DOCSLIB.ORG

On the Kinematics and Timing of Rodinia Breakup: a Possible Rift−Transform Junction of Cryogenian Age at the Southwest Cape of Congo Craton (Northwest Namibia)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
On the Kinematics and Timing of Rodinia Breakup: a Possible Rift−Transform Junction of Cryogenian Age at the Southwest Cape of Congo Craton (Northwest Namibia) P.F. HOFFMAN On the kinematics and timing of Rodinia breakup: a possible rift−transform junction of Cryogenian age at the southwest cape of Congo Craton (northwest Namibia) P.F. Hoffman University of Victoria, School of Earth and Ocean Sciences, Victoria, British Columbia V8P 5C2, Canada Harvard University, Department of Earth and Planetary Sciences, Cambridge, Massachusetts 02138, USA e-mail: [email protected] © 2021 Geological Society of South Africa. All rights reserved. Abstract After tilt correction for Ediacaran thick-skinned folding, a pair of Cryogenian half grabens at the autochthonous southwest cape of Congo Craton (CC) in northwest Namibia restore to different orientations. Toekoms sub-basin trended east-northeast, parallel to Northern Zone (NZ) of Damara belt, and was bounded by a normal-sense growth fault (2 290 m throw) dipping 57° toward CC. Soutput sub-basin trended northwest, oblique to NZ and to north- northwest-trending Kaoko Belt. It was bounded by a growth fault (750 m down-dip throw) dipping steeply (~75°) toward CC. Soutput growth fault could be an oblique (splay) fault connecting a Cryogenian rift zone in NZ with a sinistral transform zone in Kaoko Belt. A transform origin for the Kaoko margin accords with its magma-poor abrupt shelf-to-basin change implying mechanical strength, unlike the magma-rich southern margin where a gradual shelf- to-basin change implies a mechanically weak extended margin. A rift−transform junction is kinematically compatible with observed north-northwest−south-southeast Cryogenian crustal stretching within CC. Post-rift subsidence of the CC carbonate platform varies strongly across the south-facing but not the west-facing shelf. A sheared western CC margin differs from existing Kaoko Belt models that posit orthogonal opening with hyper-extended continental crust. Carbonate-dominated sedimentation over southwest CC implies palaeolatitudes ≤35° between 770 and 600 Ma. Introduction There is little consensus on where Congo Craton (CC) was et al., 2003, 2005, 2018, 2020; Poidevin, 2007; Caron, 2010; Monié positioned within Rodinia, or even if it belonged to that et al., 2012; Affaton et al., 2016; Passchier et al., 2016; Oriolo supercontinent at all (Dalziel, 1997; Hoffman, 1997; Pisarevsky et al., 2017; Cailteux and De Putter, 2019; Hoffman et al., 2021). et al., 2003, 2008; Trindade and Macouin, 2007; Li et al., 2008; This implies that surrounding oceanic basins opened and Evans, 2009, 2013; Scotese, 2009; Ernst et al., 2013; Merdith et al., closed, concurrent with the Rodinia-to-Gondwana geotectonic 2017a, b, 2019, 2021; Salminen et al., 2018; Zhou et al., 2018; reorganization. This is easier to account for if CC was part of de Wit et al., 2020; Jing et al., 2020; Wen et al., 2020). Nonetheless, Rodinia than if it was not. CC (Figure 1a) is ringed by late Neoproterozoic ‘miogeoclines’ One reason for CC’s poorly-defined palaeogeographic role (former continental terrace wedges, Dietz and Holden, 1966) is a dearth of palaeomagnetic poles between ca. 748 and 570 Ma that were deformed during Pan-African/Brasiliano aggregation (Meert et al., 1995; Wingate et al., 2004; Moloto-A-Kenguemba of Gondwana (Stanton et al., 1963; Cahen and Lepersonne, 1967; et al., 2008). On this front, I am sad to report the absence of Porada, 1979, 1989; Miller, 1983, 2008b, 2014; Cahen et al., 1984; detectable primary remanence (Shihong Zhang, 2017, personal Stanistreet et al., 1991; Trompette, 1994; Prave, 1996; Goscombe communication) in the 747 ± 2-Ma Upper Naauwpoort SOUTH AFRICAN JOURNAL OF GEOLOGY 2021 • VOLUME 124.2 PAGE 401-420 • doi:10.25131/sajg.124.0038 401 ON THE KINEMATICS AND TIMING OF RODINIA BREAKUP: A POSSIBLE RIFT−TRANSFORM JUNCTION OF CRYOGENIAN AGE AT THE SOUTHWEST CAPE OF CONGO CRATON (NORTHWEST NAMIBIA) Formation trachydacite lavas in northwest Namibia (Miller, 1974, The Damara Belt has two branches (Martin, 1983; Miller, 1980b, 2008b; Hoffman et al., 1996). 1983, 2008b), the Northern (NZ) and Southern (SZ) basinal Another reason for CC’s ill-defined role is under-utilization of zones, separated by a Central (CZ) ‘ribbon’ continent aka the epi-cratonic stratigraphic record to infer timing and kinematics Swakop terrane (Figure 1b). In the standard model for Damara of Neoproterozoic rifting and break-up at the margins of the Belt, CZ is an extension of CC and crustal thickening in NZ was craton. Carbonate-dominated epicratonic sedimentation across a consequence of collision with Kalahari Craton in SZ (Barnes southwest CC implies low palaeolatitudes from 770 until 600 Ma and Sawyer, 1980; Kasch, 1983; Stanistreet et al., 1991; Miller, (Halverson et al., 2005), consistent with palaeomagnetic poles for 2008b, Figure 13.291; Goscombe et al., 2018). However, 765 ± 5 Ma (Wingate et al., 2004), 748 ± 6 Ma (Meert et al., 1995; structure−metamorphic geochronology indicates that crustal Mbede et al., 2004) and 571 ± 6 Ma (Moloto-A-Kenguemba et al., thickening in NZ began ≤50 Myr before the collision in SZ 2008). Not all palaeogeographic models adopt the carbonate- (Lehmann et al., 2016). This finding bears out an earlier facies constraint at 600 Ma, although early Ediacaran (Narbonne inference that synorogenic deposits (Mulden Group) on the CC et al., 2012) is the most carbonate-dominated interval across foreland are older than those (Nama Group) on the Kalahari southwest CC (Hedberg, 1979; Miller, 2008b, 2014; Delpomdor foreland (Germs, 1974). If crustal thickening in NZ is not et al., 2016; Cailteux and De Putter, 2019). One model that does attributable to Kalahari collision, then CZ−CC convergence could honour this constraint is de Wit et al. (2020). have been driven by southward subduction in NZ, or back-arc This paper is an attempt to structurally restore sedimentary shortening associated with northward subduction beneath CZ, half grabens, bounded by growth faults of known stratigraphic age, provided it had begun when thickening of NZ occurred. at the southwest corner of CC in northwest Namibia (Figure 1). Radiometric age constraints on crustal thickening can be ‘Growth faults’ are synsedimentary faults on which the throw obtained by dating foredeep deposits and synkinematic increases with depth. Strata of the downthrown side are thicker metamorphism of underthrust epicontinental rocks including than correlative strata on the upthrown side. Downthrown strata stretched continental crust. The onset of such metamorphism generally thicken toward the fault. Orogenic shortening at this gives a minimum age constraint on when continental crust first corner of the craton has previously been discussed (Coward, passed beneath the leading edge of an overthrust plate (e.g., 1981; Maloof, 2000; Clifford, 2008; Lehmann et al., 2016; trench inner wall). Existing radiometric constraints on the onset Passchier et al., 2016; Goscombe et al., 2017, 2018, 2020; of crustal thickening in each basinal zone–NZ, CKZ and SZ Hoffman, 2021), as have aspects of initial rifting (Miller, 1983, (Figure 1b)–are as follows. In widely spaced areas of NZ, 2008b; Porada, 1983; Henry et al., 1990, 1992/93; Stanistreet phengite growth synkinematic with early south-southeast−north- et al., 1991; Stanistreet and Charlesworth, 1999). The goal here northwest shortening yields 40Ar/39Ar laser-ablation plateau ages is to constrain the kinematics and timing of break-up in this of 598 ± 4, 594 ± 7 and 584 ± 4 Ma (Lehmann et al., 2016). From sector of CC. these ages it is inferred that crustal thickening in NZ was The specific area of the growth faults described here was underway by 595 to 600 Ma. In western NZ, D2 folds and systematically mapped and studied by Frets (1969) and lies foliations related to west-southwest−east-northeast crustal within the 1:250,000-scale Fransfontein Sheet 2014 (Schreiber, thickening in Kaoko Belt clearly postdate D1 structures (Coward, 2006). It is situated within the Northern Margin Zone (NMZ) of 1981; Maloof, 2000; Lehmann et al., 2016). the Damara belt, as defined by Miller (2008b), and corresponds In Kaoko Belt itself, metamorphic U-Pb and Sm-Nd mineral to the distal foreslope zone (Hoffman et al., 2021) of the ages east of the Coastal Terrane (CT) range 580 to 540 Ma, with Otavi/Swakop Group, the ca. 770 to 600 Ma carbonate platform 40Ar/39Ar cooling ages down to 520 Ma (Goscombe et al., 2003, covering the southwest CC (Hedberg, 1979; Miller, 1997, 2008b). 2005). The Cambrian ages are broadly coeval with final closure of the Clymene palaeocean bordering Amazonia (Figure 1a) (Tohver Regional tectonic setting et al., 2012; McGee et al., 2015a, b). In CKZ (Figure 1b), metamorphic garnet in pelitic schist of CC affinity (Swakop Group) Southwest CC is bounded to the west and south by the Kaoko has a Sm-Nd isochron age of 574.3 ± 9.7 Ma (Goscombe et al., and Damara belts, respectively (Figure 1). Kaoko Belt is an 2003), while a SHRIMP 207Pb/206Pb zircon mean age of 580 ± 3 Ma oblique sinistral collision zone between western CC and the (Seth et al., 1998) was obtained from an anatectic orthogneiss in Coastal Terrane (CT, Figure 1b) (Guj, 1970; Dürr and Dingeldey, westernmost CKZ (Hoarusib Domain of the Orogen Core of 1996; Goscombe et al., 2003, 2005, 2018; Will et al., 2004; Goscombe and Gray, 2008). These ages imply that crustal Konopásek et al., 2005; Goscombe and Gray, 2007, 2008), which thickening of the western CC margin was underway by 575 to represents the leading edge of the Dom Feliciano−Ribeira 580 Ma, closely following that of the southern (NZ) margin. composite magmatic arc (Figure 1a) (Oyhantçabal et al., 2011; Collision in Southern Zone (SZ, Figure 1b) between Kalahari Chemale et al., 2012; Alves et al., 2013; Konopásek et al., 2016; Craton (lower plate) and Greater Congo (upper plate: CC + CZ Basei et al., 2018; Hueck et al., 2018; Percival et al., 2021). and Dom Feliciano-CT-Ribeira terranes) is radiometrically Whether the basin that lay between CC and CT was a forearc or constrained by foredeep subsidence at 548.8 ± 1 Ma (Grotzinger backarc basin is not agreed upon.
Load more

Recommended publications
  • Glacitectonic Deformation in the Chuos Formation of Northern Namibia Busfield, Marie E.; Le Heron, Daniel P
    Aberystwyth University Glacitectonic deformation in the Chuos Formation of northern Namibia Busfield, Marie E.; Le Heron, Daniel P. Published in: Proceedings of the Geologists' Association DOI: 10.1016/j.pgeola.2012.10.005 Publication date: 2013 Citation for published version (APA): Busfield, M. E., & Le Heron, D. P. (2013). Glacitectonic deformation in the Chuos Formation of northern Namibia: Implications for neoproterozoic ice dynamics. Proceedings of the Geologists' Association, 124(5), 778- 789. https://doi.org/10.1016/j.pgeola.2012.10.005 General rights Copyright and moral rights for the publications made accessible in the Aberystwyth Research Portal (the Institutional Repository) are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the Aberystwyth Research Portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the Aberystwyth Research Portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. tel: +44 1970 62 2400 email: [email protected] Download date: 26. Sep. 2021 Elsevier Editorial System(tm) for Proceedings of the Geologists' Association
    [Show full text]
  • The Onset of Widespread Marine Red Beds and the Evolution of Ferruginous Oceans
    ARTICLE DOI: 10.1038/s41467-017-00502-x OPEN The onset of widespread marine red beds and the evolution of ferruginous oceans Haijun Song 1, Ganqing Jiang 2, Simon W. Poulton3, Paul B. Wignall3, Jinnan Tong1, Huyue Song1, Zhihui An1, Daoliang Chu1, Li Tian1, Zhenbing She1 & Chengshan Wang4 Banded iron formations were a prevalent feature of marine sedimentation ~3.8–1.8 billion years ago and they provide key evidence for ferruginous oceans. The disappearance of banded iron formations at ~1.8 billion years ago was traditionally taken as evidence for the demise of ferruginous oceans, but recent geochemical studies show that ferruginous con- ditions persisted throughout the later Precambrian, and were even a feature of Phanerozoic ocean anoxic events. Here, to reconcile these observations, we track the evolution of oceanic Fe-concentrations by considering the temporal record of banded iron formations and marine red beds. We find that marine red beds are a prominent feature of the sedimentary record since the middle Ediacaran (~580 million years ago). Geochemical analyses and thermo- dynamic modelling reveal that marine red beds formed when deep-ocean Fe-concentrations were > 4 nM. By contrast, banded iron formations formed when Fe-concentrations were much higher (> 50 μM). Thus, the first widespread development of marine red beds con- strains the timing of deep-ocean oxygenation. 1 State Key Laboratory of Biogeology and Environmental Geology, School of Earth Science, China University of Geosciences, Wuhan 430074, China. 2 Department of Geoscience, University of Nevada, Las Vegas, NV 89154-4010, USA. 3 School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
    [Show full text]
  • Toward a Neoproterozoic Composite Carbon-Isotope Record
    Toward a Neoproterozoic composite carbon-isotope record Galen P. Halverson† Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138-2902, USA, and Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Building 54-1126, Cam- bridge, Massachusetts 02139, USA Paul F. Hoffman Daniel P. Schrag Adam C. Maloof‡ Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138-2902, USA A. Hugh N. Rice Department of Geological Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria ABSTRACT framework for a new, high-resolution model Various workers have compiled composite carbon-isotope record for the Neoproterozoic !13C records for the Neoproterozoic (e.g., Hayes Glacial deposits of Sturtian and Marinoan comprising new !13C (carbonate) data from et al., 1999; Jacobsen and Kaufman, 1999; Wal- age occur in the well-studied Neoproterozoic Svalbard (Akademikerbreen Group) and ter et al., 2000), but like attempts to construct successions of northern Namibia, South Aus- Namibia (Otavi Group) and data in the lit- 87Sr/86Sr records for this time period (Melezhik tralia, and northwestern Canada. In all three erature from Svalbard, Namibia, and Oman. et al., 2001), these compilations have suffered regions, the Marinoan glaciation is presaged A new U-Pb zircon age of 760 ± 1 Ma from from low sample density, limited availability by a large negative !13C anomaly, and the cap an ash bed in the Ombombo Subgroup in of chronostratigraphically well-constrained carbonates to both glacial units share a suite Namibia provides the oldest direct time-cali- data, and the consequent dependence on many of unique sedimentological, stratigraphic, bration point in the compilation, but the time tenuous correlations.
    [Show full text]
  • Reconafrica-Technical-Brief-V24.Pdf
    ReconAFRICA KAVANGO BASIN TECHNICAL BRIEF TSX-V: RECO OTC: RECAF FRANKFURT: 0XD www.reconafrica.com HIGHLIGHTS • ReconAfrica has discovered + licensed a new deep (30,000’) Permian Age rift sedimentary basin in northeast Namibia and northwest Botswana “Kavango Basin” • “All of the worlds basins of this depth produce commercial hydrocarbons” - Bill Cathey, CEO, Earthfi elds Technology, Houston • ReconAfrica TSX-V RECO holds rights to the entire sedimentary basin, 8.75 million acres • Same seaway or depositional environment as Shell’s 390 TCF Permian shale (top 10 shale plays worldwide) • Expecting up to 6,000’ Permian petroleum system supporting large-scale unconventional + conventional plays • ReconAfrica has acquired a 1,000 HP drilling rig shipping to Namibia for a Q4 2020 drilling campaign KAVANGO - NEW SEDIMENTARY BASIN Based on a previously drilled well (ST-1/1964) and the acquisition and interpretation of a high quality (200m spacing) aeromagnetic survey, ReconAfrica has discovered a deep, 30,000’, predominantly Permian aged, rift sedimentary basin in NE NamibiaKAVANGO and NW Botswana BASIN (FIG 01). All of the worlds basins of this depth produce commercial hydrocarbons. 190 MILES 1 2 1 3 Up to 30,000’ of Sedimentary Rock Basin Fill PPS* *Permian Petroleum System - up to 6000’ thick ReconAfrica’s Drilling Campaign begins 2020. The main objective is to confirm organic rich shales and conventional FIG 01: 8.75 millionopportunities acre license in Namibia (from surface and Botswana. to basement) ReconAfrica held by ReconAfrica. owns 2.5 million acres in Botswana, and 6.3 million acres in Namibia, for a total property of 8.8 million acres in the Kavango Basin.
    [Show full text]
  • Fjord Network in Namibia: a Snapshot Into the Dynamics of the Late Paleozoic Glaciation Pierre Dietrich1,2, Neil P
    https://doi.org/10.1130/G49067.1 Manuscript received 20 October 2020 Revised manuscript received 19 March 2021 Manuscript accepted 21 June 2021 © 2021 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Fjord network in Namibia: A snapshot into the dynamics of the late Paleozoic glaciation Pierre Dietrich1,2, Neil P. Griffis3,4, Daniel P. Le Heron5, Isabel P. Montañez3, Christoph Kettler5, Cécile Robin1 and François Guillocheau1 1 Géosciences Rennes, Université de Rennes, CNRS, UMR 6118, 35000 Rennes, France 2 Department of Geology, University of Johannesburg, Johannesburg 2006, South Africa 3 Department of Earth and Planetary Sciences, University of California, Davis, California 95616, USA 4 Berkeley Geochronology Center, Berkeley, California 94709, USA 5 Department für Geologie, Universität Wien, Althanstraße 14, 1190 Wien, Austria ABSTRACT infer the pace of ice-margin fluctuations and Fjords are glacially carved estuaries that profoundly influence ice-sheet stability by the paleo-ice thickness that once occupied draining and ablating ice. Although abundant on modern high-latitude continental shelves, these fjords. Furthermore, we estimate glacio- fjord-network morphologies have never been identified in Earth’s pre-Cenozoic glacial epochs, isostatic adjustment following deglaciation. hindering our ability to constrain ancient ice-sheet dynamics. We show that U-shaped valleys This work highlights the dynamic nature of in northwestern Namibia cut during the late Paleozoic ice age (LPIA, ca. 300 Ma), Earth’s the LPIA in southwestern Gondwana and the penultimate icehouse, represent intact fjord-network morphologies. This preserved glacial potential for an under-appreciated deep-time morphology and its sedimentary fill permit a reconstruction of paleo-ice thicknesses, glacial carbon and sediment sink that, if valid, would dynamics, and resulting glacio-isostatic adjustment.
    [Show full text]
  • Partners in Biodiversity
    AWF FOUR CORNERS TBNRM PROJECT : REVIEWS OF EXISTING BIODIVERSITY INFORMATION i Published for The African Wildlife Foundation's FOUR CORNERS TBNRM PROJECT by THE ZAMBEZI SOCIETY and THE BIODIVERSITY FOUNDATION FOR AFRICA 2004 PARTNERS IN BIODIVERSITY The Zambezi Society The Biodiversity Foundation for Africa P O Box HG774 P O Box FM730 Highlands Famona Harare Bulawayo Zimbabwe Zimbabwe Tel: +263 4 747002-5 E-mail: [email protected] E-mail: [email protected] Website: www.biodiversityfoundation.org Website : www.zamsoc.org The Zambezi Society and The Biodiversity Foundation for Africa are working as partners within the African Wildlife Foundation's Four Corners TBNRM project. The Biodiversity Foundation for Africa is responsible for acquiring technical information on the biodiversity of project area. The Zambezi Society will be interpreting this information into user-friendly formats for stakeholders in the Four Corners area, and then disseminating it to these stakeholders. THE BIODIVERSITY FOUNDATION FOR AFRICA (BFA is a non-profit making Trust, formed in Bulawayo in 1992 by a group of concerned scientists and environmentalists. Individual BFA members have expertise in biological groups including plants, vegetation, mammals, birds, reptiles, fish, insects, aquatic invertebrates and ecosystems. The major objective of the BFA is to undertake biological research into the biodiversity of sub-Saharan Africa, and to make the resulting information more accessible. Towards this end it provides technical, ecological and biosystematic expertise. THE ZAMBEZI SOCIETY was established in 1982. Its goals include the conservation of biological diversity and wilderness in the Zambezi Basin through the application of sustainable, scientifically sound natural resource management strategies.
    [Show full text]
  • The Development and Evolution of Etosha Pan, Namibia
    The Development and Evolution of Etosha Pan, Namibia Dissertation zur Erlangung des naturwissenschaftlichen Doktorgrades der Bayerischen Julius-Maximilians-Universität Würzburg Vorgelegt von Martin HT Hipondoka Würzburg 2005 To the demise of the Bantu Education System Table of Contents Table of Contents.................................................................................................................. ii List of Figures...................................................................................................................... iii List of Tables.........................................................................................................................iv Acknowledgments..................................................................................................................v Abstract .................................................................................................................................vi Ausführliche Zusammenfassung...................................................................................... vii 1. Introduction ................................................................................................ 1 1.1 Background..........................................................................................................1 1.2 Aims and Objectives of the Study......................................................................1 2. Methods and Techniques ............................................................................. 4 2.1 Remote Sensing (RS)
    [Show full text]
  • IN THIS ISSUE GSA TODAY May Vol
    Vol. 8, No. 5 May 1998 INSIDE • Upcoming Penrose Conference GSA TODAY p. 16 • Book Reviews, p. 19 A Publication of the Geological Society of America • Calls for Service, p. 3, 23, 26 Comings and Goings of Global Glaciations on a Neoproterozoic Tropical Platform in Namibia Paul F. Hoffman, Department of Earth & Planetary Sciences, Harvard University, Cambridge, MA 02138 Alan J. Kaufman, Department of Geology, University of Maryland, College Park, MD 20742 Galen P. Halverson, Department of Earth & Planetary Sciences, Harvard University, Cambridge, MA 02138 ABSTRACT many Neoproterozoic glacial deposits are Kennedy, 1996)—a climatological or geo- rich in carbonate debris and are directly chemical paradox, given that inorganic An enduring enigma of Neoprotero- overlain by carbonates containing struc- zoic Earth history is the intimate associ- tures indicative of sea-floor precipitates ation of glacial diamictites with typical (Fig. 1)(Roberts, 1976; Fairchild, 1993; Global Glaciations continued on p. 2 warm-water carbonates. Among the many hypothesized explanations for this paleoclimatic dichotomy are high orbital obliquity, true polar wander, reduced solar luminosity, snowball albedo, CO2 drawdown, stagnant ocean overturn, and reinterpretation of diamictites as mega-impact ejecta. The Otavi carbonate platform on the Congo craton in Namibia contains two discrete intervals of diamictite and associated glaciomarine deposits, sand- wiched by thick carbonates from which we have obtained detailed carbon-iso- topic records. From subsidence analysis,
    [Show full text]
  • Wanke Et Al Karoo Unconformities
    Communs geol. Surv. Namibia, 12 (2000), 291-301 Karoo unconformities in NW-Namibia and their tectonic implications A. Wanke1, H. Stollhofen1, I.G. Stanistreet2 and V. Lorenz1 1Institut für Geologie, Universität Wurzburg, Pleicherwall 1, 97070 Würzburg, Germany email: [email protected] 2Department of Earth Sciences, University of Liverpool, PO Box 147, Liverpool L69 3BX, United Kingdom The Karoo-Etendeka depositories in northwestern Namibia can be subdivided into (l) a Carboniferous-Permian, (2) a Triassic- Jurassic and (3) a Cretaceous megasequence, recording successive extensional periods, separated by time-stratigraphic gaps. Close to the present-day Atlantic coastline the Karoo Supergroup is only represented by the Permian succession in the Huab area. This is discon- formably overlain by the Lower Cretaceous Etendeka Group. Further east, the Karoo succession becomes successively’ more complete, but correlation with the main Karoo Basin in South Africa and the Brazilian Paraná Basin indicates major gaps in the sedimentary record. The gaps can be attributed to the combined effects ofthe long-lived South Atlantic rift evolution and orogenic pulses derived from the Samfrau active margin. Introduction roo Supergroup were indicated by Porada et al. (1996) and Miller (1997) and the most obvious gap between The Karoo Supergroup is widespread in various Up- Permian and Cretaceous strata in the Huab area has been per Carboniferous to Lower Jurassic depositories across used by Milner et al. (1994) as a basis for stratigraphic the Gondwana supercontinent. Of these depositories, separation of the Carboniferous-Jurassic Karoo Super- two major basin types are developed in southern Africa: group from the Cretaceous Etendeka Group.
    [Show full text]
  • Organization of African Intra-Plate Tectonics*
    Organization of African Intra-Plate Tectonics* James W. Granath¹ and William Dickson² Search and Discovery Article #30555 (2018)** Posted March 12, 2018 *Adapted from extended abstract prepared in conjunction with oral presentation given at AAPG/SEG 2017 International Conference and Exhibition, London, England, October 15-18, 2017 **Datapages © 2018 Serial rights given by author. For all other rights contact author directly. ¹Granath & Assoc. Consulting Geology, Highlands Ranch, CO, United States ([email protected]) ²Dickson International Geosciences Inc., Houston, TX, United States ([email protected]) Abstract Arrays of fault blocks loosely aligned in belts often comprise fields of extensional basins and/or compressional uplifts within continents, for example in the forelands of orogenic belts (e.g. the late Paleozoic Ancestral Rocky Mountains in the interior western North America) or as failed arms of plate triple junctions (as in the case of Central African Rift System). Transfer faults occur within and between individual elements of such systems (as intra- and inter-basinal faults): they are fundamental features and are necessary to facilitate the kinematic integrity of the system. At their extreme, these transfer fault systems may be localized into inter-basin/uplift, regional ‘mega-shear’ systems that exploit pre-existing defects in the crystalline basement, pre-existing lineaments and terrane boundaries for example. The Central African Shear Zone or the here-proposed Southern Africa Trans-Africa Rift and Shear System are examples of such systems that cross-cut the continent. These mimic wrench fault systems in many details of their geometry, but insofar as they only accommodate the net extension or compression of the overall system, they do not necessarily display a consistent sense of offset or accumulate much net strike-slip offset at the continental level.
    [Show full text]
  • Namibia: Africa’S Next Oil and Gas Frontier Awaits
    Namibia: Africa’s next oil and gas frontier awaits Featuring ReconAfrica Jenny Xenos, MBA, CFA Quester Advisors April 18, 2021 Quester Advisors | www.questeradvisors.com Table of Contents Executive summary ............................................................................................................................................ 2 Namibia: Africa’s next oil and gas frontier awaits .............................................................................................. 6 One of Africa’s newest countries .................................................................................................................... 6 Fragile economy and the need of foreign investment .................................................................................... 8 Attractive place to do business ....................................................................................................................... 9 A century of oil and gas exploration ............................................................................................................... 9 Promising geology ........................................................................................................................................ 15 Attractive fiscal regime and licensing system ............................................................................................... 25 Energy security and access to world markets .............................................................................................. 29 High hopes for oil and
    [Show full text]
  • De-Risking Oil and Gas Prospects
    Pioneer Oil & Gas Consulting NAMIBIA Namibia onshore Hydrocarbon Prospectivity Ansgar Wanke University of Namibia Petroleum Geology Purpose of Talk Pioneer Oil & Gas Consulting NAMIBIA 1. Overview of Namibian Onshore Basins 2. New encouraging insights 3. How and why to Explore Namibia 825 419 km2 Two groups of onshore basins: 1. Neoproterozoic- Early Cambrian rift- foreland basins 2. Karoo (rift) basins (Upper Carboniferous – Jurassic) Onshore basins cover some 350 000km2 > 40% of the country Map of Namibian Basins, adapted 12 onshore wells with TD from Bray & Lawrence (1998) between 600-2500m Neoproterozoic / Early Cambrian Basins 1: Owambo-Etosha Basin 2: Nama Basin Owambo – Etosha • Basins are bordered by early Cambrian Orogenic Belts • Rift, Platform and Molasse deposits • Foreland Basin architecture • Partly covered by Karoo Nama succession • Largely covered by a veneer of Cainozoic sediments Map of Namibian Basins, adapted from Bray & Lawrence (1998) Distribution of Pan- Extent of Cainozoic African Belts in Africa and Kalahari Cover adjoining parts of South excluding the Namib America Haddon & McCarthy Cahen & Snelling (1966) (2005) Martin & Porada (1977) Norton & Sclater (1979) Owambo Basin Vintage Exploration • Seismic campaigns 1969-1995 • 12 wells of which 5 HC exploration wells (1964-1986) Exploration from 2000 • Four aerial surveys (mag/gravity) (2004, 11, 13, 14) • Soil gas sampling (2012) • 120km 2D test lines (2017) • Airbus remote sensing study (2018) • Passive seismic (2018) Summary of exploration history in the Owambo
    [Show full text]