Dynamics of the Norwegian Margin: an Introduction

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Integrated Basin Studies- Dynamics of the Norwegian Margin: an introduction

ARVID NOTTVEDT

Norsk Hydro Research Centre, N-5020 Bergen, Norway Present address. Norsk Hydro Canada, l ll-5th Avenue SW, Calgary AB, T2P 3 Y6, Canada

Several lithospheric and upper crustal processes theless, the Voring margin is among the best interact in the formation of rift basins and studied volcanic margins globally due to a evolution of such basins into passive margins. regional coverage of multichannel seismic lines, Similarly, the fillings of rift basins depend on a expanded spread profiles and other geophysical variety of tectonic, morphological and sedimen- and geological data. In addition, the successful tary processes. Areas that have passed through scientific drilling through a sequence of sea- a complete evolution from intra-cratonic rift- ward dipping reflectors on the Voring Plateau ing through breakup and passive margin forma- has greatly contributed to the understanding tion offer particular opportunities to study and of the margin. link the different processes of basin formation This setting makes the study region an and filling. One such area, that has a unique excellent laboratory in which to study progres- combination of a well-preserved rock record and sive rift evolution and its inter-relationship with abundant data, is the Norwegian North Sea- basin formation and filling, including the inter- North Atlantic margin, herein referred to as plays between structural evolution, erosion, the Norwegian margin. sedimentation and magmatism, on both regional During post-Caledonian times the North Sea and local scales. Consequently, the region allows and mid-Norwegian margin underwent several research into fundamental earth processes, which episodes of lithospheric extension (multi-phase also have direct implications for hydrocarbon rifting), of which the latest led to crustal break- exploration and assessment. up and accretion of oceanic crust between Norway and Greenland near the Paleocene- Eocene transition. Prominent pre-breakup extensional episodes, in late Permian-Triassic, late The Integrated Basin Studies (IBS) project Jurassic, early Cretaceous and mid-Cretaceous time, led to the development of the North Sea The papers and research results presented here rift system, the large Cretaceous Voring and have been prepared as part of the Integrated More sedimentary basins off Norway, and con- Basin Studies project (Fig. 1).This project was jugate equivalents off eastern Greenland. Latest funded under the DG IIX, JOULE II pro- Cretaceous-Paleocene rifting and breakup were gramme, with the objective to study the litho- accompanied by large-scale igneous activity, spheric and upper crustal processes governing developing the present conjugate volcanic mar- the formation and evolution of extensional and gins of the North Atlantic. foreland basins and to decipher the role of The North Sea, in particular, is covered with tectonics, sea-level and sedimentary processes in an exceptionally good geological and geophysi- the filling of such basins. As part of this task, the cal industry and academic database, comprising project also aimed at studying the physical laws both high-quality geophysical profiles and a of compaction in fine-grained sediments. Based large number of industrial wells. About 30 years on these results, a new generation of descriptive of active exploration in the North Sea has led to as well as numerical basin formation and basin an advanced level of understanding of the geo- fill models has been derived. logical evolution and complexity of the basin. Results from the Integrated Basin Studies Numerous papers have been published on the project have been reported in an extensive Final formation and filling of the North Sea intra- Report to the DG IIX, and selected papers cratonic rift structure. prepared within Modules 1 and 2 have been The mid-Norwegian margin has a less exten- published in two previous Geological Society sive, but increasing, industry database. Never- Special Publications, nos 134 and 156.

From: NOTTVEDT, A. et al. (eds) Dynamics of the Norwegian Margin. Geological Society, London, Special Publications, 167, 1-14. 1-86239-056-8/00/$15.00 ~ The Geological Society of London 2000. Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

2 A. NOTTVEDT

This book has been prepared with the inten- Thematicalh', the project module focused on tion to give a representative picture of the sci- three related themes: (i) Intra-plate rifting and entific span and results of the project Module 3: basin formation, (ii) Basin infill and (iii) Con- Dynamics of the Norwegian Margin. It includes jugate volcanic margins. The data coverage and papers prepared by PhD students funded geological setting resulted in a topical focus on directly through the project, as well as papers two geological provinces, the northern North Sea written by researchers in academia and industry and the Norwegian-Greenland Sea rifted volca- that have been working in, or closely associated nic margins. The More Basin, on the volcanic with, the project. More margin, links these two provinces. Geo- graphically, the two former research themes (Intra-plate rifting and basin formation and IBS Module 3: Dynamics of the Norwegian Basin infill) focused on the northern North Sea Margin (IBS-DNM) and the More Basin, while the latter (Conjugate volcanic margins) primarily dealt with the More- The Integrated Basin Studies project Module 3, Voring margins and their conjugates. Dynamics of the Norwegian Margin (Fig. 2), was Of particular interest in the intra-plate setting technically part of the IBS project, but received is the kinematics and relative importance of funding directly from the Research Council of deeper versus shallow crustal processes and how Norway (RCN). The module was coordinated by these control overall subsidence patterns; the Norsk Hydro, and contractual arrangements erosional and provenance history of sediment were made between Norsk Hydro and EU, supply areas: and the architecture, composi- Norsk Hydro and RCN, and Norsk Hydro and tion and history of basin fill. The work con- partners. The module was organized into three centrated on syn-rift basin fill, but included also themes and subordinate topics (Fig. 3). post-rift strata. It has been attempted to establish general and coupled models for rift basin Research objectives formation and sediment filling in the northern North Sea. The scope of the IBS-DNM project module was The Norwegian-Greenland Sea represents to analyse and model the dynamics of the basins complete extension and thinning of the litho- off mid-Norway and in the northern North Sea, sphere. Therefore, the margin basins bear an in order to establish a better understanding of the imprint not only of the same events as the processes controlling basin formation and filling intra-plate basins, but have also undergone and to develop new models for multiphase, a structural, magmatic and depositional his- intraplate rifting and volcanic margin formation. tory reflecting the formation and subsequent

Projects Modules INTEGRATED ~Tertiary Extension within'~ BASIN STUDIES theAIpine Orogen )

Cenozoic Foreland STRATIGRAPHIC Basins of W. Europe MODELLING Dynamics of the Norwegian Margin

STRUCTURAL IMAGING ( Compactionand Fluid ~ Flow in f-g sediments

RESERVOIR Modelling 1 ENGINEERING

IBS Co-ordinating Team: B.Durand, Institut Francais du Petrol S.Cloetingh, Vrije Universiteit Amsterdam C.Puigdefabregas, Servei Geologic de Catalunya Fig. 1. DG IIX: Joule II Geoscience II Programme Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

INTEGRATED BASIN STUDIES 3 development of the present volcanic passive It is important, therefore, that the project had margin. To understand the basin evolution and access to much of the existing seismic, structural tectono-magmatic history it is necessary to and stratigraphic framework in the study region assess the timing and magnitude of the different to define and select the optimal target areas for tectonic, magmatic and subsidence episodes for the detailed studies described in the various the various basins. In order to determine the project topics. The industrial partners were style of deformation for each tectonic episode instrumental in achieving this objective. and to quantify the magnitude of crustal and The work on crustal structure and basin lithospheric extension, restoration of the struc- formation concentrated around seven transects turally defined extensional deformation through from the northern North Sea to the Voring time was particularly emphasized. margin (Fig. 4), whereas the topic on stress field covers the entire Norwegian continental shelf. The syn-rift infill studies focused on selected Database and methods fault-blocks in the northern North Sea, whereas the post-rift (Cenozoic) infill studies integrated The project database (Fig. 4) consisted of data from the Danish and Norwegian sectors scientific deep reflection and refraction seismic of the North Sea, up to 62°N. The work on data, large volumes of industry regional 2D erosion and provenance included the northern reflection seismic data, 3D seismic data, well North Sea. The studies on volcanic margins data, potential field data, industry special concentrated on the mid-Norwegian margin, but studies and reports, in addition to published comparative studies were made with other vol- literature. canic margins around the world.

EU RCN

I I[ m

GERTH HYDRO

I I I I I I I

Norwegian partners

Vrije University (VU) University of Oslo (UO) University of Karlsruhe (UKa) University of Bergen (UB) Catalunya Geol. Survey (CGS) Norwegian Technical University (NTU) University of Edinburgh (UEd) Norsar Rogaland Research Centre (RF) Legend Continental Shelf Institute (IKU) Statoil Saga [----~ Sponsors Hydro Norwegian Petroleum Directorate (NPD) I I C°°rdinat°rs

~ Partners

Fig. 2. IBS-DNM contractual framework and involved partners. RCN, Research Council of Norway. Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

4 A. NOTTVEDT

subsidence and may therefore contribute sig- Steering Committee: Olav Eldholm, UO nificantly to the stretching factor as calculated Roy H. Gabrielsen, UB from subsidence analysis of later rift episodes. Tony Spencer, Statoil Editorial board A major question is the relative contribution to Snorre Olaussen, Saga Bj~rn Y. Larsen. Hydro Arvid Nottvedt, Hydro Snorre Olaussen, Saga final extension contributed by each of the main Oqan Birketand. Statod Harald Brekke. NPD episodes of extension. I +++-o+: I Jakob Skogseid. UO Arvid N~ttvedt, Hydro Roy H. Gabdelsen, UB Arvid NotWedt, Hydro Key resuhs. The deep seismic reflection survey NSDP84 has formed the basis for numerous [ t I Theme I Theme 2 Theme 3 papers on the crustal structure and basin evolu- Topic 1.1 Topic 2.1 Topic 3.1 tion of the northern North Sea rift system. Crustal Syn-rift sediment Rift dimensions structure architecture and duration However integration with all available geophysi-

Topic 1.2 Topic 2.2 Topic 3.1 1 cal and geological data from both offshore and Sedimentary basin Post-rift sediment Geodynamic onshore areas provided some interesting new formation architecture modelling J results. Topic 1.3 Topic 2.3 Topic 3.1 ] Reprocessing of the deep reflection seismic Regional Erosional episodes Comparative stress fieId and provenance studies data resulted in enhanced data quality. By Topic 1,4 Topic 2.4 integrating seismic refraction data, ESP data Tectonic Stratigraphic and gravity/magnetic data, and combining these modellin 9 transects with high-quality commercial reflection Principal Investigators: seismics, it has been possible to map out the 1.1 Jan Inge Faleide, UO 2.2 Jan I. Faleide. UO 1.2 Roy H. Gabrielsen, UB 2.3 Knut Bjodykke, UO structural outline of the graben geometry of 1.3 Arne Myrvang, NTU 2.4 Martin Hamborg. IKU the northern North Sea (Christiansson et aL, Hilmar Bungum, Norsar 3.1 Jakob Skogseid, UO 1.4 Willy Fjeldskaar, RR 3.2 Jakob Skogseid, UO Odinsen et aL (a)). including linkage between 2.1 Ron J. Steel, UB 3.30lav Eidholm, UO upper and mid crustal faults+ fault geometries of the deep crustal levels and structure of Fig. 3. IBS-DNM project structure and organization. the lowermost crust. Of particular interest is Past members of the Steering Committee include the improved identification of top basement, the Alv Orheim (Statoil), Jan Volset (Statoil) and Ron confirmation of intra upper mantle dipping J. Steel (UB). reflectors and identification of a high-velocity lower crustal rock body. New information on the levels of detachment and general geometries of the different fault Theme 1: Intra-plate Rifting and systems has also been gained (Fossen et aL). Basin Formation These investigations reveal a more complex interaction between fault systems than antici- Topics 1.1: Crustal structure, pated earlier. The kinematics of the faulting was 1.2." Sedimentary basin formation and studied by the use of analogue models (Fossen & 1.4." Tectonic modelling Gabrieisen 1995). In addition, the confirmation of the existence of "graben units,' which are The dynamic framework for Mesozoic and characterized by shifting polarities along the Cenozoic basin development in the northern basin axis of the Permo-Triassic basin axis, is North Sea and on the mid-Norwegian margin important (F~erseth et al. 1995a). has been well documented over the last decade. Forward/backward numerical modelling of However, there is major uncertainty as to the crustal geometry, palinspastic graben topogra- nature of the deep crustal structure and its phy and thermal development have resulted in relation to the sedimentary cover. In addition, better insight in the formation of the North Sea the detailed nature, significance and areal extent rift (Odinsen et aL (b). ter Voorde et al.). These of the faulting and differential subsidence in the investigations conclude that the Permo-Triassic post-rift intervals are poorly known. stretching event has been underestimated in For a complete understanding of evolution of many previous works in the area. The Permo- the northern North Sea and More Basin it is Triassic event is responsible for a more extensive essential to consider the earlier Permo-Triassic extension than the Late Jurassic event and the rift, which generated the structural framework former event also resulted in extension of a on which the later Jurassic and Cretaceous rifts wider area than did the latter. acted (Fig. 1.3). Compaction of Permo-Triassic The results from the structural mapping of the basin fill and residual Permo-Triassic thermal More Basin particularly emphasize the complex- anomalies may enhance Cretaceous-Cenozoic ity of the basin, where large basement-involved, Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

INTEGRATED BASIN STUDIES 5 rotated fault-blocks have contributed to the in- new concepts to the industry that are relevant ternal compartmentalization of the basin. As for for the understanding of sand distribution in the North Sea, the More Basin was subject general, and in search for the subtle trap in to multi-phase extension (Grunnaleite & Gab- particular. It is also expected that the results will rielsen 1995). Lithospheric stretching probably be of importance in basin modelling, both on commenced in the late Permian-early Triassic, the regional (crustal) scale, and for maturation followed by a second episode in the late Jurassic. and migration studies on the sub-regional scale. In contrast to the North Sea, however, early-mid- In addition, the focus on the pre-Jurassic basin Cretaceous rifting and successive Palaeogene development has opened new perspectives that breakup strongly influenced further development may be of importance for future exploration, of the basin, resulting in a cumulative beta-factor particularly in the deeper parts of the North in excess of 3. Regional-scale antiforms along the Sea Basin. northeastern basin margin, basin inversion in the Slorebotn Sub-basin and the northeastern More Basin, compressional reactivation of faults Topic 1.3." Present regional stress field as seen on the near base Cretaceous level, and reverse drag and folding associated with faults of Some rift episodes in the northern North Sea- primarily extensional origin, suggest that pro- More Basin-Voring Basin correlate with break- nounced multi-phase late Mesozoic-Cenozoic up and initial sea floor spreading in other basins inversion has taken place (Mogensen et aL, within the North Atlantic rift system and Gabrielsen et al. 1999). the inter-relationships between pre-rift structures (structural fabric) and the regional stress Relevance to the petroleum industry. The im- field probably played an important role in proved models for basin development and fault structural evolution, by rejuvenation of inher- geometries obtained within this topic provide ited structures.

~oo "~oo "10" 10"

->oo 53 Ma (Chron 24n,3) Early Tertiary flood basalt province

Jan Mayen micro-continent

Late Jurassic-Early Ooo Cretaceous central rift zone

[--] Late Paleozoic-Early Mesozoic basins

AI~ Caledonian orogenic front -% ======Plate boundary

"10 ° ~ ~0"

Fig. 4. Schematic outline of the IBS-DNM study area and database (after Skogseid et a/., this volume). Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

6 A. NOTTVEDT

The orientation and magnitude of the present measurements onshore. Compressive differen- stress field are reflected in both well data and tial horizontal stresses are found in all parts earthquake focal mechanism solutions. The use of the margin analysed, and the data indicate of both in situ measurements and earthquake that the stress regime in the upper crust often based data enables mapping of crustal stress as a alters with depth. A stress homogeneity through- function of depth. Most important are strain out the brittle crust is, however, well documen- markers for individual time intervals. ted by the homogeneous stress directions Regional and local variations in stress direc- obtained from complementary data (deep earth- tions and magnitude yield information on the quakes and shallow boreholes). intra-plate forces, plate tectonics and recent geological history. Thus, it provides impor- Relevance to the petroleum hulustrv. On a short- tant input to the tectonic modelling. Coupling term basis, this topic has provided important of non-linear lithosphere theology to a model information to the general understanding of involving stress changes acting on a basin offers the stress field along the Norwegian Margin, the prospect of understanding non-thermal sub- which is of considerable importance when sidence and of solving discrepancies in present entering into new areas like the Voring Basin. crustal extension estimates. In addition, detailed information on in situ stresses in several petroleum fields is expected Key results. A database of unprecedented to be directly relevant to activities in those fields. quality and quantity for the region has been In situ rock stress data are particular important established, comprising stress information from for the planning and drilling of stable and safe a variety of sources. The project has contributed wells. The state of stress in and around the to the compilation of an earthquake focal hydrocarbon reservoir is also important for field mechanism database that is constantly being development and reservoir management, and expanded, and which currently comprises 109 the success of hydraulic fracturing and injec- solutions for northwestern Fennoscandia and tion depends on knowing how fractures and Svalbard (Lindholm et aL. Lindholm et al. 1995). fluid fronts propagate under different stress In addition, a total of 345 borehole breakout systems. The use of such data may on a long- observations and 104 overcoring measurelnents term basis reduce costs and help optimize dril- have been collected and quality-assessed into a ling and production. high-quality database (Fejerskov & Lindholm (a), Borgerud & Suave 1995, Fejerskov et al. 1995. Golke et al. 1995). Theme 2: Basin Infill All these data were used in a joint interpretation of the crustal stress field in Norway Topic" 2.1: Syn-r(fi sediment architecture and adjacent offshore regions (Fejerskov & Lindholm (b)). Regionally, the analysis has The stratigraphy and architecture of the Trias- revealed a crustal horizontal compressive stress sic-lower Jurassic and Cretaceous-Cenozoic with a dominating WNW-ESE direction(sn .... ) post-rift basinal infill of the North Sea are in southern Norway, which gradually rotates relatively well documented, whereas the Permo- into N-S compression in the Barents Sea Triassic and upper Jurassic syn-rift infill are region. The observed stress is largely consistent known only in broadest outline. Details of throughout the upper crust, indicating that timing, style and rates of the events that make large-scale tectonic mechanisms are the main up the syn-rift episodes, and of the sedimen- source. This can, with a high degree of con- tary response to these events, have only recently fidence, be attributed to crustal spreading along started to emerge. Extension across the northern the mid-Atlantic Ridge. The consistent stress Viking Graben is known to vary between the pattern shows regional variations probably Tampen Spur, Viking Graben proper, Horda caused by regional stress generating mechanisms Platform and Sogn Graben segments. This like the continental margin-ridge push and variability in space, together with temporal sediment loading. Faults that perturb and variations (Permo-Triassic, Late Jurassic) has deviate the regional stress locally also have considerable consequences for the composi- been observed. tion of syn-rift infill. These lateral changes and With important exceptions in local areas, related provenance and sediment transport the dominant type of faulting is found to be issues have been addressed by analysis of dif- contractional and, to some extent, strike-slip, ferent patterns of syn-rift stacking and by indicating that the continental margin is subject studies of the relation between rates and style to compression, as also indicated by in situ of structural events. Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

INTEGRATED BASIN STUDIES 7

Key results. A database of seismic examples as and architecture and seismic facies offer a sensi- well as field analogues has been built to illustrate tive tool for analysing the detailed sequential the variability of syn-rift architecture, involving basin development and predicting reservoir sand integration of data on rift topography, erosional distribution. The models erected may serve as and drainage patterns, relative sea level and its important references to the conceptual training changing position, sediment transport processes of explorationists. and facies and resultant sand body geometry and distribution (Marjanac 1994). In several such examples, the spatial and temporal evolution of reservoir sand facies has been semi-quantita- Topics 2.2." Post-rift sediment tively linked to the structural evolution of the architecture and 2.3." Erosional episodes parent half-graben and neighbouring footwall and provenance area sediment source areas (Farseth et al. 1995b; Ravnfis & Bondevik 1997; Nottvedt et aL). Post-rift intervals commonly have a duration of A synthesis has been compiled of various 50-100Ma. Thermal relaxation following the aspects of the three-dimensional geometry of late Jurassic rift event had ahnost ceased and syn-rift stratigraphic architectural elements and the North Sea basin was in a state close to their stacking pattern, and the spatial organiza- thermal equilibrium during the transition to the tion of potential facies tracts and stratigraphic Cenozoic. Subsidence and deposition during the surfaces present in marine syn-rift basin fills Cenozoic, therefore, were controlled by other (Gabrielsen et al. 1995; Nottvedt et al. 1995; factors. The Cenozoic succession in the Norwe- Ravnfis et al. 1997a; Ravn~ts & Steel 1998). This gian North Sea can be divided into genetic includes an analysis and comparison of a sequences of 8-16Ma duration, representing number of half-graben sub-basins in the north- major periods of clastic wedge progradation and ern North Sea (F~erseth & Ravnfis 1998; Ravnfis retreat with respect to the Norwegian hin- et aL ). terlands. The clastic wedges are bounded by The studies have led to a classification of major flooding surfaces and reflect variable sub- marine rift-basins and syn-rift successions in sidence rates. The character of these variations terms of sediment supply into overfilled, and of the resulting genetic sequences have been sediment-balanced, sediment-underfilled and investigated and related to the uplift and erosion sediment-starved basins (Ravnfis & Steel 1997). of the surrounding land areas. Dependent on whether the rift-basin was over- The sand/clay ratio in sedimentary basins is filled/sediment-balanced, sediment-underfilled commonly viewed as a function of depositional or sediment-starved, a three-fold, sand-clay- energy. A factor that tends to be overlooked sand package, two-fold sand-clay package or is the primary provenance area composition. one-fold mud-prone package constitutes the A better understanding of the processes that syn-rift succession, respectively. In cases where cause changes in the composition of the sedi- the rift episode was characterized by repetitive mentary sequence in the North Sea Basin there- rift phases, results show that the successive fore is needed. The relative contributions of the rotational tilt events are often separated by Norwegian mainland and East Shetland Plat- periods characterized by less intense faulting, form as source areas has been evaluated, based the so-called intra-rift quiescence or relaxa- on analysis and description of basin fill composition stages. tion and characteristics, mapping of palaeodrai- The project also included a study of the syn- nage directions and transport routes, estimations rift infill of the Lusitanian Basin in Portugal of palaeo-provenance areas and source rock (Ravnfis et al. 1997b). lithologies, and correlation of basin fill to provenance area. Relevance to the petroleum industry. The results and interpretations obtained within this topic Key results. The project has integrated seismic provide new insight and ideas for analysis of rift- data from the Danish sector with the Norwegian basin development and syn-rift infill. The recog- North Sea (Jordt et al. 1995). It also includes nition of the different types of syn-rift sedimen- mineralogical and geochemical analyses of 1600 tary architectures provides a step forward in samples of cuttings and cores from about 40 erecting predictive models for the analysis of wells in the Norwegian sector of the North Sea, half-graben syn-rift sediment fill. In addition, and thus represents the most comprehensive integrated detailed analysis of rift basin struc- database currently available. These data are tural evolution, high-resolution biostratigraphic important in terms of understanding the prove- zonation, reworked biozonation, basin-fill facies nance and provide a new basis on which to Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

8 A. NDTTVEDT interpret directions of sediment transport and tematic way. Understanding the regional varia- areas of tectonic uplift. tions in the velocity/depth function and the The seismostratigraphic study shows that processes responsible for these trends is impor- changes in seismic sequence geometry occurred tant when depth converting seismic profiles. in-phase with intra-continental stress variations The data on mineralogy and diagenesis is also on the European Platform and that sediment of value to calibration of seismic response to supply and differential tectonic movements in lithology, in order to understand better the the basin and in the provenance areas controlled information that can be extracted from seismic Cenozoic deposition in the central and northern attributes. North Sea (Jordt et al.). Seismic sequences were The demonstrated relationship between miner- generated largely independent of marked global alogical composition, diagenesis and overpres- glacio-eustatic sea level falls. Generation of sure is expected to be of great interest to drilling, seismic onlap appears to have been controlled particularly horizontal drilling, and for handling by sediment supply and basin floor topography. of rock mechanical problems during production. Thinning of sedimentary strata towards inclined Moreover, the present study has shown that the surfaces results in marked seismic onlap and North Sea Cenozoic rock properties cannot be apparent unconformable relationships. realistically represented as a simple function It is further shown that seismic velocities in the (i.e. linear or exponential) of burial depth. This North Sea Cenozoic mudstones vary system- has important consequences to basin modelling, atically as a function of mineralogical composi- as porosity reduction (compaction) is usually tion. A commonly observed velocity inversion at assumed to be a function of overburden or the base of the Pliocene and Pleistocene sequence effective stress. (Reemst et aL 1996) has been found to relate to a low content of smectite and therefore much faster compaction of these sediments compared Topic 2.4: Stratigraphic modelling to the underlying smectite-rich mudstones (Thy- berg et al.). Silica cementation from biogenic Numerical modelling is becoming increasingly silica, as well as alteration of opal-A to opal-CT, important in the understanding of sedimentary have been shown to cause abrupt increases in basin deposition and filling. In particular, it helps seismic velocities. evaluate the complex interplay between tectonics, It has been demonstrated that pore pressure in eustacy, climate, erosion and sediment transport, the Tertiary succession is governed by miner- and better constrain the boundary conditions alogical composition. Thick sequences of mud- of geological interpretations and models. stones with high smectite content, which The overall sedimentary architecture of the typically have high specific surface and low upper Jurassic syn-rift infill in the Oseberg area permeability, typically give rise to overpressure, as well as the Cenozoic infill along one of providing there are no sandy beds causing lateral the North Sea regional profiles have been drainage. Moreover, because of their high water modelled, as a function of sediment input, sub- content smectite rich mudstones usually have sidence and sea level fluctuations to obtain lower density than the overlying mudstones and additional information about their interplay sandstones. This density inversion frequently and relative importance. The modelling has caused diapirism. used forward process-based simulation pro- Finally, the project has provided results grams of dynamic-slope type. Comparisons have contributing to the understanding of the Cen- been made between observed stratigraphic archi- ozoic uplift of Norway (Fjeldskaar 1994; Stue- tecture and synthetic stratigraphic models where void & Eldholm 1996). the most important controlling factors have been considered. Relevance to the petroleum industo'. This topic has contributed to the understanding of the Key results. The numerical modelling of the Cenozoic basin formation and filling in relation syn-rift infill of the Oseberg area demonstrate to the uplift and erosion history of Southern the interaction between structural evolution, Norway. This uplift may strongly influence sedimentation and resulting stratigraphic pat- secondary and tertiary migration and trapping tern across the rotating fault-blocks (terVoorde of petroleum, particularly in areas close to the et al. 1997). The modelling further confirms coast of Norway. that the sedimentary architecture of the North The present project is one of the first in the Sea Cenozoic infill cannot be explained by sedi- North Sea where seismic stratigraphy has been mentary processes and/or eustacy alone (Kyrk- related to mineralogical composition in a sys- jeba et al.). Periods of anomalous subsidence, Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

INTEGRATED BASIN STUDIES 9 deviating from the post-rift thermal subsidence, (4) location of continent-ocean transition; (5) ex- are required in the late Paleocene and late tent of post-rift thermal margin subsidence. The Miocene. However, some of the Paleocene availability of data also off Greenland offers a subsidence may be related to the initial basin possibility to map and model the entire rift and form e.g excess water depth after late Cretac- to compare the late Cretaceous-Paleocene rift eous. The Miocene event, on the other hand, dimensions with the previous rift episodes. includes basinal subsidence in the northern In addition, comparative studies of the North Sea, as well as source area uplift in the volcanic margin formation in the North Atlan- Norwegian mainland, and is believed to repre- tic, as well as globally, have been undertaken, sent an intraplate effect coupled to the opening with the objective to improve our understanding of the North Atlantic. of tectono-magmatic volcanic margin setting and the processes governing volcanic mar- Relevance to the petroleum industry. The itera- gin initiation and development. It has also tive process between interpretation and model- helped in providing a framework for analysis ling allows the geologist to better constrain the of the implications of volcanic margins for possible geological models and to narrow in erosion and sedimentation on local and regional on a less number of likely interpretations. This scales, and for the environment (palaeoceano- type of modelling is also an excellent tool to graphy, palaeoclimate) on local, regional and visualize the complex interaction between sedi- global scales. ment supply, sea-level and tectonics in filling of sedimentary basins. Key results. A number of crustal transects has been constructed across the North Atlantic margin by use of deep seismic data across the margin. It is estimated that the conjugate Theme 3: Conjugate Volcanic Margins margins experienced some 140km of crustal stretching during the Maastrichtian-Paleocene Topics 3.1: Rift dimensions and duration rifting and breakup, and about 50-70km of rifting, 3.2." Geodynamic modelling and of lateral displacement during Late Jurassic- 3.3: Comparative studies Cretaceous rifting (Skogseid 1994; Skogseid & Eldholm 1995; Skogseid et aL). The Rockall It has long been recognized that the forma- Trough has, however, experienced far more tion of the northern North Atlantic conti- stretching, which is interpreted to be related to nental margins was accompanied by excess separate rifting in the mid-Cretaceous. By using magmatic activity. This caused a sub-division the stretching estimates, palinspastic maps have of rifted margins into volcanic and non-volcanic been constructed based on restorations to 53 Ma types. Until recently, the volcanic margins were pre-drift, 75Ma pre-Cenozoic breakup and thought to be an exceptional case. Recent com- 170Ma Late Jurassic pre-rift plate configura- parative studies involving other rifted margins tions. The results also include an evaluation of now suggest that excess magmatism during the tectono-magmatic events associated with breakup is far more common than previously plume-lithosphere interaction during rifting, thought. In fact, the volcanic margin might with particular focus on relative vertical move- represent the normal evolutionary case rather ments and provenance development. than being anomalous. The tectonic development of the Voring and The volcanic signature of the North Atlantic More basins is controlled by two structural margin has been explored by seismic reflection trends, NE-SW and NW-SE. It is suggested data and scientific drilling, whereas the tectonic that the NE-SW trend was established in the signature, and thus development, have to a large Paleozoic and was active during all subse- extent been hidden below the volcanic rocks. quent tectonic phases, whereas the NW-SE The project has involved geophysical-geologi- trend, probably reflecting the old Precambrian cal mapping of the Voring, More and conjugate grain of the basement, controlled the tectonic margins, in order to obtain key dimensions activity throughout the Cretaceous and Ceno- and timing of the late Cretaceous-Paleocene zoic (Brekke). The results show that during the rift episode, by focusing on: (1) width, style Cretaceous and Cenozoic the Voring Basin was and timing of syn-rift lithospheric extension; tectonically active, with repeated phases of nor- (2) extent and timing of syn-rift regional uplift; mal faulting and contraction causing large-scale (3) extent, character, time of emplacement folding. The More Basin, particularly towards and dimensions of igneous units (extrusives, the south, was overall more tectonically quiet intrusives, lower crustal high-velocity bodies); and experienced mainly continuous subsidence. Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

10 A. NDTTVEDT

Comparative studies between the NE Atlan- Concluding remarks tic, the Namibian, the US Atlantic and the NW Australian margins show that all margins seem The results of the Integrated Basin Studies- to have had a protracted rift development prior Dynamics of the Norwegian Margin project to continental separation, that significant crustal emphasize the value of academia and in- thinning is observed adjacent to the continent- dustry working together in order to make signifi- ocean boundary, and that the main pulse of cant scientific progress. It shows how public igneous activity coincides with the time of scientific grants and industry funding can be breakup (Eldholm et al. 1994; Eidholm et aL: focused to leverage investments put into research. Planke & Eldholm 1994). On the other hand, it It also presents a model for how academia and is also recognized that excess volcanism may industry research can be effectively organized occur without a direct link to an active mantle into a single project. plume, which may explain the large variety in The achievements of the Dynamics of the tectono-magmatic development of volcanic mar- Norwegian Margin project have brought our gins worldwide. understanding of this region forward, and it is An extensive Norwegian-Greenland Sea ther- our hope that the results presented in this book mal field data base named HEAT has been com- will serve as an important reference for the area piled, containing all public domain data in the in the years to come. The project has also estab- region; i.e. 436 heat flow values (Sundvor et aL). lished a database that will serve as a good basis The heat flow on oceanic crust reveals a clear, for continued research on the Norwegian margin first-order heat flow-crustal age relationship, and several new research projects have already whereas continental slope maxima on the More been initiated that build on the results of this and Barents Sea margins contrast greatly with project. In addition, it has highlighted some new the typical low heat flow of old oceanic and avenues of research that may further increase thinned continental crust. our understanding of this margin and of multi- phase rift evolution in general.

Relevance to the petroleum industry. The understanding of basin geometries, rift dimensions Project staff and participants and subsidence history is important to explora- Direct project participation tion companies working offshore mid-Norway. New information on magnitude and temporal Principal Investigators (PI), Doctorate Students development of intra-basinal vertical movements (PhD), Participating Scientists (PS), Master Students in combination with palinspastic reconstruction (MS) and Research Associates (RA) provides a tool for predicting reservoir facies in the outer margin basins. Such vertical movements, including the formation of a land Theme I: lntra-plate Rifting and Basin bridge from the Charlie Gibbs Fracture Zone to Formation the SW Barents Sea margin, may have led to the Topics 1.1." Crustal structure, 1.2." Sedimentary hasiJ1 establishment of large drainage systems and Jbrmation, 1 .4. Tecloniic modelling the probability of prospective well-sorted sedi- PI: Prof. 3. I. Faleide (UO), ment sequences of generally Late Cretaceous Prof. R, H. Gabrielsen (UB), Paleocene age in the adjacent subsiding parts of Dr. W. Fjeldskaar (RF) the basins. PhD: M.sci. P. Christiansson (UO), In addition, the geometrical definition of C.sci. T. Odinsen (UB), units of igneous materials at crustal levels C.sci. I. Grunnaleite (UB) has relevance for calculation of heatflow his- RA: C.sci. K. Lokna (UB) Industry: Dr. A, M. Berge (Hydro), tory, as bodies of underplated materials at C.real. B. T. Larsen (Hydro), the base of the crust can spike heatflow and Prof. R.B. F,'erseth (Hydro), may have caused maturation of organic mat- Dr. A. Nottvedt (Hydro), ter that cannot be predicted by present heat- Dr. H. Fossen (Statoil) flow measurements. The compilation of the EU: Dr. P. Reemst (VU), heat flow database is an important tool in Dr. P. van der Beek (VU), this respect. M.sci. M. ter Voorde (VU), The comparative work between volcanic Prof. S. Cloetingh (VU) margins worldwide is important for the under- Topic 1.3." Present regional stress fieht standing of basic geodynamic processes and PI: Prof. A. Myrvang (NTH), tectono-magmatic development in general. Prof. H. Bungum (Norsar) Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

INTEGRATED BASIN STUDIES 11

PhD: Siv.ing. M. Fejerskov (NTH) Referees. The following persons kindly served as PS: Dr. C. Lindholm (Norsar) technical and linguistic referees for the book: MS: T. Jorgensen (NTH), L. Borgerud (NTH), John Akselsen, Arild Andresen, Kuvet Atakan, W. E. Svare (NTH), Scott Baldridge, Giovanni Bertotti, Qrjan Birkland, M. Villgran (Norsar/UB), Eric Bogoslowski, Lars Boldreel, Ross Boutilier, E. Hicks (Norsar/UO) Nicolas Chamot-Rooke, Sierd Cloetingh, Denis Cou- Industry: Dr. T. H. Hanssen (Hydro), turier, Tom Dreyer, Richard England, Doug Gardner, C.real. B. T. Larsen (Hydro), Rob Gawthorpe, Felix Gradstein, Pill Haremo, Jens C.real. R. K. Bratli (Saga), Havskov, William Helland-Hansen, Helge Hjelmeland, Dr. L. N. Jensen (Statoil) Chuck Hurich, Erik P. Johannesen, Reidar Kanestrom, EU: Dr. M. Golke (UKa) Ridvan Karpuz, Oddbjorn Klovjan, John Knight, John KorstgSrd, Yngve Kristoffersen, Axel Makurat, Ole J. Martinsen, Alain Mascle, Jock McCracken, Theme 2: Basin Infill Wojtec Nemec, Johan P. Nystuen, Arvid Nottvedt, Topic 2.1: Syn-rift sediment architecture Lars NorgSrd-Jensen, Nigel Platt, John Palmer, Sarah Prosser, Garry Quinlan, Phil D. Rice, Jan Rivena~s, PI: Prof. R. J. Steel (UB), Ellen Roaldset, Alan Roberts, Yngve Rundberg, Alf Dr. J. Underhill (UEd) Ryseth, William Sassi, Ken Saunders, Roger Scrutton, PhD: C.sci. R. Ravnfis (UB) Michel Seranne, Morten Sparre Andersen, Gerald PS: Dr. P. Theriault (UB/Statoil), Sullivan, Tore Torske, Bjorn Torudbakken, Jan Vol- D. Mellere (UB/Statoil) set, Erling V5gnes, John Walsh, Marjorie Wilson, Industry: C.sci. K. Bondevik (Hydro), Graham Yielding and four anonymous referees. Prof. R. B. F~erseth (Hydro), Dr. A. Nottvedt (Hydro), Acknowledgements. The project was funded by the J. Windelstad (Statoil) European Union and of Norway Research Council Topic 2.2." Post-r~ft sediment architecture, under the JOULE II research programme (contract 2.3." Erosional episodes and provenance area No. JOU2-CT 92-0110). Norsk Hydro, Statoil and PI: Prof. J. I. Faleide (UO), Saga provided additional funding. Are B. Carlsson at Prof. K. Bjorlykke (UO) the Research Council of Norway is gratefully acknowl- PhD: M.sci. H. Jordt (UO), edged for supporting the project. As project leader, I C.sci. B.I. Thyberg (UO) am very grateful to Bjorn T. Larsen for his involve- RA: ment in the project on an industry client basis and to Industry: Dr. P. van Veen (Hydro), Vigdis Michelsen for her secretarial efforts. I also owe Dr. L. J. Skjold (Hydro), many thanks to past and recent members of the Dr. A. Ryseth (Hydro), project Steering Committee, Olav Eldholm, Roy H. Dr. M. Ramm (Hydro) Gabrielsen, Snorre Olaussen, Alu Orheim, Tony Dr. A. N. Nottvedt (Hydro) Spencer, Ron J. Steel and Jan Volset and to my fellow colleagues on the Editorial Board, Bjorn. T. Topics 2.4." Stratigraphie modelling Larsen, Orjan Birkeland, Harald Brekke, Roy H. PI: C.real. M. Hamborg (IKU) Gabrielsen, Snorre Olaussen, Jakob Skogseid and MS: R. Kyrkjebo (NTH) Bjorn Torudbakken, without whom this book would PhD: C.sci. R. Ravn~s (UB) never have come to light. Some extended thanks also Industry: C.sci. K. Bondevik (Hydro) go to the many scientists who reviewed the manu- EU: M.sci. M. ter Voorde (VU), scripts. However, the principal investigators, partici- Prof. S. Cloetingh (VU) pating researchers and students, who showed great efforts and a remarkable spirit of co-operation throughout, of course are the key to the success Theme 3: Conjugate Volcanic Margins of the project. Finally, I would like to pass a word of Topics 3.1; Rift dimensions appreciation to Bernard Durand, Sierd Cloetingh, and duration, 3.2: Geodynamic modelling, Cai Puigdefabregas and all other scientists in the 3.3. Comparative studies Integrated Basin Studies project, for 3 years of stimulating co-operation. PI: Dr. J. Skogseid (UO), Prof. O. Eldholm (UO) MS: B. Flakstad (UO), U. Byrkjeland (UO), Research contributions F. Neverdal (UO), S. Ren (UO), Publications E. Alvestad (UO) PhD: C.sci. T. Gladszenko (UO) BLYSTAD, P., BREKKE, H., FAERSETH, R. B., LARSEN, PS: Dr. S. Planke (UO), B. T., SKOGSEID, J. ~ TORUDBAKKEN, B. 1995. Dr. T. Pedersen (UO), Structural elements of the Norwegian continental Prof. A. M. Myhre shelf. Part II: The Norwegian Sea region. Nor- Industry: C.real B. T. Larsen (Hydro) wegian Petroleum Directorate Bulletin, 8. Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

12 A. NOTTVEDT

BORGERUD, L. & SVARE, E. 1995, ln-situ stress field on NESSEN, E. P. & MATHIEU, C. (eds) Sequence the Norwegian margin. In: FEJERSKOV, M. & Stratigraphy on the Northwest European Margin. MYRVANG, A. (eds) Workshop on Rock Stresses in Norwegian Petroleum Society Special Publica- the North Sea. NTU Trondheim, 13-14.02.95, tion, 5, 325-346. pp. 165-178. GABRIELSEN, R. H. & STRANDENES, S. 1994. Dynamic CLOETINGH, S., SASSI, W. & TASK FORCE TEAM 1994a. Basin Development A complete geoscientific The origin of sedimentary basins: a status report tool for basin analysis. Proceedings World Petro- from the task force of the International Litho- leum Congress 1994, 13 21 sphere Program. Marine and Petroleum Geology. GABRIELSEN, R. H.. GRUNNALEITE, I. & RASMUSSEN, E. 11, 659-683. 1997. Cretaceous and Tertiary inversion in the CLOETINGH, S., ELDHOLM, 0., LARSEN. B. T.. GAB- Bjornoyrenna Fault Complex, south-western Bar- RIELSEN, R. H. & SASSl, W. (eds) 1994b. Current ents Sea. Marine and Petroleum Geology, 14(2), state and perspectives of models for extensional 165 178. and inverted basins. TectonoptLvsics, Special Vol- GABRIELSEN, R. H.. ODINSEN, T. & GRUNNALEITE, I. ume, 240. 1999. Structuring of the northern Viking Graben ELDHOLM, O. & THOMAS. E. 1993. Scratching the and the More Basin: the influence of basement surface: Environmental impact of volcanic margin structural grain, and the particular role of the formation. Earth and Planetary Science Letters. More-Trondelag Fault Complex. Marine attd 117, 319-329. Petrolewn Geology, 16, 443-465. ELDHOLM, O., MYHRE, A. M. & THIEDE, J. 1994. GABRIELSEN. R. H., STEEL, R. J. & NOTTVEDT, A. 1995. Cenozoic tectono-magmatic events in the North Subtle traps in extensional terranes: A model with Atlantic: potential paleoenvironmental implica- reference to the North Sea. Petroleum Geo- tions, bl: BOULTER, M. C. & FISHER. H. C. (eds) science. 1,223-235. Cenozoic' Plants and Clhnates of the Arctic. NATO, GOLKE, M.. COBLENTZ. S., CLOETINGH, S. & FEJERS- ASI Series, 127, Springer, Heidelberg. 35-55. KOV, M. 1995. Stress system of the Norwegian ELDHOLM, O.. SKOGSEID, J., PLANKE. S. & GLADC- Continental Margin- Part I, In-situ rock stress ZENKO, T. P. 1995. Volcanic margin concepts. In: pattern on the Norwegian continental shalf and BANDA, E., TALWANI, M. & TORNE, M. (eds) mainland, hi: FEJERSKOV, M. & MYRVANG, A. R(fied Ocean. Continent Boundaries. NATO AS/ (eds) Workshop on Rock Stresses in the North Sea. Series Volume. Kluwer. Dordrecht, 1-16. NTU Trondheim, 13-14.02.95, pp. 250-274. FEJERSKOV, M., MYRVANG, A. M.. LINDHOLM. C. & GRUNNALEITE, I. & GABRIELSEN, R. H. 1995. The BUNGUM, H. 1995. In-situ rock stress pattern on structure of the More Basin. Tectonophysics, 252, the Norwegian continental shelf and mainland, hi: 221-251. FEJERSKOV, M. & MYRVANG, A. (eds) Workshop JORDT, H., FALEIDE, J. I., BJORLYKKE, K. & IBRAHIM, on Rock Stresses in the North Sea. NTU M. T. 1995. Cenozoic stratigraphy of the central Trondheim, 13-14.02.95, pp. 191-201. and northern North Sea Basin: tectonic develop- FJELDSKAAR, W. 1994. The amplitude and decay of the ment, sediment distribution and provenance areas. glacial forebulge in Fennoscandia. Norsk Geolo- Marine and Petroleum Geology, 12, 845-879. gisk Tidsskrift, 74, 2-8. LINDHOLM. C. D.. BUNGUM, H., VILLAGRAN, M. & FOSSEN, H. & GABRIELSEN, R. H. 1995. Experimental HICKS, E. 1995. Crustal stress and tectonics in Nor- modelling of extensional fault systems. Journal of wegian regions determined from earthquake focal Structural Geology, 18(5), 673-687. mechanisms. In: FEJERSKOV, M. & MYRVANG, A. FROSTICK, L. E. & STEEL, R. J. 1993a. Tectonic (eds) Workshop on Rock Stresses in the North Sea. signatures in sedimentary basin fills: an overview. NTU Trondheim, 13-14.02.95, pp. 77-91. International Association of Sedimentologists Spe- MELLERE. D. & Steel. R. J. 1996. Tidal sedimentation cial Publication, 20, 1 9. in Inner Hebrides half-grabens, Scotland: the mid- FROSTICK, L. E. & STEEL, R. J. 1993b. Sedimentation Jurassic Bearreraig Sandstone Formation. bl: DE in divergent plate-margin basins. International BATISTE, M. & JACOBS, P. (eds) Geology of Association of Sedimentologists Special Publica- Siliciclastic Shelf Seas. Geological Society, tion, 20, 111-128. London. Special Publications, 117, 49-79. FA~RSETH, R. B. & RAVNJi.S, R. 1998. The structural NOTTVEDT, A., GABRIELSEN, R. H. & STEEL, R. J. configuration of the Oseberg Fault Block in the 1995. Tectonostratigraphy and sedimentary archi- context of the northern North Sea structural tecture of rift basins, with reference to the framework. Marine and Petroleum Geology, 15. northern North Sea. Marble and Petroleum 467-490. Geology, 12, 881-901. F,'ERSETH, R. B., GABRIELSEN, R. H. & HURICH, C. A. PLANKE, S. & ELDHOLM. O. 1994. Seismic response 1995a. The influence of basement in structuring of and construction of seaward dipping wedges of the North Sea Basin offshore west Norway. Norsk flood basalts: Voring volcanic margin. Journal of Geologisk Tidsskrift, 75, 2/3, 105-119. Geophysical Research. 99. 9263-9278. FA~RSETH, R. B., SJOBLOM, T. S., STEEL, R. J., LILJE- RAVNAS, R. & BONDEVIK. K. 1997. Architecture and DAHL, T., SAUAR, B. E. & TJELLAND, T. 1995b. controls on the Bathonian Kimmeridgian shal- Tectonic controls on Bathonian-Volgian syn-rift low-marine syn-rift wedges of the Oseberg-Brage successions on the Visund Fault Block, northern area, northern North Sea. Basin Research, 9, North Sea. hi: STEEL, R. J., FELT, V. L., JOHAN- 197-226. Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

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RAVNA.S, R. & STEEL, R. J. 1997. Contrasting styles of FEJERSKOV, M. 1993. Bergspenninger i Norge og ph den late Jurassic syn-rift turbidite sedimentation: a norske sokkel. In: MYRVANG, A., JOHANSEN, T., comparable study of the Magnus and Oseberg HANSEN, A. & BERG, K. R. (eds) Fjellsprengings- areas, northern North Sea. Marine and Petroleum teknikk, bergmekanikk, geoteknikk. Oslo 1993, Geology, 14, 417-449. 17pp. RAVNAS, R. & STEEL, R. J. 1998. Architecture of marine FEJERSKOV, M. 1994. Breakout as a tool for stress rift-basin successions. AAPG Bulletin, 82, 110-146. determination in deep wellbores. NTH Report RAVNAS, R., BONDEVIK, K., HELLAND-HANSEN, W., No. 1, 15pp. LOMO, L., RYSETH, A. & STEEL, R. J. 1997a. Sedi- FEJERSKOV, M. 1994. Breakout interpretation. Methods mentation history as an indicator of rift initiation and software used at NTH. NTH Report No. 3, and development: The late Bajocian-Bathonian 14pp. evolution of the Oseberg-Brage area, northern FEJERSKOV, M. 1994. Breakout identification in 7 wells North Sea. Norsk Geologisk Tidsskrift, 77,205-232. neat" the Troll Field on the eastern flank of the RAVN~S, R., HANSEN, J. W., MELLERE, D., NOTT- northern Viking Graben. NTU Report No. 4, 39pp. VEDT, A., SJOBLOM,T. S., STEEL, R. J. & WILSON, FEJERSKOV, M. 1995. Criteria for breakout identifica- R. C. L. 1997b. A marine late Jurassic syn-rift tion based on 4-arm oriented caliper logs. NTU succession in the Lusitanian Basin, western Report No. 2, 17pp. Portugal-tectonic significance of stratigraphic FEJERSKOV, M. 1995. Breakout interpretation-ll signature. Sedimentary Geology, 114, 237-266. wells on the Visund Field, northern Viking REEMST, P., SKOGSEID, J. & LARSEN, B. T. 1996. Base Graben. NTU Report No. 5, 39pp. Pliocene velocity inversion on the eastern Voring FEJERSKOV, M., in prep 1995. Breakout interpretation margin- causes and implications. Global and in the Tampen Spur area. NTU Report No. 6. Planetary Change, 12, 201-211. GLADCZENKO, T. P. & ELDHOLM, O. 1995. LIP SKOGSEID, J. 1994. Dimensions of Late Cretaceous- Database: Large Igneous Provinces- distribution Paleocene Northeast Atlantic rift derived from Ce- and references. Geophys. Res. Group, Dep. Geol., nozoic subsidence. Tectonophysics, 240, 225-247. Univ. Oslo, Computer Pgm./Database Doc. Ser. SKOGSE1D, J. & ELDHOLM, O. 1995. Rifted continental No. 15, 5pp. margins off mid-Norway. In: BANDA, E., TAL- HAMBORG, M., KYRKJEBI0, R. & RAVNAS, R. 1995. WANI, M. & TORNE, M. (eds) Rifted Ocean. Syn- and post-rift depositional modelling, northern Continent Boundaries. NATO ASI Series Vol- North Sea. IKU report xxxxx. ume, Kluwer Academic PUBLISHERS, pp. 147-153. MARJANAC, L. T. 1994. Reference data base for rift SKOGSEID, J., ELDHOLM, O. & PLANKE, S. 1994. basins (syn-rift). UiB Report, 41pp. Mesozoisk kontinental rifting og Kenozoisk mar- NOTTVEDT, A. & IBS-DNM working group 1993. IBS gindannelse: dypseismikk og skorpestruktur ph Module 3- Dynamics of the Norwegian Margin. Voringmarginen. Geonytt, 21, 3-18. First Periodical Report - Project Description, June STEEL, R. J. 1993. Triassic-Jurassic megasequence 1993, 28pp. stratigraphy in the northern North Sea: rift to NOTTVEDT, A. & IBS-DNM working group 1993. post-rift evolution. In. PARKER, J. R. (ed.) Petro- Minutes of Meeting, IBS-DNM Project Seminar. leum Geology of Northwest Europe. Geological Geilo, November 1993, 57pp. Society, London, 299-315. NOTTVEDT, A. & IBS-DNM working group 1993.1BS STUEVOLD, L. M. & ELDHOLM, O. 1996. Cenozoic Module 3- Dynamics of the Norwegian Margin. uplift of Fennoscandia inferred from a study of Second Periodical Report, December 1993, 24pp. the mid-Norwegian margin. Global and Planetao' NOTTVEDT, A. & IBS-DNM working group 1994. Change, 12, 359-386. Minutes of Meeting, IBS-DNM Project Seminar. TERVOORDE, M., RAVN~S, R., F~ERSETH, R. B. & CLOE- Stavanger, May 1994, 8 lpp. tingh, S. 1997. Tectonic modelling of middle Juras- NOTTVEDT, A. & IBS-DNM working group 1994. IBS- sic syn-rift stratigraphy in the Oseberg-Brage area, DNM Project Status Report, May 1994. northern North Sea. Basin Research, 9, 133-150. NOTTVEDT, A. & IBS-DNM working group 1994. IBS THER1AULT, P. & STEEL, R. J. 1995. Aspects of synrift Module 3- Dynamics of the Norwegian Margin. sedimentation in the Upper Jurassic (Helmsdale Third Periodical Report, June 1994, 32pp. Boulder Beds) of the Inner Moray Firth Basin. In: NOTTVEDT, A. & IBS-DNM working group 1994. IBS STEEL, R. J., FELT, V. L., JOHANNESSEN, E. P. & Module 3- Dynamics of the Norwegian Margin. MATHIEU, C. (eds) Sequence Stratigraphy on the Fourth Periodical Report, December 1994, Northwest European Margin. Norwegian Petro- 49pp.NOTTVEDT, A. & IBS-DNM working leum Society Special Publication, 5, 365-387. group 1995. IBS-DNM Project Status Report, February 1995. Three volumes. NOTTVEDT, A. & IBS-DNM working group 1995. IBS Reports Module 3 Dynamics of the Norwegian Margin. Fifth Periodical Report, June 1995, 37pp. Reports listed herein are public and can be made NOTTVEDT, A. & IBS-DNM working group 1994. IBS available through the Research Council of Norway Module 3- Dynamics of the Norwegian Margin. (RCN), University of Bergen (UB), University of Final Report, December 1995. Oslo (UO) and Norwegian Technical University in PLANKE, S. 1993. HEAT-Heat flow data base Trondheim (NTU = NTH). program. Geophys. Res. Group, Dept. Geol., Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021

14 A. NOTTVEDT

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