oceans – resources – climateinkaba.aeon.org.za/publications/workshops/workshop... · tswaing...
TRANSCRIPT
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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
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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
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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
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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
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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
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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
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Tswaing Crater Lake – Core study
Kristen et al., South African Journal of Geology 110 (2007) 311-326
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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
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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
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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
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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
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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
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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
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Late Cenozoic evolution of the margin
Compton and Wigley (2004; 2006)
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Western Margin
Interglacial (Holocene)highstand records
Shelf storage of terrigenous mud and organic carbon
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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
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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
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Southern Ocean Productivity
Nutrient (P, Fe)supply fromcontinental sourcessources
Dust andlateral (deep water)advection
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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
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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
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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
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Stratigraphy of the Orange Basin
Kuhlmann et al., Marine and Petroleum Geology 27 (2010) 973-992
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Evolution of the southern part of the Orange Basin
Paton et al., AAPG Bulletin 92 (2008) 589-609
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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
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Southern Orange Basin:Present Day Hydrocarbon Migration
Paton et al., South African Journal of Geology 110 (2007) 261-274
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� 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
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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
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Study Area: The Orange Basin
Paton et al., South African Journal of Geology 110 (2007) 261-274
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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
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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.
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Marine Cenozoic Record Precambrian - Jurassic
A B
Uplift
OrangeBasin
Thin Cenozoic cover on the margin
SA Petroleum Agency
Compton (2004)
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-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
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Tswaing Crater Lake – Core study
BacteriaLand plants
Aquat. Prod.XRF
Climate
globalregional
K/Al
salinity
detritalinput
Cl/Al
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Tswaing Crater Lake – Core studyFrauke Schmidt, Tuesday 09:45
Kristen et al., Journal of Paleolimnology 44 (2010) 143-160