Living Africa

Oceans – Resources – Climate

Phase I Goals

���� Linking ocean and continent processes from sediment ation histories

���� Linking sedimentation to tectonic uplift and subsid ence���� Linking sedimentation to tectonic uplift and subsid ence

���� Changes in climate: upwelling dynamics and continen tal aridity

���� Ocean current dynamics: Agulhas rings and Benguela upwelling

���� Hydrocarbon generation and migration: methane seeps

Living Africa

Oceans – Resources – Climate

Phase I Projects

� Generation, migration and sequestration of natural gas duringpost-breakup history of the South African continent al margin

� Seismic stratigraphy of the South Atlantic marine b asins: clues to Neogene-Quaternary changes in tectonics, o cean currents and sea level

� Neogene-Quaternary paleo-oceanography from the geoc hemistry of sediment successions on the South African margin

� Past precipitation patterns in South Africa from la ke climatearchives, relation to southern oscillation and the Antarctic ice regime

Living Africa

Habitat – Resources – Global Change

Phase II Topics and Projects� Ecosystems and Climate Change

� Natural gas generation, migration and sequestration –implications for greenhouse gas budgets on continen tal slopes, South Africa

� Slope deposits and (palaeo)soils as geoarchives to reconstruct � Slope deposits and (palaeo)soils as geoarchives to reconstruct Late Quaternary environment of southern Africa

� Present and past lake ecosystems in southern Africa –natural variability and anthropogenic impact

� Understanding past episodes of global change –the Late Ordovician record in southern Africa

� Soil Systems and Land Use� Multi-scale assessment of the hydrologic situation

around Sutherland and the western Karoo� Vulnerability of the critical zone of central South Africa –

climate, ecosystems, soils and sustainability

� Mineral resources, mining and the environment� Natural resources of Africa: the platinum value cha in

Living Africa - Scope� Spatial Scales

Ångstrom – Hundreds of Metres – Hundreds of Kilometre sMolecules – e.g. Lakes – Sedimentary Basins

� Temporal ScalesModern Ecosystems – Late Ordovician record

Days – 460 Mio years

Basin Modelling Remote SensingGeophysics

Geochemistry

Hydrological ModellingPaleo-Oceanography

Sedimentology

GeomicrobiologySoil Science

Soil Science

Paleo-Limnology

Economic Geology

Petrology

Mineralogy

Tswaing Crater Lake – A climate archive for the sout hern hemisphere

African Atmospheric Circulation and Rainfall Pattern

Austral summer(November to February)

Austral winter(June to August)

ITCZ

CAB

ITCZ

CAB

HH

http://iridl.ldeo.columbia.edu

25°24´S, 28°04´E

Location

Lithology

Lake Tswaing (Pretoria Saltpan)Iris Kristen, Frauke SchmidtAndreas Fuhrmann, Hedi Oberhänsli, Tim Partridge, Birgit Plessen, Ursula Röhl, Jo Thorpe, Andrea Vieth-Hillebrand, Heinz Wilkes, Klaus-Gerhard Zink

• pH ~ 10• Rich in carbonates,

salts• Salinity ~ 280 ‰ at

the bottom• Meromictic and

mostly anoxic• Bacteria and

diatoms

~90 m lake sediments

crater diameter:depth:

lake diameter:depth:

1130 m119 m

~ 300 m< 3 m

Tswaing Crater Lake – Core study

Kristen et al., South African Journal of Geology 110 (2007) 311-326

The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

XRF core scanning

(1) X-ray source(2) Sensor (He-flowed)

(3) Detector

is a fast and non-destructive method to measureelement intensities ( ≈concentrations)

Tswaing Crater Lake – Methods

Isotope Ratio Monitoring-Gas Chromatography-

Mass Spectrometry (IRM-GC-MS)

δ13C (‰) ���� ratio of 13C/12C

Stable carbon isotope value

more negativelighter

more positiveheavier

13C/12C 13C/12C

δ13C (‰) ���� ratio of 13C/12C

Stable carbon isotope value

more negativelighter

more positiveheavier

13C/12C 13C/12C

Retention Time (min)

0

50

100

Rel

ativ

e A

bund

ance

40 50 60 70Retention Time (min)

0

50

100

Rel

ativ

e A

bund

ance

40 50 60 70

n-C17

InternalStandard

δ13CTOC (‰)= -24.0δ13CnC17 (‰)= -34.6

Algae ( Botryococcus )

Filamentous bacteria

Terrigenous particle

Microscopy

Tswaing Crater Lake – Modern lake environment

Acacia Broadleavedtrees and

bushes

Characterisation of the present-day ecosystemKristen et al., Journal of Paleolimnology 44 (2010) 143-160

Microbial matsand

CyanobacteriaGrassesReeds

Tswaing Crater Lake – Modern lake environment

C4 plants C3 plants

~ 6 ~ 6 ‰‰

Stable carbon isotopes δ13C (‰) – tracing the carbon cycle

~ 10 ~ 10 ‰‰Sediments

Kristen et al., Journal of Paleolimnology 44 (2010) 143-160

Tswaing Crater Lake – Modern lake environment

~ 22 ~ 22 ‰‰ ~ 8 ~ 8 ‰‰

FractionationFractionation

Stable carbon isotopes δ13C (‰) – tracing the carbon cycle

Sediments

MethanogenesisMethanogenesisKristen et al., Journal of Paleolimnology 44 (2010) 143-160

Tswaing Crater Lake – Core study

BacteriaLand plants

Aquat. Prod.XRF

Climate

globalregional

incr. methano

K/Al

increasedaridity

incr. methano-

trophysalinity

detritalinput

Cl/Al

Kristen et al., Journal of Paleolimnology 44 (2010) 143-160

Orange Riverdischarge

aridificationCenozoic climate: Wet and warm to Cool and dry

Marine – terrestrial connections

Neogene palaeoceanography John Compton, Caren Herbert, James Wiltshire, Rochelle Wigley, Livuhwani Maake, Ralph Schneider, Timm Hoffman, Jan-Berend Stuut

discharge

upwelling

wind

Continental Uplift & Erosion

Agulhas Rings- heat transfer

Changes in sea level

Late Cenozoic evolution of the margin

Compton and Wigley (2004; 2006)

Western Margin

Interglacial (Holocene)highstand records

Shelf storage of terrigenous mud and organic carbon

Orange River Terrigenous Mud Flux

Pre-dam flux (1930-1969) = 49 million tons/yr(comparable to Cretaceous/Paleogene flux)

1980-1990 flux = 17 million tons/yr(trapping of sand and coarse silt by dams)

(Brem

ner et al., 1990)

Mean Holocene flux = 5 million tons/yr

Indicates an approximate 10 fold increasein sediment flux to the western margin

Soil E

rosion

Agriculture – loss of top soils

Rain + relief = sediment factory

Drakensberg escarpment

Soil E

rosion

Dongas (gullies) – weathered bedrock + colluvium (Pleistocene valley fill) erosion

Southern Ocean Productivity

Nutrient (P, Fe)supply fromcontinental sourcessources

Dust andlateral (deep water)advection

Seismic Evidence of Gas Leakage in the Orange Basin

Syn-rift structural closure Stratigraphic pinchout

Aim: To constrain thermogenic methane contribution to thehydro- and atmosphere as a function of geologic time

Paton et al., South African Journal of Geology 110 (2007) 261-274

Seismic Interpretation

� of basin structure

� of vertical fluid migration in

relation to the basin

structure

Petrel© 2009

3D

Basin

structure &

evolution

Organic

matter type &

deposition

Approach

Petroleum System Model of the Orange Basin

Source Rock

Potential

� generation potential,

petroleum type

� organo-facies variability

� phase kinetics

Basin modeling

� burial and thermal history

� hydrocarbon generation,

migration and squestration

PetroMod © 11

3D

Petroleum

System

Model

evolution

Kerogen type &

compositional

kinetics

deposition

2006

Douglas Paton,

Katja Hirsch

2008

Gesa Kuhlmann,

Curnell Campher,

Inkaba yeAfrika

Petroleum System Model of the Orange BasinKlaus Bauer, Rolando di Primio, Brian Horsfield, Magdalena Scheck-Wenderoth,

David van der Spuy, Jan-Diederik van Wees and …

PASA (2010)

2009 Donna Boyd2009 Donna Boyd

Curnell Campher,

Selwyn Adams

2010

Alexander Hartwig

2010

Alexander Hartwig

Stratigraphy of the Orange Basin

Kuhlmann et al., Marine and Petroleum Geology 27 (2010) 973-992

Evolution of the southern part of the Orange Basin

Paton et al., AAPG Bulletin 92 (2008) 589-609

Southern Orange Basin: Spatial temperature distribu tion within the Barremian/Aptian source rock interval

Hirsch et al., Marine and Petroleum Geology 27 (2010) 565-584

74 Ma 16 Ma

Southern Orange Basin:Present Day Hydrocarbon Migration

Paton et al., South African Journal of Geology 110 (2007) 261-274

� Conceptual model of natural gas generation from the Aptian source rock in the outer part of the basin

� Subsequent proposed migration

Kuhlmann et al., Marine and Petroleum Geology 27 (2010) 973-992

proposed migration through the sedimentary column along different pathways

� Observed leakage sites at the sea-floor

Living Africa

Habitat – Resources – Global Change

Phase II Topics and Projects� Ecosystems and Climate Change

� Natural gas generation, migration and sequestration –implications for greenhouse gas budgets on continen tal slopes, South Africa

� Slope deposits and (palaeo)soils as geoarchives to reconstruct � Slope deposits and (palaeo)soils as geoarchives to reconstruct Late Quaternary environment of southern Africa

� Present and past lake ecosystems in southern Africa –natural variability and anthropogenic impact

� Understanding past episodes of global change –the Late Ordovician record in southern Africa

� Soil Systems and Land Use� Multi-scale assessment of the hydrologic situation

around Sutherland and the western Karoo� Vulnerability of the critical zone of central South Africa –

climate, ecosystems, soils and sustainability

� Mineral resources, mining and the environment� Natural resources of Africa: the platinum value cha in

Study Area: The Orange Basin

Paton et al., South African Journal of Geology 110 (2007) 261-274

Seismic interpretation, distribution, and numerical modelling of natural gas leakage in Block 2 of the Orange Basin

Donna Boyd, Tuesday 12:15

Kuhlmann et al.,Marine and Petroleum Geology

27 (2010) 973-992

Living Africa – PublicationsCompton, J.S., Herbert, C.T., Hoffman, M.T., Schneider, R.R., Stuut, J.-B., 2010. A tenfold increase in the Orange River mean Holocene mud flux: implications for soil erosion in South Africa. The Holocene 20, 115-122.

Compton, J., Herbert, C., Schneider, R., 2009. Organic-rich mud on the western margin of southern Africa: Nutrient source to the Southern Ocean? Global Biogeochem. Cycles 23, GB4030.

Compton, J.S., Maake, L., 2007. Source of the suspended load of the upper Orange River, South Africa. South African Journal of Geology 110, 339-348.

Compton, J.S., Wigley, R., McMillan, I.K., 2004. Late Cenozoic phosphogenesis on the western shelf of South Africa in the vicinity of the Cape Canyon. Marine Geology 206, 19-40.

Compton, J.S., Wiltshire, J.G., 2009. Terrigenous sediment export from the western margin of South Africa on glacial to interglacial cycles. Marine Geology 266, 212-222.

Herbert, C.T., Compton, J.S., 2007. Geochronology of Holocene sediments on the western margin of South Africa. South African Journal of Geology 110, 327-338.

Hirsch, K.K., Scheck-Wenderoth, M., Paton, D.A., Bauer, K., 2007. Crustal structure beneath the Orange Basin, South Africa. South African Journal of Geology 110, 249-260.

Hirsch, K.K., Scheck-Wenderoth, M., van Wees, J.D., Kuhlmann, G., Paton, D.A., 2010. Tectonic subsidence history and thermal evolution of the Orange Basin. Marine and Petroleum Geology 27, 565-584.

Kristen, I., Fuhrmann, A., Thorpe, J., Röhl, U., Wilkes, H., Oberhänsli, H., 2007. Hydrological changes in southern Africa over the last 200 Ka as recorded in lake sediments from the Tswaing impact crater. South African Journal of Geology 110, 311-326.

Kristen, I., Wilkes, H., Vieth, A., Zink, K.-G., Plessen, B., Thorpe, J., Partridge, T., Oberhänsli, H., 2010. Biomarker and stable carbon isotope analyses of sedimentary organic Kristen, I., Wilkes, H., Vieth, A., Zink, K.-G., Plessen, B., Thorpe, J., Partridge, T., Oberhänsli, H., 2010. Biomarker and stable carbon isotope analyses of sedimentary organic matter from Lake Tswaing: evidence for deglacial wetness and early Holocene drought from South Africa. Journal of Paleolimnology 44, 143-160.

Kuhlmann, G., Adams, S., Campher, C., van der Spuy, D., di Primio, R., Horsfield, B., 2010. Passive margin evolution and its controls on natural gas leakage in the southern Orange Basin, blocks 3/4, offshore South Africa. Marine and Petroleum Geology 27, 973-992.

Paton, D.A., di Primio, R., Kuhlmann, G., van der Spuy, D., Horsfield, B., 2007. Insights into the petroleum system evolution of the southern Orange Basin, South Africa. South African Journal of Geology 110, 261-274.

Paton, D.A., van der Spuy, D., di Primio, R., Horsfield, B., 2008. Tectonically induced adjustment of passive-margin accommodation space; influence on the hydrocarbon potential of the Orange Basin, South Africa. AAPG Bulletin 92, 589-609.

Schlüter, P., Uenzelmann-Neben, G., 2007. Seismostratigraphic analysis of the Transkei Basin: A history of deep sea current controlled sedimentation. Marine Geology 240, 99-111.

Schlüter, P., Uenzelmann-Neben, G., 2008. Conspicuous seismic reflections in Upper Cretaceous sediments as evidence for black shales off South Africa. Marine and Petroleum Geology 25, 989-999.

Schlüter, P., Uenzelmann-Neben, G., 2008. Indications for bottom current activity since Eocene times: The climate and ocean gateway archive of the Transkei Basin, South Africa. Global and Planetary Change 60, 416-428.

Uenzelmann-Neben, G., Schlüter, P., Weigelt, E., 2007. Cenozoic oceanic circulation within the South African gateway: indications from seismic stratigraphy. South African Journal of Geology 110, 275-294.

Wigley, R.A., Compton, J.S., 2006. Late Cenozoic evolution of the outer continental shelf at the head of the Cape Canyon, South Africa. Marine Geology226, 1-23.

Wigley, R., Compton, J.S., 2007. Oligocene to Holocene glauconite-phosphorite grains from the Head of the Cape Canyon on the western margin of South Africa. Deep-Sea Research Part Ii-Topical Studies in Oceanography 54, 1375-1395.

Marine Cenozoic Record Precambrian - Jurassic

A B

Uplift

OrangeBasin

Thin Cenozoic cover on the margin

SA Petroleum Agency

Compton (2004)

-6.00

-5.00

-4.00Drakensberg Group basaltic soil clay

Upper Orange River suspended clay (Free State border)

UNIT 1

UNIT 2UNIT 3

UNIT 5

PLEISTOCENEUPPER

CRETACEOUS

75m

100m

> 11 ka

~9 – 10,9 ka~5 – 8,8 ka

< 1,5 ka

PRECAMBRIAN

125m

GeoB 8333 GeoB 8332 GeoB 8331UNIT 4

~2 – 3,5 ka

Caren Herbert PhD – Holocene mudbelt

-14.00

-13.00

-12.00

-11.00

-10.00

-9.00

-8.00

-7.00

-6.00

0.710000 0.715000 0.720000 0.725000 0.730000 0.735000 0.740000 0.745000 0.750000 0.755000

87Sr/86Sr

Nd

Orange River palaeoflood clays (Prieska)

Holocene slope clays

Fish River palaeoflood clay

Lower Orange River suspended clay

Caledon River suspended clay

Vaal River palaeoflood clay

Upper Orange River suspended clay (Aliwal

North)

(Free State border)

Holocene offshore mudbelt clays

Tswaing Crater Lake – Core study

BacteriaLand plants

Aquat. Prod.XRF

Climate

globalregional

K/Al

salinity

detritalinput

Cl/Al

Tswaing Crater Lake – Core studyFrauke Schmidt, Tuesday 09:45

Kristen et al., Journal of Paleolimnology 44 (2010) 143-160