoric patrimony. exclusively been studied on the basis of classical shelly faunas alone. Exceptionally preserved faunas from the Lower Ordovician of References: the Anti-Atlas, Morocco Destombes J. (1962)- Stratigraphie et paléogéographie de Peter Van Roy1, Bertrand Lefebvre2, Khadija El Hariri3 & l’ordovicien de l’Anti-Atlas (Maroc). Un essai de synthèse. Ahmid Hafid3 Bulletin de la Société géologique de France, 7: 453-460. 1. Research Unit Palaeontology, Department of Geology & Soil Lefebvre B., El Hariri K. & Hafid A. (2003) - Les faunes Science, Ghent University, Krijgslaan 281, building S8, B-9000 ordoviciennes de l’Anti Atlas. Un patrimoine géologique Ghent, Belgium marocain. Rapport CNRS, inédit. 2. UMR CNRS 5125 Paléoenvironnements et Paléobiosphère, Lefebvre B., Nardin E. Hunter A.W. & Regnault S. (sous bâtiment Géode, campus de la Doua, Université Claude presse). Les échinodermes de l’Ordovicien supérieur de l’Anti- Bernard-Lyon 1, 2 rue Raphaël Dubois, F-69622 Villeurbanne Atlas (Maroc): biostratigraphie et paléobiodiversité. Africa Cedex, Lyon France Geoscience Review. 3. Faculté des Sciences et Techniques, Département des Moret L. & Neltner L. (1928)- Découverte du Cambrien à Sciences de la Terre, laboratoire de Géosciences et Trilobites dans la partie axiale du Haut Atlas comprise entre Environnement BP. 549, Boulevard Abdelkrim Khattabi, 40000, l’Oued Nfis et l’Oued Ourika (Maroc). Comptes-rendus Marrakech, Maroc sommaires de la Société géologique de France, 16: 272-274.

The Ordovician is well-represented in Morocco by Keywords : Patrimony, Lower Ordovician, Anti Atlas, Morocco. extensive marine outcrops which are primarily situated in the eastern and central Anti-Atlas regions, and in the west of the country, around Rabat. As a result of the large outcrop volume, and the varied environments that are represented, the Moroccan Ordovician is a prime target for palaeontological research. Historically, Cambro-Ordovician faunas from Morocco were first mentioned in the 1920s, but studies started only in earnest from the 1930s onwards. By the 1950s, the classical shelly faunas of the Cambro-Ordovician had become one of the main research topics in Moroccan palaeontology, a situation which persists to the present day. Work on the Ordovician took on a new dimension with the discovery in the Anti-Atlas region of several Konservat-Lagerstätten, i.e. sites

The First MAPG International Convention, Conference & Exhibition 141 Marrakech Convention Center, October 28 - 31, 2007 GS 10: Salt Tectonic & Sedimentation France, C.R.A.A.G., Bouzareah, Algiers, Algeria Pre-Salt and Salt Geometry as Controlling Factors in Post- The Plio-Quaternary tectonics in the deep Western Salt Tectonics Mediterranean is dominated by gravity gliding and spreading Steve Henry1, Al Danforth2, Gabor Tari3 and Sujata above thick Messinian evaporites, characterized by proximal Venkatraman4, extension, mid-slope translation, and distal shortening. The 1 Innovative Exploration Services, Houston, Texas, USA distal region comprises circular or elongate diapirs whose rise 2 Consultant, Houston, Texas, USA was driven by combined shortening and sediment loading, 3 AllyGabor Geoscience, Bellaire, Texas, USA rather than density inversion. Our study aims at to precisely 4 GX Technology, Houston, Texas, USA identifying the salt-related structures and determining their geometry, their distribution and the associated structural Regional pre-stack depth migrated (PSDM) seismic data, features in the overburden, in order to better understand the acquired by GX Technology (CongoSpan) along the West interaction between sedimentation, salt tectonics, structural African margin of Angola, Congo and Gabon, has provided pattern and neotectonics. We use SIMRAD EM300 multibeam deep (25 km) images of the crust, sub-salt sediments and bathymetric data and 6-channel seismic profiles of two recent overlying sediments from the shallow water shelf (20 m) out surveys (2003), respectively the PROGRES cruise over the onto the abyssal plain (4000 m). One of the advantages of deep-water North-Balearic Basin, including in and westward of PSDM data is that images are in depth. This has revealed the the Rhône deep-sea fan, and the MARADJA cruise on the geometries of the pre-salt sag basin lows and paleo-rift flank margin and in deep basin offshore Algeria to investigate the highs. These highs and lows influenced salt deposition, and relationships between thick-skinned, crustal tectonics and the styles of the overlying salt deformation. This work focuses gravity-driven thin-skinned salt tectonics. on understanding the relationship of the styles of the deformed overlying post salt sediments and salt, to the pre-existing sub- The morphology of the top of the mobile salt results from a salt structures. combination of at least three main parameters:

Estimates of the original depositional thickness of salt have 1. For both areas, the regional depth distribution and the also been possible using the PSDM data. Significant variations upslope boundary reflect the initial morpho-structure of the in depositional thickness are associated with crustal thickness, basin (i.e., variations in shape and orientation of the margin) and crustal-scale faulting that continued into the drift (Albo- and the basin’s late evolution (i.e., the effects of the Messinian Aptian) as displacement on the primary rift faults developed a salinity crisis and the subsidence of the sediments). mega- accommodation zones. 2. The local perturbations result from salt tectonics and An extensional style of salt tectonics developed during the especially the numerous diapirs in the deepest parts, i.e., in Albian, as blocks of sediment moved down dip towards the front of the Rhone deep sea fan and in the western part of the sag basin depocenters. With the uplift of the African craton in Algerian area. The 3-D geometry (orientation and location) of the Miocene, rafts of shelfal sediments were remobilized and the salt anticlines, diapirs and ridges and associated continued to move downdip into the sag depocenters. Salt depocenters (minibasins) is due mainly to differential diapirs are observed to overlie the centers of the sag basin, sedimentary loading during gravity spreading and gliding of the and the beginning of the compressional salt features is on the brittle-ductile series. The 3-D network of salt ridges, observed upslope, seaward side of the sag basin. Salt thrusts and in both areas suggests that salt-related thin-skinned nappes are observed where salt is extruded over the rift flanks. contraction was multi-directional. Within the drift grabens that developed in the accommodation zones, “snake heads” of allochthonous salt have been 3. The role of thick-skinned tectonics depends on the local observed. All of these various styles of salt deformation can be geodynamic setting. In the North-Balearic basin, reentrants of associated with pre-salt features. the upslope diapir boundary are unmistakably aligned above the Catalan and North-Balearic transfer zones (corresponding Role of thick-skinned tectonics on thin-skinned salt to basement steps). This geometry attests that the subsalt tectonics in the western Mediterranean : a comparison basement exerts significant “passive” structural control on salt tectonics. Conversely, in some places along the Algerian between the Algerian and North-Balearic basins margin, located on the inner Europe-Africa convergent plate V. Gaullier1, B. C. Vendeville2, J. Déverchère3, L. Droz3, A. boundary, salt is more passively involved in the play of active Domzig3, K. Yelles4 and the Maradja and Progres Scientific ramps and flats, and depicts an uplifted eastern area and Parties squeezed salt walls and anticlines outlining the NW-SE crustal LEGEM, University of Perpignan, France, compressional stress direction. UMR 8110, Université de Lille 1, France, Domaines Océaniques, UMR 6538, University of Brest, In the North-Balearic basin, the regional thickness changes

142 in the brittle layer are related to the distributary channel-levees are discussed. system of the Rhone deep-sea fan whereas local variations are directly associated with the salt-related deformation Shale Tectonics and Sedimentation of the Offshore Niger (segmentation in ridges and minibasins). In the Algerian basin, Delta the lateral thickness changes correspond, in the west, to the Christopher D. Connors1, Barbara Radovich2, Al Danforth3 segmentation in ridges and minibasins whereas, in the east, and Sujata Venkatraman4 tectonic uplift has created a wedge-shaped basin, where strata 1 Washington and Lee University, Lexington, Virginia, USA thicken upslope. 2 Silver Grass Enterprises, Sugar Land, Texas, USA In both cases, the influence of the crustal tectonics on salt 3 Independent Consultant, Houston, Texas, USA tectonics is strong whether this influence is active or passive. 4 GX Technology, Houston, Texas, USA Conversely, studying the geometry and distribution of the salt We present a new regional analysis of the structure and structures and the relationship between the depth of the top stratigraphy of the offshore Niger Delta from interpretation of salt and the brittle cover thickness appears to be a very good the new NigeriaSpan regional 2D seismic survey, acquired and way to distinguish between deformation caused by salt processed by GX Technology. These data have optimal tectonics alone and deformation directly controlled by characteristics (long-offset, long-recording time, prestack- neotectonics or by inherited structures. depth migrated) that provide advanced imaging of the previously enigmatic mobile shale structures, as well as the Origin of Large Antithetic Rollovers in the Lower Congo better understood fault-related folds. On the shelf we Basin: the Role of Conjugate Strike-Slip Shear Zones recognize the soling out of syndepositional, listric normal faults X. Fort1 and J.-P. Brun2 along a unambiguous detachment surface at over 11 km 1 Norsk Hydro, Oslo, Norway, subsea. This detachment sits near the base of the Tertiary. 2 Rennes University, Rennes, France. This fundamental detachment in the contractional toe of the delta shallows to about 7 km subsea rather uniformly in the The mechanisms that favor the development of antithetic upper Eocene to lower Oligocene section. The inner slope is versus synthetic rollovers, during gravity spreading above salt, both translating and accommodating shortening from updip have not yet been identified. We present here a model for the extension, and exhibits a ductile and complex shale response. formation of large antithetic rollovers within the Lower Congo In the past, these mobile shale structures have been poorly Basin. imaged by seismic data and have sometimes been referred to In the upslope domain, synthetic rollovers are present in, as ‘diapiric’ structures. Based on improved NigeriaSpan both, the Kwanza and Lower Congo Basins, whereas antithetic imaging we interpret these as primarily contractional, rollovers are restricted to the Lower Congo Basin. The Kwanza asymmetric, sometimes thrusted, detachment folds with Basin exhibits less extension compared to that observed in the mobile, Eocene-Early Oligocene prodelta and marine shale Lower Congo Basin. chaotically deformed in the cores of these structures. Growth commenced in the late Oligocene, and continues to the To explain this difference between Kwanza and Lower present day on many of these structures. These long-lived Congo Basins, we use an analogue experiment performed structural highs often show later thrusting, with substantial cut- using silicone putty and sand to represent salt and sediments, and-fill geometries and several unconformities on their crests. respectively. At the end of the experiment, the sand is removed In places, adjacent basins sometimes show evacuation of the giving a direct image of the top silicone surface (equivalent of prodelta and marine shale out of the synclines forming welds top salt in nature) and the basal geometry of rafts. on the underlying lower Tertiary strata. This structural and stratigraphic style is in stark contrast to the deepwater The model displays three structural domains, parallel to the contractional toe of the delta which is primarily a brittle fold- slope direction. A central domain is characterised by a high and-thrust belt of imbricate fault-bend, fault-propagation folds, spreading rate and salt structures perpendicular to the slope and shear fault-bend folds. The Eocene-Early Oligocene direction. Two lateral domains are characterised by low prodelta and marine shale is locally mobilized here into spreading rates and curved salt structures. Antithetic rollovers symmetric, shale-cored detachment folds. Growth strata on are only located in the central domain. Lateral variations of these fault-related folds, constrains timing from late Miocene to spreading rates are accommodated by conjugate strike-slip the present day, but individual structures do not generally show shear trending at 45° to lateral boundaries, which tend to join long-lived activity. Instead, thrusting in the more brittle toe each other downslope, creating a V shape. Conjugate senses tends to be a relatively systematic break-forward sequence. of shear are compatible with the concave upslope curvature of the antithetic rollovers.

This experimental pattern directly compares to the structures observed in the Lower Congo Basin. Implications

The First MAPG International Convention, Conference & Exhibition 143 Marrakech Convention Center, October 28 - 31, 2007 Exploration Potential of Offshore Madagascar Based on deposition. During the past two years new 2D pre-stack time Regional-scale Seismic Imaging migrated seismic data were acquired and used to examine the Gabor Tari1, Al Danforth2, Elise Razaka3, Barbara Radovich4, large-scale structural, depositional, and salt tectonic features Bill St John5, Peter C. Wakeling6 et Sujata Venkatraman of the Libyan shelf and slope. The data cover approximately 1 AllyGabor Geoscience, Bellaire, Texas, USA 38,000 line kilometers in water depths ranging from 15 to over 2 Independent Consultant and Geologic Advisor to GX 3000 meters. Technology, Houston, Texas, USA Some existing models for offshore Libya have interpreted a 3 OMNIS, Antananarivo, Madagascar widespread layer of halite lying at the Messinian unconformity 4 Silver Grass Enterprises, Sugar Land, Texas, USA which thickens basinward. This interpretation was probably 5 Independent Geological Consultant, Kerrville, Texas, USA based on the fact seismic reflection continuity was lost over 6 GX Technology, UK much of the basin just beneath the unconformity. Recent data 7 Program Manager, GX Technology, Houston, Texas, USA and current understanding of salt behavior do not support this About 5,000 km of high quality, regional-scale, long-offset interpretation. We interpret the presence of a relatively thin, 2D seismic was acquired in the Majunga, Ambilobe and high amplitude and high velocity, layer of non-halite evaporates Morondava offshore basins of Madagascar, as part of a (mainly anhydrite) to be associated with the Messinian continent-wide seismic acquisition program in East Africa. unconformity. Where this high amplitude and high velocity layer Preliminary results confirmed that the Majunga and Ambilobe is absent or eroded, seismic continuity below the unconformity Basins, as part of the Madagascar subplate, developed in a is restored. lower plate position as opposed to their upper plate True halite is interpreted to exist in offshore Libya only in the counterparts in Somalia/Kenya on the African plate. far west of the Pelagian shelf near the Tunisian border and the Exploration efforts intensified in the Majunga and Ambilobe far east of the Marmarica shelf near the Egyptian border. basins in the last few years, partly because of the existence of Beneath the Pelagian shelf are a series of tight contractional an offshore salt basin. The new GXT regional lines were folds interpreted to be salt cored. Basins adjacent to the folds positioned to image several important aspects of the margin, have geometries characteristic of salt withdrawal and true salt such as the large-scale architecture of depositional sequences, diapers exist just to the west in Tunisian waters. Beneath the including potential Mesozoic source rock intervals, the Jurassic Marmarica shelf we do not observe any folds or diapirs. syn-rift structure of the margin, the salt tectonics in the However, we do see the basin geometries characteristic of salt deepwater, the position of the continent/ocean transition and withdrawal and so interpret the presence of mobile halite. the extent of Tertiary volcanics in the ultra-deepwater.

The Morondava Basin of western Madagascar is an Basin Evolution and Tectonics of the Northern Alboran Sea obliquely rifted margin with the pronounced Davie Fracture during the Plio-Quaternary (Western Mediterranean) Zone at its western edge. The new regional lines were acquired Juan I. Soto1, María del Carmen Comas1, Asrar Talukder2, along this margin to link together the existing vintage seismic Rick A. Mountfield3, Yves M.R. Chevalier3 data sets and key offshore wells drilled to date. The long 1 Instituto Andaluz de Ciencias de la Tierra (CSIC-Universidad recording (i.e. crustal-scale) and PSDM processing of the data de Granada) and Departamento de Geodinámica, Campus offers specific insights into the evolution of the unexplored Fuentenueva s/n, 18002-Granada, Spain deepwater areas of the broader Mozambique Channel. The 2 IFM-GEOMAR, Wischhofstrasse 1-3, 24148 Kiel, Germany, regional context which can be understood from the new data 3 ConocoPhillips, Ltd. P.O. Box 2197, Houston, TX 77252- set is critical to have better constraints on the presence of 2197, USA. source rocks and reservoir sequences and also to generate new play concepts in the deepwater of the Morondava Basin. The West Alboran Basin (WAB) was surveyed by ConocoPhillips in 2000 and 2001, which performed a Salt sediment interaction Offshore Libya: “Where is the regularly-spaced grid of 2D seismics, seabed coring, and a complete multibeam-swath bathymetry mosaic. In conjunction Salt?” with other data from different scientific cruises carried out in the Fiduk, J. Carl, Lynn E. Anderson, and Thomas R. Schultz area, it is confirmed the existence of a broad field of fluid CGG Americas, Inc., Houston, TX, USA 77084 venting structures in the basin floor, like mud volcanoes and The presence of Messinian evaporites is interpreted to be pockmarks. These features appear in relation to major shale widespread across much of offshore Libya, particularly within diapirs in the WAB, being developed either from their flanks or the Sirt Embayment. However, the presence of mobile halite is at their culminations. restricted to the westernmost and easternmost offshore areas. The most-recent evolution of the northern margin of the The age of the mobile halite is interpreted to be WAB has been studied using the multichannel seismic dataset Triassic/Jurassic and not related to Messinian evaporate of ConocoPhillips, completed with commercial and scientific

144 seismics. Seismic interpretation has been tied with boreholes tectonics. The Zg?obice unit in the Wieliczka area is also at the Spanish shelf, in particular with ODP-Leg 161 data (Site characterized be triangle zone, but it is cored by highly 976). We have distinguished four major, seismostratigraphic deformed thick salt units known from the Wieliczka Salt Mine. units in the Plio-Quaternary series of the WAB. These units are The Wieliczka triangle zone might have formed where lateral bounded by regional discontinuities which have been mapped changes of evaporitic facies occurred at the transition from through, thus completing a pseudo-3D seismic model (~1650 thick rock salt to thinner anhydrite facies. km2) for the post-Messinian sediments (<5 Ma). GS 01: Provenance and sedimentary features of The inferred sedimentation rates for this period reflect a turbiditic sedimentation within Tertiary basins of strong sedimentary input from the Spanish margin (>0.3 mm/y) centrooccidental Alpine Mediterranean belts. with lower sedimentation rates at the deeper portions of the basin and at the top of shale diapirs (<0.2 mm/y). The ascent of shale diapirirs and their collapse (developing symmetrical Lithostratigraphy and provenance of the syn-orogenic grabens) condition the broad geometry of the seismic units, terrigenous deposits of the Bokoya “Dorsale Calcaire” although important global sea-level fluctuations during the (Internal Central Rif, Morocco): geodynamic significance and early Pliocene and early Quaternary seem to determine the new palaeogeographic scenario. formation of major turbidite systems. Turbidite canyon courses, M.N.Zaghloul1, A. Distaso2, D. Puglisi3, O. Azzouz4 sedimentation rates, and the internal geometry of the 1 Département des Sciences de la Terre FST, Tanger (Maroc); sedimentary units are in summary clearly controlled in the WAB 2 Dipartimento di Scienze della Terra, University Federico II, by deep-seated processes, mainly by the shale diapirism. (Napoli–Italy); 3 Dipartimento di Scienze Geologiche, University of Catania Role of Evaporites in Compressional Tectonics – Examples (Italy); from the Frontal Carpathians, Southern Poland 4 Laboratoire de Geodynamique LGVBS, Université Mohamed Piotr Krzywiec Ist FS, Oujda (Maroc); Polish Geological Institute, ul. Rakowiecka 4, 00-975 Warsaw, The Bokoya Dorsale Calcaire at East of the Al-Hoceima is Poland mainly consists of a Triassic-Liassic carbonate platform with a It has been for long recognized that evaporites in general, Tertiary succession usually formed by Paleocene-Eocene and rock salt in particular, is of key importance for evolution of carbonatoclastic lithofacies evolving to terrigenous and fold-and-thrust belts, as evaporitic layers often form preferred siliciclastic deposits of Late Oligocene-Aquitanian or levels of detachments within the orogenic wedge. The majority Burdigalian? of the detached fold-and-thrust belts displace above pre- The vertical organisation of the sections shows mainly shortening evaporites, however, some of fold-and-thrust belts coarsening upward cycles with different petrofacies The also use syn-compressive evaporitic levels related to arenites of the Rouadi sucession, probably of Upper Oligocene deposition within their foredeep basins. Amongst primary age show abundant lithic fragments, almost completely factors that influence structural style of orogenic front are (1) represented by a carbonate fraction. Petrographic data type of evaporites (salt vs. anhydrite) and (2) thickness of obtained from arenites of the Tagadant-Tizi-Ali section (West of evaporitic units. Rouadi), instead, show a considerably low textural maturity, The Outer Carpathians are genetically linked to the due to the presence of abundant siliciclastic matrix and of very Miocene Carpathian foredeep basin that developed in front of frequent angular shaped clasts. The lithic fragment, are mainly the advancing orogenic wedge. Foredeep infill consists of the represented by epimetamorphites (quartzites, semischists and Eggerian to Sarmatian sedimentary sequence and includes metasedimentary rocks) and abundant quartz important Badenian evaporitic formation. Presently, in front of These compositions are in agreement with those of the the Outer Carpathian flysch (pre-Miocene) units, a zone of arenites of other outcrops of the Internal and External “Dorsale deformed foredeep deposits of variable width exists, reaching Calcaire” (s.s.) and Haouz “Dorsale Calcaire” respectively for max. 10km in the area between Kraków and Tarnów. In vicinity Tagadant Tizi-Ali and Rouadi sections. They reflect a common of Tarnów Carpathian front is dominated by wedge tectonics, provenance from source areas mainly related to the carbonate induced by presence of relatively thin anhydrite that acted as suites of the “Dorsale Calcaire” and also to their Ghomaride local detachment. Tectonic wedging produced a well- Paleozoic basement. developed triangle zone of the Miocene Zglobice unit. Core of this triangle zone is built by passive-roof duplex consisting of Key words: Provenance, “Dorsale Calcaire”, terrigenous, siliciclastic the supra-evaporitic siliciclastics. In vicinity of Kraków (Wieliczka region) Badenien evaporites include thick rock salt, and this resulted in partly different style of compressional

The First MAPG International Convention, Conference & Exhibition 145 Marrakech Convention Center, October 28 - 31, 2007 Intrabasinal Oligocene-Lower Miocene ophiolitic Turbidites Geology and hydrothermal alteration at the Hercynian in the Val Marecchia Nappe (Northern Apennines; Italy) Koudiat Aïcha massive sulphide deposit (Zn, Pb, Cu), Central S. Perrotta1, S. Critelli2 and V. Perrone1 Jebilet, Morocco 1 Istituto di Scienze della Terra dell’Università “Carlo Bo” – Lotfi F.1, Belkabir A.2, Brown A.C.3, Marcoux E.4 and Brunet Campus Scientifico – Località Crocicchia, 61029 – URBINO S.5 (Italy) 1 Université Cadi Ayyad, Faculté des Sciences Semlalia 2 Dipartimento di Scienze della Terra dell’Università della Marrakech, Maroc, Calabria – Via P. Bucci, 87020 ARCAVACATA di RENDE (Italy). 2 Université Cadi Ayyad, Faculté des sciences et techniques, Marrakech, Maroc, In the North-Apenninic Sub-ligurian Val Marecchia Nappe, 3 Ecole Polytechnique de Montréal, Canada, some peculiar microbreccias occur in the lowermost part of the 4 ISTO, Université d’Orléans France, Lower Miocene Argille Varicolori Formation. 5 Reminex-MANAGEM The rock is a disorganized breccia, made up of The Koudiat Aïcha polymetallic deposit (Zn-Pb-Cu) is subrounded to highly angular monolithic dark-to-light located in the southern part of the Moroccan meseta, 32 km to ultramafic clasts, cemented by light-grey, fine-grained the NW of Marrakech and 7 km to the SW of the old pyrrhotine carbonate matrix. mine of Kettara in the central part of the massive Hercynian of Microscopic study points out that the rocks show randomly Jebilet in Morocco. It is enclosed in the visean Saghlef volcano- oriented fabric, serpentinite (more than 95%), diabase, chert sedimentary series composed mainly of mudstones and and limestone clasts. Cathodoluminescent analysis reveals occupying the central part of Jebilet which enclose several that serpentinite fragments are frequently grouped as derived sulphide deposits. from a single clast, and show very common crackle and rarer The study of hydrothermal alteration effects showed a jigsaw textures. The serpentinite clasts display hourglass and mineralogical zonation well pronounced in relation to the ore bastite and, most recurrent, mesh textures. Olivine and body. This zonation is marked by a net change in terms of pyroxene are preserved as relicts. The matrix is generated by modal proportions of secondary alteration minerals (sericite, comminution and/or alteration of serpentinized peridotite chlorite, quartz and carbonates). This alteration is illustrated by clasts, later obliterated by calcite replacing. the development of an envelope of local alteration (5-20 m) Similar structural-petrographic features are known in rocks around mineralization, materialized by a strong chlorititization drilled in the Atlantic Ocean (Vema fracture zone; Iberia Abyssal of proximal sedimentary facies. Plain), and this allows to consider for the microbreccias an The chemical changes are accompanied by hydrothermal intrabasinal origin. The microbreccias deposited close to alteration and the deposition of the ore body. They are shown transform faults, that uplifted the magmatic substratum, in the Koudiat Aïcha deposit by a band of maximum chemical feeding with clasts a pelagic succession. A similar origin can be weathering of approximately 60 m in thickness in the lower part proposed for the coarse magmatic and sedimentary breccias of the ore body. This band illustrates a gain (addition) and loss and olistoliths characterizing also the Cretaceous-Oligocene (scrubbing) in chemical elements. It is materialized by a mass rocks of the Val Marecchia Nappe. increase of ?FeOt, ?MnO, ?MgO, provided by a corresponding This interpretation is in agreement with the ophiolitic reduction in ?CaO, ?K2O, ?Na2O. This enrichment in Fe-Mg- detritism of the North-Apenninic oceanic belts, related to the Mn as well as the loss of K-Ca-Na well indicates the reduction occurrence of transform faults and peridotite diapyrs. in sericite and a substantial enrichment in chlorite, associated with albititization of plagioclases. This type of alteration Considering the intrabasinal origin and the early Miocene suggests high temperatures and the high wather/rock ratio in age of the studied rocks, also the Sub-ligurian Domain has to the discharge zone, with almost maximum scrubbing of K2O, be interpreted as an oceanic domain, which must be located Na2O, CaO and moderated in SiO2 and the precipitation of in a branch of the Central Tethys, deformed since the early FeOtotal, MgO and MnO. Miocene, instead of on the thinned continental crust of the westernmost Adria margin. Keywords : Massive sulfide, Koudiat Aïcha, Hercynian, Hydrothermal Alteration, Central Jebilet.

146 Provenance and Geotectonic Setting of the Ourika Gneissic However, most of the data collected by oil companies have Rocks (High-Atlas, Morocco) remained confidential. Barakat Ahmed1, El Baghdadi Mohamed, Rais Jamila This paper aims to give facies and environments evolutions 1 Laboratory Georessources and Environment, Faculty of in order to able one to define correlatable surfaces and make Sciences and Techniques, Béni-Mellal correlations at high resolution. For this purpose the faciologic The gneissic massif of Ourika is composed by various stratigraphy based on the analysis and the succession of facies facies that gather in two distinct and concordant groups: is applied. amphibole and biotite gneisses (GBA) in center and The Cambro-ordovician facies of this region show a amphibolites and amphibole gneisses (GAA) in periphery. The progression from the continent to platform rather than platform difference in their compositions would be related to the to basin; that is the reason why the faciological stratigraphy ( diversity of the protoliths. This study made it possible to have Homewood and al., 1992 ) is applied. some information on their origin and tectonic significance. The genetic units, corresponding to third order sequences, i) The two gneissic protoliths represent a medium-K calc- are limited at their bases and tops by Maximum Flooding alkaline from a subduction-related origin. They were Surfaces (MFS); these surfaces mark the time of the reverse of peraluminous and S-type granitoids for GBA and the tendency between retrogradation and progradation; metaluminous I-type diorites for GAA gneisses. therefore, they are excellent surfaces and easy to identify. ii) The GBA and GAA protoliths that have until now been We have evidenced third order cycles, limited by key regarded as the PI terranes by many previous works, belong to surfaces ( MFS) which have been dated by biostratigraphy. a Pan-African orogeny. The GBA protholith seem to be generated by the melting of the crustal or immature Correlations have been done between sedimentary series sedimentary rocks after crustal thinning during the earlier Pan- in Tassilis outcrops and wells in the Illizi and Ahnet-Timimoun African orogenic events, at c. 780 to 750 Ma. GAA protolith basins. were formed in Panafrican island arc/fore-arc basin environments, at c. 743 Ma, from an anatexie related to the New stratigraphic oil traps and argillaceous seal rocks have mantellic injection in the juvenile continental crust. been found.

iii) The two gneissic protoliths have been affected by an A geodynamic interpretation is proposed and a amphibolite to granulite-facies metamorphism (700±50°C) comparison with the Ahnet-Timimoun Basin is done. during the earlier Pan-African orogenic event and by a Key words: Lower Paleozoïc, Genetic Sequences, Correlations, greenschist-facies metamorphism (570±30°C), very developed Stratigraphic traps, Geodynamic, Illizi, Ahnet-Timimoun Basins, in GBA protolith, during the late Pan-African orogeny. Sahara, Algeria.

iv) The strong N-S gradient of Pan-African deformation would be thus responsible for the overlapping of the GBA on GS 03: “Stratigraphie séquentielle”, carrefour de the GAA protolith as well as for the dome shape of the Ourika nos connaissances des séries alpines de plateforme, gneisses. The dome core corresponding to the GBA gneisses pente et de bassin which has been srongly affected by this deformation, would have intruded, by ascending movements convectifs, in the Paleogeography and sea-level history forcing eco- heavy cover formed by the GAA gneiss. sedimentary contexts in Late Jurassic Epicontinental Shelfs (Prebetic Zone, Betic Cordillera) Genetic sequences and correlations of the Lower Paleozoïc Olóriz, Federico1, Reolid, Matías2, Rodríguez-Tovar, Francisco Series in the Illizi Basin and Tassilis Outcrops. Propositions of J.1 geodynamic evolution and comparisons with the Ahnet- 1 Dept. Estratigrafía y Paleontología, Facultad de Ciencias, Timimoun Basin (Algerian Sahara ) Universidad de Granada. Campus Fuentenueva, 18071, Khemissi Zellouf1 and Hamid Aït Salem2 Spain. 1 Université de Boumerdès, Département Gisement, 2 Dept. Geología, Universidad de Jaén, Campus Las Boumerdès, 35000, Algeria Lagunillas, 23071 Spain, 2 Sonatrach/CRD , avenue du 1er Novembre, Boumerdès, 35000, Algeria The Prebetic Zone of the Betic Cordillera (southern Spain) represents part of the epicontinental shelf system developed in Lower paleozoïc clastic sequences of the Eastern algerian the South Iberian palaeomargin during the Mesozoic. Analyses Sahara and adjoining regions, have been investigated mainly of abiotics (mainly lithofacies) and biotics (foraminifera and since1950’s in conjonction with hydrocarbon exploration. macroinvertebrates fossil assemblages), together with

The First MAPG International Convention, Conference & Exhibition 147 Marrakech Convention Center, October 28 - 31, 2007 taphonomic observations, were performed to evaluate geodynamic evolution of this region indicates a change from a palaeoecologic and depositional conditions throughout the compressive to a transpressive tectonic regime. Three Middle Oxfordian to Earliest Kimmeridgian p.p. (Transversarium successive detachment fold generations and their relative axial to Planula Chrones) sections. Differences in the studied cleavages can be recognized. Its development is linked to the parameters are clearly determined by palaeogeography and progressive deformation of a Variscan orogenic wedge. First sea-level history. phase detachment folds (320-330 Ma) were formed in relation to a subhorizontal detachment (not outcropping). They are Comparatively distal sectors (outer shelf) were isoclinal folds in the northern domain of the SPZ, which have characterized by lower sedimentation rates (resulting in lumpy been tilted to the north. They have an associated cleavage of lithofacies), with higher proportions of ammonoids, planktic continuous type. Second phase detachment folds (310 Ma) are foraminifera, corrasion degree, microboring and encrustation. linked to the development of brittle (and brittle-ductile) regional Towards the mid-shelf, eco-sedimentary conditions resulted in thrusts, showing a ramp-flat geometry characterized by the spongiolithic limestones and marly-limestone rhythmites with presence of frontal and lateral ramps. Upright to moderately local microbial-sponge buildups. inclined horizontal folds are linked to the frontal ramps, while Increasing distance from shore during relative sea level upright to moderately plunging folds were developed near to highs accords with higher: (i) stratigraphic condensation; (ii) lateral ramps. A discrete crenulation cleavage is associated to abundance in ammonoids, planktic foraminifera and these second folds. Finally, third phase detachment folds (300 nubeculariids; and, (iii) corrosion, microboring and Ma) were generated under a sinistral transpressive regime, encrustation. These features agree with shelf retrogradation, distributed along heterogeneous deformation bands where increasing ecoespace and relatively longer exposition of shelly reclined fold trains formed. The most frequent interference remains on the sea bottom. patterns are Ramsay´s Type-1 and Type-0. First and second detachment folds are distributed along bands parallel to the Decreasing distance from shore during relative sea level main structural pattern of the region. These bands are related lows reveals opposite trends in the studied features with: (iv) to southward migration of the deformation front and to the increasing terrigenous input and decreasing stratigraphic propagation of a piggy-back thrust sequence. Third folding condensation; (v) impoverishment in ammonoids and planktic phase originated synthetic bands oblique to the main structural foraminifera; and, (vi) diminution of corrasion, microboring and pattern of the orogenic belt. encrustation. These trends accord with shelf progradation and Keywords: detachment folds, thin-skinned tectonics, transpression, sediments aggradation, reduction of ecoespace for necto- progressive deformation planktic organisms, and comparatively rapid burial of shell remains.

Key words: Paleogeography, Sea-level, Eco-sedimentary conditions, Decollement and tectonic inversion duality during tangential Upper Jurassic, Prebetic Zone (Betic Cordillera) processes initiation in the Palaeozoic Cover of South- Western Anti-Atlas and its Zemmour Extension (Morocco). Mhamed Alaeddine Belfoul1, Farid Faik1, et Mohamed GS 19 : Phanero- and Palaeozoic Evolution of the Bouabdelli2. NW African, West European and NE American belts 1 GESCAT laboratory (Laboratoire de Géologie Structurale et de Cartographie Thématique) Department of Geology, Faculty 4-D evolution of detachment folds in the South Portuguese of Science, Ibn Zohr University, Po Box: 8106, Agadir 80000, Zone (SW Iberia) linked to thin-skinned tectonics Morocco. Elena Mª Mantero1, Encarnación García-Navarro1, Francisco 2 “GEODE : Terre et Patrimoine” Sarl, BP 7004 Sidi Abbad - M. Alonso-Chaves1 and Antonio Azor2 40014 –Marrakech, Morocco. 1 Departamento de Geodinámica y Paleontología, Universidad Detailed analysis of the Hercynian deformation in the south- de Huelva, Campus Universitario “El Carmen”, 21007 Huelva, western part of the Anti-Atlas leads to highlight three sub- Spain meridian juxtaposed structural zones of different tectonic styles 2 Departamento de Geodinámica, Universidad de Granada, associated with a deformation gradient that decreases towards Campus Fuentenueva, 18071, Granada, Spain the east: The South Portuguese Zone (SPZ) is a fold–and-thrust belt - allochthonous domain : the most western region, related to thin-skinned tectonics. South-vergent structures are involving Atlantic offshore, where tangential tectonics prevail, widespread in the region. Thrusts are rooted to the north at with overthrust folds dipping eastwards as imbricate slices, different detachment levels in the upper crust. These developed during major ante-phase D1 episode and detachments are coeval to the development of several overprinted by clear tectonic succession of D2 and later D3 cleavages in a progressive deformation context. The deformation. Palaeozoic cover is disconnected from its base

148 by reduced tectonic inversion in a typical thin-skinned in the mixed carbonate-siliciclastic Koudiat es-Senn deformation style. Formation, which forms a single shallowing-upward cycle - Parautochthonous domain: where cover decollement completing the basin fill. Surrounding carbonate facies results from tangential slides without total tectonic inversion of indicates initiation of reef growth between storm wave base base block. Toward the Precambrian inliers border, the and fair weather wave base. The reefs always consist of a rigid, Palaeozoic cover behaved in dextral strike-slip movements and self-supporting sponge-microbe framework. During shallowing rare vertical movements that correspond to a mixed tectonic biodiversity increased, reef fabrics diversified, and bedded model which links thin-skin and thick-skin deformation styles. flank facies developed. Especially bryozoans and rugose corals - Autochthonous domain: the most eastern area, inversion became important. Reef formation ceased with deposition of tectonics control the deformation distribution into thick-skin cross-bedded crinoidal and oncolitic grainstones/rudstones, style, recording a reduction in tangential mode as well as a lack which contain undifferentiated Girvanella patch reefs. At the of D1 and D3. northern flanc of the synclinorium, a single coral patch reef is recorded within oolitic shoal deposits from the upper part of a The reactivation of successive tectonics states suggests a second shallowing-upward cycle of the Koudiat es-Senn continuum of deformation where Hercynian structures are Formation, not developed in the south. developed by tensor fluctuations between WNW and WSW directions remaining sub-horizontal; although the possibility of Aretz et al (2007): Les bioconstructions du Viséen a Caledonian event associated with the early episode of D1 is supérieur (Carbonifère) du Bassin de Jerada (Maroc oriental). – still likely. 21ème Réunion Science d la Terre, Dijon 2006: 227.

The south-western Anti-Atlas and the linkage of Zemmour- Huck, S. et al. (2006): Facies and depositional setting of Mississippian Ouled Dhlim presents clear affinities with the Mauritanides and (Late Viséan) microbial mounds in the Jerada massif, NE Morocco. – together these comprise a completely external tectonic Kölner Forum Geol. Paläont., 15, 43-44. foreland for this and the Appalachian Mountain chains. Keywords : Morocco – Carboniferous – microbial reefs

The Palaeozoic kinematics and geodynamic imply the possibility of an expulsion toward north of all the NW edge of An example of calc-alkaline, orogenic-type volcanism the craton by a dextral transpressive movement subsequent to emplaced in a rift setting (Cambrian Oued Rhebar horst, a relative anti-clockwise rotation of the whole Gondwana. Western Meseta, Morocco) Hassan El Hadi1, Abdelfatah Tahiri2, Fernando Simancas3, Key words: Hercynian, Thin-skin tectonic, tectonic inversion, Anti- Francisco Gonzalez Lodeiro3, Antonio Azor3, David Martinez Atlas, Zemmour-Ouled Dhlim, Morocco, Gondwana. Poyatos3 1 Faculté des Sciences Ben Msik-Sidi Othmane, Casablanca, Microbial reefs from the late Viséan of the Jerada Maroc synclinorium (NE Morocco) 2 Institut scientifique, BP 703 Rabat-Agdal Maroc 3 Faculté des Sciences, Granada, Espagne Markus Aretz, Hans-Georg Herbig and Stefan Huck Universität zu Köln, Institut für Geologie und Mineralogie, In the northwestern part of the Hercynian Moroccan Zülpicher Str. 49a, 50674 Köln, Germany; Meseta, the Oued Rhebar volcanic complex is interbedded within the middle Cambrian (“Acadian”) Schistes à Paradoxides In spite of the general late Viséan transgression in series. The volcanic series includes andesites, tarchyandesites Morocco, which introduced widespread platform carbonates, and coarse pyroclastic materials. bioconstructions from that time slice are rarely reported. A notable exception are spectacular late Viséan reefs in the basin New major, trace and rare earth element analyses make it fill succession of the Jerada Synclinorium, NE Morocco (Huck possible better to characterize the magmatic affinity, nature et al. 2006, Aretz et al. 2007). They share similarities in respect and origin of the Oued Rhebar magma. Chemical analyses of to framework facies, sizes, and depositional environment with the studied rocks were carried out at the Granada University bioconstructions from Algeria, Britain, France, and Eastern (Spain). Australia. Three distinctive reef intervals are differentiated along the southern flanc of the synclinorium. The oldest reefs Extrusive rocks display a microlitic and porphyritic texture are olistolites within the Oued el Koriche Formation, which and include a mineral paragenesis made up of plagioclase, represents toe of slope facies. They might attain sizes of sanidine, quartz, brown amphibole, biotite, clinopyroxene several thousands of cubic meters. Reef framework is relics, iron oxides, chlorite and calcite. The matrix mainly constructed by siliceous sponges, microbialites, and contains plagioclase and opaque minerals. Accessory minerals subordinate bryozoans. Complex cavity systems are are apatite and zircon. widespread. Reefs of the same fabrics occur in situ up-section

The First MAPG International Convention, Conference & Exhibition 149 Marrakech Convention Center, October 28 - 31, 2007 Compatible elements contents are weak; Ni<27ppm, V with those in Morocco (Figure. Although two of these zones varying between 157 and 70ppm, Cr<50ppm, reflecting a mimic the I-type and S-type subduction paired belts, the rather evolved character. The values of the alumina, varying intrusion of the granitoids was mostly late-collisional. Calc- between 16 and 19% are although higher and similar to those alkaline, metaluminous (I-type) potassic granitoids of the from calc-alkaline rocks. southern zone may reflect a source of enriched mantle (such an enrichment taking place during Devonian Variscan Rocks are also characterized by high contents in Y (9- subduction or latest Precambrian subduction) and different 35ppm), Zr (80-170ppm) and in Th (2-3ppm). The low Hf/Th degrees of crustal contamination. Considerable volumes of (<3) ratios are the same than those from volcanic arc calc- peraluminous S-type granites in the central magmatic zone alkaline basalts. This can be also demonstrated in the Ti/100- reflect a widespread melting of fertile levels in the crust. The Zr-Y.3 diagram. The Th/U and Th/Ta ratios (>1) are closer to third magmatic zone is characterized by the precocity (Middle rocks originated in an orogenic context. Devonian to Early Carboniferous) of its magmatism with All the analysed rocks samples display fractionated light respect to the two other zones and the abundance of basic REE and flat heavy REE (4,95

In a primitive mantle-normalized plot, all the volcanic samples exhibit similar patterns. They are parallel and States of stresses in the Moroccan Permian Mesetian basins fractionated (LILE/HFSE>10 ratio) and display Nb, Ta and Zr Saidi1 Amal, Tahiri2 Abdelfatah, Ait Brahim3 Lahcen relative depletions typical of calc-alkaline orogenic and/or 1 Institut scientifique, Département de Télédétection, Rabat. metasomatized mantle magmas. These anomalies and the 2 Institut scientifique, Département de géologie, Rabat. high Ba/Nb ratios (>30) are similar to those from orogenic 3 Faculté des Sciences, Département de géologie, Rabat. andesites In the Moroccan permian mesetian basins, the deposits .The La/Nb ratios are relatively high (5.2), suggesting a recorded an important britle deformation materialized by lithospheric mantle origin. The La/Ta ratios, higher than 26, and breachified faults, fault planes striated and breaks. Various the negative Nb anomaly indicate a lithospheric source microtectonic measurements enabled us to highlight various contaminated by the continental crust. In conclusion, the Permian and post-Permian compressive and extensive middle Cambrian calc-alkaline Oued Rhebar volcanic complex tectonic phases in the evolution of this basins (Saidi, 2005). is comparable to rocks generated in a mesetian mid-cambrian - Compressive-transtensif episode with s1 NNE-SSW to rift and inherited the orogenic signature from the partial melting NE-SW trending and s2 NNW-SSE to NW SE (Permian I) of a previously metasomatized mantle. responsible of the opening basins along the E-W accidents Key words: calc-alkaline volcanism, Middle Cambrian, Oued Rhebar, (bordering) us a senestral strike sleep associated with normal Western Meseta, Morocco faults, some of them present synsedimentary characters. - Compression oriented E-W to ENE-WSW (Permian II) Comparative review of the Variscan granitoids of Morocco responsible for NE-SW dextral and N110-135 senestral strike and Iberia: proposal of a broad zonation slip associated with sub N0 inverse faults. Hassan EL Hadi1*, J.Fernando Simancas2, Abdelfatah Tahiri3, - Compression NNW-SSE to NS responsible for dextral Francisco González-Lodeiro2, Antonio Azor2, David Martínez- NW-SE strike sleep and NE-SW senestral accidents. This Poyatos2 episode is responsible also for the E-W opposite faults. 1 Department of Geology, Sciences Faculty, Ben Msik-Sidi - An bidirectional extensive episode NW-SE to NE-SW Othmane, Casablanca, (Triassic-Lias), with s3 NW-SE trending associated with normal 2 Departamento de Geodinámica, Universidad de Granada, faults and s3 NE-SW responsible of N110 to N140 normal Granada, Spain faults us a permutation between s2 and s 3. 3 Departement of Geology, Institut Scientifique, BP 703 Rabat- Key wordssins, states stress Agdal Morocco

Remarkable differences stand out between the Western Moroccan Meseta (peraluminous granites) and the Eastern Moroccan Meseta (potassic to shoshonitic, calc-alkaline granitoids). In Iberia, the Variscan magmatism can be arranged into distinctive zones too (Figure), which have been compared

150 Geological map of the Moroccan Central Massif; a structural continental subduction of the African plate under the Moroccan interpretation of the Hercynian Belt Meseta. Our field observations and analyses of SPOT, Landsat-MSS, and DEM (digital elevation model) imagery have Driss Fadli1; Mohamed Bouabdelli3; Yves Cailleux4; Ahmed El permitted mapping of faults, joints, and volcanic edifices. The Hassani2; Mohamed El Wartiti1; Christian Hoepffner1; Fatima elongate shape of volcanoes and linear clusters of adjacent Kharbouch1; Abdelfattah Tahiri2 and Mohamed Zahraoui1. edifices, together with their relationships with faults, show that 1 Faculty of Sciences, Mohammed V Agdal University, Rabat magma ascent was favored by tectonic crustal scale open Morocco fractures, essentially tension fractures, tail-cracks, and open 2 Scientific Institute, Mohammed V Agdal University, Rabat, faults. These fractures, together with other nonvolcanic, Morocco narrow, NNE-striking troughs, provide valuable information on 3 Geode Society, Marrakech, Morocco the regional deformation since the Late Miocene. The 4 Louis Pasteur University, Strasbourg, France shortening–extension type strain, which is responsible for the open fractures, is situated near the Azdem transform, a zone The geological map presented is a compilation and a of active faults striking NNE, parallel to the convergence trend. synthesis of the work carried out on this area since the The transform links two segments of the “Accident Sud- beginning of the Eighties. The choice of the scale of the 1/200 Atlasique,” which constitute the border between the Moroccan 000 permit to obtain a convenient to handle and sufficiently Meseta and the African plate. The magma seems to originate detailed document. The Moroccan Central Massif or Central from the lithospheric mantle, but asthenospheric material had Hercynian Massif, located in the Western Meseta, is limited to previously migrated upward along the Panafrican suture zone. the West by the Atlantic Ocean, to the North by the plain of the This mixed magma finally was transferred to the surface as a Gharb, to the South by the Phosphates Plateau and to the East result of the onset of the open fractures prior to fault motions. by the mesozoïc terranes of the Middle Atlas. It is the greatest The Siroua volcanic activity results from the conjunction of (1) area of paleozoic outcrops which allows to observe, on more a Panafrican suture zone and (2) a zone of open fractures due than 200 km, a quasi continuous section through the hercynian to “strike-slip” strain near a local transform inside the area of belt of Morocco. A simplified legend allows to distinguish collision. several structural units which were brought closer during the hercynian orogenesis. They are limited by great fault or shear zones. From the West to the East, we can distinguish: the Use of Spatial Remote Sensing and MNT for the fracturing Sehoul Block (“caledonian terranes”); the Rabat-Tiflet Fault analysis in the Al Hoceima (Relationship with the distribution Zone (complicated zone with Ordovician to Visean terranes); of the landslides) Rif, Morocco the Coastal Block (Cambrian to Devonian); the Western L. Ait Brahim. C. Nakhcha and Abdellah Abdelouafi Meseta Shear Zone; the Khatouat Sidi-Bettache Tiliouine units Université Mohammed V, Faculté des Sciences de Rabat, (Late Devonian to Carboniferous basins); the Tsili-Tafoudeit Equipe de recherche Risques géologiques télédétection et thrust zone; the Khouribga-Oulmès unit (early Ordovician to Environnement, avenue Ibn Battouta Rabat – Agdal, B.P. 1014, Devonian antiformal structure); the Smaala-Oulmès El Rabat, Maroc ; GSM +212 61 297031; télécopie : +212 37 Hammam Fault Zone; the Fourhal-Telt unit (Carboniferous 77 19 57 ; basin); the Azrou Khénifra Zone (a complicated zone with a neoproterozoic to lower paleozoic basement, a carboniferous The Al Hoceima area in eastern Rif is located on the and permian cover and many allochtonous units). Moroccan Mediterranean edge. Its an area where the very Keywords: geological map, hercynian belt, Meseta, Morocco. broken and karstic character of the calcareous dorsal often associated with a reduced field of view because of the greenness cover, constituted a major handicap to follow the GS 27 : Remote Sensing and GIS applied to layout of the faults. By using satellite images (HRV XS of SPOT, Geosciences RADAR SAR of ERS-1) and aerial photographs accompanied by a control in site, we carried out a structural map of the Tectonics and volcanic edifices in a collisional zone of the Northern Rif internal domain. We have find out four principal neogenic massif of Siroua (Moroccan Atlas) - Combined directions of faults: N-S, NE-SW, NW-SE and E-W. This effects of a local transform and the Panafrican suture zone fracturing which guides on the surface the majority of the Emran Anas1 and Chorowicz Jean2 hydrographical network, shows also a relationship with the 1 Institut Scientifique, Dép. Télédétection UM5A B.P. 703 distribution of landslides. These latter are developed along NE- Rabat-Agdal Maroc SW, NW-SE and E-W faults . Or, especially at tectonic nodes 2 Université Paris 6, case 129, 4 Place Jussieu 75252 Paris which correspond to various crossings combinations of these cedex 05, France accidents. The relationship fracturing – landslides underlined and the maps carried out allow to direct the choice of the new The Late Miocene – Early Pliocene Siroua strato-volcano is pattern roads, as well as sites of urbanization in this part of the made of particular hyperalkaline rocks. It lies between the Al Hoceima. This fracturing associated with the slope, the High-Atlas and the Anti-Atlas, in a collisional zone related to the lithology, the geotechnical quality of certain grounds, and the

The First MAPG International Convention, Conference & Exhibition 151 Marrakech Convention Center, October 28 - 31, 2007 anthropic action correspond to the predisposing factors of the structure characterized by significant lithological differences, landslides. Whereas, the water, the erosion, the tectonic severe fracturing, and thrust sheets where tectonic contacts activity and the seismicity constitute the starting factors of the play a major role in groundwater circulation. This may landslides. subsequently involve the entire slope. Possible scenarios have been imagined and mapped as a GIS which, in spite of its Key words : SPOT XS, ERS-1 SAR, Fracturing, landslides, Al obvious limits, could constitute a preliminary step towards a Hoceima , Morocco decision support system.

In order to draw up a chart of the landslides hazard in the Using spatial remote sensing and DEM to map the landslides Central Rif, The use of satellite images and cartographic hazard in the tangier peninsula (northern morocco) documents, enabled us to follow and to quantify the alterations Faïçal Sossey Alaoui, Lahcen Ait Brahim, Abdellah Abdelouafi, that affected the semi-mountainous area of El-hoceima and to Tachfine ouchani and Ali Chaouni Ali define, in hierarchic order, their potential risk. For that we had Université Mohammed V, Faculté des Sciences de Rabat, Equipe de recherche Risques géologiques télédétection et recourse to a DEM of the area like to optical data satellite and Environnement, avenue Ibn Battouta Rabat – Agdal, B.P. 1014, radar to which one applied a series of spectral and space Rabat, Maroc ; GSM +212 61 297031; télécopie : +212 37 raisings in addition to one multispectral classification from 77 19 57 ; which we could establish a chart of the occupation of the ground. The Tangier peninsula is subject each year of a significant number of landslides due to its geological, morphological and The cartography of the principal limits of the lithological climatic complexity. The landslides occurrence increased by formations, realized starting from the photo-interpretation of the starting of the management plan of the northern Morocco. the images resulting from the improvements spectral. Thus, a This phenomenon is caused by the changes in the slopes model of spatial and temporal variations in the factor of safety during the construction of an important network of roads, is proposed. highways and railways. The combined use of ERS-1 SAR and LANDSAT TM data, aerial photographs, associated to Keywords: Landslide, Hazard, GIS analysis, Central Rif, geological data of the area (maps and ground truth), allowed to carry out maps of lithology, land cover and fault networks. Geology, DEM, rainfall and seismicity in association with the Building of a real 3-D geologic map from analysis of previous results allowed to map the landslides hazard. The Reference 3D data in the Ain Sefra area (western Saharian accuracy of the results was tested by the overlapping of the Atlas mountains) 1451 inventoried landslides. The principal results show that: 15 % of the landslides are in areas of high landslide hazard, 55 Damien Dhont1, Pascal Luxey2, Jean-Paul Xavier1, Jean- % are in areas of intermediate landslide hazard and only 30 % François Gouyet3, Emmanuel Pajot1 and Yves Hervouët1 are in areas of low landslide hazard. The landslide hazard map 1 CNRS- UMR 5212: Modélisation et Imagerie en Géosciences can be used in management plan of the Tangier peninsula. - Pau, CURS-IPRA, Université de Pau et des Pays de l’Adour, avenue de l’Université, 64013 Pau cedex, France. Key words: ERS-1 SAR, LANDSAT TM, aerial photographs, 2 Dynamic Graphics Inc., 1015 Atlantic Avenue, Alameda, CA landslides, hazard, Rif, Morocco 94501-1154, USA. 3 SPOT IMAGE, 5 rue des Satellites, BP 14 359, F-31030 Contribution of gis and remote sensing in assessing Of Toulouse Cedex, France landslides hazard: A case study from Northern Area of the We present an innovative method to produce a three- Central Rif, Morocco dimensional geological map consisting of the volume and A. Zenasni1, L. Asebriy1, H. Rahali2. shape of all geological features in the Ain Sefra area located in 1 Département du Physique du Globe, Institut Scientifique, B. P 703, Université Mohammed V Rabat. the Western Saharian Atlas Mountains. This approach is 2 Dép. de Géomorphologie et de Cartographie, Institut pioneer in that it is based on surface information only coming Scientifique, B. P 703, Université Mohammed V Agdal, Rabat from the Reference3D product consisting of a SPOT5 Digital Elevation Model and a SPOT5 HRS ortho-image, which allow The landslides constitute a major concern as regards a remarkable accuracy for geologic mapping. In a first step, we installation management of the territory. performed a tele-analysis of the SPOT5 image draped over the In the northern area of the Central Rif, they are not only DEM in order to present an updated geological map of the related on the occurrences of rains and faults generated by the area. Due to its perfect matching between elevation data and last earthquake, but it’s a multidisciplinary approach that surface information combined with its superior accuracy combines geomorphology, geology, hydrogeology, and without GCPs (planimetric accuracy of 15 m at 90%, elevation geotechnics in order to understand how such slope failures are accuracy of 10 m at 90%), such analysis can be performed generated, especially in a region with a heterogeneous prior to any field survey, with results fully compatible with GPS

152 measurements. In a second step, we used the EarthVision 3- Session: The tectonics of vertical movements, D modeller to generate surfaces from each digitized geological mountain building and subsidence, Morocco contour (limits between layers, faults) and to intersect these surfaces following geological rules in order to generate layer Geological evidence for the timing of long-wavelength volumes. The 3-D map makes the geometry of the studied surface uplift of the Atlas mountains of Morocco area understandable at first glance, even by non specialists, J. Babault1, A. Teixell1, M.-L. Arboleya1, M. Charroud2 and B. the relationships between layers and faults being self Charai2 explanatory. The interest the geometrically correct 3-D 1 Departament de Geologia, Universitat Autònoma de geological map is of primarily importance for institutions and Barcelona, 08193-Bellaterra, Spain people managing underground resources like water, oil, or 2 Département de Géologie, Faculté des Sciences et mineral resources. From surface information only such 3-D Techniques Fès-Saïss, Université Sidi Mohammed Ben map predicts where geological structures should be found at Abdellah, Fes, Morocco depth, and it therefore allows the characterization and visualisation of potential oil reservoirs in the area of study. The timing of the rise of mountains is important to understand the relationship between tectonics and erosion. It Key words : 3D, modelling, Atlas, Oil reserves is also critical to determine the degree to which various mechanisms -thickening of the crust, thinning of the mantle The use of GIS and remote sensing for spatialization of water lithosphere- contribute to the elevation. One of the main difficulties in establishing uplift histories lies particularly in EROSION: Application to the Rheraya catchment (High Atlas, defining paleoaltitudes. This is the reason why the occurrence Morocco). of elevated marine sediments, deformed paleohorizontal Aouatif Cheggour1 and Vincent Simonneaux 2 markers or particular drainage patterns can provide powerful 1 Salle 26 Centre Geber, Faculté des Sciences Semlalia, geological tools to unravelling the poorly known uplift history of Université Cadi Ayyad, Marrakech, Maroc. mountainous regions such as the Atlas of Morocco. Tel/Fax: 212 24 43 16 26. 2 IRD-CESBIO, 18 Av. Edouard Belin, 31401 Toulouse Cedex Three observations yield evidence for the history of surface 9, France. uplift in the Atlas domain. First, late Miocene (Messinian: 5.3- 7.1 Ma) undeformed marine sediments outcrop in the Skoura The land management against water erosion requires long area of the Middle Atlas at an elevation of 1100 m. Second, and expensive studies, but specific measurements, even if they early Pliocene lake deposits in the Saharan region south of the are very precise, cannot lead to the synoptic vision which the High Atlas (Hamada du Guir) are tilted to the south over 250 scientists and the managers need. The complexity of this km, implying ca. 700 m of relative uplift of the High Atlas phenomenon and the extent of the study area require the use piedmont since then. Third, the rivers draining from the of methods and powerful means for the geographical northern slopes of the Middle Atlas flow N to NE to cross the information management. In this context, this work aims at Rifian front and enter the Pre-Rif thrust belt. This pattern mapping the risks of water erosion in the Rheraya catchments indicates a northward tilt of the surface that dominated over (228 km2), through the spatialization of some measurements the topographic building of Rif wedge, and its timing is achieved on erosion plots (140 m?) using a Geographical constrained by Pliocene-age lacustrine limestones of the Saiss Information System (GIS). This extrapolation is based on a basin incised by the rivers. stratification of the basin in physical units characterized by the combination of the type of soil, the vegetation and ground These lines of evidence point to a recent, long-wavelength surface features. This stratification is obtained through the use surface uplift of the Atlas domain in post-Miocene times. The of visual interpretation of satellite SPOT 4 image (20 m scarce compressional deformation of the mentioned resolution) and a geological map within a GIS. The results of sedimentary formations and the wavelength of the doming the erosion plots installed on the main soils of the Rheraya indicate a mantle origin for the uplift. A mantle component of catchments are extrapolated for all the polygons of the same uplift for the Atlas mountains and plateaux has yet been put class for the entire basin providing a map of erosion forward by several authors, but its chronology remained assessment. These results are validated by measurements of uncertain. Our observations indicate that the current mean the suspended matter carried out at the outlet of Rheraya elevation of the system is young in comparison with the catchments. Cenozoic crustal thickening that built the High and Middle Atlas deformed belts. Key words: erosion, GIS, remote sensing data, spatialization.

The First MAPG International Convention, Conference & Exhibition 153 Marrakech Convention Center, October 28 - 31, 2007 Orogenic growth and tectonic geomorphology in the Atlas the Ras-el-Abiod leucogranite from the Rehamna massif, ca. Mountains of SW Morocco 70 km north of the Jebilet. Additionally, we consider 9 results G.M.H. Ruiz1, F. Negro1, O. Saddiqui2, R. Wieler3, S. Ivy- obtained with the same technical procedure by Sabil (1995) from the Sebt-Brikyine granite of the Rehamna. All these Ochs3, M. Burkhard, D. Frizon de Lamotte4 and J.P. Schaer1 granites emplaced during the Variscan orogeny, and both the 1 Neuchâtel, Switzerland Jebilet and Rehamna massifs belong to the West Moroccan 2 Casablanca, Morocco Arch, uplifted and eroded from 295 Ma-290 Ma to 140-125 3 ETH Zurich, Switzerland Ma. Paradoxically, these Mesetan granites yield two clearly 4 Cergy-Pontoise, France distinct groups of apparent ages, 185-200 Ma in the Jebilet versus 81-112 Ma in the Rehamna. Once excluded technical This project aims at quantifying the orogenic growth of the bias, we may assume that the observed differences in the AFT Atlas Mountains in SW Morocco. The target area is the WSW- results are linked to one or both of the only two differences ENE oriented Atlas range between 32 and 30°N of longitude. which can be noted between the studied massifs, i) the depth It is a key natural laboratory: this region is characterized by of emplacement of the granites which intrude country rocks spatially and temporarily uniform large scale plate tectonic equilibrated at 15-20 km in the Rehamna, vs 9 km in the forces – pushed by the convergence between Europe and Jebilet; ii) the importance of the Neogene subsidence and Africa. Phases of shortening, uplift and exhumation are poorly subsequent uplift (more marked in the case of the Jebilet). constrained, and there is little quantitative data available at Track length modelling allows us to conclude that the depth of present. The presence of high surface elevations in both the intrusion is the dominant factor accounting for the apparent High Atlas chain (>4000m) and Paleozoic Anti-Atlas belt AFT age discrepancies. (>2500m) to the south of the High-Atlas is subject to debate. Little is known about phases of uplift and places where the associated erosion products are accumulated. First zircon fission track analysis in Western Anti-Atlas, Morocco: evidence of early Variscan deformation of the We dedicated our effort to a North-South transect across Mauritanide foreland belt both Atlas chains by the combined use of in situ cosmogenic dating, low temperature thermochronology (Fission-Track & (U- Omar Saddiqi1, Samira Sebti1, Lahssen Baidder1, André Th)/He dating) but also a new thermometer. The choice of the Michard2 and Dominique Frizon De Lamotte2 study area is such that tectonism is regionally the single most 1 Laboratoire Géosciences, Equipe « Géodynamique et significant varying parameter as climatic conditions do not vary Thermochronologie », Faculté des Sciences, Université across the chain. Cosmogenic nuclides in present-day fluvial Hassan II Aïn Chock, BP 5366 Maârif, Casablanca, Maroc. sediments constrain (sub-) recent erosion rates whereas (U- 2 Département des Sciences de la Terre et de l’Environnement Th)/He and Fission-Track thermochronometry quantify the (CNRS, UMR 7072), Université de Cergy Pontoise, 5, mail Gay denudation of the uppermost 1-8 km, i.e. rates of medium to Lussac, Neuville/Oise 95 031 Cergy-Pontoise cedex France. long-term processes. Comparing these results to existing geological records enable us to identify and quantify the The Western Anti-Atlas fold belt corresponds to the relevant tectonic process that shape the landscape of this basement-cored, eastern foreland fold belt of the Appalachian- mountain range in the frame of the Africa-Europe convergence. Alleghanian-Variscan-Mauritanide belt. The age of deformation and uplift is still poorly constraint in Western Anti-Atlas (WAA), Keywords: Morocco, Atlas, geomorphology, orogen, because of the lack of Carboniferous deposits in the belt itself. thermochronology, cosmogenic In this work, fission track (FT) analysis was performed on zircon grains extracted from the Proterozoic granites (either Eburnian Triassic-to-Present exhumation history of Moroccan Meseta or Pan-African in age) cropping out in the Kerdous and Ifni massifs assessed by apatite thermochronology on granite inliers. We obtained 9 apparent ages spanning from 391 ± 41 samples: how to explain apparent age discrepancies Ma to 324 ± 37 Ma, with 8 dates on 9 fairly grouped between between the Jebilet and Rehamna massifs? 352 ± 26 and 324 ± 37 Ma, whatever the age of the granite Omar Saddiqi1, Fatima-Zahra El Haimer1, El Mehdi Mansour1, emplacement may be. This implies (if we do not consider the André Michard2 et Dominique Frizon De Lamotte2, isolated date) that the WAA basement has been heated above 1 Laboratoire Géosciences, Equipe « Géodynamique et Thermochronologie », Faculté des Sciences, Université 280°C (partial annealing T for zircon) before and/or during the Hassan II Aïn Chock, BP. 5366 Maârif, Casablanca, Maroc; Tournaisian (359 ± 2 - 345 ± 2 Ma), and was subsequently 2 Département des Sciences de la Terre et de l’Environnement cooled below 180°C before the Namurian (326 ± 1 – 312 ± 1). (CNRS, UMR 7072), Université de Cergy-Pontoise, 5, mail Gay We propose an interpretation of the T-t evolution of the studied Lussac, Neuville/Oise 95 031 Cergy-Pontoise cedex France. rocks, taking into account the subsidence curves published by Burkhard et al. (2006) for the WAA during the Cambrian- The Moroccan Meseta constitutes a relatively stable block Carboniferous interval. These curves allow us to assume that between the Atlas and Rif belt. We studied for apatite fission burial metamorphism alone could explain annealing of the tracks (AFT) 6 granite samples from the Jebilet, i.e. the Proterozoic zircon grains as early as the Late Devonian. southernmost massif of western Meseta, and 1 sample from Obviously, this does not preclude the role of a compressional

154 event which could have triggered the circulation of hot, Cosmogenic nuclide dating of landscape evolution in the overpressurised fluids in the tectonic prism of the WAA Ouarzazate foreland basin (Morocco) foreland belt. Erosion of the WAA mountain range is testified by M.-L. Arboleya1, J. Babault1, L.A. Owen2, A. Teixell1 and R.C. the dominantly northwestern sources for the detrital input in Finkel3 the upper Namurian Reouina Sandstones of the Tindouf Basin 1 Departament de Geologia, Universitat Autònoma de (Cavaroc et al., 1976). This constrains the slope of the WAA T- Barcelona, 08193, Bellaterra, Spain t curve around 320 Ma to dip toward low T. Additional 2 Department of Geology, University of Cincinnati, Cincinnati, constrains are given by previous Rb-Sr and K-Ar datings on OH 45221, USA recrystallized micas from the Lower Paleozoic formations close 3 Center for Accelerator Mass Spectrometry, L. Livermore to the Kerdous (370-290 Ma; Bonhomme & Hassenforder, National Laboratory, Livermore, CA 92521, USA 1985), and by K-Ar dates from the Kerdous inlier (360-310 Ma; Margoum, 2001, in Soulaimani & Piqué, 2004). We conclude The Atlas Mountains, like other intracontinental orogenic that uplift and cooling of WAA occurred throughout the Early belts, experienced moderate crustal shortening and Carboniferous, from ca. 350 Ma to 320 Ma, within a exhumation. Magnitudes of crustal shortening are defined by dominantly compressional regime. This is consistent with the cross-section restorations; however, denudation and sediment timing of the eclogite-facies metamorphism (ca. 330 Ma; Le transfer from the mountains to the forelands have not been Goff et al., 2001) and nappe emplacement in the Mauritanide previously defined. Such determinations are important to belt (ca. 310 Ma; Lécorché et al., 1991). Additional isotopic understand the dynamics of earth surface processes and and zircon FT dates are required to better constrain the WAA landscape evolution, and for defining and quantifying tectonic thermal evolution during the Variscan orogeny. and geomorphic models for intracontinental mountain belts.

References: The Ouarzazate foreland basin lies along the southern margin of the Central High Atlas. Impressive alluvial fans and Bonhomme M., Hassenforder B., Le métamorphisme hercynien dans terraces rising >100 m high present within the basin record a les formations tardi et post-panafricain de l’Anti-Atlas occidental history of sedimentation and denudation that allow rates of (Maroc). Données isotopiques Rb/Sr et K/Ar des fractions fines. Sci. denudation and sediment transfer to be determined. Using géol. Bull. Strasbourg 38 (1985) 175-183. geomorphic mapping, sedimentology and terrestrial 10Be Burkhard M., Caritg S., Helg U., Robert Ch., Charrue Ch., Soulaimani cosmogenic nuclide (TCN) dating, the history of sedimentation A., Tectonics of the Anti-Atlas of Morocco, in D. Frizon de Lamotte, O. and erosion within a stretch of the Ouarzazate basin is Saddiqi, A. Michard (Eds.), Recent Developments on the Maghreb Geodynamics. C. R. Geoscience 338 (2006) 11-24. reconstructed. The alluvial fans and terraces in this region date from the Holocene to >>250 ka. The alluvial fan and terrace Cavaroc V.V., Padgett G., Stephens D.G., Kanes W.H., Boudda A.A., Wollen I.D., Late Paleozoic of the Tindouf basin, J. Sedim. Petr. 46 incision occurred while thrust loading was still active in the High (1976) 77-88. Atlas margin. In this framework, the incision was induced Lécorché J.P., Bronner G., Dallmeyer R.D., Rocci G., Roussel J., The primarily by a drop in base level as the outlet channel, the Draa Mauritanide Orogen an dits northern extensions (Western Sahara and River, progressively cut through the Anti-Atlas mountains to the Zemmour), West Africa, in R.D. Dallmeyer & J.P. Lécorché (eds.), The south of the Ouarzazate basin. West African Orogen and Circum-Atlantic correlatives, Springer Verl., 1991, 187-227. The alluvial fan and terrace sediments have abandonment Le Goff E., Guerrot C., Maurin G., Iohan V., Tegyey M., Ben Zarga M., ages that date to at least the past four interglacials (marine Découvertes d’éclogites hercyniennes dans la chaîne septentrionales isotopes stages 9c, 7e, 5e and 1). The geomorphic analysis des Mauritanides (Afrique de l’Ouest), C. R. Acad. Sci. Paris 333 and TCN surface exposure ages show that alluvial fan and (2001) 711-718. terrace formation was strongly modulated by climate change Soulaimani A., Piqué A., The Tasrirt structure (Kerdous inlier, Western on glacial-interglacial timescales as the base level dropped. Anti-Atlas, Morocco): a late Pan-African transtensive dome J. Afr. Earth Incision occurred during interglacial times when the region was Sci., 39 (2004) 247-255. wetter and streams more pervasive, albeit still ephemeral, while during the more arid glacial times the sedimentation dominated as sediments were deposited in a flash flood regime and the rivers were less effective transportation agents. The data demonstrate a climatic control on sediment transfer and landscape denudation in this region during the Quaternary. Furthermore, they show that mean rates of fluvial incision range between 0.3 to 1.0 mm/a for the later part of the Quaternary.

The First MAPG International Convention, Conference & Exhibition 155 Marrakech Convention Center, October 28 - 31, 2007 Tectonic and metamorphic evolution of the Temsamane these mountains. Generally, main rivers in mountain belts flow units, External Rif, Northern Morocco. Implications for the perpendicular to the chain following the regional slope. In evolution of the Rif and the Betic-Rif arc contrast, the drainage pattern in the High Atlas is dominated F. Negro1,2, P. Agard3, B. Goffé2 and O. Saddiqi 4 by longitudinal rivers (parallel to the strike, following the main 1 Institut de Géologie, Université de Neuchâtel, Switzerland structures, folds and thrusts). 2 Laboratoire de Géologie, Ecole Normale Supérieure, Paris, The aim of this work is to study the influence on drainage France pattern of a lithospheric mantle thinning beneath a 3 Laboratoire de Tectonique, Université Paris VI, France compressional mountain belt characterized by a small 4 Département de Géologie, Université Hassan, Casablanca, shortening rate. We use geodynamical and kinematical Morocco numerical models where deep and surface processes are Located at an intermediate position in the External Rif coupled. The model links conservation laws of moment, mass nappe pile, the Temsamane units (northern Morocco) present and energy at lithospheric scale with constitutive equations of an abnormally intense metamorphism and a penetrative ductile rocks (rheology) and assumed boundary conditions of the deformation. We present new metamorphic data showing that, velocity field. Erosion and fluvial transport of sediments and in spite of their external position in the Rif, part of the flexural isostasy are calculated coupled with the lithosphere Temsamane underwent medium-pressure low-temperature deformation. We investigate numerically the role of two (MP-LT) conditions (c.a 7-9 kbar; 330-430°C), possibly during mechanisms on the resulting drainage evolution (1) the strain the Oligocene. Structural data show that the exhumation of rate of tectonic shortening, and (2) the timing and geometry of these units, during Middle to Late Miocene times, was a mantle source uplift, asthenospheric plume or lithosphere characterized by an intense ~E-W stretching and by top-to- root removal. These models show that drainage pattern the-west shear senses. We discuss two possible origins for the reorganization occurs after a rapid uplift due to the lithosphere MP-LT Temsamane units: (1) an internal origin related to the thinning. subduction and the HP-LT event recorded in the Internal Rif (Alboran Domain) or (2) an external origin, implying a second Quaternary neotectonic elevation of the Sais basin between subduction system within the External Rif, parallel and almost the Rifian and Atlasic belts (Morocco): sedimentary contemporaneous with that of the Alboran Domain. The dynamics and geomorphologic impact tectonic and metamorphic evolution of the Temsamane is set M. Charroud1, B. Cherai1, J. Babault2 and M. Benabdelhadi back within the External Rif tectonic time frame and compared M1 with the Alboran Domain units of the internal Rif. At a larger 1. Département de Géologie, Faculté des Sciences et scale, we show that the exhumation history of the Temsamane, Techniques Fès-Saïss, Université Sidi Mohammed Ben which strongly resembles the one documented in the Sierra Abdellah, Fes, Morocco Nevada in the Betics, is compatible with the westward slab 2. Departament de Geologia, Universitat Autònoma de retreat occurring during the Middle to Late Miocene in the Barcelona, 08193 Bellaterra, Spain Betic-Rif region. The Sais basin is located between the Rifian and Middle Keywords : Alboran, metamorphism, Rif, Temsamane Atlas mountain chains; its Plio-quatrenary evolution can be sumarized as follows: Session: The tectonics of vertical movements, mountain building and subsidence, Morocco Upper Pliocene: The Sais, then filled, formed a continental lacustrine basin alimented by the Sebou paleoriver. We define the discharge system of PaleoSebou in the Eastern part of the Numerical modelling of intracontinental mountain building basin at Fez. and drainage evolution in the Atlas Ivone Jimenez-Munt1, Daniel Garcia-Castellanos1, Julien Quaternary: The creation of belts is made by the progress Babault2, Antonio Teixell2 and Maria-Luisa Arboleya2 of prerifian ramp which overthrust Pliocene deposits of the 1. Institute of Earth Sciences ‘Jaume Almera’ CSIC, Lluis Sole northern edge of Sais. i Sabaris s/n, 08028 Barcelona. Spain 2. Departament de Geologia, Universitat Autònoma de The Prerifian ridges migrate toward the south by means of Barcelona, 08193 Bellaterra, Spain the Zalagh, Sebou and Sidi Hrazem ramps. The “South Rifian Front” towards the south in the plain reorganized a change of The Atlas Mountains are part of an intraplate alpine orogen course of the Sebou paleoRiver. This deformation translates N- characterized by a very small strain rate and tectonic S to NNW-SSE compresional strain and allows reactivation of shortening (< 30 km in 40 m.y.). Because the slight crustal the preexistent Miocene basin structures. thickening cannot explain the observed topography, a remarkable lithospheric thinning has been proposed below

156 A change in the evolution of Sais results also from major New High-Resolution seismic data through the Rharb neotectonic reactivation of the flexures of the northern middle Atlas. continental shelf (North-Western Morocco) : Characterization of the recent evolution of the western limit of the Southern This new structural state allows the rise of the Sais who becomes an elevated plain related to the northern Middle Rif Corridor Atlasic catchment basin. The Sais Pliocene formations and Nissrine Maad1, Pascal Le Roy2, Mohamed Sahabi3, their Miocene substrate are subject to intense erosion whith Mohamed Dakki4, Mohamed Hssain5, Marc André Gutscher6, incisions exceeding 100m. Nadia M’Hammdi7, Khaled Mehdi8, Karim El Archi9 and Bendehhou Zourarah10 Currently, the Sais plain corresponds to the median part of 1, 2, 6. UMR Domaines Océaniques, IUEM, Place Nicolas the Sebou catchment basin located between the Middle Atlas Copernic, 29280 Plouzané, France upstream and Prerif downstream. 3, 8, 9, 10. Laboratoire Géosciences Marines, Département des Sciences de la Terre, Faculté des Sciences d’El Jadida, 24 Jurassic basins of Agadir-Essaouira: Post-rift evolution of an 000 El Jadida, Morocco atypical passive atlantic margin (Atlantic Atlas, Morocco) 4, 5. ONHYM, Rabat Agdal, Morocco Mostafa Amrhar 7. Institut Scientifique, Av. Ibn Batouta, BP 703, 10106, Rabat Laboratoire GEOHYD, Département de Géologie, Faculté des Agdal, Morocco Sciences, BP. 2390, Université Cadi Ayad, Marrakec The recent high-resolution seismic survey Protit2, carried The coastal basins of west Morrocan Atlantic passive out during summer 2003 and conducted by the University of margin, between Agadir and Essaouira are located on the Brest in France and the Faculté des Sciences d’El Jadida in western part of the Moroccan High Atlas. The post-rift Morocco recorded 900 km of seismic lines through the Rharb evolution of this Atlantic margin part is atypical, it is continental shelf. The integration of new data with industrial characterized at the same time by thermal subsidence, seismic lines, bathymetry (Vanney, 1982 ; Gutscher, Delila tectonic and halocinetic activities. cruise report 2004) and field observations collected along the coastline allows us to identify the formation and the recent The Bajocian - Bathonian red beds of the Amskroud evolution of the western termination of the Southern Rif formation are affected by NNE-SSW to NE-SW normal faults. Corridor. This coastal basin corresponds to the foredeep basin At the top of this succession, basic lavas and doleritic sills, linked to the Rif Cordillera and extends southwards through the dated from 156 + 7 My and with transitional affinity, were northern Moroccan Meseta that defines the forleand region of installed in an intraplate geodynamic context. A phase of the Western Rif. Seismic stratigraphy analysis clarifies the main hydrothermal alteration marks also this period; it is of propylitic steps in the postnappe evolution of the offshore Rharb basin type in the Agadir atlasic basin and phyllitic in the microdiorites during Neogene times.The Tortonian/Lower Pliocene step of the Massif Ancien. These tectonic and magmatic activities corresponds to the foredeep stage induced by loading of the are sealed by oolitic limestones of the Ouanamane formation Rif thrust sheets. Results show evidence of flexural extension whose base is of later Bathonian age. of the Adjacent Rif foreland during these stage. It consists of reactivation of Hercynian N150°E trending faults corresponding From the Callovian - Oxfordian until the top of the lower to the offshore extension of the Cherrat Horst. The basin Kimmeridgian, the carbonate platform evolution is controlled at records a new uplift of its southern margin during Upper the same time by the thermal subsidence of the Atlantic margin Pliocene and Pleistocene times. Seismic profiles display the and by the movement of the atlasic transverse faults. This new segmentation of the continental self controlled by the clear structuring, within a ENE-WSW to E-W transforming zone, individualisation of the present-day topographic front of the individualized the Agadir, Essaouira and Haha coastal basins. Prerifaine Nappe. Tectonics remains active until Upper These basins are structured by NE-SW, ENE-WSW, E-W and Pleistocene as shown by faulting of the coastal deposits. This ESE-WNW anticlinal ridges, which delimit depressions with the segmentation constrains the distribution of the Sebou deposits same orientation. This structural architecture of losangic form, through the continental shelf. Preliminary results show that controlled by parallel and transverse faults with the Atlantic deformation occurs from Tortonian to Quaternary times and margin, caused in the margin a preatlasic structuring, and was controls the evolution of Rharb foreland basin system. preserved during the cretaceous basins evolution with a first positive inversion at Maastrichtian times. The structural evolution of the Agadir-Essaouira coastal basins is characterized by an interference of atlasic structures in a passive margin geodynamic context.

Key words: Jurassic basins, post-rift, passive margin, thermal subsidence,magmatism, atlasic orogenesis.

The First MAPG International Convention, Conference & Exhibition 157 Marrakech Convention Center, October 28 - 31, 2007 Petroleum systems modelling in Algeria and its implications (Tlalett or Ghomrassen Members), the M’rabtine Formation in terms of lithospheric speculation and vertical movements ranging from the Latest Callovian to the Tithonian in age, was Christian Nino, Rod Graham and Dean Griffin abruptly capped by prograding fluvio-deltaic complexes of the Hess Limited, Level 9, The Adelphi Building, 1-11 John Adam Early Cretaceous. Regional discontinuity characterizes the Street, London WC2N 6AG uppermost M’rabtine Formation is associated to important erosion in connection with a major sea level fall. Petroleum systems modelling suggests that maturation of the Silurian source rock in the part of the Oued Mya Basin to Based upon Jeffara outcrops and subsurface data such as the west of the Hassi Messaoud field took place during Upper lithological description and wireline log characteristics, Cretaceous to Paleogene time, but further south in the area integrate study using sequence stratigraphy tool and west of the Gassi, Zotti and Agreb fields it is older and geological modelling contribute to considerate the rendered the source rocks overmature before the beginning of lithostratigraphic nomenclature used until now, the stratigraphy the Mesozoic. Basin modelling suggests that there was an interpretation and sandy bodies distribution. Therefore, spatial additional influx of heat to the lithosphere in the south which and temporal distribution and geometries of oil-bearing sand has since decayed away, yet there is precious little sign of bodies (channels or sheets) and their related depositional significant rifting in the area. Like other structures in cratonic environment established within M’rabtine Formation gain Algeria, the Gassi, Zotti and Agreb fields are very subtle and precision in exploration efforts where some uncertainties gentle. They were not strongly affected either by extensional constrain the reservoir delineation. faulting, or the limited Late Cretaceous and younger inversion Sequence stratigraphy applied in southern Gulf of Gabes that post dated it. The really impressive tectonism that occurs has led to recognize several transgressive intervals picked at in cratonic Algeria is the relative elevation and depression of the max gamma ray reading and/or the occurrence of extensive areas through time. Analogies are made with important carbonate bed markers as of the Kimmeridgian? Bir Precambrian rocks elswhere in the world. Miteur carbonate unit. The whole carbonate Tlalet Member and the alternating carbonates, clays, sandstone and evaporites of Key words: Algeria, modelling, lithosphere, tectonism. the M’Rabtine Formation encountered in the Wells constitute three major transgressive-regressive major cycles, where, the GS 02 : Formations Clastiques potentiellement M’Rabtine Formation has been itself subdivided in several half pétrolifères du Maroc et des régions limitrophes cycles, labelled M1 to M4 in ascending order. Each half cycle shows a distinct wire line logging signature related facies and Sequence stratigraphy of the Upper Jurassic deposits and interpreted as shallowing-up or deepening-up depositional associated clastic marginal marine reservoir deposits of sequences. M’rabtine Formation (Gulf of Gabes, Offshore Tunisia). The sandy bodies particularly those associated to the lower Chaeib Soufiane11, Soussi Mohamed2 and Benjemia Hella3 unit (M1) have a multi- kilometric spatial distribution and occur 1 SEREPT, 8 rue Slimane Ben Slimane, B.P. 46, 2092, Tunis as a progradational sheets. Those associated to the third unit 2 Département de Géologie, Faculté des Sciences de Tunis, (M3) were postulated to be developed in retrogradational Tunisie. phase and crowned by a dolomitic level referred at Early 3 ETAP, 27 bis Avenue, Khereddine Pacha, BP. 83, 1073, Kimmerdgian in age. Those of M4 are capped by a major seal Tunis. represented by evaprites.

The Upper Jurassic shallow marine carbonates include the Clastic influx was introduced into southern Gulf of Gabes most prolific reservoirs in the southern tethyan margin (Ghawar from the south and the southwest by a flooding stream and field); whereas, in Tunisia, only small-sized fields are discovered redistributed by marine currents; whereas, a decreasing sand since seventies with oil-bearing paralic to marine sandstones supply (Ezzaouia and El Bibane) and gas-condensate shows are hosted in dolomites (Ali Ben Khalifa, Chaal). These oil occurrences are reported in southern Gulf of Gabes that lying at the north-western edge of the Saharan craton and occurring as a depositional basin developed mainly in responses stage of tethyan rifting.

The productive reservoirs in M’rabtine Formation are identified in the sandy bodies interpreted as channel or sheets that took place in marginal to marine environment. Setting above a broad shallow carbonate shelf of Late Callovian in age

158 GS 24: Risque sismique en Méditerranée Palaeosismic approach in Agadir Region using Wintimdouine occidentale cave speleothems analysis (South-Western High-Atlas, Morocco). An updated North Moroccan Poissonian Seismic Catalog M. Alaeddine Belfoul, Sophia Bouzid and Farid Faik (1045-2005). Laboratory of Structural Geology and Thematic mapping J.A. Peláez1, M. Chourak2, B.A. Tadili3, L. Ait Brahim4, M. (GESCAT) Department of Geology, Faculty of Science, Ibn Zohr Hamdache5, C. López Casado6 and J.M. Martínez Solares7 University, Po Box : 8106, Agadir 80000, Morocco. 1 Dpt. of Physics, Univ. of Jaén, Spain The analysis of the endokarstic system of Wintimdouine 2 Dpt. de Geologie, Univ. Moulay Ismail, Morocco (High-Atlas mountains), is presented as an original approach 3 Dpt. de Physique du Globe, Institut Scientifique, Morocco for the palaeosismic study of Agadir region. The karst 4 Dpt. de Sciences de la Terre, Univ. Mohammed V, Morocco processes occur under the conditions of Quaternary and 5 Dpt. d’Études et Surveillance Sismique, CRAAG, Algeria recent tectonics associated to a considerable seismic activity. 6 Dpt. of Theoretical Physics, Univ. of Granada, Spain 7 IGN, Spain This work expose some comprehensive results performed by the analysis of speleothems observed inside Wintimdouine In this work an updated Poissonian earthquake catalog for cave, one of the greatest underground systems in Africa. Northern Morocco is presented. It has been compiled specifically to perform seismic hazard studies in this region. The karst system of Wintimdouine is made by a several The final version shows all known available data in the area in surface and subsurface relief disturbances, caused by the coordinate range 27º-37ºN and 15ºW-1ºE, spanning from catastrophic paleo-earthquakes. Impressive speleothems years 1045 to 2005. especially in shapes of stalactites and sodastraws show various damages that can be linked to brutal coseismic Among the goals that have been pursued, there is the solicitations into different directions. Main examples are compilation of a main earthquake catalog as complete and illustrated with collapses and slender speleothems break homogeneous as possible. About its completeness, data from locally covering the cave floor. Some stalactites indicate recent different national and international agencies have been horizontal fragile shears while others are fossilised by collected, as well as from numerous papers from different successive calcite neo-crystallisation stages. Elsewhere, authors in the region under study, both of historic and speleothems coating is clearly unstuck from the cave roof that instrumental seismicity. Afterwards, a process of unification of may indicate continuous vertical movements. magnitudes has been performed. Given our aim, the assessment of seismic hazard in Northern Morocco, the Using isotopic dating coupling to successive calcite neo- moment magnitude has been used. Finally, all non-Poissonian crystallisation analysis leads to investigate a new way to earthquakes, including foreshocks, aftershocks and swarms, establish first, a relationship between age and coseismic have been removed. solicitations, then to improve events frequency and palaeosismic regional calendar. This is subsequently, very The obtained final catalog, although not as complete and helpful to predict potential seismic events. uniform as it should be desirable for this type of studies, improves significantly those developed until now in the study Such endokarstic palaeosismic study and its monitoring region. As an example, it can be considered complete since present a great practical implications for the region, since it 1910 for magnitudes above MW 4.0, and since 1700 for concerns the biggest balneological center of the country and magnitudes above MW 6.0. the largest urbanized and economic area in south of Morocco.

Key words: Northern Morocco, Earthquake catalog; Poissonian It leads, particularly to carry out a risk assessment that must take precedence to pretend addressing regional natural hazard.

Key words: endokarstic, palaeosismicity, speleothems, wintimdouine, seismic hazard.

The First MAPG International Convention, Conference & Exhibition 159 Marrakech Convention Center, October 28 - 31, 2007 SS 02 : 3rd Meeting of the Moroccan Jurassic The Liassic of the High Atlas, Morocco (Ait Bou Guemmez System Atlantic and tethyan Margins : Area): Sedimentologic and structural pattern Geodynamics during the Jurassic time Fatima El Bchari1-2 and Abdellatif Souhel1 1 University of Chouaib Doukkali, Faculty of Sciences, Liassic plateform in North of Errachidia: Edification stages Department of Geology. P.O. 20, EL JADIDA, MOROCCO. and controling processes (Southern border of Central Eastern 2 Faculty Polydisciplinaire, P.O. 4162, SAFI, Morocco High Atlas, Morocco) Stratigraphical studies carried out in the Aït Bou Guemmez A. Kaoukaya1, M. Laadila2, A. Hilali1, B. Fedan3, L. Baidder1, area (Central High Atlas, Morocco), lead us to precise the A. El Kochri2 and M. Nassili2 nature and the spatial organisation of liasic deposits. The series 1 Département de géologie, faculté des sciences, Université is composed of four sedimentary units: Hettangian? - Lower Hassan II B.P. 5366 Mâarif- Casablanca Ain-Chock Sinemurian; Upper Sinemurian - Lower Carixian; Middle 2 Université Mohammed V Rabat, Carixian - Upper Domerian; Late Domerian - Toarcian pp., 3 Institut Scientifique Rabat, each of these produces a cyclic evolution: transgressive then The sedimentological analysis of sections plotted bed by regressive. These units are limited by regional unconformities, bed, the paleontological inventory, the identification of the coinciding with the main periods of accentuating the tectonic synsedimentary markers and the sequential structuration in the axis of the central High Atlas belt. organization, allowed us to establish the building history of The structural analysis undertaken in various sites along liasic carbonate platform of Errachidia High Atlas in the Eastern Jbel Tizal - Jbel Azourki fault, shows a local framework us high Atlas (lower and middle Lias) and its place in the 2nd order distention during all the Lias, related to the phenomenous of eustatic cycles. rifting which has marked out the ouest-tethysian margin Four lithomorphological stages were defined according to durand the Lias. The direction of extension NW - SE recorded the associations of contemporary facies: the stage Installation in the lower Lias implies the continuity, in the central High Atlas, corresponds to a homoclynale rampe, the stage of the same mecanisms responsible for the creation of the Individualization develops in depends on a carbonated basin of Upper Trias at the Atlasic domain. The one which is platform with external barrier, the stage Differentiation marks oriented NE - SW during the Middle - Upper liasic periods the flooding of this platform and the appearance of distally implies a reorientation of the main contraints axis in the region steepened platform, and the stage Senesence characterizes of Aït Bou Guemmez. This change induce a new geodynamic an exonded distally steepened platform. Every morphology is evolution of which left overs to specify the mecanisms at the marked by a redistribution of the sedimentary areas. scale of Atlasic domain.

These stages are traced in two transgressif / regressive Key words : Sedimentologic, Structuration, Liassic, Aït Bou Guemmez, 2nd order tectono-eustatical cycles (sensu Jacquin and al., Central High Atlas, Morocco. 1992) which integrate eight depositional sequences (SD1 to SD8). Tectonic- sedimentary evolution in Southern Tehyan Margin: The first lower Sinemurian–upper Sinemurian cycle, which The Moroccan High Plateaux during the Jurassic Times is little developed, includes two depositional sequences SD1 Mohammed Charroud1, Edgard Laville2 and SD2 . The second Carixian-Domerian cycle is formed by 1 Faculté des Sciences et Techniques, Fès Maroc six depositional sequences (SD3 to SD8). The important 2 laboratoire Morphodynamique continentale et côtière , morphologic changes coincide with the passage of a Université de Caen, 14032 France transgressive to a regressive phase of every cycle. They The atlas system of North Africa is one of the best exposed underline the impact of tectono-eustatical factors on the segments of the southern margin of Tethys. Its Mesozoic lithological evolution and the role of the climatic regulation on history especially at the Jurassic times can be taken as a guide the petrography of sediments. to the tectonic-sedimentation evolution: Key words. – Morocco, High Atlas, Liassic, Carbonate platform, Sequence stratigraphy. The Jurassic High plateaux sedimentation constitutes a shallow tidal carbonate-platform. This platform is surrounded by the deep basins of Middle Atlas and High Atlas.

A number of specific tectonic units manifested the part of east-west synsedimentary trending fault. The Mechkakour, for example, is a small subsiding basin located at the southern part of High plateaux. He is filled by thick deep sedimentary accumulation and limited by mud-mounds NE narrow

160 depressions which were controlled by transtensive tectonic Dolomitization, Porosity Evolution and Diagenetic History Of regime. Upper Jurassic Reefal Prograding Shelf Sediments, Agadir Basin, Western High Atlas Of Morocco. The architecture of the High plateaux consisted of rhombic shallow platform extended at the south part of tethyan margin. Brahim Ouajhain1, Thilo Bechstaedt2, Rainer Zuehlke2, Hadou This canvas is is related with Atlantic distension stage. Jabour3, Kamal Labbassi1 and Mhamed El Mostaine 3. 1 Marine Geology Laboratory, Faculty of Science, Dept. of Key words: Jurassic, Tethys, high plateaux, Atlas. Geology, El Jadida, Morocco. 2 Ruprecht-Karls-University, Geologisch-Palaeontologisches Institut, Heidelberg, Germany. Magnetic susceptibility of Jurassic mafic rocks in Beni 3 National Office of Hydrcarbon and Mines (ONHYM), 5 Av. Mellal High Atlas Moulay Hassan, B.P.99, 10050, Rabat, Morocco. El Baghdadi M., Barakat A., Guezal J., Rais J. Laboratoire Géo-Ressources et Environnement, Faculté des Upper Jurassic reefal dolostones of a prograding shelfal Sciences et Techniques, B.P. 523 Béni Mellal, Maroc. ramp of the Lalla Oujja Formation, Tidili locality, Imouzzar area, in the Agadir Basin represent an important and promising The mafic intrusions in the High-Atlas of Beni Mellal occur hydrocarbon reservoirs in western Morocco. Contrasting styles as dykes, sills and flows which are interbedded with, or of dolomitization have been identified within the Tidili reefal intruded into, middle Jurassic sedimentary rocks. In Idemran, dolomites . In different localities in the Immouzzer area from they have gabbroic nature and are installed as a sill within east to the west to the south-west (Witn’doun, Ankloute, Tizi Dogger limestone. Mafic dykes that crosscut Guettioua Izouaren, Tidili, Aoussir, and Taghrate Ouankrime), these styles continental red series are mainly represented in Tagleft. vary. Basaltic flows are largely widespread and overcome the greso- argillaceous formations in Naour, Sgat and Tabarouch. The sills Partly, they seem to be directly related to the with average thickness of 60m are intercalated into Bin-El- paleogeographic setting on ramp/basin transitions, partly to Ouidane blue limestones. With a coarse grained texture and a differing diagenetic regimes and essentially sea-level change. green light colored rock, the sill of Idemran contains Petrographic studies (both TL and CL) reveal that plagioclase, k-feldspar, amphibole, clinopyroxène and biotite dolomitization is the most important diagenetic feature of the with scarcely small olivine crystals. The Tagleft and Ichichi Lalla Oujja Formation carbonates. dolerites contain plagioclase, clinopyroxene and orthopyroxene. In addition to the latest minerals, euhedral Dolomitization, six regionally correlative generations has olivine occurs predominately in gabbro-norite small intrusion of affected all lithofacies to varying degrees and was the result of Ait-Ouchen. Naour and Sgat basalts show a fluidal microlitic several diagenetic events. Sea-level changes and probably texture and contain plagioclase, olivine and clinopyroxene. All also tectonics played an important role in controlling rocks contain magnetite, ilmenite, hematite and sulfide, but dolomitization, modifying porosity evolution and determining their abundances vary widely. reefal reservoir quality within reefal dolostones.

The Tagleft and Ichichi dolerite dyke show the highest Diverese cements, pores, mineral assemblages, and values of magnetic susceptibility (1780 and 1550?10-5SI diagenetic styles demonstrate several diagenetic processes respectively). The Boulmane intrusion (1010?10-5SI), and the operated in theTidili area. Microbial boundstones were Idemran sill (794?10-5SI) and the Ait-Ouchen dyke (810?10- extensively cemented by marine cements during marine 5SI) show medium magnetic susceptibility values. Basalt diagenesis. Subsequent vug formation in these boundstones shows the lowest values with 130 to 327?10-5SI at Naour and occurred during multiple dissolution phases as indicated by 37?10-5SI in Sgat and Tabarouch. In basaltic flow, magnetic their occlusion by a variety of early marine and burial cements. susceptibility is much lower when the rock shows vesicular Fracture cements formed later in the paragenetic sequence. texture. The magnetic susceptibility values in the outcrop of Late diagenetic burial alteration (e.g., dissolution) positively various mafic rocks show significantly differences because all impacts reservoir quality. rocks haven’t the same abundance in strongly magnetic minerals such as magnetite and others ferri-magnetic. These differences are in agreement with mineralogical content and texture of our mafic rocks.

Key words: mafic rocks, High Atlas, magnetic susceptibility, Jurassic.

The First MAPG International Convention, Conference & Exhibition 161 Marrakech Convention Center, October 28 - 31, 2007 Burial diagenesis comparison between Agadir and Essaouira The comparison of clay sedimentation between two Jurassic Series (Western High Atlas – Morocco) sectors submitted to the same geological history, permits to Brahim Ouajhain1 and Lahcen Daoudi2 precise the modality of clay diagenesis, and its obliterate of the 1 Marine Geosciense Laboratory, Faculty of Sciences, Box.20, palaeonvironmental message, acquired before burial. The EL Jadida 24000, Morocco. mineralogical differences observed between the Agadir and 2 Laboratoire de Géosciences et Environnement, Faculté des Essaouira Jurassic series, show that the clay diagenesis, Sciences et techniques, Guéliz, B.P.549, Marrakech 40000, during burial, depends more than temperature than age or Maroc lithostatic pressure.

In the Agadir basin, the effects of burial diagenesis on clay Modelling test of a subsidence: Example of the Ksour Basin assemblages expressed, clearly with depth, by: 1) The illite and during the Jurassic (203-137 MA) (Western Saharian Atlas, chlorite abundance downward to the detriment of smectite and Algeria) kaolinite; 2) Improvement, with depth, of illite cristallinity witch Marok Abbas1, Sebane Abbès2, Hadji Fatiha1, Benyahia evolve from 7 to 3 °2q. The major modifications on clay Mohammed3, Bensefia Kamer Eddine1, Belmouhoub assemblages of Agadir series, take place from 2000m of Abdelkader1, Belfatmi Hichem1 & Benachour Boumedienne1 depth. Moreover, the comparison with data of 1 Department of Earth Sciences, Faculty of Sciences, contemporaneous atlantic (D.S.D.P. sites), permits to University of Tlemcen, B.P. 119, Tlemcen, emphasize the conjugated effects of tectonic instability of the 2 Department of Earth Sciences, Faculty of Earth Sciences, margin and burial depth. Thus, the clay transformation Geography and Amenagment of Territory, University of Es- resulting from diagenesis is superposed to initial variations Senia, B.P. 1524, Oran, Algeria. resulting from detrital process. 3 Department of Environment, Faculty of Sciences, University In the Essaouira basin, clay assemblages identified on of Sidi Bel Abbès, Algeria. Jurassic sedimentary series is mainly composed by smectites The basin of ksour is situated in the western part of the and smectite mixed-layers (chlorite-smectite or C-S, illite- Algerian Saharan Atlas. It is limited by the northern atlasic smectite or I-S and vermiculite-smectite or V-S). Kaolinite is fracture in North and the southern atlasic fracture in South. It is also present in these series with small quantities. Among the marked by carbonated and silico-clastic filling during the minerals associated with clays, the quartz seems to be Jurassic period thus testifying the diversity of the sedimentary ubiquistic, whereas the feldspaths and oxides appear in some environments. levels of the series. Illite cristallinity shows variable values comprised between 4 and 9 °2q. Generally, the vertical In the aim to study the geodynamic evolution of this basin variation of illite contents and its cristallinity doesn’t show a during the interval 203-137 Ma, quantification and modelling significant evolution in depth. This suggests that the effects of tests of subsidence completed by isopach and isobath maps the depth of burial on clay assemblages of these series are is carried out in four sectors (Aïn Ben Khelil, Mekalis, Aïn negligible. Thus, variations in clay assemblages express Ouarka and Kerdacha). The results obtained are summarized palaeogegraphic evolution rather than variations on post as follows: sedimentary processes. During the liasic period (203-174 Ma), the basin of Ksour is Furthermore, contrary to Agadir basin, where burial of characterized by a progressive tectonic subsidence which upper Jurassic series is more than 3000m, the one of constitutes a response to the tectonics of the tilting blocks type Essaouira basin doesn’t exceeds 2000 m. However, the (maximum available space and an acceleration of subsidence difference in thickness of these two series can not be the only in the Mekalis, Aïn Ouarka and Aïn Ben Khelil areas). reason of the mineralogical differentiation between the two Differentiation between depocenters, expressed here by the localities. Several studies show that the temperature and the isopach and isobath maps, is related to the important role of environment of sedimentary series are the most important the local (tectonics of tilted blocks type), regional and global factors than pressure and time. Indeed, in the Essaouira basin, (the Atlantic opening) factors. geothermal gradient is moderated, identical to the one of passive margin with slow overstretching (2,7 °C/100m). This During this interval (174-154 Ma), the heterochrony takes along a banal effect of sedimentary burial on clay between the sedimentary deposits in the center and on the composition, with temperatures of about 75°C from 2000 m of margins of the basin did not last a long time. We can assist at depth. However, in the Agadir region, several studies show that the beginning in the Upper Bajocian to an arrival of the silico- the temperature conditions are most important than those of clastic material (Delta Ksour installation) which announces the Essaouira. This explains by the proximity of south atlasic zone beginning of the closing of the basin. faults. During the interval (154-137 Ma), the sedimentary signature (quality and thickness of deposits) testifies in favour of a

162 generalized closing of the Ksour basin. This situation persists Tectosedimentary features in pelagic swells during Late for all the period of the lower Cretaceous. Jurassic (External Subbetic, SE Spain) Luis M. Nieto1, José M. Molina1, Federico Oloriz2, Matías This subsidence quantification test completes the results Reolid1, Francisco J. Rodríguez-Tovar2 and Pedro A. Ruiz- obtained by AIT OUALI (1991, 1995) concerning modalities of Ortiz1 the Ksour basin opening during the liassic which belongs to 1 Departamento de Geología. Universidad de Jaén. E-23071 Jurassic rifting in the Maghreb. Jaén, Spain. Key words: Ksour basin, Algeria, Jurassic, Geodynamic evolution, 2 Departamento de Estratigrafia y Paleontología. Universidad Subsidence modelling, Isopachs, Isobaths, Depocenter. de Granada. E-18002 Granada, Spain.

The External Subbetic Mountains resulted from Mesozoic Crustal structure of the Morrocan margin from wide-angle and alpine evolution of the South Iberian Continental and reflection seismic data Palaeomargin. Tectono-stratigraphic units show platform and F. Klingelhoefer1, D. Aslanian1, J.-L. Olivet1, M. Sahabi2, J. pelagic carbonates deposited on swells throughout the Perrot3, L. Geli1, H. Nouze1, I. Contrucci1, J.-P. Rehault3 and Jurassic. A complex fini-Bathonian event is recorded in swell P. Unternehr4 limestones. This event resulted from the turnover from the 1 Ifremer, France “main intracontinental rifting stage” to the “transform 2 Univ. El Jadida continental margin stage” (Vera, 2001). The associated first- 3 Univ. Brest order unconformity involves stratigraphical gaps ranging 4Total between upper Bathonian (minimal) and middle Bathonian – lower Kimmeridgian (maximal). Hardgrounds, Fe-Mn crusts, Two deep seismic cruises were conducted as joint projects condensed levels, palaeokarst features and neptunian dykes between Ifremer, Total, and the Universities of Brest, El Jadida occur, typically associated to the unconformity surface. and Lisbon to constrain the deep crustal structure of the Moroccan continental margin. During the SISMAR cruise four Late Jurassic tectonics increased the trough-and-swell combined wide-angle and reflection seismic profiles were relief. Deposition on pelagic swells resulted in Ammonitico acquired on the northern Moroccan passive margin. Two Rosso (AR) facies showing marly (Oxfordian) and nodular profiles were shot parallel and two profiles perpendicular to the limestone (AR s.s.) subfacies (Kimmeridgian - Lower margin. During the DAKHLA cruise, a total 1500 km of seismic Berriasian). Syn-sedimentary movements affected AR-deposits reflection and wide-angle profiles were acquired off the forcing slumps, pebbly mudstones and mass sliding. Scar southern Moroccan margin. surfaces related to sliding sheets and slumps, also occur. Palaeoslope data within a tectonic unit are compatible but Modelling of the reflection and wide-angle seismic data differ from those obtained from nearby ones, revealing block from the SISMAR survey images the thick sedimentary cover of tectonics and/or alpine tectonic rotation. the margin, which is locally perturbed by salt tectonics. The sedimentary basin thickens from 1.5 km on normal oceanic Pelagic swells were affected by normal and wrench faulting crust to a maximum thickness of 6 km at the base of the and, occasionally, diapirism has been recognized in transitional continental slope. The crust thins from 35 km underneath the zones between pelagic swells and troughs. Without correction continent to about 7 km at the western end of the profile. of alpine rotation, present orientation of External Subbetic units Modelling of the seismic data from the DAKHLA cruise reveals shows the mean strike of normal faults changing between a 10 km deep sedimentary basin including two high velocity N70ºE and E-W. The wrench faults are arranged almost at carbonate layers. The crustal thinning from 30 km at the right-angle in respect to normal faults. continental part to 7 km in the oceanic part occurs over a 100 References: km wide zone. Oceanic crust east of the M25 magnetic anomaly displays higher velocities in layer 3 than west of the Vera, J. A., 2001. Evolution of the South Iberian Continental Margin. In: magnetic anomaly. This change in velocity suggests a possible P. A. Ziegler, W. Cavazza, A. H. F. Robertson & S. Crasquin-Soleau link to changes in accretionary processes of the oceanic crust. (eds.), Peri-Tethys Memoir 6: Peri-Tethyan Rift/Wrench Basins and A comparison of wide-angle models from the northern and Passive Margins. Mém. Mus. Natn. Hist. nat., 186: 109-143. southern experiment show similar continental crustal thickness Key words: hardgrounds, neptunian dykes, synsedimentary sliding, and structure in both regions, but a wider ocean - continent ammonitico rosso transition zone in the south.

Keywords: Crustal Structure; Moroccan Margin; Seismic data;

The First MAPG International Convention, Conference & Exhibition 163 Marrakech Convention Center, October 28 - 31, 2007 Fe-Mn Macrooncoids in the Eastern External Subbetic (SE Implications of the tectono-sedimentary soft sediment Spain): Evidence for microbial mediated origin structures in Lower Pliensbachian sediments of the SW Reolid, Matías, Nieto, Luís M., Jiménez-Millán, Juan Algarve Basin, PORTUGAL Departamento de Geología. Universidad de Jaén. E-23071 Carlos Ribeiro1, Brahim Ouajhain2, Pedro Terrinha3. Jaén, Spain. 1 Dept Geociências University of Evora; Portugal 2 Laboratory of Marine Geoscience, Faculty of Sciences, During the Mid-Late Jurassic boundary, the Southern Box.20, EL Jadida 24000, Morocco. Iberian Palaeomargin showed mixed features of a transform 3 Department of Marine Geology, National Institute for and a passive margin where the External Subbetic was made Engeneering Technology and Innovation; Portugal up by a lot of pelagic swells. A major unconformity with a Middle Bathonian-Middle Oxfordian gap is represented in this A Lower Pliensbachian 60 metre thick succession of sector by neptunian dykes, firmgrounds, hardgrounds and Fe- limestone, dolomitic limestone and dolostone containing inter- Mn banded crusts. The surface is characterized by Fe-Mn layered chert beds and chert dykes was investigated in the SW macrooncoids coating ammonoids moulds. The macrooncoids of the Algarve Basin, South Portugal. The work was based on are 6 cm mean-size and the coat is usually less than 3 cm field description of the outcrops, and study of thin sections thick. under transmitted optical microscopy, cathodoluminescence and SEM. The mineral composition of the coating is goethite, calcite, lithiophorite and cryptomelane. In general, the chemical The transmitted light and scanning electron microscopy, as composition of the crusts is mainly dominated by Fe2O3 (≈ well as field structures, showed that the chert and the dolomite 40%) and MnO (≈ 20%). are products of the pre-lithification, early diagenetic evolution of the original carbonates. In a first stage the primary coarse The banded crusts are constituted by microbial laminated grained calciclastic and bioclastic sediments were replaced by fabrics with planar and arborescent morphologies. Alternation silica by reaction with a fluid of unknown origin, and in a between planar and arborescent morphologies responds to second stage occurred the pervasive dolomitization of the minor changes in sedimentation rate. primary fine grained limestone by the percolation of a mixture Some agglutinated foraminifera participate in the Fe-Mn of formational and land derived fluids. crusts such as Thurammina, Placopsilina and Tolypammina. At the base of the Formation, irregular chert beds and Frequent microspheres with spherical to ovoid shapes nodules are prevalent, while at the upper 30 metres of the probably corresponds to microbes. Bacterial and fungal Formation the chert occur as well defined chert beds and filaments are observed in SEM analyses. The microbial mats spatially regular chert dykes and nodules. are constituted by a disperse web of filaments with a branching tube-like morphology with rectangular and y-shaped The chert dykes and nodules longest axis are grossly ramifications with variable diameters between 2 and 8 μm. parallel to the strike of the syn-sedimentary normal faults and Taxonomical approximation of the microbiotas is difficult but the spacing of the nodules has a linear correlation with the the morphology resemble to filamentous cyanobacterium thickness of the host limestone beds. Microcoleus. It is argued that after the sedimentation the deformation The precipitation of Fe-Mn is interpreted in relation to affected a sequence of fine grained, semilithified limestone, chemoorganotrophic behaviour of the benthic microbial and unlithified, water saturated coarse grained calciclastic and communities. The key is in the Mn content of the crusts. It is bioclastic lithologies. The deformation led to the development well established that in modern environments efficient of vertical tension joints in the fine grained more cohesive beds. precipitation of Mn from natural water depends largely on the The loose and water saturated coarse grained calciclastic presence of Mn-oxidizing microorganisms. Inorganic sands were injected into the joints forming calciclastic dykes. precipitation mechanisms are regarded as insufficient for The dykes were disrupted by a syn-sedimentary compressive accumulation of significant amount of MnO in natural episode after which the extension resumed. environments. Sediment-starved zones of pelagic swells of External Subbetic were favored places for microbially mediated All these events occurred in a time interval of approximately authigenesis. 2 Myr as could be demonstrated by cross-cut relationships of unconformities in the two consecutive carbonate formations Key words: Laminated microfabric, Microbial chemosynthesis, Pelagic well dated by ammonites. swells, Middle-Upper Jurassic

164 Shallow shelf sedimentation of the Jurassic Samana Suk Brasilian and Angolan Passive Margins: the kinematic Limestone, Kala Chitta Range, Lesser Himalayas, Pakistan. constraints Muhammad Kaleem Akhter Qureshi1, Aftab Ahmad Butt2, Maryline Moulin1, 2, Daniel Aslanian1, Jean Louis Olivet1, Shahid Ghazi Cinthia Labails1, 3, Frauke Klingelhoefer1, Luis Matias1, 4, 1 Geological Survey of Pakistan, Lahore, Pakistan. Patrick Unternehr5, Isabelle Contrucci6, Hervé Nouzé1. 2 Institute of Geology, Punjab University, Quaid-e-Azam 1 Ifremer, LGG, Brest, France, Campus, Lahore-54590, Pakistan. 2 Lattex (FCUL), Portugal, 3 NGU, GSN, Trondheim, Norway, Detailed sedimentological studies of the Samana Suk 4 CGUL, FCUL, Portugal, Limestone (type section Samana Suk Peak,Samana Range, 5 TOTAL, France, Pakistan) have been carried out from the Kala Chitta Range, 6 INERIS, France Pakistan as the first comprehensive contribution of its kind.The stratigraphic name refers to the Upper Triassic to Liassic Kioto The thinning of continental passive margins is usually Limestone of earlier literature which has now been explained by conservative models using stretching and/or differentiated into the Triassic Mianwali Formation, the Chak simple shear. Nevertheless, those models imply hypothetical Jabbi Limestone, the Kingriali Formation and the Jurassic extensional structures and large horizontal movements Datta Formation, and the Samana Suk Limestone. between the two homologous margins (more than 250 km for the Brazilian and Angolan Margins). Therefore, the The Kala Chitta Range is an east-west longitudinal trough consequences induced by a pre-break-up kinematic forming the northern border of the adjoining hydrocarbon reconstruction are tremendous on the genesis of the bearing Potwar Basin.The Islamabad-Peshawar Highway is the continental passives margins that marked the break-up area. dividing line between the Kala Chitta Range and the Hazara Several authors have already addressed the problem of the Mountains towards the eastern end, while the Indus River pre-opening reconstruction in the South Atlantic Ocean, in the marks the western limit. past. Nevertheless, the more recent entire reconstructions of The Samana Suk Limestone is well bedded limestone and the break-up present numerous unexplained misfits (gaps, can be identified in the field into oyster bearing beds, micritic overlaps and misalignments) that invalidated the fit. We present beds, shelly limestone composed of gastropods, and here a new reconstruction based on new interpretation of pelecypods, sandy limestone and the oolitic limestone. The magnetic data, satellite altimetry and oceanic and continental field observations are indicative of shallow shelf deposits. In geological constraints. The Zaiango refraction/reflection data other words, it represents a carbonate platform deposition. together with this new closest pre-opening fit show that the Angolan-Campos system presents a 200 km wide thinned The microscopic studies have identified most common basin which is, according to the shallow deposed salt layer, in microfacies into the mudstone(micritic facies), bioclastic high position all along its genesis and at least until the break- wackestone, packstone where the skeletal elements are the up. This basin cannot be explained by further horizontal oysters, gastropods and the pelecypods, while the grainstone movement: vertical motions prevail compared to horizontal is non skeletal represented by the oolitic grains. Apart from the motions in the formation on the huge thinned Angolan-Brazilian microfacies analysis,the diagenetic imprints have also been basin. Thus, middle and/or inferior crusts have to be involved elucidated. All these features also substantiate its shallow shelf in processes as: “flowing” in the first accreting process (for the sedimentation.. Two lithologs from Surg and Chapra have been volcanic margin), or denudation processes to create the first extensively studied to elaborate the sedimentological details. “proto-oceanic crust” and/or flowing laterally along different margin segments, or even mixing with the upper mantle Key words: Sedimentation, Jurassic Shelf, Kala Chitta Range, underneath. Pakistan. Keywords : Brasilian and Angolian Passive Margins ; Kinematic;

The First MAPG International Convention, Conference & Exhibition 165 Marrakech Convention Center, October 28 - 31, 2007 GS 07: Gaz seepage, Mud volcanism and related gaz Seepage-related authigenic carbonates in the Gulf of Cadiz: hydrate and carbonate formations, distribution and controls V.H. Magalhães1,2,4, L.M. Pinheiro2, M.K. Ivanov3 Geochemical preconditions of Oil-Gas-Bearing capacity of 1 Departamento de Geologia Marinha, Instituto Nacional de the Alboran Basin Engenharia, Tecnologia e Inovação I.P., 2721-866 Alfragide, E. Poludetkina1, M. Comas 2, E. Kozlova1, M. Ivanov1 Portugal. 2 Departamento de Geociências, Universidade de 1 - UNESCO/MSU Centre for Marine Geology and Aveiro, 3810-193 Aveiro, Portugal; Geophysics, Geological Faculty, Moscow State University, 3 UNESCO-MSU Centre for Marine Geosciences, Moscow GSP1, Leninskie Gory, 119991, Moscow, Russia, State University, Russia; 2 - Instituto Andaluz de Ciencias de la Tierra, CSIC and 4 Department of the Geophysical Sciences, The University of University of Granada. Spain Chicago, USA.

Neogene basin of the Alboran Sea corresponds to the Numerous seafloor occurrences of authigenic carbonates westernmost Mediterranean extensional basin located within a have been discovered in the Gulf of Cadiz during the last 7 Miocene arc-shaped thrust belt formed by Betic and years. Mineralogic, isotopic and biomarker analyses indicate Maghrebian Cordilleras (Comas et al., 1999). It has been the that these authigenic carbonates (dolomite crusts, nodules, site of a vigorous program of oil and gas exploration since chimneys or filled burrows and aragonitic slabs or pavements) 1970`s and attracts attention nowadays as a potential oil-gas- are related to gas seepage. U/Th dating of samples from the generating basin. Iberico mud diapir indicates that they were formed during episodes of intense methane flux to the seafloor, in a long span of time (at least during the last 250 ky). Materials to research work are obtained during TTR-9 and TTR-12 UNESCO cruises. Four mud volcanic structures were Seep sites and authigenic carbonate deposits were initially discovered, investigated and subsampled (Kalinin and Perejil assumed to be isolated occurrences but, with the increase of on the Spanish margin, Dhaka and Granada on the Morocco the survey coverage they now have been encountered in margin). Cores from mud volcanic structures are characterized several other locations (between 500 and 4000 m water by relatively high concentrations of HC gases as comparing depth), indicating that they are far more common features than with background concentrations. Geochemical data suggest previously anticipated. thermogenic or mixing origin of gases and their migration through the sedimentary sequence. Geochemical data show This work describes an evaluation of the distribution of that sedimentary sequence of the Alboran Sea includes seafloor fluid seepage indicators observed on underwater medium and high-quality source rocks able to generate HC video profiles, during sample retrieval by video controlled grab, fluids. These are Upper Miocene claystones accumulated in which are correlated with sediment samples and acoustic anoxic subbasin (TOC=7,37%, S2=43,5HC,mg/rock,g; characteristics on the seismic profiles and on the side-scan HI=622HC,mg/TOC,g); Upper Paleocene carbonates sonar backscatter images. A relationship between the (TOC=0,68%, S2=1,27HC,mg/rock,g; HI=186HC,mg/TOC,g); occurrences of the authigenic carbonates with other fluid Upper Cretaceous siltstones (TOC=2,94%, escape structures such as mud volcanoes and mud diapirs is S2=17HC,mg/rock,g; HI=577HC,mg/TOC,g). Content, postulated. composition and level of maturity of organic matter from rock The occurrences of the seeping sites are in close relation clasts of mud breccia suggest that these rocks can generate with mud volcanoes and mud diapirs, indicating that those significant amounts of HC fluids. structures are the preferential pathways for fluid escape. The Presence of thermogenic gas and gas and oil inflows from Mediterranean Outflow Water (MOW) appears to have an Miocene silty beds in seabed cores provides strong evidence effective control on the occurrence of the different types of for presence of an active petroleum system within this basin authigenic carbonates, dolomite crusts, nodules and (Weinzapfel et al., 2003). Highly HC-potential strata are chimneys, occur in places where the MOW has a strong identified along the 7-9 km thick sedimentary sequence. These erosive effect. geochemical compilations will prove to be a critical guide for Key words: Cold seepage; authigenic carbonates; Gulf of Cadiz. future exploration and thorough investigations within the basin.

Key words: mud volcano, oil-bearing capacity, source rock potential

166 GS 17 : Geodynamics of mountain belts Kinematic analysis of the High Atlas in the Tinerhir Area (Southern Morocco): Evidence of a transpressional fold- Transpressional evolution of the Variscan Belt in the Tinerhir thrust belt Area (Eastern Anti-Atlas, Morocco) Andrea Cerrina Feroni 1, Alessandro Ellero 1, Giuseppe Ottria Andrea Cerrina Feroni 1, Alessandro Ellero 1, Marco Malusà 2, 1, Marco Malusà 2, Riccardo Polino 2, Giovanni Musumeci 1,3, Giovanni Musumeci 1,3, Giuseppe Ottria 1, Riccardo Polino 2 Piero Carlo Pertusati 1,3 1 CNR - Istituto di Geoscienze e Georisorse, Via S. Maria 53, 1 CNR - Istituto di Geoscienze e Georisorse, Via S. Maria 53, I-56126, Pisa, Italy I-56126, Pisa, Italy 2 CNR - Istituto di Geoscienze e Georisorse, Via Valperga 2 CNR - Istituto di Geoscienze e Georisorse, Via Valperga Caluso 35, I-10125, Torino, Italy Caluso 35, I-10125, Torino, Italy 3 Dipartimento di Scienze della Terra, Università di Pisa, Via S. 3 Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, I-56126 Pisa, Italy Maria 53, I-56126 Pisa, Italy

The Tinerhir region, located in the eastern sector of the The Tinerhir region (Southern Morocco) is a key area to Anti-Atlas, represents the southern margin of the Variscan belt study the relationships between the Alpine High Atlas belt and of the Moroccan Meseta which is interpreted as a foreland belt the Cretaceous deposits unconformably overlying the consisting of Paleozoic allochtonous units overlying the Saghro Paleozoic cover at the northern boundary of the West African Precambrian basement along thrust faults gently dipping to the Craton. Recently, the southern margin of the High Atlas has north. been interpreted as a top to the south frontal thrust (South Atlas front) bounding a thin-skinned thrust system of Triassic- New field and structural data from the Paleozoic sequence Jurassic rocks detached from their basement in the frame of a exposed on the northern side of the Saghro inlier unravel a pure compressional deformation. polyphase deformation history developed during the Late Carboniferous under anchizonal metamorphic conditions. This Our structural geological study focuses on the kinematic deformation history is sealed by Late Cretaceous deposits analysis of fault systems outcropping along different transects unconformably overlying the Paleozoic belt. The first in the Tinerhir area. In this area the overall structure of the deformation phase (D1) is marked by tight to isoclinal folds Meso-Cenozoic successions consists of south-verging associated to a slaty cleavage (S1) well developed in the pelitic asymmetrical fold systems with sub-vertical axial planes, formations. The syn-D1 tectonic contacts between associated to steeply NNW-dipping faults that are broadly allochthonous units consist of top-to-the SE low-angle thrusts parallel to the fold axes and to the steeply dipping bedding. with down-dip to oblique slickenlines. The second deformation These faults display down-dip slickenlines, with a top to the phase (D2) is characterized by E-W striking upright open folds SSE sense of movement, associated to widespread oblique or developed from decametre to hectometre scale, gently horizontal striations that highlight an important strike-slip overturned toward south, with an upright crenulation to slaty component. Paleostress determinations, obtained from fault- cleavage axial-plane foliation (S2). D1 tectonic contacts are in slip data collected from several measurament sites, indicate turn reactivated by D2 fault systems. These latter systems the occurrence of strike-slip and compressional tensors, with a have a N70°- 80°E strike, dip steeply to the north, and bear quite steady sub-horizontal ?1 trending NW-SE. oblique to down-dip slickenlines. Kinematic analysis performed These results suggest a transpressional evolution for the on thrust surfaces and high-angle faults indicates that reverse High Atlas southern margin comparable with those of the slip was coupled with dextral strike-slip movement. northern boundary of the High Atlas, whose features of These data point to a polyphase transpressional transpressive fault are already recognized, and emphasise the deformation of Variscan age in the eastern Anti-Atlas, importance of fault-slip analysis to define the geodynamic characterized by southward folding and thrusting coupled with evolution of orogens. dextral strike-slip, as already documented for other sectors of the southern margin of Moroccan Meseta. Key words: fault-slip analysis, fold-thrust belt, transpression, High Atlas, Southern Morocco Key words: Variscan belt, polyphase deformation, transpression, Southern Morocco

The First MAPG International Convention, Conference & Exhibition 167 Marrakech Convention Center, October 28 - 31, 2007 Impact of the friction along the subducting floor at Muroto Mantle deformation below a back-arc continental rift: Transect (SW Japan) on the formation of the thrusting wedge Example from the Ronda peridotites revealed by experimental analogue models. Precigout Jacques1, Gueydan Frédéric1, Garrido Juan- Driss Elouai1 and Yasuhiro Yamada2 Carlos2, Gapais Denis1, Essaifi Abderahim3 and Gogne 1 Ex Affiliation at Kyoto university Nathan1 2 Department of Civil and Earth Resources Engineering, 1 Géosciences Rennes (UMR CNRS 6118), Université de Graduate School of Rennes1, Bâtiment 15, Campus de Beaulieu, CS 74205, F- Engineering, Kyoto University, Kyoto 606-5801 Japan 35042 Rennes Cedex, France 2 DP. Mineralogia y Petrologia, Universidad de Granada, Nankai Trough is one of the active tectonic plate margins. 18002, Granada, Spain It is located geographically south-west of the Japanese Islands 3 Département de Géologie, BP 2390, Faculté des Sciences Arc. Geologically, it traces the site where the Philippine Sea Semlalia, 40000 Marrakech, Maroc plate sinks underneath Southwest Japan. This zone has recorded large earthquakes (M = 8) and may generate more The Ronda continental peridotite (southern Spain) exposes hazardous ones in the future. several ductile structures formed at different metamorphic facies with very debated geodynamical signification. Spinel Simulation of the geological structure developed in this part tectonite and a spinel/garnet mylonite are exposed in the of the Nankai Trough using scaled analogue models was Northern rim of the massif while plagioclase tectonite are based on the friction variation from northwest to southeast. present in the southern part of the massif. These two domains are separated by a partial melting-related granular peridotite. A Three experiments of high, medium and low friction floor new structural study of the massif has thus been made in order were performed. Based on results of the previous experiments to better constrain all deformations. The foliation in the spinel and referring to seismic data acquired at Muroto Transect, a tectonite becomes progressively parallel to the contact with the final scaled model similar to the seismic section was country rocks, imaging a kilometre-scale shear zone. successfully reproduced. Consistently, pyroxenite layering are folded in the less strained Results of this research show clearly the great influence of rocks while they are parallel to the foliation and strongly the friction along the subducting floor on the style of the stretched in the garnet mylonite. Furthermore, Mylonite foliation deformation and the type of the geological structures is parallel to the main foliation in the strongly thinned crustal developed in the sediment pile accumulated in the accretionary rocks on the top, suggesting an overall deformation of the prism. High friction material imposes the development of low crust and mantle during an extensional event. As for the angle thrusting wedges with the least spacing and the highest plagioclase peridotites, local mylonite and further folds suggest relief, which was interpreted to be the equivalent of the low another deformation but not clearly different from the latter. landward-dipping reflector of the seismic section. Medium Finally, thrusts with numerous crustal imbrications at the base basal friction lead to the development of large scale thrust of the peridotite massif cut and fold the plagioclase foliation, faults. This zone corresponds to the large thrust-slice zone of indicating a late and cold deformation related to the massif the above cited section. With low basal friction, imbricate emplacement into the crust. Thereby, we propose that most of thrust faults was developed in an organized thrust succession; the ductile deformation of the Ronda peridotites are formed which was interpreted as the imbricate thrust zone of the during lithosphere extension related to the Oligocene African seismic section. slab roll-back with, successively, a mantle shear zone in the garnet/spinel facies, a partial melting, then a deformation in the Keywords: Analog modeling, Nankai Trough, Muroto Transect, plagioclase facies at the end of the unroofing. Finally, a Subducting zone, Japan compressive event integrated the Ronda massif into the crust when it was at midcrustal depths.

Keywords: Peridotite; Ronda; ductile deformation; extension.

168 Pn Tomography in northern Morocco and geodynamic the whole tectonic calendar during the pre- , syn- and post- implications paroxysmal Faiçal Ramdani1, Inmaculada Serrano2, Ihssane Ibnsaid1, We would like to give here a special emphasis to the Jose Morales2 paroxysmal events that strikingly generated two kind of 1 Physics of the Earth Department, Scientific Institute compressional deformations orthogonally crossing each other: Mohamed V-Agdal University, Rabat, Morocco, one of them was related to a submeridian shortening and 2 Instituto Andalouz de Geofisica, Universidad de Granada, generated asymmetric folds and locally north-vergent 18071 Granada, Spain overlapping. The other was equally induced by a Recent high seismic activity in the Rif-Alboran boundary compressional shortening but had an almost equatorial zone (Al-Huceima region) provides new data to reconsider direction and expressed by overturned folds associated with geodynamic aspects in this part of the Ibero-Maghreb plate overlapping and ramp structures of a pronounced western and boundary. Upper mantle tomography structure in Northern part eastern vergences. of Morocco is investigated by imaging Pn variations and These two perpendicular structures can satisfactorily be anisotropy. The results obtained indicate zones of high velocity explained within the context of a stress field involving two in eastern Rif and Meseta while low velocity dominates the compressions directed NNW-SSE and ENE-WSW, Atlas upper mantle. The lower lithosphere structure in the Rif respectively. The first compression resulted from the mountains show marked variations between Eastern Rif and convergence of the Iberian and African plates in an overall western parts. Low velocity of the Atlas lithosphere, and NNW direction. The resulting shortening was consumed, Miocene and Quaternary magmatism fit with a process of mainly by the Betic-Rif deformation, and secondarily by the upwelling mantle. However, intermediate depth seismicity Middle Atlas chain. This compression seems to have lasted beneath the central Atlas mountains is evidence for until the post-paroxysmal period and then propagated extern- descending flows. Both upward and descending motions wards up to the frontal part of the Rif belt. The second seem better explained by a process of delamination. In central compression was associated to the westward drifting of the Rif, the faults system may be deeply seated from Al huceima Alboran microplate that progressively became trapped region to Taounate basin to explain East West complex Pn between the Iberian and the African plates. The resulting variation and related anisotropy in this region. tectonic blockage (that was likely to have been enhanced by Key words: geodynamics, seismicity, Pn velocity, Atlas mountains, the simultaneous European-African convergence) caused the Morocco northward subduction of the African plate and the formation of an accretionary prism along the frontal lines of the Alboran terrane, i.e., the future lines of the Gibraltar arc. GS 17 : Geodynamics of mountain belts This twofold deformational scenario is proposed here as Evidence of two alpine orthogonal deformations in the being the principal plate-tectonic mechanism that structured the arcuate Betico-Rifian belt during the Miocene times (late Northwestern Rif Chain : Implications on the convergence of Burdigalian–late Tortonian). Iberian, African and Alboran Plates Key words: Flysc nappes, Rif chain, Alboran, orthogonal convergence,

A. Chalouan1, Kh. El Kadiri2, A. El Mrihi2, A. Bahmad3 and F. Salhi4 New paleomagnetic and geochronologic data from the 1 Univ. Mohammed V-Agdal, Faculté des Sciences, Geology Middle-Atlas, Morocco Department, , 10000 Rabat, Vicente Carlos Ruiz-Martínez1, Gregg McIntosh1, Víctor 2 Univ. Abdelm.Essaadi, Fac. Sciences, Geology Department, Villasante2, Ahmed Chalouan3, Khalil El Kadiri4, Margarita BP. 2121, 93003 Tetouan López-Martínez5 (Morocco) 1 Dpto. FTAAI, Fac. CC. Físicas, Univ. Complutense de Madrid, 3 Société Nationale d’Etudes du Détroit (SNED), 31 r. Al Spain. Alaouyine, Rabat , Morocco 2 Observatorio Geofísico Central, Instituto Geográfico 4 Université Chouaib Doukali, Faculté des Sciences, El Jadida, Nacional, Spain. Morocco. 3 Univ. Mohammed V-Agdal, Rabat, Morocco. 4 Fac. Sciences, Univ. Tetuan, Morocco. Mapping and detailed microstructural analyses carried out 5 Laboratorio de Geocronología, CICESE, Mexico. along the southern bank of the Gibraltar Strait (northernmost Rif belt) allowed us to reconstruct the deformation geometry, Here we report the results of a paleomagnetic study near the structural stacking pattern of the Flysch nappes as well as the western margin of the North-Middle Atlas Fault. 16 volcanic

The First MAPG International Convention, Conference & Exhibition 169 Marrakech Convention Center, October 28 - 31, 2007 sites (130 specimens) from the Middle Atlas were sampled The described Aljibe unit organization strongly differs from along a 50 km transect. In addition, 40Ar-39Ar dating has been the chaotic geometry and the gravitational mode of performed in one site that was located in the central part of this emplacement proposed by previous authors. By contrast, it fits transect and yielded a mean age of (200 ± 100) Ka. The main a push-from-behind mechanism for its emplacement, in which goals of this palaeomagnetic study were: (i) to constrain, both the relatively ‘‘rigid’’ back stop would be represented by the spatially and temporally, the occurrence of block rotations in Alboran Domain. Since the Flysch Trough units derive from a this complex geodynamic area; (ii) and to contribute to the deep water infill located on a much attenuated lithospheric (Brunhes age) generalised database of Palaeosecular Variation domain (Flysch Trough), they represent as a whole a particular from Lavas (PSVL) in this scarcely covered continent. Rock- case of accretionary prism nowadays emplaced onto their magnetic properties are fairly uniform across the sampled neighbouring paleomargins. They also have a special tectonic transect. Two magnetic phases dominate throughout, a low Ti significance, as a suture marker between the Alboran Domain titanomagnetite and an intermediate Ti titanomagnetite. AF internal zones and the external zones. Our data provide demagnetisation of NRM shows a unidirectional behaviour, important constraints to generate more refined reconstructions isolating a well-defined ChRM that always exhibits normal of the Betic-Rif orogenic building. polarity. Site-mean directions do not support any vertical-axis Key words: Gibraltar Arc, Flysch Trough Complex, accretionary prism, rotation in this part of the volcanic province. The Virtual Aljibe unit, thin-skinned deformation. Geomagnetic Poles show a far-sided effect (shallowing of inclination of 10 degrees) whose scatter is close to that expected from consideration of the PSVL generalised Acknowledgements: This study was supported by grant BTE200305057C02 and CTM200508071C0301/MAR (Spain). database.

Key words: paleomagnetism, geochronology, Middle-Atlas, Morocco, Quaternary The jurassic succession of the inner northern apennines (italy) and rif belt (marocco): records of the pangea break-up in the Mediterranean Area Structure and tectonic evolution of the flysch trough thrust Andrea Brogi1, Alessio Cerboneschi1, Ahmed Chalouan2, imbricate in the Northern Branch of the Gibraltar Arc Lorenzo Fabbrini1, Khalil El Kadiri3, Antonio Lazzarotto1, Orogenic Wedge. Domenico Liotta4, Marco Meccheri1, André Michard5, M. Luján1, A. Crespo-Blanc 2,1, and J.C. Balanyá 3 Federico Oloriz6 1 Instituto Andaluz de Ciencias de la Tierra, CSIC - Universidad 1 University of Siena, Department of Earth Sciences, Via de Granada, 18071 Granada. Laterina 8, 35100 Siena, Italy 2 Dpto. de Geodinámica, Universidad de Granada, Campus 2 University Mohammed V-Agdal, Faculty of Sciences, Fuentenueva s/n, 18071 Granada Department of Geology, BP 1014, Rabat, Morocco 3 Dpto. de Sistemas Físicos, Químicos y Naturales, 3 University Abdelmalek Essaadi, Faculty of Sciences, Universidad Pablo de Olavide, Cra. de Utrera km 1, 41013 Department of Geology, BP 2121, Sevilla. 93003 Tetuan, Morocco 4 University of Bari, Department of Geology and Geophysics, The Gibraltar Arc accretionary prism, constituted by the Via Orabona 4, 70125 Bari, Italy Flysch Trough units, is sandwiched between the fold-and- 510 rue des Jeûneurs, 75002 Paris, France. thrust belt derived from the South Iberian and Maghrebian Domain and the metamorphic rocks of the Alboran Domain, on 6 Facultad de Ciencias de Granada, Depto de top. In the northern branch of the Gibraltar Arc, the main Paleontologia, Av. Fuentenueva, 1802 Granada, Spain. tectonic unit of this inactive accretionary prism is the Aljibe unit, The Jurassic succession of the inner Northern Apennines is composed by upper Jurassic to lower Miocene rocks, mainly mainly composed of, from bottom to top: a) white massive siliciclastic. It shows a well-organized structure of thrust limestones (Hettangian-Early Sinemurian); b) red nodular imbricates, characteristic of a thin-skinned type deformation, ammonites-bearing limestones (Sinemurian-Pliensbachian); c) produced by an approximately EW shortening event, post- grey cherty-limestones (Pliensbachian-Toarcian); d) red and lower Burdigalian in age. The structural style and vergence grey marls and limestones (Dogger); e) radiolarites (Dogger- within this unit permit to recognize three structural domains, Malm). In the Colline Metallifere and in the southern part of the separated by major accommodation zones. This can be Mt. Amiata geothermal area, the Jurassic succession shows explained as a consequence of the variations of rock type widespread syn-sedimentary extensional structures (i.e., syn- along the basal décollement. The general architecture of sedimentary normal faults and Neptunian dykes) and imbricate thrust fan, characteristic of all the structural domains sedimentary records (slumps, debris flows) indicating tectonic of the Aljibe unit, can locally be affected by late deformations. instability of the substratum. These features characterise the Lias-Dogger succession, particularly. Furthermore, a syn-

170 sedimentary mafic volcanic episode was documented within Ma), probably following westward slab rollback. Middle to the succession of the nodular ammonites-bearing limestones. upper Miocene arc and oceanic crust formation at the Alborán and Algero-Balearic basins, respectively, was coeval to core- A similar Jurassic succession crops out in the Dorsale complex style exhumation of HP-LT rocks formed by Lower Calcaire of the internal Rif belt: a) white massive limestones Miocene collision in the Betic-Rif margins, manifesting the (Earliest Liassic); b) red nodular ammonites-bearing limestones strong lateral heterogeneity of the Gibraltar arc subduction- (Late Sinemurian in the External Dorsale, ED; Middle collision system; in great measure related with the pre- Domerian-Middle Toarcian in the Internal Dorsale, ID); c) grey collisional distribution of oceanic and thinned continental crust cherty limestones, accompanied in many places by basal among the African and Iberian paleomargins and the Flysch coarse grained debris flows (rock faults) and olistostromes Trough domain in between. (Middle Domerian, mainly); d) marly and nodular limestones (Middle-Late Toarcian); e) Radiolarites (Dogger-Malm, ED; Early Active subduction as the driving force behind recent Tithonian, ID). This succession is widespread exposed with a deformation and long-term seismicity in the Gibraltar - Gulf significant tectonically-controlled diachronism in the onset of Cadiz region (from external to internal Dorsale units) of the three key facies: M.-A. Gutscher1, P. LeRoy1, D. Graindorge1, N. Babonneau1, rosso-ammonitico, cherty limestones and radiolarites. As in the N. Maad1 ; S. Dominguez2, R.M.S. Fernandes3, J.M. inner Northern Apennines, syn-sedimentary extensional Miranda3, features, mainly represented by normal faults and sedimentary 1 UMR6538 Domaines Océaniques, IUEM/UBO Plouzané records (slumps, debris flows), characterise the Liassic 2 UMR 5573, Univ. Montpellier II G. Westbrook, Earth succession. This suggests that both regions might share an Sciences, Univ. Birmingham overall similar evolution during the Pangea break-up. New 3 Geophysics Dept. Univ. Lisbon investigations are required to account for the differences between these successions (e.g. possible emersions in the The SW Iberia/ NW Morocco region has been the site of Dorsale vs submarine hiatuses in the Apennines). strong historical seismicity, most notably the M8.7 Great- Lisbon earthquake of 1 Nov. 1755, (60,000 casualties and a Key words: Jurassic succession, syn-sedimentary extension, Pangea 5-15 m high tsunami). Recent geophysical results reveal an break-up, Northern Apennines, Rif Belt east dipping subduction zone, beneath the Gulf of Cadiz and Gibraltar arc, whose activity remains the subject of debate. Seismic images of the Middle to Upper Miocene Alboran Bathymetric data from numerous recent cruises indicate ongoing, widespread deformation as expressed by a fresh, magmatic arc. continuous horseshoe shaped deformation front (more than G. Booth-Rea1, C. Ranero2, J.M. Martínez-Martínez1, 3, I. 400 km in length), defining the limit of an elongate accretionary Grevemeyer4. wedge. New high-resolution seismic data across this 1 Departamento de Geodinámica, Universidad de Granada. deformation front, offer evidence of outward vergent thrusting 2 ICREA, at Instituto de Ciencias del Mar-CSIC, Barcelona (directed W, NW, and SW). An E-W trending basement high 3 Instituto Andaluz de Ciencias de la Tierra (C.S.I.C.- (Coral Patch Ridge) can be seen indenting the deformation Universidad de Granada) front in an asymmetric manner. Analog modeling using granular 4 IfM-GEOMAR Leibniz-Institute fuer Meereswissenschaften, materials demonstrates how WSW directed tectonic Kiel, Germany shortening can reproduce this indenter pattern.While regional Multichannel seismic reflection images of the transition GPS data confirm an overall NW motion of most Moroccan stations (relative to stable Eurasia) at velocities of 3-4 mm/yr, between the Alboran and the Algero-Balearic basins show a several stations in the Rif-Betic Alboran region show W to SW crustal thickness decrease from west to east from about 5 s motion at velocities ranging from 1-2 to 5-6 mm/yr. The Two way Travel Time (TWTT,~15 km thick) to ~2s TWTT typical westernmost stations (in particular San Fernando) show the of oceanic crust (~6 km thick). Most crustal thinning occurs highest velocities. These data require active E-W extension in gradually without apparent thinning related to faulting, tilted the W Alboran Sea (confirmed by the current stress field here) blocks are very scarce and all sampled basement outcrops are and imply W to SW shortening in the Gulf of Cadiz. Together, volcanic suggesting that the crust was dominantly formed by these data indicate active subduction, with back-arc extension magmatic processes in the transition between a magmatic arc (in the W Alboran Sea) is the driving mechanism for and a backarc setting, from west to east. The sediments compressional deformation in the Gulf of Cadiz. This supports onlapping the igneous basement young from east to west a subduction fault plane origin as the likely source of the 1755 between 12 and approximately 8 Ma in agreement with earthquake. Future research will focus on the activity (surface radiometric dating of volcanic rocks in the region. Minor deformation, GPS displacement vectors, seismicity) of the eastward-directed brittle extension lagged behind oceanic and lateral bounding faults. magmatic arc crust formation migrating towards the west between the Tortonian (≈10 Ma) and the Upper Pliocene (≈3 Key words: Subduction; seismicity; Gibraltar; Gulf of Cadiz

The First MAPG International Convention, Conference & Exhibition 171 Marrakech Convention Center, October 28 - 31, 2007 The structure of the ras afrou and Temsamane Units (Eastern lithospheric rebound has been reported with geological data. External Rif, Morocco) However, some lithospheric flexure models (e.g. Norman and Azdimoussa, A.1, Jabaloy, A.2, Asebriy, L.3, Booth-Rea, G.2 Chase, 1986) show that a massive unload of water implies and González-Lodeiro, F.2 necessarily an isostatic rebound in the basin and an associated 1: Faculté Pluridisciplinaire de Nador. uplift of the mediterranean shores. Here, we examine this 2: Departamento de Geodinámica, Universidad de Granada. paradox by using a new model that encompasses a 3: Inst. Scient. Universite Mohamed V, Agdal (Rabat) lithospheric flexure model (due to unload of sea-water), and a sedimentation model (due to deposition of evaporites in the The deepest units of the external Rif crustal wedge outcrop desiccating basin). We show that the concordance or not of in the Temsamane Massif in the Eastern Rif. These units the evaporites layers can bring some constraints about the underwent IP/LT metamorphism during the development of pertinence of a preserved messinian rebound in their main foliation (Sp) which is axial-planar to large SE- Mediterranean. vergent recumbent folds. This main deformation stage was produced in a non-coaxial regime with an ENE-WSW transport Keywords: Messininian Salinity Crisis, isostatic rebound, lithospheric flexure model, evaporites deposition direction and a sense of movement of the hanging-wall towards the WSW and it involved both Palaeozoic basement and its Mesozoic sedimentary cover. We have differentiated GS 31 : Organic geochemistry applied to petroleum three main units separated by brittle-ductile thrusts with a top- exploration to-the-south sense of movement that cut the recumbent folds and have inverted the metamorphic order. Normal faults record Apport of the modelling to reconstitution of oil histiry of the later thinning of the thrust pile. The older fault system is formed by low-angle normal faults that record extension parallel to the Qasbat-Tadla Basin (Central Morocco) ductile lineation in the Temsamane Massif, and to the Rif Chain Hassan Er-Raioui1, Habib Belayouni2 and Mohamed orientation. This extension is similar to the WSW-ENE Bouabdelli3 extension described in the Betics producing the exhumation of 1 Faculté des Sciences et Techniques de Tanger, laboratoire de the Nevado-Filabride Complex during the Upper Neogene. The Géochimie organique, B.P. 416, Maroc. younger system records N-S extension controlling the 2 Faculté des Sciences de Tunis, département de Géologie, formation of the Kert Basin during the Messinian-Pliocene. The laboratoire de Géochimie organique, 1060 Belvédère, Tunisie. Movement of the Nekor Fault during the Upper Miocene to 3 Faculté des Sciences Semlalia-Marrakech, laboratoire de Quaternary with a lateral motion and a normal component Géodynamique, U.F.R . « Dynamique de la lithosphère. translated the upper Subrif units towards the WSW, producing Structure et géoressources », B.P. S.15, Maroc. also the final exhumation of the Temsamane rocks and the The presence of seismic anomalies and the identification of formation of the Boudinar Basin. an important petroleum source rocks in the Qasbat Tadla Keywords: Structure; Metamorphism; Ras Afraou; Temsamane; basin, mature incites to a modelling which roving to the Morocco reconstitution of oil history of the basin. This modelling is based on a simulation of the organic matter evolution during its burial, which is governed by the chemical mechanisms of Lithospheric isostatic rebound during the Messinian Salinity depolymerisation. The burial simulation integrates the main Crisis in Mediterranean geological and geochimical concepts. The reconstitution of the Loget Nicolas1, Karpytchev Mikhail2, Van Den Driessche basin thermal burial history consists in determining amounts Jean3 geothermal gradient which takes into account the evolution of 1 Collège de France, Chaire de Géodynamique, Trocadéro, lower Silurian source rocks and all thermal phenomena which Europôle de l’Arbois BP80, 13545 Aix-en-Provence (France). took place in the basin during the geological time. This flux can 2 Centre littoral de géophysique, Université de La Rochelle, be simulated at the transformation rate of the organic matter 17042 La Rochelle (France). that can be deduct from the evolution curve of the IH versus to 3 Géosciences Rennes, Université de Rennes 1, 35042 the depth. The geodynamic evolution of the basin can be Rennes (France). simulated to pale burial curve of source rocks.

The Messinian Salinity Crisis that occurred between 5.96 The simulation permitted to determine the main periods of Ma and 5.32 Ma in Mediterranean is one of the most formation and the extrusion of hydrocarbons The generation of spectacular geological events of desiccation of an enclosed hydrocarbons occurs in two phases. The first phase sea with a drop of the base-level that reached at least 1500m (Tournaisian – Visean) is generalized for all the basin. The as well as a massive deposition of evaporites. Surprisingly, generation continues until the upper Visean and Namirian in despite the enormous mass of sediment and water displayed the gutter piggy-back and gutter synclinal respectively. The (charge or discharge) during this period, no evidence of second phase which corresponds to the uplifed anticline and

172 last from the Permian until the end of the Jurassic. The Geothermal gradient in the South Moroccan Basins extrusion of hydrocarbons takes place also in two phases. The determined from oil well temperature data first phase (Tournaisian -upper Visean) is generalized for all the Y.Zarhloule1, M. Boughriba1, A. Lahrach2, A. Rimi3, L. basin and the second phase (Permian-Jurassic) is peculiar to Boudchich1 the central sector. Their mature character having produced the 1 University of Mohamed I, Faculty of Sciences, Department of considerable quantities of hydrocarbons of which a great part Geology, B.P, 524, Oujda, Morocco. 2 FST, Fès, Morocco (until 50%) migrated toward the potential traps. 3 Department of Earth’s Physics, Scientific institute, B.P. 703, Rabat, Morocco Key words : simulation - Genex model - organic matter generation - extrusion - hydrocarbons. The study concerns the Errachidia-Boudenib, Essaouira- Agadir and Tarfaya-Laayoune basins. It attempts to study the geothermal behaviour of the Anti-Atlas structure and the GS 40 : Geothermics geodynamic activity in the region, well known by the 1962 earthquake of Agadir. New evaluation of the heat flow in Morocco This work is based on 580 temperature measurements A. Rimi1, F. Lucazeau2, B.Goutorbe2, N. Mhammdi1, Y. obtained from 128 on shore and off shore oil wells distributed Zarhloule3, A. Chakor Alami 4, A. Ouarghioui4, A. Aït Salem4 as follows: 49 Tb (mud temperatures) and 14 Tdst (Drill Stem 1 Département de Physique du Globe/ Institut Test) in the Errachidia-Boudenib basin, 298 Tb and 48 Tdst for Scientifique/Avenue Ibn Battouta B.P. 703 Rabat Essaouira-Agadir basin, and 155 Tb and 16 Tdst for the 2 Géosciences Marines, (UMR7154)/ Institut de Physique du Tarfaya-Laayoune basin. An empirical relation based on the Globe/ 4, place Jussieu/ Paris difference between Tb and Tdst is used to correct mud 3 Université Mohamed I, Faculté des Sciences/Bd Mohamed temperatures. Estimated geothermal gradients range between: VI, BP 524Oujda 16°C/km and 36°C/km, with an average value of 28°C/km in 4 Office National des Hydrocarbures et des Mines (ONHYM) 34 the Errachidia-Boudenib basin; 14°C/km and 35°C/km, with Ave Al Fadila Rabat 10050 Maroc an average value of 21°C/km, in the Essaouira-Agadir basin; The thermal field in sedimentary basins of continental and 17°C/km and 35°C/km, with an average value of margins is disturbed by subsurface water circulations in 21°C/km, in the Tarfaya-Laayoune basin. onshore area while classical oceanic measurements in offshore The regional distribution of geothermal gradients in the area are disturbed by seasonal fluctuations induced by surface Errachidia-Boudenib basin shows that the relatively high marine currents. geothermal gradients could be related to subsidence and the The study aims to propose a new analysis of terrestrial heat basement proximity, respectively, in the south-eastern and flow along the Moroccan continental margin, based on rocks southern sectors of the basin. thermal conductivity estimate from the oil wells geophysical In the Essaouira basin, the higher observed geothermal logs. This method uses the neurons networks technique which gradient in the centre is discussed in relation to the deep has been tested successfully worldwide in the ODP wells. hydrodynamic effects while it is related to the basement Bottom Hole Temperatures are corrected by using the faulting in the Agadir basin. cylindrical source models. The geophysical logs data will be reduced in order to estimate the heat flow, as well as the in- The Tarfaya-Laayoune basin presents two domains with a depth temperatures distribution. In the second time, the study relative high geothermal gradient (greater than 30°C/km): the will also examine the possible presence of the Bottom on-shore domain characterized by a great fault basement of Simulating Reflectors characterizing a thermodynamic N65 to N70 direction revealed by geophysics and the off shore interface between methane hydrates and free gases. These domain where the Miocene volcanoes of the Canary Islands BSR can be interpreted in term of temperature and integrated contribute to increased geothermal gradients. in a total analysis of the present day thermal transfers. The scientific repercussions will relate to the total knowledge of heat transfers on the continental margins and from an economic point of view the study contributes to a better understanding of the hydrocarbon systems and the low-mean enthalpy geothermal potential.

The First MAPG International Convention, Conference & Exhibition 173 Marrakech Convention Center, October 28 - 31, 2007 Thermal regime, hydrodynamics and petroleum occurrences nappes and the External Rif unites. in the essaouira basin Y. Zarhloule1, M. Boughriba1, L. Boudchich1, A. Rimi2, M. The K/Ar geochronology reveal in the Jurassic samples Verdoya3, A. Correa4 and J. Corneoro4 ages between 132 and 126 My. And in the cretaceous samples 1 University of Mohamed I, Faculty of Sciences, Department of the K/Ar ages give away 82 to 78 My. Geology, Laboratory of hydrogeology & Environment, BP 524, Oujda, Morocco. The Ketama and flyshs Tizirene unites are dates by fission 2 Department de Physique du Globe, Institut Scientifique, track method : the apatites delivered a Miocene age (13 and Rabat, Maroc. 19 My). However, the zircon extracting from the Jurassic of 3 Laboratory of Geophysics & Radiometry, Department of Ketama and cretaceous sediments of Ketama and Tizirene are Geology ? University of Gene, Italy dated between 505 to 76 My. 4 Geophysical Centre of Evora, University of Evora, Rua Romao Ramalho 59, 7000-671 EVORA, Portugal In another hand, the thermal characteristics of zircon and apatite fission track and the newly formed mineral deduced by Subsurface geothermal gradients play a significant role in X ray diffraction analysis have allowed fixing the degree of the oil exploration. Based on a synthesis of the shallow two cretaceous thermal events of the Ketama unit. Thus, the temperature measurements in hydrogeological wells and the first does not exceed 200 °C, the second is 300 to 350°C. deep ones recorded in electric logs from exploratory and development oil well in Morocco especially in the Essaouira In the Tizirene nappe, the olded zircon fission track ages basin. A study of heat flows and geothermal gradients was and the Miocene apatite fission track data indicate that terrains undertaken to more understanding the relation involving water, of these nappe have been reheated to more of 120 °C after temperature and oil movement within a given sedimentary their deposit and that the maximal temperature did not reach basin. 220°C during their thermal history. They evoke and confirm The possibility that positive geothermal anomalies and thus the diagenetic-anchizone character of the cretaceous hydrocarbon occurrences in deep sedimentary basins are flysh sediment. genetically related to formation water flow has been suggested We thus think that these cretaceous metamorphic events by various authors. These suggestions have been who are contemporaries at those recorded in Algerian Tell, corroborated by this study, particularly in the Essaouira basin marked an important geodynamic history in the evolution of Petroleum accumulations are located within a region of a North Africa. relatively high geothermal gradient reaching more than 35°C/km and is located in areas of formation- water Keywords: metamorphism, fission track, K/Ar dating, Exernal Rif. convergence..

Key word: Geothermal gradient, petroleum accumulations, GS 39 : Geophysical modelling aquifer, hydrodynamism, oil well, reservoir, heat flow. Contribution of gravimetric and magnetic data for making 3D GS 14: Isotopic dating in Morocco : State of the art modelling of the geological structures and formations in and perspectives Eastern Morocco A Abdelouafi1, L. Ait Brahim1, B. Tadili2, A. Manar3 and A. Evidence of cretaceous metamorpfism in the External and Bouaza1 flysch unites (Rif, Morocco) 1 Dpt. des Sciences de la Terre, Univ. Mohammed V, Rabat, Azdimoussa Ali1, Asebriy Lahcen2, Bourgois Jacques3 and Marruecos Poupeau Gérard4 2 Dpt. de Physique du Globe, Institut Scientifique, Agdal, 1 Laboratoire des G éosciences Appliquées, Faculté des Rabat, Marruecos Sciences, Oujda, Maroc. 3 Dpt. de Mathématiques et Informatique, Univ. Mohammed V, 2 Université Mohamed.V, Institut Scientifique, BP 114, Agdal, Rabat, Marruecos Rabat, Maroc. 3 Université Pierre-et-Marie Curie, Boîte 119, 4, place Jussieu, Brute measurements of the gravimetric partner (4264 75252 Paris Cedx, France. stations with a step of 1 km) covering the maps to the 1/50 4 Université Mortaigne, Bordeaux I, France. 000 of kariat Arkmane, Trifa, Zaio, Saidia, Berkan, Ahfir, Al Ayoun, Sidi Bou houria, Beni Oukil, Mestigmer, Metroh, Jerada Using K/Ar fine fraction data and apatite-zircon fission track and Oujda; realised by company LERICI in favour to the completed by the clays X ray diffraction analysis. We focus to Ministry for Energy and the Mines, firstly, allowed us to characterize the thermochronologic evolution of the flysh elaborate a database of an Excel table format (coordinated,

174 value of G, etc). Electrical tomography and geological radar investigation: Detection and 2D modelling of underground cavities in the Then, to obtain the values of the Bouguer anomaly, some Beni Mellal “Medina” corrections (of Bouguer, free air of latitude etc.) were applied to the measured values of gravity. Using the software Geosoft we A. Najine, M. Filahi, D. El Azzab, K. Elkhammari and M. Himi could obtain maps of the vertical gradient, the residual and the The collaps of underground cavities man-made or formed prolongation upwards, from the Bouguer anomaly. naturally by water flow in the “Médina” of Beni-Mellal has an Interpretation of these anomalies (positive and negative) impact on the existing structures on the surface. Recently allowed us to specify the layout and the extension of someone several tens of buildings have been sinkhole so it was tectonic accident and to delimit the principal formations and necessary to forecast the movement of the soil surface. geological structures of the area of study. This work is going to Notable contrasts of the physical properties existing between complete those realized by Van Den Bosch (1971) Kattach and the cavities and boxing to them offer a favourable context to al.. (2004) and Vanié and al.(2005) characterise them by the geophysical methods. The Modelling from the residual of the total magnetic field and techniques of the electrical pole-pole array and geological the Bouguer anomaly allow us to determine geometry and radar in the urban area were used. Results of the 2D electrical extension of the various geological formations in Eastern resistivity mapping reveal body whose top is located between Morocco. 1 to 3 m depth. We interpret this body as an underground cavity according to the local context of the survey which is led Keywords: Gravimetry; Magnetic data; 3D modelling; Morocco on a ground including a dense network of cavities. The Res2Dinv inversion program was used to create resistivity models of the subsurface that would simulate apparent Analysis of gravimetric anomalies and 3D modelling of resistivities that correlate with the measured data. One of the Mekkam granite intrusions (Morocco) most important results of inversion is better estimates of depth D. El Azzab and Y. Ghfir for cross-section plots, turning pseudo-sections into better approximations of the subsurface variation. In conclusion the The Mekkam region consists mainly of liasic limestone, cavities of Beni Mellal Medina have different and complex cenozoic deposits and shows many granite intrusions shape, located at few meters depths and are 3 to 4 m height. surrounding by the Paleozoic series recovered by triasic formations in angular discordance. The goal of our study is to GPR records show two types of reflections. The first one is constraint the shape and thickness of these granites using the superficial and represents stratifications in the shallow levels of potential field geophysical software available to the public from the ground. The second is deeper and more energetic. It USGS and Transmap program to calculate the upward corresponds probably to cavities interfacings. The two continuation. The data consist of Bouguer anomalies map investigation methods are well correlated and agree with covering the South part of Guercif, Debdou and Mekkam area. several coring at the vertical of anomalies. It was digitized and interpolated on a regular grid from which the first-degree regional field was subtracted. The residual Key Words: Cavity, electrical tomography, anomaly exhibits several anomalies especially the negative ones which are coinciding with the intrusive exposures of the GPR and Ert Modelling to detect pipeline Alouana body in the West, and Soulouina in the East part of the M. Himi1, A. Casas1, R. Lázaro1, J. Tápias2, M. Jettafi1, D. El studied area. The model is constructed using tree surfaces Azzab3, A. Najine4 (top, bottom, density). It’s build up considering the top 1 University of Barcelona. Department of Geochemistry, coinciding with the pluton outcrop, while the density contrast is Petrology and Geological. Faculty of Geology. -0.12 according to the Van Den Bosch (1972) publication. The 2 University of Barcelona. Departement of Natural Products, bottom surface was calculated in order to constraint the Vegetal Biology and Soil Science. maximum intensity of anomaly. First the 2D model was carried 3 University Sidi Mohammed Ben Abdellah, FST Fez. out to have an idea on the shape and the thickness of the Department of Geology. BP 2202 granites. The final model is composed of two domes. The 4 University Cadi Ayyad, FST Béni Mellal. Department of Salouina granite represents one small part of a great mass geology which extends on a 12 km depth. This massif is connecting with a second one to the North-East without any evidence at Ground Penetrating Radar is the non-destructive the surface, but has 8 km thickness. These common electromagnetic methods that use radio waves in high characteristics enable us to suggest a common origin and frequencies, and has several applications in near surface setting of these plutonic bodies. investigations, such as mineral exploration, geological, geotechnical, hydrogeological, environmental, archaeological Key Words: granites, Bouguer anomaly, modelling, Mekkam. studies, etc. Particularly GPR is efficient to characterization and

The First MAPG International Convention, Conference & Exhibition 175 Marrakech Convention Center, October 28 - 31, 2007 interference mapping in subsoil, for example, in detection of building through 1) its detrital and thermochronological steel and plastic tank, oil, and gas pipeline, water pipeline, signatures, 2) sedimentary thicknesses, but also 3) thermal galleries of pluvial waters, electrical and telephony cables, overprint on basement rocks. It is thus the key region to trace among others. past and recent traces of mountain building in the Andes of Ecuador.

GPR has a long and sometimes checkered history of pipe Keywords: Andean Amazon Basin, Cordilleras, detrital, detection. Although it is perhaps the best general pipe locator thermochronology, accretion available, it is often mistakenly assumed to be a silver bullet. In fact, GPR has difficulty in highly conductive clay and silty soils. Sometimes clutter from other objects can obscure pipes. And Fault-slip analysis and their constraints on paleostress state most commonly, subtleties in processing and interpretation evolution mean that less skilled surveyors may fail to detect pipes that Judith Sippel and Magdalena Scheck-Wenderoth would otherwise be clearly resolved. This means that GPR can GeoForschungsZentrum Potsdam, Sect. 4.3: Organic never be 100% successful at locating pipes. However, geochemistry, Telegrafenberg C427, D-14473 Potsdam, expanding GPR’s capabilities into full 3D images has made Germany detection much more robust, and interpretation much simpler. This means that GPR is really now entering into a new phase We investigate different methods to derive the paleostress of capability, making it far more versatile than ever before. fields which controlled the evolution of sedimentary basins. Therefore, field studies are carried out along the south-western The combination of GPR and ERT for detecting pipeline margin of the Central European Basin System where Late and structure can give good results. Palaeozoic and Mesozoic rocks of the basin fill are present in outcrops bearing the imprints of several deformation phases. In this paper we have used the too methods to modelling same buried objects, varying the dielectric permittivity, the Structural analysis includes the measurement of fault-slip diameter, depth and frequency for the GPR; and resistivity, data and collection of kinematic and chronological indicators. thickness, electrode spacing and geometric array for the ERT. Relating fault kinematics to stress states implies that all faults under consideration have slipped in response to the same Session: The tectonics of vertical movements, deviatoric stress. For this reason, heterogeneous fault-slip data mountain building and subsidence -Europe and the from outcrops documenting polyphase deformation must be world separated into homogeneous subsets before stress inversion. We present a new technique facilitating both, data separation Andean mountain building: a review of 10 years study in and stress inversion, by integrating the results of the PBT- eastern Ecuador method (Sperner et al., 1993) and the Multiple Inverse Method (Yamaji, 2000). For each homogeneous subset the reduced G.M.H. Ruiz1, D. Seward2, W. Winkler2 and R. Spikings3 stress tensor is determined which fulfils both, the criterion of 1 Neuchâtel, Switzerland low misfit angles (Wallace-Bott hypothesis) and that of high 2 ETH Zurich, Switzerland shear-to-normal-stress ratios (Mohr-Coulomb criterion). 3 Geneva, Switzerland Our results indicate that the dominant signals of Our work since ten years in the Eastern Cordillera, Sub- deformation in the study area are related to different Andean Zone and Andean Amazon Basin of Ecuador aims to compressive stress regimes in response to the Alpine collision. quantify periods of vertical movements (denudation or burial) in The reliability of our technique is confirmed by correlating the frame of the geodynamic of the northern Andes. The Andes results from outcrops of different rock ages. This consistency are there constituted of five morpho-tectonic domains, from regards calculated stress states as well as chronologies locally west to east: the coastal blocks, the Western Cordillera, the derived from cross-cutting relationships. Inter-Andean Valley, the Eastern Cordillera, the Sub-Andean Zone and finally the Andean Amazon Basin. Different methods were used along and across the chain: these are Fission-Track Exhumation history of Fuerteventura on apatite and zircon, (U-Th)/He on apatite, Ar/Ar, provenance Martin Wipf1, Ulrich Anton Glasmacher1, Thilo Bechstädt1 and analysis and tectonic subsidence. Results point toward Axel Emmerich2 accelerated periods of denudation in the Early Cretaceous, 1 Institute of Geology and Paleontology, Heidelberg University, Eocene, and Late Miocene that can be related to the accretion Germany; of allochtone terranes against the Ecuadorian margin to the 2 RWE Dea AG, Hamburg, Germany West but also to the subduction of the buoyant Carnegie ridge. The basal complex of Fuerteventura has been reported to The syn-orogenic basin to the east is the Andean Amazon be of Late Cretaceous age (Balogh et al.; 1999). Based on Basin that partly or totally preserved the record of mountain

176 published K-Ar-ages, the volcanic rocks are grouped into three Ridge (CPR) and the adjacent Horseshoe and Seine Abyssal classes; older than 20 Ma, 14-16 Ma and 5-3 Ma (Ancochea Plain corresponding to the profiles SW8 to SW16. Seismic et al.; 1996). Only two apatite fission-track ages are published acquisition was performed using a 10 m long 8-airgun array so far from an alkaline pluton in NW-Fuerteventura (de Ignacio totalling 1050 c.i. and a streamer with 2.4 km of active section, et al., 2002). The fission-track ages of 25.4±3.6 Ma and totalizing 96 channels with 25 m separation. Standard MCS 29.3±3.5 Ma are in agreement with K-Ar ages from the same processing was accomplished using PROMAX software, and area indicating rapid exhumation. Volcanic rocks and dikes of included: data re-sampling at 4 ms, channel and shot editing, Micocene age show a second phase of magmatic activity. In top mute in shot gather domain, true amplitude recovery, anti- the west of Fuerteventura, the occurrence of a palaeo-surface alias, FK fan filter, band-pass filter, predictive deconvolution, indicates exhumation of the basal complexes in the Upper geometry CMP gather, NMO, stack, and Stolt FK migration Miocene. This palaeo-surface is partially covered by sediments (1500 m/s). The MCS lines presented here were acquired in that are subsequently covered by Pliocene basaltic flows order to obtain the best image of the structure and tectonic (Coello et al.; 1992). Intrusive, dikes, and extrusive rocks of evolution of the Horseshoe Abyssal Plain (HAP), the Seine various ages as well as Cretaceous siliciclastic sedimentary Abyssal Plain (SAP) and Coral Patch Ridge (CPR). This set of rocks were sampled and analysed by low-temperature lines help us to understand the distribution of the deformation thermochronometry. Apatite and zircon fission-track and (U- in the study area, the involvement of basement in the regional Th)/He data will be presented together with thermal modelling tectonics, and the seismic activity occurring on the region. The to reveal the complex exhumation history of Fuerteventura. basement and sedimentary cover are clearly imaged on the Additionally, a DEM from Fuerteventura was built to gain a MCS profiles. We have differentiated six seismo-stratigraphic better understanding of the transport direction of the units: I) a Triassic to lower Jurassic unit, composed of sediments. While massif landslides towards the west have evaporites and carbonates; II) an upper Jurassic to Aptian unit, been reported (Stillman, 1999), sediment transport towards the made up of marls and limestones; III) an upper Cretaceous to eastern offshore area is poorly constrained due to a lack of lower Eocene terrigenous unit; IV) an upper Oligocene to seismic data. Analysis of the DEM shows however that Miocene unit, only recognized at the HAP; V) the Allocthonous sediments have been transported towards the east and Unit of Gulf of Cadiz of Tortonian age, and VI) the uppermost northeast. unit of Plio-Quaternary age, composed of hemipelagites, countourites and turbidite layers. The structure of the Key words: Exhumation, Fission track, (U-Th)/He basement follows a horst and graben geometry corresponding to the Mesozoic tectonic pattern, reactivated during the Tectonics of the Coral Patch Ridge area and adjacent Neogene. The CPR is composed of a series of positive relieves corresponding to the eastern prolongation of the Coral Patch Horseshoe and Seine Abyssal Plains (Gulf of Cadiz) based on Seamount which abruptly ends against a NW-SE trending new multichannel seismic data fault. The CPR consists of a series of narrowly spaced ENE- Sara Martínez1, Eulàlia Gràcia1, Rafael Bartolomé1, Pedro WSW trending folds and thrusts mainly with NW vergence, Terrinha2, Abdelouhad Birouk3, Juanjo Dañobeitia1, Valentí although conjugated faults are also observed, corresponding Sallarès1 and SWIM-06 cruise party to the Seine Abyssal Hills. We have also identified a 300 km 1 Unitat de Tecnología Marina–CSIC, Centre Mediterrani long WNW-ESE trending lineament corresponding to an active d’Investigacions Marines Ambientals, 08003 Barcelona, Spain dextral strike-slip fault that cut across most of the HAP, the 2 Instituto Nacional de Engenharia, Tecnologia e Inovação, Horseshoe Fault and the western part of the Gulf of Cadiz 2721-866 Alfragide, Portugal accretionary wedge. Present-day active faulting is observed at 3 Centre National pour la Recherche Scientifique et Technique, the HAP and SAP, mainly subvertical faults cutting the whole Institut National Géophysique, 10102 Rabat. sedimentary sequences up to the surface. They are also During June 2006 we carried out the ESF-EuroMargins associated with earthquake swarms. Forthcoming pre-stack SWIM marine geophysical cruise on board the Spanish RV migration of selected MCS profiles in the frame of the EU- Hespérides (PI. E. Gràcia) with the main objective to NEAREST project will allow us to obtain the corrected characterize the geometry, deep structure and timing of geometry for detailed neotectonic interpretation and deformation of the active faults located at the westernmost calculation of fault seismic parameters. Gulf of Cadiz (SW Iberian Margin). This region is where the epicentres of recent large magnitude earthquakes are located, such as the 28 February 1969 (Mw 8.0) and the 12 February 2007 (Mw 6.0). We acquired 16 high-resolution multi-channel seismic (MCS) profiles together with Simrad EM120 swath- bathymetry and TOPAS sub-bottom profiler, totalizing more than 2700 km of data. Here we will focus on the Coral Patch

The First MAPG International Convention, Conference & Exhibition 177 Marrakech Convention Center, October 28 - 31, 2007 An isostatic residual gravity map of the Iberian Chain and the lithospheric scale boundaries in Europe. In SE Poland, the TTZ significance of isostatic residual anomalies together with surrounding crustal blocks is characterized by Luís Rivero1, Joan Guimerà2, Ramon Salas1 and Albert particularly complex structure, formed during entire Casas1 Phanerozoic, during several phases of continental collision, 1 Departament de Geoquímica, Petrologia I Prospecció strike-slip movements, basin formation and inversion. Its Geològica. structure at various depth levels has been studied using deep 2 Departament de Geodinàmica i Geofísica. Facultat de refraction and industry reflection seismic data as well as gravity Geologia, Universitat de Barcelona, C/ Martí i Franquès s/n, and magnetic maps. During Devonian – Carboniferous, the 08028 Barcelona, Spain Lublin – Lviv Basin developed along the TTZ, that belonged to the far-distance foreland of the Variscan orogen. Following An isostatic gravity map of the Iberian Chain and period of subsidence and sedimentation this sedimentary surrounding areas has become possible with the compilation basin was inverted in Late Carboniferous. Inversion was of a gravity data base of the University of Barcelona associated with formation of various compressional / Gravitimetric Prospection Geologic Group. transpressional structures, partly rooted in the Precambrian basement, partly detached at shallower levels in the Silurian The relief of the Iberian Chain is a direct consequence of shales or mid-Devonian evaporites. During Permian – the tectonic structure. The isostatic gravity map allows us to Cretaceous, the Mid-Polish Trough evolved above the TTZ, observe a good correspondence between relief and the that formed easternmost part of the Central European Basin distribution of isostatic residual anomalies. System. Regional subsidence of this sedimentary basin was In this way, the central and NW sectors of the Iberian Chain associated with extensional activity of normal faults, generally display two WNW-ESE high anomaly areas (up to 40 mGal) parallel to the TTZ. In Late Cretaceous – Paleogene the Mid- which match the structurally uplifted basement structures Polish Trough was inverted and its axial part was deeply (more than 100x50 km) giving rise to the topographic elevated eroded. In SE segment of the Mid-Polish Trough inversion- areas. These high anomalies are separated by a low anomaly related erosion reached Palaeozoic basement. Late area that coincides with the Tertiary Almazán piggy-back basin Cretaceous – Paleogene inversion was associated with displaying a synclinal structure. Moreover, these highs also compressional / transpressional reverse reactivation of major display a linear NW-SW trend, which was possibly caused by normal faults and uplift of basement blocks. It also involved a basic deep pluton below the Iberian Chain. This pluton strike-slip movements, both parallel to the TTZ, as well as intruded simultaneously with the opening of the oceanic N perpendicular to the TTZ, e.g. along the Grojec fault zone. Atlantic and Bay of Biscay Basins during the Mid-Late During inversion inherited Paleozoic fault zones were Cretaceous and gave rise to a regional thermal event and a reactivated and new fault zones were formed. significant aeromagnetic anomaly along the Iberian Chain. The Rwenzori, a small mountain range in a rift system – uplift Nevertheless, in the SE sector of the Iberian Chain, despite and exhumation history the high topography of the area, low anomalies (up to –25 F. Bauer1, U.A. Glasmacher1, P. Reiners2, U. Ring3, A. mGal) affecting a broader area of the Chain (150 x 200 km) Schumann4, B. Nagudi4, and T. Bechstädt1 were calculated. This low area also contains a NNW-SSE linear 1 Institute of Geology and Paleontology, Heidelberg University, low, which is oblique to the NW-SE trend of the Alpine Germany structures. 2 Department of Geosciences, University of Arizona, USA Other relevant features are the very low anomalies (up to 3 Department of Geological Sciences, University of Canterbury, –60 mGal) calculated in the Tajo and Duero Tertiary basins New Zealand (more than 25x100 km), both separated by the low anomaly 4 Department of Geology, Makerere University, Kampala, area of the Sistema Central Ranges basement uplift. Uganda

The Rwenzori Mtns. are situated in the northern part of the Devonian-Cretaceous tectonostratigraphic evolution along western branch of the East African Rift System (EARS), along the Tornquist – Teisseyre zone in SE Poland – new models the border between the Democratic Republic of Congo and based on seismic data Uganda. They represent an uplifted basement block that Piotr Krzywiec consists of metamorphic rocks of Precambrian origin, showing Polish Geological Institute, ul. Rakowiecka 4, 00-975 Warsaw, similar lithologies to the metamorphic rocks of the Tanzania Poland craton. Due to their significant height of more than 5000 m and their extraordinary position within a rift setting, the Rwenzori The Tornquist – Teisseyre Zone (TTZ) separates the East Mtns. represent a key area for rift-flank uplift in the EARS. European Craton (EEC) from the Palaeozoic Platform, and Furthermore they seem to play a significant role regarding could be regarded as one of the most fundamental crustal / climate changes in eastern Africa by influencing regional

178 atmospheric circulation resulting in a significant impact on the Improving accuracy of structural model in thrust belt using climate in central and eastern Africa. integrated workflow Anne Jardin1, Martin Bêche1, Muriel Thibaut1, Siegfried Apatite fission-track and apatite (U-Th)/He Lallemant2 and Donna Kirkwood3 thermochronometric data are combined with thermokinematic 1 IFP, 1-4 av. de Bois-Préau, 92500 Rueil-Malmaison, France modelling to reveal the uplift and exhumation history of this 2 Université de Cergy-Pontoise, France small mountain range. Similar to other areas of the EARS the 3 Commission Géologique du Canada, Québec, Canada thermochronometric data cover the evolution since the Early Cretaceous. A large gap in ages occurs between the Lower In thrust belt settings, the accurate determination of Cretaceous and the Oligocene. The exhumation rates increase subsurface structures often remains a challenge. This in Paleogene to Neogene times. The present study is part of presentation aims at showing that a strong combination of the DFG-financed RiftLink-research project. geological and geophysical studies including field work, laboratory measures, seismic imaging and geological Key words: Thermochronology, East African Rift system, Exhumation modelling is essential to ensure the quantitative evaluation of the main structural features: fault characteristics, layer Session: The tectonics of vertical movements, thickness variations, depth interfaces, erosion time mountain building and subsidence -Europe and the parameters. world This method benefits from advances in structural modelling and seismic migration software and the workflow is a Constraints on deformation mechanisms during folding by sequence of successive applications requiring efficient control combined analyses of Anisotropy of Magnetic Susceptibility criteria between steps. The structural model is then built step (AMS), calcite twins and fractures. Exemple of Sheep by step with various types of model grid parameterization. The Mountain Anticline (Wyoming, USA) consistencies between these different models must be Khalid Amrouch1,2, Philippe Robion3, Jean-Paul Callot2, checked using structural coherency controls. Olivier Lacombe1, Nicolas Bellahsen1 and Jean-Marc Daniel2 1 Université Pierre et Marie Curie, Paris, France The case study of the central part of the Gaspé belt 2 Institut Français du Pétrole, Rueil-Malmaison, France (Northern part of Canadian Appalachians) is used to illustrate 3 Université de Cergy-Pontoise, Cergy, France the benefits of this integrated geological-geophysical approach, especially the limitation of the geological ambiguities On the basis of the analyses of AMS data, calcite twins and and the estimation of quantitative structural parameters. The fractures, we discuss the relationship between stress, strain present belt geometry is complicated by the fact that the and fold evolution in a folded-fractured reservoir analogue, the Siluro-Devonian rocks were deposited on and deformed over Sheep Mountain Anticline (Wyoming, USA). The NW-SE the previously structured Cambro-Ordovician basement. Our trending fold is asymmetric, basement-cored, and formed objective is to propose and validate a new 3D structural model during the Laramide orogeny. AMS results reveal three different for the Acadian fold belt. directions of K1 (maximum susceptibility axis), parallel, perpendicular and oblique (E-W) to the fold axis, respectively. Firstly, depth imaging of 2D seismic lines was performed to These results also show the variability of the orientation of the improve the time to depth conversion and to provide more ‘strain’ ellipsoid through the anticline, the AMS fabrics being reliable seismic interpretation. Then, the geometrical less developed in the forelimb than in the backlimb. Five main consistencies of the model were ensured by applying fracture sets are observed in the field. Among those, a NE kinematic restoration. Finally, using Kine3D, a plug-in trending joint set that formed just prior to, and during initial developed by IFP, a new 3D model was built integrating both anticline growth is only present in the hinge and the backlimb, seismic and geological data. Between each step, the model which supports, like ASM, that the backlimb was more description is checked using geometrical and geological deformed than the forelimb during early fold evolution. consistency criteria which are used to update the structural Computerized inversion of calcite twin data from veins and model. rock matrix provide information about the evolution of the stress tensor through time and space. The results especially This integrated workflow is applied to obtain more realistic document a layer-parallel maximum compressive stress geometries that provide additional knowledge in order to secondarily tilted during folding. These complementary identify new potential structural traps for hydrocarbon approaches reveal a powerful tool to constrain both internal exploration in complex structures. rock deformation, vein chronology and kinematics, and fold evolution.

Key-words : calcite twins, rock magnetism, fracture, folded-fractured reservoir.

The First MAPG International Convention, Conference & Exhibition 179 Marrakech Convention Center, October 28 - 31, 2007 Crustal structure of the US Chukchi Shelf: Insights from 9-km Thermochronological data and denudation history along a long-offset ArcticSPAN™ 2-D seismic data transect between Chañaral and Pedernales (≈26º S), north Menno G. Dinkelman1, Naresh Kumar2, James Granath2 and Chilean Andes: orogenic implications Pete Emmet2 Thierry Nalpas1,2, Gérard Hérail2, Constantino Mpodozis3, 1. Chief Geologist, GX Technology, Houston, Texas 77042, USA Rodrigo Riquelme4, Jorge Clavero5 and Marie-Pierre Dabard1 2. Consultants, GX Technology, Houston, Texas 77042, USA 1 Géosciences Rennes, Université de Rennes1, Campus de Beaulieu, 35042 Rennes cedex, France In 2006, GX Technology acquired 3,132 km of 2-D seismic 2 IRD-LMTG, Román Díaz 264, Casilla 53390, Correo Central, data in the US part of Chukchi Sea, offshore northwest Alaska. Santiago, Chile and Departamento de Geología, Facultad de The acquisition was designed to image down to the base of Ciencias Físicas y Matemáticas de la Universidad de Chile. the crust with a 9-km long cable and 18-second recording. Santiago, Chile Pre-stack Time Migration (to 16 sec) and Pre-stack Depth 3. SIPETROL, Av. Vitacura 2736, Las Condes, Santiago de Migration (to 40 Km) was carried out on the entire data set, Chile, Chile thus imaging MOHO. To the best of our knowledge, it is the 4 Universidad Católica del Norte, Avenida Angamos 0610, only dataset of its kind available in the area. Antofagasta, Chile 5 SERNAGEOMIN, Av Santa María 0104, Providencia, The post-Devonian extensional crustal structure of Chukchi Santiago, Chile Shelf related to rigid rotation of Arctic Alaska and Chukotka from the Mackenzie region to form the Beaufort-Canada basin The Chilean Andes along the southern Atacama Desert is widely accepted, but the basement geology of Chukchi is (26°-27°S) include into five morphotectonic units: (Coastal poorly imaged by previous seismic surveys and is not well Cordillera, Central Valley, Precordillera, Preandean depression understood. An integration of magnetic and gravity data with and Western Cordillera). Uplift and denudation have produced these long-record seismic data has allowed the recognition of a large amount of sediments during the Cenozoic but only in a deep pre-Franklinian crystalline basement and associated the Preandean depression, thick sequences of Tertiary internal crustal inhomogeneities. sediments has been preserved, while in the Precordillera and Central Depression a thin blanket of Miocene Atacama Gravels The sequence regionally recognized as prospective for infill paleovalley (Mortimer 1980; Riquelme, 2003; Gabalda et hydrocarbons consists of 8-10 km of well-imaged post-Upper al., 2005). In this contribution we present a new set of Devonian sedimentary rocks. These new data also image thermochronologicals data that will allow us to establish the several kilometers of pre-Ellesmerian rocks that record multiple ages of main exhumation episodes, which can be tied to as-yet poorly understood tectonic events. In the eastern periods of erosion and Andean uplift along the western slope Chukchi platform a mildly deformed and apparently of the southern Central Andes. That regional exhumation unmetamorphosed pre-Ellesmerian sedimentary section, >10 occurred in three steps along the Chañaral-Pedernales km thick, transitions to the west into a deformed region with a transect: Mid-Cretaceous to Paleocene on the Coastal number of Franklinian and possibly older extensional and Cordillera, Eocene from the Central Valley to the Pedernales compressive features. In the north, a thick (>10 km) Basin, and Oligo-Miocene at Cordillera Claudio Gay. Data sedimentary wedge, a significant part of which is less than 80 shows the eastwards propagation of the exhumation that is my old, has been recognized in the North Chukchi Basin. With interpreted as propagation of the deformation. Only sediments further analysis, this new data set should lead to a originated during the Eocene Oligocene events seem to have comprehensive reevaluation of the Chukchi Shelf. been preserved in the compressive pre-Andean Pedernales basin. At the same time, withdrawal of material towards the Evolution of the Calabrian accretionary prism ocean prevailed along the western Precordillera and Central L. Minelli, P. Casero and C. Faccenna Valley. These considerations indicate that topography is not the Dipartimento di Scienze Geologiche, Università Roma TRE, major factor controlling the amount of mass transfer during Rome, Italy Andean uplift as the adjustments in the volume of mass transferred out of the system seem to track climatic changes We have analysed available reflection multi and single towards semiarid-hyper arid conditions during the Miocene. channel seismic profiles (Calabrian Arc, Ion, Prismed 1, CROP Gabalda G., Nalpas T. and Bonvalot S., 2005. Base of the Atacama mare, Archimede, MS), in Ionian offshore in order to define the Gravels Formation (26°S, Northern Chile): first results from gravity data. structures and the evolution of the Calabrian accretionary ISAG VI, Barcelona. prism during the last 30 Ma. We map out the main structures Mortimer, C., 1980, Drainage evolution of the Atacama Desert of with their timing of activity, and the geometry of the principal northernmost Chile. Revista Geológica de Chile, no. 11, p. 3–28. Riquelme, R., Martinod, J., Hérail, G., Darrozes, J. and Charrier, R., basins. On the base of these data we show that the Calabrian 2003. A geomorphological approach to determining the Neogene to prism changed its style of accretion and deformation during Recent tectonic deformation in the Coastal Cordillera of northern Chile the last 10-15 Ma. (Atacama). Tectonophysics 361, p. 255-275.

180 Quaternary erosion-induced isostatic rebound in the western the upper Silurian to the Dinantian. Those palynozones are Alps based on the inventory of organic microfossils as spores, J.D. Champagnac1,2, P. Molnar2, P. van der Beek3, R.S. Acritarchs and Chitinozoa. Different index taxa with Anderson4, C. Sue4, and B. Delacou6 stratigraphic distribution well establish in others areas (North 1. ETH, Zurich, Switzerland America, Europe and North Africa) allowed to precise the age 2. Department of Geological Sciences and CIRES, University of of Moroccan zones wich recovered almost all the Upper Colorado, Boulder, Colorado, USA Palaeozoic: 3. LGCA, Grenoble University, France • 1 zone in the Upper Silurian (Pridoli) 4. Department of Geological Sciences and INSTAAR,University • 2 zones in the Lower Devonian (Praguian-Emsian) of Colorado, Boulder, Colorado, USA • 2 zones in the Middle Devonian (Eifelian-Givetian) 5. Université de Bretagne Occidentale, 29280 Plouzané, • 5 zones in the Upper Devonian (Frasnian-Famennian- France Strunian) 6. Institut de Géologie, Université de Neuchâtel, Switzerland 3 zones in the Dinantian (Tournaisian-Lower Visean)

Here we test the idea that enhanced Quaternary erosion of This biozonation established for the first time in Morocco, the Alps and isostatic compensation of the mass removed can allowed very interesting correlations not only locals (Moroccan account for the distribution of present-day geodetically Meseta, Middle and oriental Morocco) and regionals (Algeria, measured rates of vertical movement in the western Alps and Libya and Tunisia) but also intercontinentals (South-West quaternary deformation (tilting) of benchmarks. Using the so- Europe, Ardenno-rhenans basins, Canada and North America). called Geophysical Relief (Small and Anderson, Geology, 1998) Those correlations also help to trace the palaeobiogeographic and Kuhlemann’s (e.g., Kuhlemann et al., Tectonophysics evolution of Morocco wich always constituted a bridge 2002) estimated average erosion rate for the Alps, we quantify between gondwanian and laurasian domains. the spatial distribution of erosion and the volume of eroded Key words : Palaeozoic, Spores, Biozonation, Correlation, rock, respectively. From these, we obtain a synthetic map of paleobiogeography. rock eroded within a given time span (1Ma for this study, Champagnac et al., Geology, 2007). GS 09: Hight impact of the Mesozoic-Cenozoic The calculated isostatic response of the Alpine lithosphere Palynology in Petroleum Geology to erosional unloading for a variety of values of the flexural rigidity of the Alpine lithosphere reaches a maximum of ~500 m The Role of Palynology for Dating the Liassic Successions of since 1 Ma in the inner Swiss Alps, and vertical movement extends across the entire belt, including peri-Alpine basins. the Silici Volcanic Deposits of Oued El Maleh, Coastal Meseta, Assuming a steady erosion rate since 1 Ma, this rebound Morocco accounts for half of the measured vertical motion of 1.1 mm/yr S. Rouh1, Z. Youssfi, R. Zahour1, T. Hssaida and F. Oumalch2 in the southern Valais (Kahle et al., NRP20, 1997). 1 Université Hassan II, Mohammedia, Faculté des sciences, Furthermore, finite deformation of lower to middle quaternary Ben M’Sik, Casablanca, Maroc. sedimentary basins of both sides of the belt exibit a tilting 2 ONHYM, Direction de l’Exploration Pétrolière, Division des consistent with our modeling. Thus, the isostatic response to Laboratoire Pétrole, Rabat, Maroc enhanced erosion during Plio-Quaternary times appears to be The studied area is one of the Triassic – Liassic basins of a first-order agent in the alpine realm. the Moroccan coastal Meseta, near the city of Mohammedia.

GS 08: Recent advances in North African The Triassic silici volcanic deposits of Oued El Maleh, more Palaeozoic palynology for petroleum exploration than 70 meters thick, are composed of a silty to sandy conglomeratic unit (20m thick), overlain by basalts (10m) and Palynological Biozonation in the Moroccan Upper Palaeozoic. claystone with gypsum layers (40m). Correlation with Biozonations Established in Europe, North These series, having a fault contact with the cambro- America and North Africa. ordovician micaceous schist basement, are overlain by the K. Rahmani-Antari: Neogene (Villafranchian) conglomerates. Université Mohammed V, Département des Sciences de la Terre, Faculté des Sciences, The tectono-volcanic investigation, together with a Avenue Ibn Batouta, B.P 1014, Rabat, Maroc. sedimentological study, allowed us to propose the kinematics for the opening of this basin, during the Triassic, into a sub- The palynological study of Palaeozoic levels in 5 wells and meridian hemi-graben. one cross section in western and southern Morocco has permit to establish 13 palynological zones or palynozones from

The First MAPG International Convention, Conference & Exhibition 181 Marrakech Convention Center, October 28 - 31, 2007 The sedimentation and the volcanism are guided by the GS 20: Neogene depositional systems Sidi Bouchaïb fault. This fault, striking approximately N10-30, could represent a structural heritage which induced the vertical Clastic deposition of chlorides from Marginal Basins – movement and shifting of the series during the Triassic Examples from the Neogene of Poland and Slovakia distension. Bukowski Krzysztof1, Czapowski Grzegorz 2 The gypsiferous clay horizons, herein investigated, have 1 AGH University of Sciences and Technology, Mickiewicza previously been assigned to the Permo-Triassic. The present 30, 30-056 Cracow, POLAND palynological study allowed us to precisely date this unit, 2 Polish Geological Institute, Rakowiecka 4, 00-975 Warsaw, based on rich Liassic dinoflagellate cysts assemblages. POLAND

Keywords: Dinoflagellate, Liassic; Oued El Maleh; Morocco The studied salt-bearing succession was deposited in the Central Paratethys seaway. The Paratethys was an enclosed sea that existed from the Oligocene to the Middle Miocene Dinoflagellate cyst biostratigraphy and paleoenvironmental times as an interrelated chain of basins of diverse tectonic interpretation of the Cretaceous sequences in the Agadir origin. Evaporites of the Middle-Upper Badenian age (the –Tarfaya region, southwestern Morocco period equivalent to the upper Langhian-lower Serravalian Touria Hssaida1, Aïcha Slimane2 and Fatima Oumalch2 stages) were accumulated in the foredeep area stretching from 1 Faculté des Sciences Ben Msik, Université Hassan II, Poland to Romania. Contemporaneous evaporites also were Casablanca, Morocco deposited in the Transylvanian Basin in Romania, the Trans- 2 ONHYM, Direction de l’Exploration pétrolière, Division des Carpathian Basin of the Ukraine and the East-Slovakian Basin. Laboratoires pétrole, Rabat, Morroco The evaporite series were formed at the boundary of The primary focus of this paper is to report the results of nannoplankton zones NN5/NN6 and/or to the lower part of the palynological investigation carried out, using dinoflagellate NN6 zone. Its absolute age was defined by K-A dating of tuffite cysts, on the Cretaceous sequences in Morocco. interbed (Bochnia Salt Mine, Poland) as 13.6+/- 0.2 Ma.

The study is centred in the Tarfaya - Agadir region (western Deposition of these clastic-evaporite deposits both in the Morocco), where ditch cuttings samples, from boreholes East Slovakian Basin (called Zbudza Formation) and in the sections, provided by ONHYM, were analysed for palynology, Polish Carpathian Foredeep (Wieliczka Formation) was supplemented by selected Foraminiferal analyses. controlled by frequent tectonic and seismic phenomena and a high continental clastic supply. The effect was the repeated The diverse organic-walled microfossils yielded, comprise slump sediments with dominant proximal mass flow and distal spores, pollen grains, foraminiferal test linings and flow (turbidites) facies, evidenced by diverse salt types dinoflagellates. (salt/clay rhythmites, finer halite-arenites, coarse halite-rudites, with relatively limited lateral continuity). These slump deposits The rich and well-preserved dinocysts assemblages are separated by primary salt units (halite) precipitated in situ recovered, belonging to yet more than 35 genera and ranging from bottom brines during calm periods. The observed cyclicity from Berriasian to Albian, allowed the refining of the ages, (I-V cycles) reflected varied tectonic activity of the basin inferred by previous micropaleontological studies, on the basis margins, that mechanically remobilised the sediments from of poor foraminifera assemblages and have been useful in marginal salt pans, flats and adjacent uplifts, and could be interpreting the paleoenvironments of the Cretaceous correlable in profiles of both studied basins. sequences. Key words: salts, Neogene, Carpathian area The present work stresses the use of dinoflagellate cysts in biostratigraphical analysis of sedimentary deposits, especially Evaporites of the Messinian salinity crisis: natural those where environmental factors and diagenetic processes radioactivity in the Gessoso-Solfifera Fm of central Italy from have rendered ineffective the use of the Foraminifera and the results may have a wider application for the Moroccan Atlantic surface and subsurface data margin as a whole and could assist in the ongoing offshore Gianluca Sampalmieri, Domenico Cosentino, Annalisa Iadanza, exploration activity. Vincenzo Pasquali Dipartimento di Scienze Geologiche, Università degli Studi Roma Tre, L.go S. Leonardo Murialdo, 1 I-00146 Roma, Italy

This paper deals with the natural radioactivity (NRD) of the evaporitic (ev) and post-evaporitic (p-ev) deposits connected with the Messinian Salinity Crisis (MSC) of the Mediterranean

182 area. Gamma-ray profiles have been acquired in the north- granitoid and from Proterozoic sandstones of the Saghro western Maiella area (Abruzzo, Italy), along stratigraphic succession. Apatite fission-track ages span a wide range sections showing late Messinian deposits, by using a Rainbow between 212 Ma and 20 Ma. 7010 MCA gamma-spectrometer. At the base of the traverse on the northern side, samples The field gamma-ray profiles from the Maiella sections have have old ages ranging from 185 and 72 Ma, while samples been compared with the gamma-ray log of wells drilled at the from the upper portion yielded a younger age of about 20-25 Adriatic side of the central Apennines for hydrocarbon Ma (mean length 13.9 μm and s.d. 1.51 μm) indicating a fast exploration. cooling – exhumation phase from temperatures above about 120°C in early Miocene times. Lower altitude samples with The Messinian evaporitic deposits of the Maiella composite older ages, before early Miocene were at lower temperatures. section consist of a cyclical alternation of selenitic gypsum beds and sapropelitic layers. The gamma-ray log of this Modelling of thermal histories of samples of the southern succession is characterized by low emission from the side seems to indicate that they participated to the early evaporitic beds (8-12 Cps) and maximum peaks of NRD from Miocene cooling phase but starting from temperatures well the sapropelitic horizons (33-40 Cps). below 120°C at which they resided for a consistent portion of their history (˜100-200 myr). The boundary between the evaporitic deposits and the overlying post-evaporitic marls (intra-Messinian unconformity) is evidenced by an abrupt increase of the NRD (20-63 Cps). Apatite fission-track data from this study represent the first record of a Miocene rapid cooling-exhumation phase in the The gamma-ray log from wells drilled south-eastern of the High Atlas of Marrakech, which testifies an important tectonic Maiella Mts show the same profile of the Maiella composite pulse in Miocene times that activated important ENE-WSW section, which correlate the Lower Evaporites of the Vena del trending transpressive faults. Gesso (northern Apennines) and Sicily. On the contrary, the Messinian deposits drilled north-western of the Maiella Mts show different gamma-ray profiles, which could be correlated Coral Reef bioconstructions and their biodetritic equivalents: with re-sedimented evaporites. a tool for the Terminal Miocene paleogeography of the southern edge of the Southern Riffian Corridor (Morocco) Key words: atural radioactivity, gamma-ray profile, Messinian salinity Omar El Hamzaoui1, Jean-Paul Saint Martin2, Christian crisis, Gessoso-Solfifera Fm, central Italy. Chaix2, Abdelkhalak Ben Moussa3, Simona Saint-Martin2 and Khalil El Hajjaji3 Neogene exhumation in the High Atlas of Marrakech 1 Sidi Mohamed Ben Abdellah University, Faculty of Sciences (Morocco) Dhar Mehraz, Department of Earth Sciences , B.P. 1796, Fès- Giovanna Moratti1, Maria Laura Balestrieri1, Giulio Bigazzi2, Atlas, Fès, Morocco. Ahmed Algouti3 2 National Museum of Natural History, Department of Earth 1 CNR, Institute of Geosciences and Earth Resources, Via La History, UMR 5143 “Paleobiodiversity and Paléoenvironment”, Pira 4, 50121 Firenze, Italy 8 street Buffon, 75231 Paris Cedex 05, France. 2 CNR, Institute of Geosciences and Earth Resources, Via 3 Abdelmalek Essaâdi University, Department of Earth Moruzzi 1, 56124 Pisa, Italy Sciences, BP 2121, Tetouan, Morocco. 3 Université Cadi Ayyad, Faculté des Sciences Semlalia, The Terminal Miocene coral reefs and their biodetritic Laboratoire GEOBASSMA, Boulevard Prince Mye Abdellah, equivalents of the Southern Riffian Corridor belong to the BP 2390, 40000, Marrakech, Maroc. largely developed Mediterranean reef complexes.

The High Atlas is the final product of the polyphasic The hermatypic Scleractiniaire fauna is relatively poor, tectonic inversion of the Atlasic rift basins. To unravel the Alpine generally represented by Porites lobatosepta and incidentally tectonic history in the Western High Atlas, where fission-track by Tarbellastraea reussiana. This oligospecificity is related to data are completely lacking, eight samples from a traverse the Middle Miocene-Tortonian boundary climatic cooling. across the High Atlas of Marrakech were analyzed. In this sector of the chain rocks from the Precambrian basement with Rhodophycea, a fundamental biotic group among the their Paleozoic to Neogene cover, affected by numerous ENE- Corals, belong primarily to the Melobesioideae, WSW trending transpressive faults, crop out. Lithophylloideae, and Mastophoroideae subfamilies; Corallinoideae are very rare. Samples coming from the northern side of the traverse belong to the Paleozoic to Mesozoic sedimentary cover. Foraminifera, Bryozoa, Molluscs, Anellids and Sea urchins Samples of the southern side come from the Precambrian Tidili compose the accompanying fauna.

The First MAPG International Convention, Conference & Exhibition 183 Marrakech Convention Center, October 28 - 31, 2007 The characterization of the ecosystems, based on coral barely represented although Quercus and Olea can be morphoses, facies and microfacies, allowed to define: emphasized. Also semiaquatic species from riverbanks and floodplains have been identified (Cyperaceae, Liquidambar). highly diversified Reef environments with locally complete Other palynodebrys include algae cysts, fungal spores and paleoecological spectrum, indicating fairly developed marine vegetal tissues. platforms (Tazouta, south-east of Fes); The palynoflora suggest a very open landscape in which diversified Reef environments, characterized by “patch- the few arboreal forms would be located in the most humid reefs” of medium back reef or internal platform (Aghram zones, where the phreatic level is more accessible. Amallal, south-east of Fes and Agouraï, south of Meknes); Key words. Palynology. Vegetation. Pliocene. Safi Basin. Morocco. monotonous Reef environments (P. lobatosepta being almost the unique constructor), corresponding to narrow Acknowledgments: Financial support of the FEDER (European Union) marine platforms (El Ouata and Bir Tam Tam areas, south-east and Ministerio of Educación y Ciencia (Spain). Project: CGL 2006- of Fes); 05473/BTE

environments where the Reef preparation stage is only locally clear or visible, characterizing small or non-coralline Neogene tectono-sedimentary evolution of the Guercif Basin marine platforms (Sefrou area, Al Mehraz, Mechka, Ribat Al Giovanna Moratti Khayr et al Menzel, south-east of Fes). CNR-Istituto di Geoscienze e Georisorse – U. O. Firenze – Via This leads to a regional paleogeography where in the La Pira, 4- 50121 Firenze (Italy) Eastern Skoura basin (Tazouta) a fringing reef underlined a The Neogene-Quaternary Guercif Basin, developed as a sub-meridian shoreline, in the Aghram Amallal and Agouraï foreland basin in front of the eastern termination of the Rifian sectors the “patch reefs” were located near fluviatile paleo- Arc and located above the major Middle Atlas Shear Zone, mouths, in the El Ouata and Bir Tam Tam area the built terms which affects the foreland, represents a hybrid basin with a colonized a marine deltaic front system with marine complex tectono-sedimentary evolution. An integrated communications and, finally, the small or non-coralline approach was applied to study the basin: basin stratigraphy platforms of Ribat Al Khayr, Al Menzel, Mechka and al Mehraz reconstruction was based on the recognition of widespread indicate an intramontane sea arm, and sometimes the paleo- unconformities and on detailed facies analysis. A detailed shorelines (Sefrou area). structural analysis was carried out through the entire basin and The paleogeography of this part of the southern edge of a grid of seismic profiles was interpreted. Fieldwork, structural the Southern Riffian Corridor testifies to a generalized marine and stratigraphical analyses led to recognize two different invasion able to reach the heart of the folded Middle Atlas. This areas, where both characters of the stratigraphic succession enabled us to review the paleo-reliefs and to highlight and geometry and kinematics of the structures differ. The area important vertical movements postdating the reef period. located in the northwesternmost side of the Guercif Basin, where the Rifian front overlies the Middle Atlas foreland, shows Keywords: Coral reef; Biodetritic; Miocene; Rifian Corridor; Morocco a maximum thickness of the sediments of 600m and is predominantly affected by E-W-oriented normal faults tied to First results on the palynology of the Pliocene of the Safi the extension which took place contemporaneously with basin Region (Morocco) development. The major part of the basin, where thicknesses Rosario Rivas-Carballo, Maria Valle, Jose Ángel González- reach at least 1500 m in the depocentre, is characterised by Delgado, Jorge Civis and Gaspar Alonso-Gavilán NE-trending structures aligned along and in direct prosecution Dpto. Geología. Facultad de Ciencias. Universidad de with the Middle Atlas structures. Interpretation of seismic Salamanca. 37008 SALAMANCA (ESPAÑA) profiles confirms 1) the presence of three main unconformities within the succession: main basal unconformity, base of the A palynological study has been carried out in several Messinian lagoonal-lacustrine deposits, base of the continental sections of the Safi basin (Morocco) corresponding to the sediments, and 2) the presence of normal faults related to the Pliocene. Some of the sections have been very rich in early phases of basin formation. palynomorphs (Jorf Al Yhoudi) whereas others are completely sterile. On the whole, abundance and diversity decrease from In conclusion, the Guercif Basin evolution reflects a two- lower to upper levels of the outcrops. phase history. During Tortonian it was part of the South Rifian Corridor, conditioned by the advancing Rifian front, then, after The vegetation represented by pollen is mainly herbaceous, the closure of the Corridor, the sinistral transpressive tectonics of dry environments (Asteraceae, Caryophyllaceas, Plantago), related to the Middle Atlas Shear Zone prevailed. and saline soils (Amaranthaceae-Chenopodiaceae). Trees are

184 Comparative analysis of the palinoflora in Pliocene Basins of The planctonic assemblage leave us to assign all the the Atlantic and the Mediterranean Realm (Spain and Neogene of the Basin to the Zanclian (biozone PL-2 of Morocco) Berggren et al. 1995), highlighting the coexistence of María Valle, M. Rosario Rivas-Carballo, Jorge Civis y J. Angel Globoratalia margaritae and G. puncticulata. Gónzalez-Delgado The bentonic assemblages show the spatio-temporal Dpto. Geología (Paleontología). Facultad Ciencias. Universidad relationships of the basin. The basal levels are of transgressive de Salamanca. (C. del Parque s/n. 37008 Salamanca) character, and Elphidium crispum, Lobatula lobatula, Ammonia Comparative palynological analysis is made in the beccarii and Nonion boueanum are the most abondant. In sediments of Lower Pliocene age of three basins, two in the upper levels, N. boueanum and A. beccarii are the most Eastern Atlantic realm: Asilah (Morocco) and Guadalquivir (SW reperesentative taxa, and the diversity and the planctonic taxa Spain), and one in the Western Mediterranean realm: Bajo are higher. Llobregat (NE Spain). The associations of bentonic and planctonic foraminifers confirm a progressive deepening, inside the internal platform, The palynology of the Bajo Llobregat basin reflects a with several episodes of a more restricted marine circulation change in the vegetal cover, of probably climatic origin. conditions, marked by peaks of abondance of Buliminidae and Progressive disappearance of taxa from dense and warm Fursenkoina schreibersiana. The malacofauna and forest is observed (Taxodiaceae, Nyssa, Carya, Engelhadtia, ostracofauna record are in agreement with this results. etc.) and they are replaced by taxa from more xerophitic Key words: Foraminifers, biochronology, paleoecology, Plioceno environmentes belonging to the mediterranean flora. Zancliense, Asilah, Morocco In the Atlantic realm, the palynological assemblages of the Oued Messaoud section in the Asilah basin, show variations in Acknowledgments: Financial support of the FEDER (EU) and the the taxonomic composition of the vegetation. The lower levels Ministerio of Educación y Ciencia (Spain), Project CGL2006- suggest a humid climate, (abondance of deciduous and 05473/BTE evergreen Quercus, Poaceae and Pteridophyta). The upper ones show a drier climate dominated by evergreen Quercus New paleontological data in the neogene of Safi (Morocco) and Plantago. González-Delgado J. A.1, Civis J.1, Alonso Gavilán G.1, El In the Guadalquivir basin, the palinological study is focused Hajjaji K.2, Ben Moussa A.2, Rivas Carballo R.1 and Valle M.1 on the Lower Pliocene “Arenas de Huelva” Formation, where a 1 Dpt. Geology. University of Salamanca, c/Parque 8, 37008 mixed forest with warm (mainly Pinus and Pteridophyta with Salamanca (Spain) Nyssa, Taxodiaceae, Sapotaceae, Arecaceae, etc.) and 2 Faculté de Sciences, Université A. Essaadi, Tétouan, temperate taxa (Quercus, Juglandaceae, Salicaceae…) is Morocco observed. In the uppermost levels, the landscape was probably more arid, with an increase of taxa such as Several classical (Jorf Al Yhoudi, Jerifat, Si Bel Krakra) and Chenopodiaceae. other new sections of the Neogene around Safi (W of Morocco) Key words: Palynology.Vegetation. Pliocene. Atlantic. Mediterranean. are studied. The basal levels consist in yelow tabular or Acnowledgments: Financial support of the FEDER (EU) and Ministerio sigmoidal calcarenites, ordered in fining-upwards sequences, of Educación y Ciencia (Spain). Project: CGL 2006-05473/BTE and disposed in several outcrops as thickening-upwards macrosequences. Cross-bedding and bioturbation is Paleoenvironmental and chronological significance of the common. The upper levels are fine to coarse yelow sands, foraminiferal record in the Pliocene Asilah Basin (NW locally with conglomerates. The correlation between the Morocco) different deposits is difficult because they are isolated in general. J. Civis and J.A. González Delgado Departamento de Geología (Paleontología) Facultad de Taphonomic signature of macrofossils suggest more or less Ciencias Universidad de Salamanca; 37006 Salamanca, Spain protected nearshore environments. Removing and redeposit of the shells, in more continous or discontinuos vawe action In the most representative stratigraphic sections in the settings, have produced several macrofaunal shell Pliocene Basin of Asilah (Morocco), the associations of concentrations, very rich in Ostrea lamellosa, or Pecten, or in bentonic and planctonic foraminifera were analyzed. More than the echinoid Rotuloidea fimbriata, sometimes alternanting with 50 taxa of bentonic foraminifers and 17 of planctonic were levels with articulated bivalves in life-position, like Panopea or determined. Lutraria. Diagenetic dissolution of aragonitic shells are important, with a great presence of moulds.

The First MAPG International Convention, Conference & Exhibition 185 Marrakech Convention Center, October 28 - 31, 2007 The more abundant macrofauna preserved are Ostreids, We show that this heterogeneous structuring was Pectinids, Balanids and Echinoids. The presence of the controlled by a transtensif tectonic mode, with radial pectinid Palliolum excisum, wich starts in the Pliocene, agree extensions, chiefly mediated by N160 sinistral faults. On a large with previous age supposed by workers of the middle of last scale, these faults determine a system of blocks tilted towards century. With respect to microfauna, Foraminifers are scarce, the East, before integrating downwards a detachment crustal and poorly preserved. Elphidiidae, (E. crispum and E. fault, testifying for the installation of an intracontinental rift. advenum), Lobatula lobatula, Ammonia beccarii, Cibicides refulgens, Asterigerinata planorbis and Pararotalia sp. are the The stratigraphic and structural data allow connecting the most common taxa. Ostracods are also scarce, with presence Alboran micro plate to the Iberian Peninsula. Its detachment of Aurila, Loxoconcha and Callistocythere. Palinology is started during the Middle Triassic due to the installation of an represented by xeric, halophytic herbs (Amaranthaceae- intra continental rift located in the southern prolongation of the Chenopodiaceae, Artemisia), with a small percentage of Triassic-Iberian chain rift. The differential process of these aquatic or semiaquatic plants (Cyperaceae), suggesting extensional movements is accompanied by the influence of fresh water. individualization of several pull-a-part basins delimited by the N40 and N130 faults which control the structural architecture Both the macro and microfauna, the taphonomical, of the internal zones. It is guided by a trans-tensional regime sedimentological and stratigraphical data are according with imposed by the migration the Alboran micro plate towards NE. nearshore changing marine environments from inner platform This structural feature attests for the oblique nature of this intra to intertidal in the area. continental rift, witch is partly adapted to the late Hercynian discontinuities. Key words: taphonomy, paleoecology, Neogene, Safi (Morocco) Key words: Alboran, external Dorsale Calcaire, Triassic, Synsedimentary normal faults, oblique rift Acknowledgments: Financial support of the FEDER (EU) and the Ministerio of Educación y Ciencia (Spain), Project CGL2006- 05473/BTE Stratigraphy and sequential organization of the Triassic Series of the External Dorsale Calcaire of Bokoya Massif GS 15: Stratigraphy, environments, climates, and (Internal Rif, Morocco) petroleum systems of the Triassic and Earliest Omar Azzouz, Ahmed Chalouan and Mohamed Laadila Jurassic of the subtropics Pangea 1 Dept. of Geology, Fac. of Sciences, Univ. Mohammed Ier. BP: 524, Oujda, Morocco. Synsedimentairy tectonic Instabilities of the triassic series of 2 Dept. of Geology, Fac. of Sciences, Univ. Mohamed V. Rabat, the external Dorsale Calcaire of Bokoya Massif(internal Rif, 10106, Morocco. Morocco): geodynamic implications The external Dorsale calcaire constitutes the typical alpine Omar Azzouz1, Ahmed Chalouan2 cover of the Alboran Domain. It is characterized in particular by 1 Dept. of Geology, Fac. of Sciences, Univ. Mohammed Ier. an important Triassic dolomitic series, which may exceed 600 BP: 524, Oujda, Morocco. meters in thickness. The stratigraphy and sequential 2 Dept. of Geology, Fac. of Sciences, Univ. Mohamed V. Rabat, interpretation of these formations are defined on the basis of 10106, Morocco. tectono-sedimentary processes, which controlled their internal The triassic geological context of the external Dorsale architecture. Regional-scale unconformities lead the whole Calcaire of Bokoya Massif is evidenced on the basis of dolomitic succession to be split up into five intervals geometrical data from synsedimentairy tectonic disturbances characterized, each one, by distinct lithostratigraphic recorded within its dolomitic series. In this study, we highlight formations the close correspondence between the sequential organization These formations start with basal unstable doloarenitic of these carbonate deposits and the rhythmic expression of all levels exhibiting spaced and irregular stratification. Upwards, the markers of this instability. We show that the development the latter structures progressively become dense and planar of these series is conditioned as a whole by repetitive and determine near the top uniform dolomicritic bars with algal subsident downthrows and sedimentary fillings. laminations.

The sequence of these tectono-sedimentary phenomena is These two stratigraphic components correspond to well controlled on various scales by extensional normal faults, differentiated sedimentary entities, which present a commonly which derive from the same genetic processes. These regressive evolution of filling. We respectively define them as structures are organized in hierarchical arborescent tectonic sedimentary formations and channelisant meso- sequences. systems characterizing deformations growth, which evolve in Their vertical spreading out is integrated in well defined accommodation with sedimentation.

186 evolutionary processes characterizing a sequential GS 18 : Recent evolution of the Betic-Rif chain organization of two orders. Thrusting fronts frame (3D) and their relations with the main We show in this study that the differentiation of these two kinds of sequences occurred in a subsidence context. The strike-slip faults in the Rifian limestone Dorsale (Northern geometry of their deposits is controlled on various scales by Morocco) extentional normal faults. These structures are organized El Adraoui A. and Aït Brahim L. following an arborescent tectonic systems, induced by Université Mohamed V, Faculté des Sciences, Département deformations in accommodation with sedimentation. They are des sciences de la Terre, Av. Ibn Batouta, BP 1014, Rabat, controlled by a rhythmic tectonic mode during the Triassic Maroc. time. The Gibraltar Arc constituted by the betic belt (southern Key words: Dorsale Calcaire, Rif, sedimentary subsidence, Triassic, Spain) and the Rif range (northern Morocco) was mainly tectono-sedimentary process. formed during compressive alpine stages. It is subdivided into external domain and paleozoic internal domain (Ghomarids and metamorphic Sebtids) in which the limestone Dorsale is Serravalian sequence stratigraphy and depositional the mesozoic platform. The Dorsale allochtonous units, architecture of the Northern Vienna Basin composed by limestone Mesozoic and unconformable Jana Hlavatá, Slavka Sopková, Michal Ková_ and _ubomír Eocene-Oligocene mainly detrital cover, is generally considered Sliva as the southern margin of European plate (or Alboran domain) displaced to the west and trusted upon the North-African Department of Geology and Paleontology, Faculty of margin. Natural Sciences, Comenius University, Mlynská dolina pav.G, 842 15 Bratislava The main purpose of this work is to describe the alpine structural phases and geometric framework evolution of the The northern Vienna Basin Serravallian depositional Dorsale faulting systems since the upper Triassic. On the basis systems changed from basin plain to prodelta and later to delta of a structural survey of the area, it accounts for the results of slope environment during the Early Serravallian. In the Late micro tectonics, cartography, regional fracturing, applied Serravallian, the prograding lower delta plain setting was remote sensing, geodynamics and retrotectonics. progressively substituted by environment of brackish tidal flats and coastal plains revealing toward overlaying strata character Thus the Internal Dorsale early jointing (Liassic) and of swamps and marshes. External Dorsale dissolution cleavage allows to consider them as the covers of respectively Ghomarids and Sebtids Sedimentary architecture of the Serravalllian basin fill basements before thrusting. allowed beside two individual 3rd order cycles of relative sea level changes, which can be more or less compared with the The reconstitution of the EW Dorsal margin of Tethys as the Haq´s Mediterranean cycles TB 2.5 and TB 2.6, also result of Açores senestral transform fault lays on Mesozoic identification of 4th order cycles: two Early Serravallian and extension and retrotectonic analysis. other two Late Serravallian cycles. However, these cycles reveal different features. Hence we assume the Early From the Aquitanian the Dorsal complex is thrusted, Serravallian cycles to originate as a result of deltaic avulsion backthrusted (Haouz) but specially shaped by rotations related (development was forced by frequent shifts of distributaries), with 4 main strike-slip faulting stages and associated fractures. the Late Serravallian 4th order cycles developed due to the At the Alboran plate translation westward, take turns with a effect of relative sea level changes (regional shoreline shifts). clockwise rotation of its dorsalian margin attested by the progressive rotation of the main compression stress trend ?1 The Late Serravallian sedimentary record is composed of during the Miocene. parasequence sets - high frequency cycles, which were caused by orbital forcing. These high frequency cycles with typical local character of sedimentary facies development can be more or less identified in the whole Vienna Basin (cycles were caused by eccentricity of Earth axis, with period of 100 ky).--

Key words: Sequence stratigraphy, Vienna Basin, Serravallian

Acknowledgement

This work was supported by the Slovak Research and Development Agency under the contract No. LPP-0120-06.

The First MAPG International Convention, Conference & Exhibition 187 Marrakech Convention Center, October 28 - 31, 2007 Kinematics and paleostresses in the Jebha-Chrafate Recent and active normal faults and paleostresses in Transcurrent Fault (Northern Rif, Morocco) Boudinar and Nekor Basins (Central Rif Cordillera) Mohamed Benmakhlouf1,2, Jesús Galindo-Zaldívar2, Ahmed Latifa Ameza1, Jesús Galindo-Zaldívar2, Omar Azzouz3, Chalouan3, Carlos Sanz de Galdeano4, M’fedal Ahmamou3 Ahmed Chalouan1, Patricia Ruano4, Carlos Sanz de and Angel Carlos López-Garrido4 Galdeano5, Carlos Marín-Lechado6, Antonio Pedrera2, Angel 1 Departamento de Geodinámica. Universidad de Granada. Carlos López-Garrido5, Farida Anahnah2, Ana Ruiz-Constán2, 18071 Granada. Mohamed Benmakhlouf7, M’fedal Ahmamou 1. 2 Faculté des Sciences. Université Abdelmalek Esaadi. Tetuán. 1 Département des Sciences de la Terre, Faculté des Marruecos. Sciences, Université Mohammed V- Agdal. Morocco. 3 Faculté des Sciences. Université Mohammed V-Agdal. 2 Departamento de Geodinámica, Universidad de Granada. Rabat. Marruecos. Spain 4 Instituto Andaluz de Ciencias de la Tierra. CSIC-Univ. 3 Département de Géologie, Faculté des Sciences, Université Granada. 18071-Granada. Mohammed premier- Oujda. Morocco. 4 Departament de Geologia Dinàmica i Geofísica. Universitat During the alpine deformation of the Rif Cordillera, major de Barcelona, Spain. transfer faults developed during the W-SW motion of its 5 IACT, CSIC-Universidad de Granada. España. Internal Zones in respect to the African margin before the Late 6 Instituto Geológico y Minero de España. Miocene. The Jebha-Chrafate, is an ENE-WSW sinistral major 7 Faculté des Sciences. Université Abdelmalek Esaadi. Tetuán. transcurrent fault of the central part of the Rif Cordillera, formed Marruecos. during the southwestwards emplacement of the Internal Zones on the Flysch units and the External Zones. This fault acted as The present day relief of the Rif Cordillera is consequence a transfer fault favouring the westwards displacement of the of the compressive deformation that occurs between the northern blocks. The analysis of minor structures along the Eurasian and African plates since the Miocene. The boundary Jebha area indicates the activity of top to the SW low and high between the central Rif Cordillera and the Alboran Sea, in the angle normal faults during the tectonic wedge emplacement. Al Hoceima area, has a very abrupt topography as These data suggest that the tectonic wedge corresponding to consequence of the relief uplift produced by the recent tectonic the Internal Zones has moved by a combination of activity. It continues up to Present, evidenced by the seismicity. compressive deformation in depth and extensional spreading The region is affected by the Nekor Fault, one of the main in shallow levels, corresponding to the observed faults. sinistral faults in the Rif Cordillera. Although this fault was active However, in spite that slip should be sinistral from regional during Miocene times at present is inactive. data, and locally evidences of sinistral motion are recognized, most of the kinematic indicators along the transcurrent fault The present-day relief along the coast line is determined by zone point to a reactivation as dextral fault. This last kinematics horst and graben structures separated by active normal faults. may be a consequence of the recent NW-SE Eurasia-Africa The Al Hoceima horst is separated by a set of NNW-SSE convergence. Finally, the recentmost structures corresponds eastwards dipping normal faults from the Nekor Basin. The to a final overprinting of normal faults during the late stages of NNE-SSW oriented Trougout Fault separates this basin from relief uplift. Paleostress determinations from microfault allow to the Ras Tarf horst. Eastwards, a NNW-SSE normal fault precise the tectonic evolution of this region. This field example constitutes the boundary with the Boudinar Basin. The slip of illustrates the reactivation under different stress regimes of an most of these roughly oriented N-S normal faults decrease old major brittle structure in the changing scenario of the southwards up to disappear, and does not displace the NE- Eurasian-African plate boundary in the western Mediterranean. SW oriented Nekor Fault.

Key words: Internal Rif, transfer fault, reactivation, low angle normal The paleostress analysis from microfaults suggests that faults, paleostress evolution. there is an extensional heterogeneous stress field during the development of these faults. While near the Al Hoceima area the extension trend is ENE-WSW oriented, subparallel to the coast line, in Ras Tarf, local extension orthogonal to the coast line may be a local consequence of the uplift of the horst. In Boudinar Fault, a progressive change of stress, from well directed E-W extension in the central part up to radial extension in the southern fault end is recognized. These stresses contrast with the present day stresses obtained from deeper earthquake focal mechanisms.

Key words: Al Hoceima, paleostresses, fault end, Rif Cordillera.

188 A new local non-permanent GPS Network to constraint Interaction of main strike-slip faults in Eastern Betic tectonic motions in Al-Hoceima Region (Rif Cordillera) Cordilleras (SE Spain) Jesús Galindo-Zaldívar1, Antonio Gil2, Omar Azzouz3, Antonio Patricia Ruano 1, Jesús Galindo-Zaldívar 2, Antonio Pedrera2, Ruiz2, Farida Anahnah1, Latifa Ameza4, Patricia Ruano5, Carlos Marín-Lechado 3 Ahmed Chalouan4, Clara de Lacy2 1 Departament de Geodinàmica i Geofísica. Universitat de 1 Departamento de Geodinámica, Universidad de Granada. Barcelona, Spain. Spain. 2 Departamento de Geodinámica, Universidad de Granada. 2 Departamento de Ingeniería Cartográfica, Geodesia y Spain. Fotogrametría, Universidad de Jaén. Spain. 3 Instituto Geológico y Minero de España. Spain. 3 Département de Géologie, Faculté des Sciences, Université Trans-Alboran shear zone (TASZ) has been considered a Mohammed premier- Oujda. Morocco. deep fracture zone with related volcanism, crossing the Betic- 4 Département des Sciences de la Terre, Faculté des Rif Cordilleras. Two of the main structures in TASZ are Sciences, Université Mohammed V- Agdal. Morocco. Palomares NNE-SSW and Carboneras NE-SW oriented strike- 5 Departament de Geologia Dinàmica i Geofísica. Universitat slip faults that separate the southeastern end of the Betic de Barcelona, Spain. Cordilleras and the Alboran Sea- South Balearic basin thin continental crust. Their activity, beginning in the Miocene, have The Al-Hoceima region, located in the central part of the Rif been broadly discussed on the literature, and most of the Cordilleras, has undergone an intense seismic activity, in which authors suggest a sinistral strike-slip regime with extensional the most significant events occurred in 1994 and 2004 (M= episodes. These two oblique oriented major faults, with very 6.3). Although seismicity data support the presence of straight cartographic traces, should undergone a large transcurrent faults, and available radar interferometry geometrical interaction that is not evidenced at their researches evidence surface deformations, geological data intersection. The relationships between the activity of suggest that main seismogentic fault zone has not a surface Palomares (PFZ) and Carboneras fault zones (CFZ), has not expression. Anyway, a set of N-S oriented normal faults been further discussed and it is the aim of this contribution, (Rouadi, Al-Hoceima, Trougout) determines the present-day taking into account new brittle deformation data. The geomorphology and seems to continue to be active in surface. microfaults and joints palaeostress determination evidence, during the Messinian, a clockwise rotation of compression from In order to quantify with millimeter precision the tectonic NW-SE to NNE-SSW, favoring the sinistral strike-slip of the motion of the area, a set of 6 new GPS non permanent sites CFZ and the development of large folds. During the Pliocene, have been constructed and its relative position have been an anticlockwise rotation of stresses produces NNW-SSE determined in June 2007 by Leika 1200 GPS system. Each compression. These stresses favored the sinistral activity of the GPS station consists in a bench mark anchored to solid rock PFZ, with regard to CFZ. Finally, during the Quaternary an (limestones, quartzites and volcanic rocks). During ENE-WSW extensional setting and predominated NNW-SSW measurements, an aluminum tube of 0,5 m is screwed and the to NW-SE compression, favored the sinistral strike-slip activity GPS antenna is located at the top. The simultaneous records of the PF regarding the orthogonally oriented CF that may act was done during 4 days. as a transfer fault, accommodating the displacement of secondary NW-SE normal faults. The geological field and The northern 4 stations are located subparallel to the coast geomorphological data also suport the most intense recent line, intersecting the region that has undergone the maximum activity of the PFZ, determining the coast line orientation. This motions during the last two seismic series, and monitoring fault zone probably displaces the CFZ which shows only local major fault blocks separated by N-S fractures, from Ras Tarf up evidences of recent sediment deformation and minor to the west of Rouadi. In addition, other two stations were physiographic feature displacements. located to the south, one in between Tamasint and Imzouren, Keywords: Palomares Fault, Carboneras Fault, paleostresses, recent near the epicenter of the 2004 earthquake. The last station is tectonics located soutwestwards, in a low deformed region. The repeated measurements of this network may allow to exactly determine the surface expression of deep tectonic Crustal structure of the Western Transect of the Betic deformations in this region, and to quantify the creep and the Cordilleras (Southern Spain) from geophysical Data coseismic motions in the area, that will contribute to better Ana Ruiz-Constán, Jesús Galindo-Zaldívar, Antonio Pedrera understand the seismic hazard. Departamento de Geodinámica. Universidad de Granada. 18071- Granada (Spain). Key words: Al Hoceima, GPS network, crustal motions, active tectonics. The Betic Cordilleras, located at the present-day Eurasian- African plate boundary, are the westernmost end of the Mediterranean Alpine orogenic belt and constitutes the northern branch of the Gibraltar Arc that surrounds the Alboran Sea.

The First MAPG International Convention, Conference & Exhibition 189 Marrakech Convention Center, October 28 - 31, 2007 A NW-SE cross section of the western cordilleras has been The most conspicuous structures are the Negratin dome, performed (from Internal Zones, crossing the External Zones, elongate in the N85E direction with dimensions of 1.5 Km for 1 the Guadalquivir Foreland Basin and up to the Iberian Massif) Km, and a perpendicular anticline situated immediately to the using diferent geophysical data (magnetotelluric, gravity, NW, with a length of 3.5 Km. Other structures, folds and magnetometry and seismicity) in order to obtain information on diapiric folds, are situated to the W and NW of the previous the deep structure and determine the location of the main ones. contacts. In addition, these data are important to establish the continuity in depth of the Iberian Massif, under the Betic During the formation of the diapirs and folds noticeable Cordilleras, and the relationships between major faults and synsedimentary unconformities were formed in the upper seismogenetic zones. Miocene, Pliocene and Quaternary sediments situated in the proximities of these structures. This fact indicates a 2D inversion of 12 new MT soundings along the NW-SE progressive deformation during this period of time. These profile provides the first deep resistivity image of this transect. deformations even affect the Pleistocene glacis of the Guadix- A sharp variability in depth of resistivities may evidence the Baza Basin, showing the recent activity of the tectonics in this location of crustal detachments. The heterogeneous upper basin. These deformations have been formed within a N-S to crust, characterized by high variability on resistivity values NNW-SSE compression and a ENE-WSW linked extension. according to the shallow geological structure, is separated This position of the stresses is inferred from the study of macro from the more homogeneous lower crust of the Iberian Massif. and minor structures. This Variscan basement is characterized by large resistive Key words. Diapirism, Neogene, Quaternary, Neotectonics. bodies on the northern end of the profile and flat and elongated deep conductive bodies in the central and southern part of the profile. Borehole breakout analysis characterizes present-day stress The seismicity evidences the activity of major detachment field in the Alboran Sea and the Betics faults located in the Betic Cordilleras that are responsible of the Fernández-Ibáñez, F.1, Soto, J.I.1 and Zoback, M.D.2 present day relief. In the frontal part, shallow seismicity 1 Dpto. Geodinámica e Instituto Andaluz de Ciencias de la suggests that the mountain front is now active and formed by Tierra (CSIC- Granada University), Facultad de Ciencias, a major reverse fault dipping southwards, to the Internal Zones Campus Fuentenueva s/n, Universidad de Granada. 18002. of the Cordilleras. In addition, other low-angle faults are active Granada (Spain). at different crustal levels at the boundaries of the major bodies. 2 Department of Geophysics, Stanford University, Stanford, California 94305-2215, USA. Key words: Betic Cordilleras, deep structure, resistivity image, seismogenetic zones. We select a group of 12 data sets coming from commercial and scientific wells drilled through the main geological domains of the north branch of the Gibraltar Arc to characterize the Diapirism and folding associated to recent tectonics in the present-day stress field. We established the orientation of Guadix-Baza Basin (SE Spain) breakouts using data coming from the four-arm caliper tool. Angel Carlos López-Garrido1, Carlos Sanz de Galdeano1, Zones of wellbore enlargement were recognized in 11 of the 12 Jesús Galindo-Zaldívar2; Pedro Alfaro3 and Francisco Juan selected wells to depths up to 3450 m. Mean orientation and García-Tortosa4. standard deviation of breakouts at each well have been used 1 Instituto Andaluz de Ciencias de la Tierra, CSIC-Univ. to assess the borehole quality following ranking criteria of the Granada World Stress Map (WSM). 2 Dpto. Geodinámica. Fac. Ciencias. Univ. Granada 3 Dpto. Ciencias de la Tierra y Medio Ambiente. Fac. Ciencias. Stress inversion performed in these wells evidences that Univ. Alicante. maximum horizontal stress (SHmax) tend to parallel coast 4 Dpto. Geología. Fac. Ciencias. Univ. Jaén. strike, resulting in a roughly E-W orientation along the northern margin of the Alboran Sea. In some wells, it is observed local The relation between tectonics and sedimentation is stress rotations that can be correlated with discrete active fault analyzed in several structures formed from the late Miocene to zones or interbedded salt layers. the present in the Guadix-Baza Basin. They correspond to a combination of diapirs and folds and some faults. The most These data have been gathered with other stress indicators important of them are crossed by de Guadiana Menor River. to reconstruct the present-day tectonic stress in the region. The nucleus of the diapirs is formed by Triassic materials, The Gibraltar Arc shows a complex stress pattern with major overlain by upper Neogene to Quaternary sediments. rotations with respect to the stress field imposed by the ongoing Africa-Eurasia convergence. Differential stress rotations are deeply controlled by crustal structure and by

190 differential loading imposed from the high sediment thickness The use of the results of such a study may be extended to in basin depocenters. other studies such as loss reserve bottom, artificial feeding of aquifers and water purification stations. With these results we expect to add valuable data for establishing the nature and partitioning of deformation in the Key word: Artificial recharge; Louvain-La-Neuve; Bruxellien; aquifer Gibraltar Arc. However, further work deserves to be done in the geochemistry. Rif region and in the southern Alboran Sea, where some oil well data are matter of potential interest since they may help to 3D of Gharb Aquifer. Use of GIS in the cartography. better constrain the present-day deformation processes in the western Mediterranean. El Mansouri B., Chao J. and Kili M., Key words: borehole breakouts, stress field, stress rotations, active University Ibn Tofail, Faculty of sciences, Earth sciences tectonics, Gibraltar Arc. Department, Lab. Applied Geosciences, & Technology of Water Resources, BP. 144, 14000 Kenitra, Morocco.

GS 47 : Advanced hydrogeology and information Groundwater is an important source of water supply and systems plays a crucial role in domestic, industrial and agricultural uses. The management of these resources represents nowadays a Phisico-chemical evolution of the soil water during an major stake for our future. This management makes call artificial recharge several data of land that it would agree to organize for an easy M.A. HESSANE1, H. KARRAT, L1. W. De BACKER2 use. The implementation of solutions by the Geographical 1 Departement of Geology, faculty of Sciences, Dhar Mehraz, Information System permits a better perception of the set of Fes the data facilitating the decision making and a bigger easiness 2 Agricultural Engineering Unit, the Catholic University of to interpret and to criticize at a time. In fact, the GIS techniques Louvain facilitate integration and analysis of larges volumes of data, whereas field studies help to further validate results. Integrating The artificial recharge of aquifers from artificial lakes or all these approaches offers a better understanding of features artificial treatment stations of waste waters is often taken into controlling groundwater occurrences in porous medium. account in development projects. The major difficulties come from physico-chemical reactions between the injected water In order to cartography the potentially aquiferous on the one hand, groundwater and the aquifer on the other formations of the important hydrogeologic of the Gharb (NW hand. The dissolution-precipitation reactions as well as the ion Morocco), the GIS has been used to manage the data of over exchange reactions are considered among the major problems forty hundred boreholes distributed on the whole basin. Each conducted by the artificial recharge of aquifers. borehole contains several information as boring log, it’s width, aquifer and substratum levels, hydrodynamic parameters given Here we talk about the physico-chemical evolution of the by pumping tests, data sets for soil and water chemistry … soil water during an artificial recharge induced by the infiltration Several thematic maps have been extracted of that data base, of the water stocked in a storm basin located on a stratified including several three-dimensional diagrams of the thickness profile above an unconfined aquifer. of the potentially aquiferous formations: sandstone, calcarenite, sand,…. This result is a key in the evaluation of the Chemical exchanges between the water coming from the hydrogeologic reserves of the basin and an important element lake by infiltration and the soil can contribute to the in all numeric modelling studies. modification of the hydraulic parameters of the no saturated zone of the aquifer. The overall results demonstrate that the use of GIS Technology provide potentially powerful tool to study The pond we deal with is located at Louvain-la-Neuve in groundwater resources and design a suitable exploration plan, Belgium. For a matter of aesthetics, it was decided to particularly in larger site. transform this basin into an artificial lake by maintaining its plan of water at a more or less fixed level. It was necessary, as a Key Words : GIS, Cartography, Aquifer, 3D sedimentary model,a result, to envisage a so quantitative as well as a qualitative monitoring of infiltrating water.

Equipping the lake with a monitoring well constitutes thus a true “natural” laboratory. This makes it possible to experimentally and at the same time in situ study an artificial recharge case.

The First MAPG International Convention, Conference & Exhibition 191 Marrakech Convention Center, October 28 - 31, 2007 The Steady state modelling of The Haouz aquifer. map snow cover in the High Atlas. The spatial and temporal Z. Ait’Mbarek1, L. Hanich1et B. Berjami2 variations of the snow covered area in the High Atlas as well as 1 Faculté des Sciences et Techniques de Marrakech, av. A. in the five main tributary basins of the Haouz plain are analyzed Khattabi, BP. 549, Marrakech, Maroc. by altitudes and aspects. These variations are confronted with 2 Agence du Bassin Hydraulique du Tensift the available ground data (Precipitation, temperature and Runoff). This study demonstrates how remote sensing The objective of this study is to model the hydrogeologic techniques can be used for long-term observation of snow behaviour of the waertable of Haouz. The requirements of covered area and analysis of it’s inter and intra annual variability water in the plain of Haouz, characterized by an semi arid in regions where the meteorological observation network is climate becomes from one year to another increasingly insufficient. The potential of these data to study the hydrology important considering the properties of the region which are of semi-arid region is also underlined. especially tourist and agricultural, in front of all these properties the hydraulic basin of Tensift was the object, in 2003 and 2004, Key words: High-Atlas, snow, remote sensing, SPOT-VEGETATION, of a vast study of hydrogeologic synthesis to supplement and snow index, nival hydrology. bring up to date the evaluation of its groundwater resources. The streamflow modelling by use of GR4J model. Ourika The model of watertable are today current tools for Basin Case. management and planning resource of water, in this F. Faouzi1, V. Simonneaux2 et L. Hanich1 framework, that the modeling of the aquifer of Haouz -Mejjate, 1 Faculté des Sciences et Techniques de Marrakech, av. A. is registered, in this study we are directed towards the software Khattabi, BP. 549, Marrakech, Maroc. GMS which allows the execution of simulations of the 2 CESBIO, 18 Av. Edouar Belin BPI 280 Toulouse cedex 4, groundflow. France.

This study us allowed to arise the following results: This study has like objective to model the hydrological - The space distribution of the transmissivity; behavior of mountainous basin atlasic caracterised by a semi arid climate: watershed of Ourika. The modeling of this basin - The space distribution of the coasts of substratum; characterized by a space-time heterogeneity, requires the development of a simple, robust tool with a low density of - The hydrodynamic assessment of the watertable. parameters. For this reason which are directed this study Key words: modelling, GMS, transmissivity, substratum towards the family of model GR, more precisely GR4J model developed by the CEMAGREF which is a conceptual model global with tanks, functioning with the step of the daily time The use of spot-vegetation imagery to study the spatio- which are added a snow module based on the method of the temporal of the snowy cover in the High Atlas of Marrakech degree-days. In front of all the complex climatic conditions of A. Boudhar1, B. Duchemin2, L. Hanich1, A. Chaponnière 3, P. this basin, influencing the quality and the quantity of data input, Maisongrande2, G. Boulet2, J. Stitou4 A. & Chehbouni 2 the model is able to propose a relatively correct simulation of 1 Faculté des Sciences et Techniques de Marrakech, av. A. the flows, and seems moreover to be able extrapolated on the Khattabi, BP. 549, Marrakech, Maroc. temporal scale. 2 CESBIO, 18 Av. Edouar Belin BPI 280 Toulouse cedex 4, Key words: modelling, GR4J, snow module, degree-days France. 3 IWMI-West Africa. PMB CT 112, Cantonments, Accra. Ghana. 4 Faculté Sciences de Tétouan, Mhanech II, BP:2121, Tétouan, Maroc.

The Moroccan High-Atlas mountain range represents important water storage for the neighbouring arid plains. It is the case of the Haouz plain, in the region of Marrakech, where waters resources are intensively exploited for agriculture and tourism. Sustainable water management is a priority for the regions authority and requires a good understanding of the processes and variables involved in the water cycle. The contribution of liquid and solid precipitation to the runoff of the Tensift main subbasins is of particular interest. In this context, we used a 7-year time series of SPOT-VEGETATION images to

192 Integrated analyses of the Messinian post-evaporitic section Session: Vertical movements in sedimentary basins: of Maccarone (northern Apennines, Italy): Insight into stratigraphic systems, thermal history and petroleum palaeoclimate and palaeoenvironments during the Messinian aspects salinity crisis. Domenico Cosentino1, Paola Cipollari1, Fabio Florindo2, Jurassic extensional faulting and its control on distribution Rocco Gennari3, Elsa Gliozzi1, 5, Francesco Grossi1, Silvia and extent of upper Jurassic and Cretaceous marine source Iaccarino3, Gianluca Sampalmieri1, Mario Sprovieri4 (?) rocks, deepwater Gulf of Mexico: a preliminary report 1 Dipartimento Scienze Geologiche, Università Roma Tre, L.go Claudio Bartolini San Leonardo Murialdo, 1, I-00146 Roma, Italy Repsol Services Co., 1330 Lake Robbins Dr., The Woodlands, 2 Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Texas, U.S.A. 77380 Murata, 605, I-00143 Roma, Italy 3 Dipartimento di Scienze della Terra, Università di Parma, Area Jurassic extensional faulting associated with rifting and delle Scienze 157/A, I-43100 Parma, Italy opening of the Gulf of Mexico created a topography 4 Istituto Ambiente Marino Costiero (IAMC-CNR), Calata Porta characterized by grabens, half grabens and structural highs, di Massa, I-80133 Roma, Italy which controlled Late Jurassic and Cretaceous depocenters, 5 IGAG-CNR, Via Bolognola, 7, I-00138 Roma, Italy sedimentary processes, and sediment dispersal.

The Maccarone section consists mainly of marls with thin Regional interpretation of 2D seismic data covering 14,600 intercalations of sandstone and carbonate. A volcaniclastic miles of the abyssal plain adjacent to the Sigsbee Scarp, layer and three organic-matter-rich horizons characterise the mainly in the Lund and Walker Ridge protraction areas, has lower portion of the section (p-ev1). In the uppermost part, four allowed preliminary interpretation of a Jurassic relict structural carbonate-rich horizons (“colombacci”) define the stratigraphy grain developed during the early tectonic evolution of the Gulf of the upper post-evaporitic deposits (p-ev2), passing upwards of Mexico. to Lower Pliocene marine clays. The Cretaceous, and possibly Upper Jurassic (?) sections A 50 cm regular-spaced sampling has been performed on have thicknesses that range from 850 to 3,000 m, depending a total thickness of about 230 m, which, in the uppermost part, on the depth and configuration of the rifted basins. The onlap encompasses the Messinian/Zanclean boundary. On the 460 of highly-dipping strata against structural highs in the lowest collected samples, palaeontological, CaCO3 content, rock parts of the grabens may indicate the possible presence of magnetic, stable isotope analyses have been performed. Jurassic rocks, which are the oldest strata in this area. Moreover, a field gamma-ray profile has been acquired. The deposition of the Upper Paleocene – Lower Eocene Palaeontological analyses point to the occurrence of an Wilcox Formation was essentially not affected by the Jurassic Early Pliocene marine environment overlying the oligo- structural grain, as a matter of fact, these clastic successions mesohaline late Messinian deposits, which contain the well- have a very homogeneous thickness of 750 m throughout the known Lago-Mare biofacies (M/P boundary). study area, except for local, very steep structural highs, where Micropaleontology, natural radioactivity, rock magnetic, oxygen the overlying Wilcox thicknesses are on the order of 276 to and carbon isotope analyses allowed us to recognize the main 498m. palaeoenvironmental changes that affected the Mediterranean The possible existence of Upper Jurassic (?) and area at the end of the MSC. Cretaceous marine source rocks in grabens adjacent to large Key words: Messinian salinity crisis, Lago-Mare biofacies, M/P structures along the Sigsbee Scarp may have important boundary, Palaeoclimate, Mediterranean Basin. implications from the point of view of petroleum systems, particularly if these potential source rocks are hydrocarbon generators.

The First MAPG International Convention, Conference & Exhibition 193 Marrakech Convention Center, October 28 - 31, 2007 Detrital modes and U-Pb ages of zircons from Middle Evolution of the Dead Sea brines Ordovician strata of the Murzuq Basin, Libya: Implications for Israel Zak provenance and tectonics of the western Gondwanan margin Institute of Earth Sciences, The Hebrew University, 91904 E. Ramos1, J. Fernández-Suárez2, D. Barsó1, M. Marzo1, K. Jerusalem, Israel S. Tawengi3, A. A. Khoja4 and N. D. Bolatti5 Since the beginning of its subsidence in late Neogene 1 GEOMODELS. Dep. Estatigrafia, Paleontologia i G. M. times, the Dead Sea Rift has accumulated up to 10,000 m of Universitat de Barcelona, 08028 Barcelona, Spain evaporites and clastics. The sea-flooded part of the Rift, the 2 Dep. Petrología y Geoquímica, Universidad Complutense, Gulf of Sedom, and accumulated in its distal part a thick 28040 Madrid, Spain sequence of rock salt known as the Sedom Formation. The 3 REMSA. Dat el Imad Tower Complex, Tower 3, Floor 8, entire intra-Rift sequence is defined as the Dead Sea Group. Tripoli, Libya 4 National Oil Corporation, Tripoli, Libya The Dead Sea Group and the surrounding pre-Rift 5 REPSOL-YPF Exploration, Madrid, Spain formations contain large volumes of stagnant and migrating interstitial brines, much of which interacting with neighbouring Middle Ordovician strata of the Murzuq Basin consist of formations. The so-called Dead Sea brine is the commonest, quartzarenites recording deposition in transitional to shallow- of Ca-chloridic composition, with over 330 g/l of dissolved marine environments related to the western Gondwanan salts and with a uniquely high Br content (over 5 g/l). The lake, margin. We studied the composition of 154 samples of composed of this brine, fills the over 300 m deep basin of the sandstones and analysed 28 single detrital zircon grains from Dead Sea and may be considered an outcrop of the the Middle Ordovician Hawaz Formation (Ramos et al., 2006). surrounding underground fossil brine. This water body, and brines known from springs and boreholes around the lake, can Detrital modes indicate a quartzose petrofacies (Q97F2L1) all be derived from the mixing and chemical evolution of three for the whole of the Formation with slight vertical variations. basic brines. The first is a diagenetic brine, originally Quartz grains are mainly monocrystalline, unondulatory grains, evaporated seawater of the Gulf of Sedom and later modified suggesting an igneous origin. This origin is also supported by by Mg-Ca exchange into Ca-Mg-Na-K-Cl-Br water (with the analyzed zircon grains, which have (except two of them) Ca2+> HCO3-+SO42-). In this brine, the original (marine) Mg Th/U ratios ≥ 0.2. has been exchanged for the Ca of carbonates of the Dead Sea Detrital zircons were analysed by the ID-TIMS U-Pb dating Group and of the surrounding Cretaceous and older carbonate technique. The results can be grouped into six age clusters: 1) rocks, and most of the original sulfate has been lost through early Cambrian (531 to 536 Ma); 2) Ediacaran (550 to 600 Ma); gypsum and anhydrite precipitation with this sequestered Ca. 3) Cryogenian (620 to 660 Ma); 4) late Mesoproterozoic (910 to The 87Sr/86Sr ratios in the Dead Sea brine and in evaporites 1070 Ma); 5) early Mesoproterozoic (1562 Ma); and 6) of the Dead Sea Group demonstrate their evolution from Paleoproterozoic (1966 Ma). original Pliocene open-sea water, through restricted gulf waters and finally to the land-locked Ca-chloridic diagenetic brines. Age groups 2 and 3 are characteristic of igneous and The second type of brine consists of meteoric waters, dilute to metamorphic events (Ediacaran and Cryogenian) that took mesohaline, with seawater affinity (airborne sea-salts). The place within the Panafrican peripheral orogenic belts. Age third type is a mix of metamorphic brines, which evolved by groups 4 and 5 are found in the orogenic belt (Kibaran event) incongruent alteration and dissolution of hydrous evaporite situated in south-central Africa (cf. De Waele et al., 2003). minerals (e.g. carnallite and gypsum) of the Dead Sea Group. These age clusters are also represented elsewhere in detrital The highly soluble salts are selectively and alternatingly zircons from Cambrian sandstones (cf. Avigad et al., 2003). retained in solution, in successive lakes, or recycled from solid Group 6, at ca. 1.96 Ga is typical of the Eburnean (ca. 2±0.2 deposits formed during periods of desiccation. Ga) basement found in the NW African craton. The composition of the present-day lake waters, which are Avigad, D., Kolodner, K., McWilliams, M., Persing, H. and Weissbrod, Dead Sea brine in the strictest sense, is continuously modified T. 2003. Geology, 31, 227-230. and retained by interacting with these other solutions and by multiple evaporation cycles, with occasional desiccation. The De Waele, B., Wingate, M.T.D., Fitzsimons, ICW. and Mapani, B.S.E. 2003. Geology, 31, 509-512. processes are also contolled by mixing along vertical hydraulic pathways along the rift’s marginal faults, whose porosity Ramos, E. Marzo, M., De Gibert, J.M., Tawengi, K.S., Khoja, A.A. and enables brines to sink to depths of geothermal heating. Brine Bolatti, N.D. 2006. AAPG Bull., 90, 1309-1336. properties and behavior are explained, illustrated, and predicted by application of Jaenecke’s version of Gibbs diagrams. The evolution of the Dead Sea brines provides a characteristic hydrochemical model for continental rift basins temporarily connected with the ocean.

194 Geological analogues: The geochemical evolution of the ages related to the lateral and forelandward progression of Dead Sea may be a meaningful model for continental rift basins deformation in upper crustal levels and these ages do not that are formed in the course of the early, preoceanic rifting of represent sequential limits. a continental plate. The geochemistry is comparable to the Ca- chloride evaporites of the proto-Atlantic Sergipe basin Residual caprock and fossil salt table of the Mount Sedom (northeast Brazil) and the Congo-Gabon basin (west Africa), diapir, Dead Sea basin, Israel and with the recent Ca-chloridic Hot Brine pools of the Red Israel Zak Sea. Indeed, continental rifts are predisposed to endorheic Institute of Earth Sciences, The Hebrew University, 91904 drainage, and as such they are typical, morphotectonic Jerusalem, Israel evaporite environments. The often anomalously deep subsidence of continental rift basins favors thick evaporite The Mount Sedom diapir, on the SW shore of the Dead accumulation and water-rock interaction, and their fault Sea, emerges as an N-S trending asymmetric salt-wall, systems enable strong local thermal influences. evolved parallel to the western boundary faults of the Dead Sea rift. The diapir is a simple structure, exposing steep-dipping to Tectonic control on depositional sequences in foreland locally overturned slightly deformed beds of rock salt with basins: the South Pyrenean Basin case study some non-salt partings (anhydrite, gypsum, dolomite and clastics) of the Sedom Formation, a late Neogene sequence, A. Barnolas and I. Gil-Peña over 2,000 m thick. Today the diapir forms a long and narrow (11 by 2 km), N-S trending hill, rising 260 m above the Dead IGME, Rios Rosas 23, 28003 Madrid, Spain Sea shore. The South Pyrenean foreland basin is an exceptional case The Sedom diapir, though relatively small, provides superb to study the influence of regional tectonics in depositional exposures of a) well-bedded rock salt, overlain by b) salt- sequences. The architecture and facies distribution of its distal depleted residual caprock, with c) a salt table or so-called salt carbonate margin and its relationship with the siliciclastic infill mirror, separating the caprock from the parent salt. These are of the basin-trough allow deciphering lithospheric tectonic also visible along the walls of the multitude caves and shafts of processes linked to basin evolution. On the other hand, the highly developed sub-recent-present karst system, today chronology and kinematics of deformation in the basin can be under an arid environment. Other phenomena are d) an etched traced through the study of growth structures. Regional relief, tracing the facies and strike of the underlying strata. lithospheric and upper-crustal tectonics interacted with global These inter-related features are unique in appearance and eustatic cycles to control local variations of sea level. extension, and contribute to the understanding of primary non- The main depositional sequences in foreland basins salt and secondary salt-depleted evaporite facies, as well as to (related to foreland-basin baskstepping) are overimposed to the interpretation of the structure, stratigraphy and deformation global sedimentary sequences by the influx of regional processes in the course of diapirism. tectonics. These sequences in the South Pyrenean foreland The diapir is topped by some 40 m of well-exposed, salt- basin can be viewed as the sedimentary consequence to depleted caprock, consisting of the insoluble components of successive deepening steps linked to forelandward migration the rock salt sequence, in places preserving the original of the basin trough. Each step started with a drowning phase, stratification. A pre-Holocene, fossil dissolution surface, or salt in which sedimentation could not balance subsidence; this was table, separates the caprock from the underlying parent salt. followed by a progressive increase in sedimentation rate in The diapir is still rising at an average rate of 4mm/year, and the relation to subsidence rate. This evolution is reflected in the originally horizontal salt table is presently tilted and faulted tens architecture of the foreland carbonate margin (backsteeped) of meters above Dead Sea level. The salt beds underneath are and in the siliciclastic basin fill especially when it evolves from at present being dissolved by an active karst system. Where underfilled to overfilled (Southeastern Pyrenees). The ages of the rising salt diapir enters an active aquifer its head dissolves, the main drowning surfaces are ~55 my (base of SBZ 7), ~49,5 and a horizontal to sub-horizontal salt table forms at its top. my (SBZ 12), ~43,8 my (base of SBZ 15) and ~41,2 my (top of This dissolution surface is covered by an evolving caprock of SBZ 16). These steps can be correlated all along the basin and the insoluble residue, which develops an inverse are useful to trace the basinal subsidence history. This restratification, with the newer freed material accumulating sedimentary history dates the effect of episodic orogenic underneath the protecting cover of the older freed residue. crustal thickening onto a previously thinned foreland lithosphere. The sedimentary and structural features of the Sedom diapir, on its various scales, are usually preserved in the salt- If we compare this deformation history with the kinematics depleted caprock. Insoluble layers, freed from the salt matrix, of basin deformation inferred from growth structures, we do continue un-interrupted across the salt table, into the overlying not find a good agreement. Growth structures show younger caprock, including their sedimentary and deformational

The First MAPG International Convention, Conference & Exhibition 195 Marrakech Convention Center, October 28 - 31, 2007 features. Relict structures of folded salt beds appear in the Type Numer of samples Type Numer of samples caprock as folded ghosts, occasionally with the rest of the folded salt beds visible under the separating salt table. the Istebna 111 the Cergowskie 7 The sedimentary and textural features of the salt-depleted the Krosno 9 the Menilite 15 caprock often resemble those of less extreme, saltless evaporites. For this reason they may be mistaken as primary the Ciezkowice 27 the Magura 2 deposits of the Ca-sulfate-carbonate-clastic facies. the Inoceramus 1 the Overmagura 2

Zak I., 1988. The lithostratigraphy and structure of the Sedom Diapir. Geol. Field Guide (in Hebrew), Geol.Soc.Israel ann. Meet. Structural development of the Precaspian basin Konstantin Sobornov1 and Anatiliy Nikishin2 Zak I., 1997. Evolution of the Dead Sea brines. In: The Dead Sea, the 1. TNK-BP, Moscow, Russia lake and its settings Vol. 36, 133-144. Oxford Monogr. on Geology and Geophysics. 2. Moscow State University, Moscow, Russia The Precaspian basin is one of the deepest basins in the Outcrops as one of the keys in reconstruction of petroleum world with total thickness of sedimentary cover in excess of 20 system in the Carpathian Flysch km. The basin is situated on the southeastern edge of the East G. Lesniak1, I. Matyasik1, P. Such1. and L. Jankowski2 European platform. In the south and east it is flanked by buried 1. Oil & Gas Institute, Poland fold belts. Review of geological composition and structure of 2. Polish Geological Institute the basin indicates that the basin passed through several episodes of deformation. Pre-upper Devonian history is poorly Petroleum system was recognized in Gorlice - Bóbrka constrained. It is likely that the lower part of sedimentary fill region of the Outer Carpathians in Poland. Three tectonic units includes thick Riphean and Vendian strata, deposited within (Dukla, Silesian and Magura) in the area of study are the most the rifted margin of the East European platform in front of the important for petroleum industry. There are several types of Baikalian fold belt. In Ordovician, the basin experienced rifting potentially reservoir sandstones here belonging to these units resulting in the formation of the 300-km wide deepest axial but only the Istebna and the Ci??kowice sandstones from the trough in the northern part of the basin. The rifting was related Silesian unit were investigated in boreholes. Carefully chosen either to the opening of the Urals or back-arc extension the outcrops sandstones as well as new samples from existed Scythian orogen situated to the south. In the Late Frasnian, boreholes were gathered in database (tab.1). Porosity, the basin was affected by episode of folding which is most permeability capillary pressure investigations, petrography and likely related to initial phase of the Uralian collision. During computer analyses of microscopic images were performed for Famennian-Sakmarian the Precaspian basin had been outcrops and borehole samples. ANN simulation using the developed under combination of postrift and foreland whole database gave very good permeability fit for all kinds of deposition being repeatedly affected by compressional events sandstones (also from outcrops). It means that all types of generated by the Uralian-Scythian fold belt. The progressive sandstones are petrophysically very similar. Detailed orogeny led to isolation of the basin in Kungurian time. This investigations show only a little bit higher porosity for outcrop together with arid climate resulted in deposition of thick salt samples. Petrography investigation allows explaining this fact. layers. The Mesozoic-Cenozoic history of the basin started Circulations of meteoric waters dissolute sand grains but pore with collapse of the orogens in Early Triassic and was followed throat are not changed. Correlation matrix method was applied by several pulses of compressional and transpresional events to share factors steering petrophysical properties in governed mainly by the development of the Alpine-Hymalaya sandstones from investigated region. There are number of fold system. Two major episodes of salt diapirism took place cement and content of carbonate cement. in the Late Triassic and Late Cenozoic. Due to Source rocks responsible for generation of hydrocarbons in accommodation space restrictions the salt diapers formed area of stud have been identified. Outcrop samples (60) were predominantly vertical columns and walls. taken from sediments of the Dukla and the Silesian unit. Key words: Precaspian basin, salt diapirism, Uralian orogeny. Generally outcrops samples originated from the Menilite beds located along anticlines in analyzed area. Finally hydrocarbon potential of region was estimated. Effect weathering was taken Structural model approach of the Chelif basin, North Algeria into considerations particularly due to samples showing high Rachida Ghazli level of thermal maturity. Sonatrach, Upstream Activity, Exploration Division, Avenue du 1er novembre, BP 68M Boumerdès 35000 Algérie Tab.1. Investigated sandstones from boreholes and outcrops This paper is focused on the interpretation of the middle part of the Chelif basin of the seismic reflection profile.

196 The structural model is based on the geometry of the basin Two important tectonic subsidences occurred with 1100m integrating various data sources. (Surface geology, well data, seismic thick, during the Eifelian- Fammenian period and 450m thick in cross-sections, gravity data). Available wells are the deepest ones of the the Visean period. region. The interval velocities used for the inversions of the principal profile were chosen from the seismic lines. Structuration stage: From Cambrian to Silurian period, the Reggane basin displayed the same paleo-geodynamical The Chelif basin is located in the western part of North evolution as in the surrounding basins. Algeria. It corresponds to a tertiary basin with three sedimentary cycles, Lower Miocene, Upper Miocene and The Post- Silurian period (early Devonian - early Pliocene. These deposits overlay on a basement Carboniferous) is characterized by a distensive tectonic event undifferentiated, separated by the alpine unconformity. Many creating another basin, oriented NW-SE, named Sbaa, located periods of deformation are recorded and such a structural in the north east of the Ougarta- Kahal Tabelbala horst. model was involved. Associated to these sedimentary basins, some epirogenic movements are observed in the south border of the basin, It is defined as a piggy-back basin over a main basal affecting the lower Paleozoic series, responsible of the fifth detachment corresponding to the cretaceous marls and intra-Paleozoic unconformities. sometimes to the Triassic salt. I tried to propose a thick- skinned style involving the Palaeozoic deposits beneath During the Middle and the Upper Carboniferous time, a Mostaganem plateau and thin-skinned through the south compressive event occurred, corresponding to the Hercynian border of the basin. phase. This tectonic phase was responsible of the actual architecture, such as rejuvenation of the normal faults inherited The potential of this basin is enhanced by two important from the Cambrian extensive tectonic, migration of the oilfields discovered in the thirteen’s and named Ain Zeft and depocenter axis from the North (Devonian-Carboniferous) to Tliouanet, situated respectively in the northern border and the the South (Upper Carboniferous), uplift and the upthrust of the southern one of the basin. The principal sandy reservoirs are Ougarta horst toward the South West, and at last, formation of tertiary, corresponding essentially to the basal terms of the positive flower structures, with a submeridional direction. Lower and Upper Miocene. Key words: Reggane, compressive, geodynamic, Paleozoic, The geochemical modelling (Genex) took in account the subsidence. different geological events and revealed positive results in terms of timing and source rocks especially the basement Mixed wetted carbonate reservoir: origins of mixed (Cretaceous, Palaeocene). wettability and affecting reservoir properties Key-words: Piggy-back, thin-skinned, thick-skinned, petroleum I. Matyasik, G. Le?niak and P. Such potential. Oil & Gas Institute, Poland

The Paleozoic geodynamic evolution of Reggane basin Bryozoan reef buildups show generally good reservoir (Algeria) properties in the Main dolomite sediments. They create single Mourad Issad and Rachida Ghazli porosity – double permeability, reservoir rocks showing mixed Sonatrach, Upstream Activity, Exploration Division, 16000 wettability. Mixed wettability is a result of basin history. The Algiers Algeria, main dolomite sediments were sealed very quickly between Avenue du 1er novembre, BP 68M Boumerdès 35000 Algérie salt and anhydrite sediments in a scale of the whole basin. So reservoir rocks were also source ones. It caused that residual The Paleozoic pericratonic Reggane basin is located in the organic matter is still present in the main dolomite rocks. Reef South Western part of the Algerian Sahara platform. It is a structures were strongly granulated and washed during dissymmetric depression, oriented NW-SE. The geological sedimentation. Finally these types of reservoir rocks facially events are clearly distinctive in time and space. form high energetic carbonate sands. These sands are mixed with residual organic matter. Presence of organic matter and its Sedimentation stage: The Reggane basin is formed at the way of mixing are factors affecting wettability of rocks. There Cambrian with 5166m thick in its principal depocenter. are no evident correlation between content of residual organic Extremely reduced at its south border, the thickness does not matter and wettability index. Main role plays a process of exceed 1800m. The sedimentary deposits are essentially mixing carbonate grains and organic matter. Rock Eval sandstones and shales, affected by dolerites, interbedded in analyses and several experiments of sample extractions were the Fammenian and Visean formations. conducted to determine a type of organic matter. Additionally, saturation with water under vacuum was applied to indicate a type of oil wet part of pore space. It was shared that oil wet

The First MAPG International Convention, Conference & Exhibition 197 Marrakech Convention Center, October 28 - 31, 2007 pores occupy the range from the smallest to the greatest GS 11 : Advances in Biostratigraphy and pores. Oil and water paths of fluids migration are practically Sedimentology studies of the Cretaceous dynamic independent. Great part of samples (70) are predominantly oil systems wet, 17 shows predominant water wetting. There was no pure oil or water wet rocks. Dinoflagellate cyst biostratigraphy across the Cretaceous- Such type of wettability produces irreducible oil and water Paleogene boundary at the Ouled Haddou section, south- in all samples. The content of irreducible oil in the function of eastern Rif, Northern Morocco capillary pressure was estimated. Also relative permeabilities Hamid Slimani1, Stephen Louwye2, Abdelkabir Toufiq3 and residual oil saturations were examined. 1 University Mohammed V-Agdal, Scientific Institute, Laboratory of Geology & Remote sensing, Avenue Ibn Complex rifted margins explained by dynamical models of Batouta, P.B. 703, 10106, Rabat-Agdal, Morocco depth-dependent lithospheric extension 2 Ghent University,Research Unit Palaeontology, Krijgslaan 281/S8, B-9000 Gent, Belgium Ritske S. Huismans1, 2 and Christopher Beaumont2 3 University Chouaïb Doukkali, Faculty of Sciences, Laboratory 1 Department of Earth Science, Bergen University, Bergen, of Geosciences and Environmental Techniques, B.P. 20, Norway 24000, El Jadida, Morocco 2 Department of Oceanography, Dalhousie University, Halifax, Canada A palynological investigation of the recently described and foraminifera-dated Ouled Haddou section (north of Taza, Subsidence of rifted continental margins is explained by the northern Morocco), revealed rich and well preserved isostatic response to lithospheric stretching, which leads to palynological assemblages. The dinoflagellate cysts syn-rift tectonic subsidence followed by lithospheric cooling stratigraphy indicates well that the analysed samples of the and long-term post-rift thermal subsidence. Despite the Ouled Haddou outcrop represent a latest Maastrichtian and a success of the Uniform Extension model, observations from lowermost Danian ages, on the basis of the appearance of some margins, including central South Atlantic, Exmouth index species of the Maastrichtien/Danien boundary as Plateau, and central and north Atlantic, are not consistent with Eisenackia circumtabulata, Carpatella cornuta, its predictions. For these distinctive margins, wide regions of Damassadinium californicum, Lanternosphaeridium reinhardtii, extremely attenuated crust but relatively thin overlying syn-rift Membranilarnacia tenella, Senoniasphaera inornata, and sediments with upper layers that were deposited in shallow Kenleyia spp. Age assignments based on dinoflagellate cysts seas, are more compatible with the Depth-Dependent agree with the stratigraphic interpretation of the Cretaceous- Extension model. Although the kinematics of depth-dependent Palaeogene boundary of the studied section by planktonic stretching are understood, the conditions favouring this style foraminifera (Toufiq et al., 2002). The co-occurrence of the and the consequences for a complete rift zone in space and peridinioid dinocyst species of Andalusiella, Cerodinium, time require investigation. We show that dynamical models Lejeunecysta and Senegalinium one the one hand, and which lead to depth-dependent extension explain Isabelidinium, Spinidinium and Trithyrodinium one the other characteristic features of these margins. A template developed hand, indicate that the Ouled Haddou dinocyst assemblages from the dynamical model results which divides margins into belong to the transitional tropical to subtropical Malloy/worm Proximal, Sag and Distal (P, S, D) zones is broadly compatible temperate Williams suite of Lentin & Williams (1980). with observations from approximately conjugate South Atlantic margins. Key to reproducing the observed characteristics are Eight new dinoflagellate species are present in the section: decoupling between upper and lower parts of the lithosphere Batiacasphaera rifensis sp. nov., Cerodinium mediterraneum during stretching, contrasting wide and narrow extensional sp. nov., Damassadinium spinosum sp. nov., Eisenackia styles above and below the decoupling level, and progressive msounensis sp. nov., Impagidinium maghribensis sp. nov., focusing of crustal extension toward the rift axis. This Lejeunecysta izerzenensis sp. nov., Pterodinium cretaceum sp. behaviour explains the subsidence, sedimentation and nov. and Ynezidinium tazaensis sp. nov. deformation of the associated array of sedimentary basins, the origin and context of so-called ‘sag’ basins, and the reasons Keywords: Cretaceous–Palaeogene; Dinoflagellate; Stratigraphy; these basins are prone to shallow water evaporite deposition Ouled Haddou section; Northern Morocco during the late syn-rift. Evaporite-bearing South Atlantic margins of this type have recently been sites of new giant hydrocarbon discoveries. Conceptual and quantitative insight based on the model proposed here can help evaluate the overall hydrocarbon potential of these basins.

198 Sequence stratigraphy of Passive Margin: Agadir and This new zonation is compared with the standard zonation Essaouira Basins (Morocco) during Berriasian - Aptian and (GSSP) of the Western Interior, USA (Bengtson [compiler], 1996) and allows a good correlation with the european Maestrichtian Oligocene zonation and with the major events described in the chart of Taj-Eddine Kamal1, Witam Omar1, Algouti Ahmed1, Ettachfini the European basins published by Hardenbold (1998). Mouhssine1, Rey Jacques2 and Algouti Abdellah1 1 Université Cadi Ayyad, Faculté des Sciences Semlalia, Ammonites characterise the time interval between the Laboratoire Dynamique des Bassins et Géomatique, lower part of the Upper Cenomanian and the Upper(?) Marrakech, Maroc Turonian. The Vascoceras gr. cauvini zone records the 2 Université Paul Sabatier-Toulouse III, Laboratoire de Géologie Uppermost Cenomanian, and the Watinoceras zone, the Sédimentaire, Toulouse, France Lowermost Turonian.

In the basins of Essaouira and Agadir, the Berriasian - Planktic foraminifers are also representative. The last Aptian and Maestrichtian - Oligocene intervals exhibit occurrence of Asterohedbergella asterospinosa points out the respectively 15 and 7 Lithostratigraphic Units defined by a Uppermost Cenomanian, and the first occurrence of main lithological changes. Helvetoglobotruncana helvetica, the Lowermost Turonian. The Archaeocretacea zone covers the Cenomanian-Turonian The spatial distribution, the thicknesses variations as well boundary. as the general evolution of the depositional sequences testify of an important mobility of the basement during sedimentation. Two biozones are defined by benthic foraminifers: the Thomasinella punica zone in the Cenomanian, divided in three In the Berriasian – Aptian period, the distensive reactivation sub-zones with the Spirocyclina atlasica sub-zone in the of NNE-SSW and E-W striking paleo-faults induces a Uppermost Cenomanian, and the Gabonita levis zone in the differential tectonic subsidence with highs and grabens. The Turonian. earliers are characterized by reduced series exclusively of high stand system tracts. The seconds present a thickest and most Two ostracodes biozones are proposed: the Reticulocosta complete series with transgressive and high stand system boulhafensis one in the Cenomanian, linked with the tracts. Dolocytheridea atlasica abundance biozone in the Upper Cenomanian, and the Spinoleberis yotvataensis biozone in the For the Maestrichtian-Oligocene period, the sedimentation Turonian. Moreover, the Reticulocosta gr. tarfayaensis occurred during the deceleration of the oceanic expansion and abundance biozone is very important for the Cenomanian- the beginning of the Western High Atlas uplift. These tectonic Turonian boundary. movements confer to the sedimentation a discontinuous character and a contrasted lithology with alternation of The different species of inoceramids allow to recognize carbonates and clastics. some Cenomanian-Turonian events. The evolution of the series attests of eustatic and tectonic These new biostratigraphic data are further arguments to interference in distensive and compressive general context, respectively for the Berriasian – Aptian and Maestrichtian - place with precision the Cenomanian-Turonian boundary in Oligocene intervals. Morocco, and make more complete the standard zonation edited by Hardenbol et al. (1998) for this cross point between In this study we propose, for each Lithostratigraphic Unit, a the Atlantic and the Tethyan Oceans. depositional sequence (3rd order) subdivision compared to those presented in the literature (Vail and al., 1987; Van Key Words: Cenomanian-Turonian Boundary, Biostratigraphic Wagoner and al., 1987; Haq and al., 1987). Zonation, Morocco.

Key words: Sequence stratigraphy, Passive margin, Cretaceous, Oligocene A new method to quantify carbonate accumulation: application to the Ziz section (Upper Cenomanian – Turonian, Preafrican Trough, Morocco). Integrated biostratigraphy of the Cenomanian-Turonian Lezin Carine1, Robette Aude1, Andreu Bernard1, Perrin Boundary in Morocco. Christine1 and Ettachfini El Mostafa2 Ettachfini El Mostafa1 and Andreu Bernard2 1 University of Chouaïb Doukkali, Faculty of Sciences, Lab. 1 LMTG, université de Toulouse, CNRS, IRD, OMP, 14, av. E. Geosc & Techniques of Environment, B.P. 20, 24000, El Belin F-31 400 Toulouse, France. Jadida, Morocco. 2 Univ. Chouaïb Doukkali, Faculté des Sciences, Géologie, 2 LMTG, University of Toulouse, CNRS, IRD, OMP, 14, av. E. Lab. Géosc. & Techniques de l’environnement, B. P. 20, 24 Belin F-31 400 Toulouse, Frensh. 000, El Jadida, Maroc.

An integrated biostratigraphic zonation of the Moroccan The atmospheric concentration of CO2 during geological Cenomanian-Turonian boundary is proposed from the times is difficult to estimate. It was shown that there was a distribution of the main paleontological groups: ammonites, close relationship between that concentration and the quantity planktic and benthic foraminifers, ostracodes and inoceramids. of carbonate produced in oceanic environment.

The First MAPG International Convention, Conference & Exhibition 199 Marrakech Convention Center, October 28 - 31, 2007 Thus, an indirect mean to evaluate CO2 contents is to Diagenetic history of the Late Jurassic-Cretaceous estimate precisely, on a regional scale, the quantity of Carbonate Series of Lalla Fatna Area, Safi Basin, Morocco carbonate accumulated, in order to better constrain dynamic Ouajhain Brahim1, Ettachfini El Mostafa1 and Ettachfini carbon cycle models. Mohssine 1 University Chouaïb Doukkali, Faculty of Sciences, Geology, To carry out this regional valuation, it is first necessary to B.P. 20, 24000, El Jadida, Morocco. develop a rigorous quantification method. From the study of 2 University Cadi Ayyad, Faculty of Sciences, Semlalia, the carbonate accumulation on an outcrop, we propose a new Geology, Marrakesh, Morocco. quantification method, which takes into account the diagenetic transformations undergone by the rock. The diagenetic history of Lalla Fatna Upper Jurassic – cretaceous carbonates series reflects a number of different We developed this method from the study of the Upper diagenetic environments. Cenomanian-Turonian series outcropping near the Ziz river, in Morocco. This method evaluates and quantifies the various Early stages of diagenesis took place in the marine phases of late dissolution and cementing which affected the environment with solutions of normal marine chemistry. Major rock since its formation, modifying the CaCO3 concentrations. diagenetic features include the formation of micritic envelopes We could estimate the percentage of primary porosity and thus and a minor amount of cementation in the marine environment. quantify the real carbonate content accumulated on the studied area, during the considered period. Petrographic evidence from this study supports the hypothesis that Lalla Fatna dolomite series were formed by at The accumulation rate of carbonate sediments is estimated least two episodes of dolomitization. The first episode was very at 18.94 m/Ma for the Upper Cenomanian and at 2.51 m/Ma early, produced from hypersaline brines, with location being for the Turonian. controlled by dep

We show that the quantification methods suggested in the According to the fresh-water-mixing hypothesis, chemically literature over-estimate either of 10% (calcimetry method) or of more perfect dolomite forms from dilute solutions. Fresh- and 4% (calcimetry and porosimetry method) the accumulation rate saline-mixed waters also were capable of dolomitizing by of carbonate sediments. themselves, without having hypersaline cores on which to build. Key words: Carbonate accumulation rates of, Method, Upper Cenomanian-Turonian, Preafrican Trough, Morocco.

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