Marine Cenozoic Record. Precambrian - Jurassic. Uplift. Compton (2004) Thin Cenozoic cover on the margin. Orange Basin. SA Petroleum Agency

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2 Marine Cenozoic Record Precambrian - Jurassic A B Uplift Thin Cenozoic cover on the margin Compton (2004) Orange Basin SA Petroleum Agency

3 Eustatic Sea Level (m) Quat Pliocene AGE (Ma) 0 5 Continental Margin Evolution distal calc fine sand g g Lithofacies succession g diamonds siliciclastics g proximal g erosion CLIMATE? G/IG forcings? TECTONICS oceanic circulation thermal springs? gas chimneys? Closure of isthmus of Panama neotectonism semi-arid climate Miocene middle late early erosional event carbonates rarely preserved Miocene phosphogenesis Tsondab Sandstone Formation Namibia winter rainfall/ fynbos biome? Initiation of Benguela Upwelling? E Antarctic glaciation NADW sediment starved margin tectonic uplift? superswell? deep opening of Drake Passage Oligocene Haq et al (1987) 30 erosion/ nondeposition transition to colder drier Ice House climate 35 drop in eustatic sea level Oligocene Eocene green (diamondiferous ) sands T K High sea level DRIFT ONSET RIFT ONSET Paleocene Cretaceous sediment organic matter Type II rift sediments volcanism Type III terrestrial silcretes siliciclastics continental erosion faulting 131 Etendeka doming 154 warm and humid climate provenance? mafic vs. sialic Basin Analysis hydrocarbon generation & migration Gondwana Break up multiple tectonic events? 180 flood basalts

4 Project 3.1 Generation and migration of natural gas Gesa Kuhlmann Rolando di Primio Douglas Paton Dave van der Spuy Brian Horsfield GFZ UWC - UCT PASA Petro SA De Beers marine South Atlantic Isopach Map modified from Seranne & Anka (2005) after Emery et al. (1975) Data Set: 6,000 km 2D seismic profiles, 12 oil wells in shelf area (<500m water depth)

5 Evidence of gas-seepage and mud-volcanoes (Ben-Avraham et al., 2002) Methane flux gas hydrates energy resource - climate

6 Seismic profile showing seepage of gas from the subsurface into the Atlantic Ocean Active kitchen area generating HC Migration pathway along stratigraphic horizons 3D petroleum systems model Gas flux over geologic timescales climate 100 Mt methane flux since Jurassic in southernmost part of the Orange Basin High-amplitude reflections may correlate to black shales of Ocean Anoxic Event 3 (80-90 Ma)

7 Gas leakage Seismic expression 7.5 km 22At / Inner Tertiary 15At Crater-like gas escape structure within Tertiary sediments

8 HC generation & migration at present day Tertiary overburden PASA (2003)

9 Living Africa Capacity building

10 Project 3.2 Seismic stratigraphy of the South African margin Gabriele Uenzelmann-Neben and Philip Schlüter - AWI Agulhas Passage - Antarctic Bottom Water

11 Ocean circulation - Climate

12 Evolution of ocean currents since the Cretaceous Schlüter and Uenzelmann-Neben (2007)

13 Transkei Basin - Agulhas Drift High-resolution palaeo-record since Pliocene climate transition Int. Ocean Drilling Program proposal

14 Project 3.3 Neogene palaeoceanography John Compton, Caren Herbert, James Wiltshire, Rochelle Wigley, Livuhwani Maake - UCT Marine terrestrial connections aridification Orange River discharge upwelling Cenozoic climate: Wet and warm to Cool and dry Continental Uplift & Erosion wind Agulhas Rings - heat transfer Changes in sea level

15 Late Cenozoic evolution of the margin Compton and Wigley (2004; 2006)

16 Western Margin Interglacial (Holocene) highstand records Shelf storage of terrigenous mud and organic carbon

17 Orange River Terrigenous Mud Flux Pre-dam flux ( ) = 49 million tons/yr (comparable to Cretaceous/Paleogene flux) flux = 17 million tons/yr (trapping of sand and coarse silt by dams) (Bremner et al., 1990) Mean Holocene flux = 6 million tons/yr Indicates an approximate 8 fold increase in sediment flux to the western margin

18 Rain + relief = sediment factory Agriculture loss of top soils Drakensberg escarpment Soil Erosion Dongas (gullies) weathered bedrock + colluvium (Pleistocene valley fill) erosion

19 100m GeoB 8333 GeoB 8332 GeoB 8331 UNIT 1 > 11 ka UNIT 2 ~9 10,9 ka UNIT 4 ~2 3,5 ka UNIT 3 ~5 8,8 ka UPPER CRETACEOUS UNIT 5 < 1,5 ka 75m PLEISTOCENE PRECAMBRIAN 125m Caren Herbert PhD Holocene mudbelt Drakensberg Group basaltic soil clay Nd Upper Orange River suspended clay (Free State border) Upper Orange River suspended clay (Aliwal North) Orange River palaeoflood clays (Prieska) Caledon River suspended clay Lower Orange River suspended clay Holocene slope clays Holocene offshore mudbelt clays Fish River palaeoflood clay Vaal River palaeoflood clay Sr/ 86 Sr

20 Deep Water circulation Sub Tropical Convergence upwelling

21 Southern Ocean Productivity Nutrient (P, Fe) supply from continental sources Dust and lateral (deep water) advection

22 Project 3.4 Past precipitation patterns in South Africa Hedi Oberhansli, Heinz Wilkes, Tim Partridge GFZ - WITS Sea surface temperatures monsoon orbital cycles Terrestrial records - speleothems dune activity

23 BioArchive Tswaing Crater S, E Biomarker study of the modern and fossil ecosystem and the influence of climate change 0 Lake Productivity Halite 10 Bacteria 20 Relative Abundance nc17-alkane 17-Alkene 17-Alka-diene Time (min) IS Cyanobacteria depth (m) Dinofl. Algae

24 Living Africa Publications & Theses Compton, J.S., Wigley, R. and McMillan, I Late Cenozoic phosphogenesis on the western shelf of South Africa in the vicinity of the Cape Canyon. Marine Geology 206, Compton, J.S. and Maake, L Source of the suspended load of the upper Orange River, South Africa. South African Journal of Geology 110. Herbert, C. And Compton, J.S Geochronology of Holocene sediments on the western margin of South Africa. South African Journal of Geology 110. Paton, D.A., van der Spuy, D., di Primio, R. & Horsfield, B. (accepted). Tectonically induced adjustment of passive margin accomodation space; influence on the hydrocarbon potential of the Orange Basin, South Africa. AAPG Bulletin. Paton, D.A., di Primio, R., Kuhlmann, G., van der Spuy, D. & Horsfield, B. (accepted). Insights into the Petroleum System Evolution of the Southern Orange Basin, South Africa. South African Journal of Geosciences. Schlüter, P., Uenzelmann-Neben, G. (2007), Seismostratigraphic analysis of the Transkei Basin: A history of deep sea current controlled sedimentation. Mar. Geol., 240(1-4), , doi: /j.margeo Schlüter, P., Uenzelmann-Neben, G. (2007). Indications for bottom current activity since Eocene times: The climate and ocean gateway archive of the Transkei Basin, South Africa, Global and Planetary Change. doi: /j.gloplacha Schlüter, P., Uenzelmann-Neben, G. (in review). Conspicuous seismic reflections in Upper Cretaceous sediments as evidence for black shales off South Africa, Mar. Pet. Geol. Wigley, R. and Compton, J.S Late Cenozoic evolution of the outer continental shelf at the Head of the Cape Canyon, South Africa. Marine Geology 226, Wigley, R. And Compton, J.S Oligocene to Holocene glauconite-phosphorite pellets from the Head of the Cape Canyon on the Western Margin of South Africa. Deep-Sea Research II 54, Wiltshire, J Late Quaternary sediments on the continental slope off Cape Columbine: Variations in off-shelf transport related to glacial driven sea-level fluctuations. Unpublished MSc thesis, University of Cape Town.