South Africa - Inkaba.org

Getting Getting Deeper Deeper into into into the the System
System
Inkaba yeAfrica - 7th Annual Workshop
1 - 5 November 2010
Potsdam, Germany
hosted by
GFZ German Research hosted Centre by for Geosciences
GFZ German Research Centre for Geosciences
Programme & Abstracts
for information see www.inkaba.org

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IMPRESSUM
Helmholtz-Zentrum Potsdam – Deutsches GeoForschungsZentrum GFZ
Stiftung des Öffentlichen Rechts des Landes Brandenburg
Telegrafenberg
14473 Potsdam
www.gfz-potsdam.de

7th Inkaba yeAfrica Workshop
1-5 November, 2010
GFZ German Research Centre
for Geosciences
Telegrafenberg, Potsdam
Agenda
Sunday October 31: Arrival and Orientation
16:00 Student registration and orientation workshop led by Robert
Kriger (NRF) and Robert Trumbull (GFZ)
18:00 Welcome reception – ice breaker at GFZ Telegrafenberg
Monday November 1: Registration and Opening Ceremonies
13:00 Welcome and opening address by Prof. Reinhard Hüttl
(Director, GFZ German Research Centre for Geosciences)
13:30 Greetings from the South African Embassy, Berlin and the
Brandenburg Ministry of Science, research and Culture
13:50 “Celebrating 6 years of Inkaba” by Prof. Maarten deWit
(University of Cape Town and director, AEON Institute)
14:10 Introduction to Workshop by Prof. Brian Horsfield (GFZ German
Research Centre for Geosciences)
14:30 Inkaba Showcase Lecture: “Heart of Africa” by Dr. Monika Korte
(GFZ German Research Centre for Geosciences)
15:00 Inkaba Showcase Lecture: “Margins of Africa” by Dr. Gabriele
Uenzelmann-Neben (Alfred-Wegener Institute for Marine and
Polar Research)
15:30 Tea break
16:00 Inkaba Showcase Lecture: “Living Africa” by PD Dr. Heinz
Wilkes (GFZ German Research Centre for Geosciences)
16:30 Invited Lecture: “Topo-Africa” by Prof. Francois Guillocheau
(University of Rennes, France)
17:00 Invited Lecture: “Development of South Atlantic Rifted Margins”
by Dr. Ulrich Glasmacher (University of Heidelberg)
18:00 Dinner (reception) at GFZ cantine
19:30 Evening Lecture: “Planetary Evolution and Life” by Prof. Tilman
Spohn (DLR German Aerospace Center, Institute of Planetary
Research Berlin-Adlershof)
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20:30 Concert: “Baroque music and the Prussian Court” La
Prosperina Ensemble (Berlin University of Fine Arts)
21:30 Shuttle to Hotels
Tuesday November 2: Scientific Sessions
Session 1: Living Africa
Theme A: habitat, climate and ecosystem evolution
08:30 keynote Cotterill, F. P. D.
Geodynamics and geobiological fingerprints of the Kalahari
epeirogeny
09:00 Hoffmann, V.
Tracking geobiological linkages between speciation and
landscape evolution through space and time
09:15 Schmidt, F.
Environmental changes in Lake Tswaing during the last 84 ka BP
09:30 Steyn, S. A.
Statistical downscaling of climate change projections to daily
temperatures, Upper Olifants River catchment
09:45 Roberts, D.
Climate/sealevel fluctuations along the Southern African West
Coast: regional and global context
Theme B: Natural resources and sustainability
10:00 van Huysteen, C. W.
A framework for soil-based wetland research in South Africa
10:15 Kotze, E.
Effect of Long-term residue management on organic matter in a
Plinthosol cropped annually with wheat
10:30 du Preez, C. C.
Fate of soil organic matter in South Africa crop and pasture land
10:45 Tea break
11:15 Chevallier, L.
The geothermal potential of South Africa – New Challenges for
Geoscientists
11:30 Tan, J. Q.
Shale gas in South Africa
11:45 Mikes, D.
Karoo sequence stratigraphy and facies modelling for improved
reservoir characterisation and upscaling
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12:00 Boyd, D.
Seismic Interpretation, distribution, and numerical modelling of
natural gas leakage in Block 2 of the Orange Basin
12:15 Güntner, A.
New tools for hydrologic research at Sutherland observatory:
superconducting gravimetry and satellite gravimetry
12:30 Poster presentations for Session 1
13:30 Lunch, GFZ cantine
14:30 keynote Tredoux, M.
The Platinum Value Chain – A PGE-rich rock from the
Barberton greenstone belt: core formation or extraterrestrial?
15:00 Lekgetho, T. B.
Can base metal sulphides be used as a proxy for platinumgroup
mineral flotation of UG2 ore?
15:15 Reid, D. L.
Towards a magmatic reaction model for iron-rich ultramafic
pegmatites in the Rustenburg Layered Suite
15:30 Durrheim, R. J.
Observational studies to mitigate seismic risks in mines: a new
Japanese – South African collaborative research project
Session 2: Heart of Africa
Theme A: Deep-earth processes and surface response
15:45 keynote Bell, D.
Evolution of Proterozoic mantle lithosphere: petrological and
geophysical evidence from the Kaapvaal – Namaqua boundary
16:15 Weckmann, U.
Defining the Kaapvaal Craton boundary - new electrical
conductivity images
16:30 Tea break
16:45 Kotze, P. B.
Southern Africa’s geomagnetic field secular variation since
2005
17:00 Geese, A.
Improvements to Southern African geomagnetic field and
secular variation descriptions from different modelling
techniques
17:15 Decker, J. E.
Cosmogenic nuclide-based perspectives on long-term
landscape evolution and short-term soil erosion rates
17:30 Poster presentations for Session 2
18:15 Poster Session 1 + 2
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19:00 Dinner at GFZ cantine
20:00 Evening lecture by A. Lindeque (AWI) & J. Stankiewicz (GFZ):
Two postgraduates experiences in Inkaba yeAfrica
21:00 Shuttle to hotels
Wednesday November 3: Scientific Sessions and Project meetings
Session 2, Theme B: Earth in space
09:00 Combrinck, W. L.
Using satellite laser ranging data to test general relativity
09:15 Botai, O. J.
Statistical exploration of underlying geophysical signals and
noise components in space geodetic data
09:30 Botha, R. C.
Experimental development of a high-power laser suitable for
Lunar Laser Ranging
Session 3: Margins of Africa
09:45 keynote Gohl, K.
Growth and dispersal of a southeast African large igneous
province
10:15 Uenzelmann-Neben, G.
Palaeoceanographic changes from seismic and radiogenic
isotope data from the Mozambique Ridge
10:30 Trumbull, R. B.
New insights on the role of mantle plumes in South Atlantic
breakup
10:45 Backeberg, N. R.
Petrogenesis of the False Bay dyke swarm, Cape Peninsula,
South Africa
11:00 Tea break
11:15 Scheck-Wenderoth, M.
3D lithosphere-scale models of the conjugate margins in the
South Atlantic
11:30 Andreoli, M. A. G.
Post-Gondwana tectonics of western South Africa
Session 4: Capacity Building
12:00 Fourie, C. J. S.
Development of a Science and Technology Train
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12:15 Erwee, M.
Training science educators – Investigating the problem areas
and misconceptions
12:30 Poster presentations for Sessions 3 + 4
13:00 Poster Session
13:30 Lunch, GFZ cantine
Project meetings + strategy sessions
14:30 Plenary discussion: Quo Vadis, Inkaba?
15:30 ad-hoc strategy sessions (GASHsa, PGE, SPACES)
17:30 Plenary, closing discussion
19:00 Dinner banquet in Potsdam: Alter Stadtwächter
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Poster contributions
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Poster Session 1: Living Africa
Theme A: Habitat, climate & ecosystem evolution
Poster Author Title
1-1 Browning, C. Quaternary dune gastropods of the South African west coast:
Implications for climate change
1-2 Clark, J.H.A. The morphology and development of palaeoterraces of the
Orange River in the Hopetown-Douglas-Prieska area
1-3 MacDonald, N. Aspects of palaeo-terrace formation and stream sediment
petrography of the Orange and Vaal River confluence in the
Douglas Area, northern Cape province, South Africa
1-4 Mthembi, P. Palaeoclimate & ecosystems of the Pleistocene in South Africa
as archived in the Kalkop Crater Lake deposits
1-5 Völkel, J. Records of Late Quaternary environmental changes preserved
in eolian and fluvial sediment geoarchives of the SW-Kalahari,
South Africa
Theme B: Natural resources & sustainability: water, soil, energy
Poster Author Title
1-6 Lebenya, R.M. Quantification of the soil-plant carbon stock in the Weatherley
catchment eight years after conversion from grassland to
forestry
1-7 Loke, P.F. Influence of long-term wheat residue management on soil
fertility indicators of an Avalon soil at Bethlehe
1-8 Mahed, G. Hydrogeological Conceptual model development in the vicinity
of the Superconducting Gravimeter, Sutherland, South Africa
1-9 Mathiva, R.T. Carbonate alteration of dolerite intruding coal seams:Natural
carbon sequestration during fossil fuel combustion?
1-10 May, F. Characterization and quantification of preferential flow in
fractured rock systems, using resistivity tomography
1-11 Nape, K.M. Economic benefits of varying maize production strategies under
various seasonal rainfall scenarios in the Modder River
catchment, South Africa
1-12 Ntholi, T. Low Enthalpy Geothermal Energy purification of Acid Mine
Drainage, and storage of potable water in the deep gold mines
of South Africa
1-13 Nthejane, M.M. Correlation between agronomic and environmental phosphorus
analyses of selected soils
1-14 Onaneye, A.O. A new approach to upscaling in resevoir modelling
1-15 Snyman, P.E. Monitoring the 2-D urban heat island for Bloemfontein, South
Africa
1-16 Tharaga, P.C. Downscaling climate change scenarios to daily maximum
temperatures over Bloemfontein, South Africa
1-17 Vogeli, J. Investigation of the potential for mineral carbonation of South
African PGM tailings
1-18 Nformi, E. Sequence Stratigraphic Characterisation of Petroleum
Reservoirs in block 11B/12B of the Southern Outeniqua Basin,
South Africa
1-19 Opwani, M. Petrophysical evaluation of the Albian Age Gas Bearing
Sandstone reservoirs of the O-M field, Orange Basin, South
Africa
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Theme B: Natural resources & sustainability: mineral resources
Poster Author Title
1-20 Chabangu, N. An Investigation of Nickel Mineralization in the Northwestern
Part of the Barberton Greenstone Belt, South Africa
1-21 Kennedy, B. Investigation of the behaviour of platinum group elements
(PGE), in synthetic sulphide systems
1-22 Madalal, F. Mineralogical and geochemical investigations of the nickel Bon
Accord deposit, Barberton, South Africa
1-23 Mandiwana, M.T. The role of footwall reconstitution in the genesis of Merensky
reef types at Northam Platinum Mine
1-24 Milanzi, K.S.R. The Mineralogy and PGE Geochemistry of the Middle Group
Chromitite Seams of the Western Bushveld Complex at
Kroondal Mine
1-25 Nethsitungulwana, R. An Investigation of the Trace Element Compositions of
Gold from the Zimbabwe and South Africa : Implications
for tracing the source of archeological gold
1-26 Jack, S. Some aspects of late magmatic replacement phenomena
developed in the layered sequence exposed at Northam
Platinum mine
1-27 Shadi, O. Investigation of the Merensky Reef and the associated Iron Rich
Ultramafic Pegmatite replacement bodies, Bafokeng Rasimone
Platinum Mine, Rustenburg, SA
Poster Session 2: Heart of Africa
Theme A: Deep-earth processes & surface response
A1 The Barberton Belt
Poster Author Title
2-1 MacLennan, S. Structural and geophysical transect across an Archean suture
zone, Barberton Greenstone Belt
2-2 Engelhart, J. Dating Archean sedimentary processes and rates in the
Moodies Basin, Barberton Supergroup, Barberton Greenstone
belt
2-3 Kütter, S. Overview and preliminary results of magnetotelluric
experiments across the southern Barberton greenstone belt
A2 The Cape Fold Belt & Karoo Basin
Poster Author Title
2-4 Chen, X. Study of the geo-electrical anisotropy in the Cape Fold Belt
using magnetotelluric
2-5 Arenz, R. The application of facies analysis on sedimentary evolution and
changes in sea-level on the Kookfontein and Waterford
Formation in the Permian Ecca Group, Tanqua, Karoo Basin
2-6 Arnold, A. Lithostratigraphic correlation of the Ecca Palaeo-slope and
shelf-edge deltaic deposits: Phase 1
2-7 Black, D.E. The stratigraphy of the lower and middle Karoo Supergroup,
north of Paterson, Eastern Cape, South Africa
2-8 Brunsdon, G. Structural features of the Bokkeveld Group (Cape Supergroup)
in the Eastern Cape, South Africa
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2-9 Chere, N. Exploring the Origin of Breccia Pipes in the Karoo Basin, South
Africa
2-10 Esterhuizen, L. Comparing 1960's Karoo basin seismic data with recent data
(Inkaba yeAfrica Line), to identify and correlate Karoo seismic
stratigraphy on a more regional basis
2-11 Lombard, D. Facies architecture and reservoir quality of Fan B, Permian
Laingsburg Formation, southwestern Karoo Basin, South Africa
2-12 Loots, L. Investigation of the crust in the Southern Karoo using the
seismic reflection technique
2-13 Sonibare, W.A. Deterministic approach to geological and petrophysical
modelling of field analogue data: Tanqua-Karoo deltaic
sequence, SW Karoo Basin
2-14 Olivier, W.C. Mineralogical, geochemical and structural characteristics of
quartz-arenites of the middle Witteberg Group (Cape
Supergroup) near Kirkwood, Eastern Cape, SA
2-15 Patel, M. Paleo-environmental reconstruction of the Tanqua Basin, SW Karoo,
South Africa
2-16 Malephane, H.R. Seismicity and Seismic Hazard Assessment of the arid western
regions of South Africa: a Neotectonic Perspective
2-17 Mielke, C. Topographic imprint of Geomorphology in southern Africa
2-18 Scharf, T. Denudation rates and geomorphic evolution of the Cape
Mountains determined through cosmogenic dating using 10 Be
and 21 Ne in quartz
Theme B: Earth in Space
Poster Author Title
2-19 Botai, M.C. Investigating the accuracy of gravity field models using satellite
Laser Ranging data
2-20 Croukamp, L.A Lunar Geotechnical GIS as an aid for exploration and
settlement construction
2-21 Munghemezulu, C. A proposal for the determination of intercontinental plate
velocities in Africa to support the establishment of the
African Geodetic Reference Frame (AFREF)
2-22 Nickola, G.L. High-precision steering and pointing control of a satellite/ lunar
laser ranging telescope
2-23 Nickola, M. Site characterisation: Astronomical seeing from a turbulenceresolving
model
Poster Session 3: Margins of Africa and Capacity-building
Poster Author Title
3-1 Curtis, C. Low- 18 O magmas of the Cretaceous Koegel Fontein Complex,
South Africa
3-2 Frei, O. Model-enhanced geothermobarometry of mafic dikes of the
Henties Bay Outjo dike swarm, Etendeka Igneous Province
Namibia
3-3 Khoele, K. The design of a pressurised clean water supply system for the
Science and Technology Train
3-4 Matsepe, T. The design of a Stirling engine system for the Science and
Technology Train
3-5 van Tonder, D.M. The development and evaluation of solar desalination
technology
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Post-Gondwana Tectonics of Western South Africa
M A G Andreoli 1, 2 , G Viola 3 , A Kounov 4 , O Heidbach 5 , J Scheepers 6 , I Stengel 7, 11 ,
CE Clarke 8 , F Netterberg 9 , R Durrheim 10, 2 , A Logue 1 , H Malephane 2
1. South African Nuclear Energy Corporation, South Africa, marco@necsa.co.za
2. University of the Witwatersrand, South Africa.
3. Geological Survey of Norway, Norway, Giulio.Viola@ngu.no
4. University of Basel, Switzerland, A.Kounov@unibas.ch
5. GFZ, Germany, heidbach@gfz-potsdam.de
6. Impala Platinum Rustenburg Mine, South Africa, johann.scheepers@implats.co.za
7. University of Pretoria, South Africa, Ingrid.stengel@up.ac.za
8. University of Stellenbosch, South Africa, cdowding@sun.ac.za
9. F Netterberg, South Africa, fnetterberg@absamail.co.za
10. CSIR, South Africa, RDurrhei@csir.co.za
11. Namibgeovista GeoConsult & Imaging, Namibia, Ingrid@namibgeovista.com
ABSTRACT
The Namaqualand complex is a gneissic terrane of NW South Africa stabilized at ca. 1.03 Ga. For its array of
favourable conditions a Low and Intermediate Level Radioactive Waste Disposal Facility was established in 1986
at Vaalputs, on the Bushmanland plateau of the Namaqualand complex. In spite of its great age and assumed
tectonic stability, the region was later found to display the characteristics of a moderately active intraplate seismic
province.
To monitor this type of weak neotectonics, the authors developed a multidisciplinary research program that
involves recording seismic events within a radius of 100 km around Vaalputs using two TELS 3-components
seismometers. All available seismic data will be interpreted in parallel with focal mechanism solutions for the
larger seismic events recorded from Bushmanland, orientation of maximum horizontal stress SHmax derived from
off-shore wells caliper logs from the Petroleum Agency, geomorphic-pedogenetic-palaeoclimate-geotechnical
investigations of the Cenozoic Vaalputs Formation, palaeostress analysis of brittle structures in the pre-Cenozoic
Namaqualand basement, and investigations of Post-Gondwana (neo)tectonic and dyking phenomena in the
southern Kalahari/ SW Namibia.
The seismic data show swarms in 1996, 2001 and 2010, and a trend of increasingly frequent seismicity in
Namaqualand since 1989. Furthermore, the Vaalputs area displays km-long lineaments in the geomorphic setup,
atypical pedogenic structures in Quaternary (?) palaeosoils, and numerous slickensided faults in Cretaceous
silcretes. Such features point to persistent, albeit perhaps punctuated, tectonic instability in Namaqualand and
Bushmanland since the break-up of West Gondwana. Our data also suggest that this intraplate tectonic activity
peaked between ~100 Ma and the Palaeocene, being at one stage accompanied by kimberlitic intrusions and by
multiple changes in the tectonic regime. Other areas affected by this evolution include southwestern Namibia, the
southern Cape basins and the western Kaapvaal craton
In summary, the seismicity in western southern Africa reflects a long-lived, post-Gondwana crustal instability
and strain arising out of the interaction, through time, between the complex mosaic structure of the southern
African lithosphere with changing regional stresses both compressive and extensional in nature. Whereas the
former originate from plate boundaries, the latter may arise from the upward propagation of the African
superplume. More complex, localized stress patterns appear to arise from the southward propagation of the East
African Rift. However, this interpretation cannot yet explain the Wegener stress anomaly, the contemporary NNWoriented
strike-slip regime in western southern Africa.
KEYWORDS: Neotectonics, Namaqualand, Bushmanland, Seismicity, Stress, Vaalputs.
1

The application of facies analysis on sedimentary evolution
and changes in sea-level on the Kookfontein and Waterford
Formation in the Permian Ecca Group, Tanqua, Karoo Basin
R. Arenz¹, D.Mikeš²
1. Stellenbosch University, South Africa, renitia@gmail.com
2. Stellenbosch University, South Africa, mikes@sun.ac.za
ABSTRACT
Facies are considered as deposited by a unique set of physical processes which can be interpreted from lithologies,
textures, primary sedimentary structures, fossil content and stratigraphic position. In many cases the observed
sedimentary structures alone are not sufficient to unequivocally assert the mode of deposition and in places comparison
with models described in literature may even be misleading.
The aim if this study was thus to; Analyse the sequence in which the facies occur, providing information about the
facies itself; the relationship between depositional environments and stratigraphic sequences developed through time as
a result of transgressions and regressions. Evaluating controls on sedimentary facies architecture, incorporating facies
analysis and interpretation. Evaluating the use of facies architecture to infer sea-level change. Using facies architecture
to determine depositional setting.
During a month long period of field work Phase 1 in the Tanqua and Laingsburg depocenters, an outcrop field study
was carried out to facilitate compilation of detailed sedimentary logging, and vertical profiles accompanied by outcrop
gamma log data facilitating easy comparison with subsurface data sets for correlation of the Waterford and Kookfontein
formations’ lithologies and radioactive decay properties. Detailed stratigraphic mapping was carried out using a
portable multi-channel scintillation spectrometer, SGR data collected is used as a correlation tool. The spectral gamma
ray (SGR) tool measured the total gamma ray (GR) and the individual contribution from the three major radioactive
sources, namely 40K, 238U and 232Th, in a given time. Data collected will be presented in seconds (sec). The
sedimentary successions were then logged by measuring the gamma radiation at an average vertical spacing of 50 - 75
cm over a selected time interval, namely 180 seconds for the argillaceous units and 240 seconds for sandstone.
Sedimentological and gamma ray profiles were measured from the basin-floor deposits to the base of the deltaic
successions in the Tanqua sub basin. The locations for these profiles were chosen on best outcrop positions for regional
correlation by using arial photographs geological and topographic maps. Samples were collected from fresh outcrop
surfaces where possible, concentrating mudstone sampling between fans/units, and sandstone samples at the start and
end of major depositional facies. Samples were taken at vertical intervals for the purpose of constraining regional
correlations.
Through a collaborative study at Stellenbosch University sedimentology research group, interpretation of facies, based
on spatial relations and internal characteristics (lithology and sedimentary structures) using information from
stratigraphic units and facies subdivision will be used to construct a new facies model for the Kookfontein and
Waterford Formations of the upper Ecca shelf to slope succession in the Tanqua depocentre .
KEYWORDS: Facies architecture ;sea- level change; Kookfontein Formation; Waterford Formation; Tanqua sub-
basin.
2

Lithostratigraphic correlation of the Ecca Palaeo-slope and
shelf-edge deltaic deposits: Phase 1
Andy Arnold 1 , Daniel Mikeš 2 , Willem Van Der Merwe 3
1. University of Stellenbosch, South Africa, 15905845@sun.ac.za
2. University of Stellenbosch, South Africa, mikes@sun.ac.za
3. STRATgroup, University of Liverpool, United Kingdom, W.Van-Der-Merwe@liverpool.ac.uk
ABSTRACT
The Permian Ecca Group of the Karoo Basin, South Africa preserves an extensive well-exposed siliciclastic basin
floor, slope and shelf- edge deltaic succession. These subaqueous depositional systems form a major component of
most marine and many lacustrine basin fills, and constitute primary targets for hydrocarbon exploration and
development.
Detailed regional mapping and correlation of the upper Ecca Group, Kookfontein, Fort Brown and Waterford
Formations has never been undertaken before. The current study hopes to contribute to the new understanding of:
(1) the stratigraphic development of the Karoo Basin margin during the late Permian, (2) shelf-margin construction
and (3) the internal facies architecture of these sought after deposits.
The first phase of field work has recently been undertaken over a period of six weeks, during which vertical
profiles were measured at cm-scale in both strike and dip sections. These were then used to construct the first of
many correlation panels, on which the palaeogeographic interpretations will be based. Correlation of the upper
Ecca succession will be done across the Tanqua and Laingsburg depocentres.
Expected deliveries: The study will produce the first detailed regional mapping of the upper Ecca group across
both depocentres and contribute to the knowledge of the development of the basin margin.
KEYWORDS: Karoo Basin, Shelf-edge deltas, Sequence stratigraphy, Correlation, Lowstand deposits
3

Petrogenesis of the False Bay dyke swarm, Cape Peninsula,
South Africa
N R Backeberg 1 , D L Reid 1 , R B Trumbull 3 , R L Romer 4
1. University of Cape Town, South Africa, nils.backeberg@gmail.com
2. University of Cape Town, South Africa, david.reid@uct.ac.za
3. Deutsches GeoForschungsZentrum, 14473 Potsdam, Germany, bobby@gfz-potsdam.de
4. Deutsches GeoForschungsZentrum, 14473 Potsdam, Germany, romer@gfz-potsdam.de
ABSTRACT
The False Bay dyke swarm is the southern NW-SE trending end-member of the Cretaceous dolerite dyke intrusions
on the western African margin, associated with rifting of Gondwana and opening of the South Atlantic Ocean. This
southern dyke swarm has been associated with a low-flux, passive rifting end member compared to its northern
high-flux, active rifting counterpart: the Henties Bay-Outjo dyke swarm in Namibia. The contrast in basaltic
magma types and magma flux between north and south has been related to different tectonic settings (i.e. magma
sources) along the current coast line during Cretaceous rifting. Further, the False Bay dyke swarm is characterised
by olivine-tholeiites with quite extreme differentiation to ferro-tholeiites within a monogenetic magma system. The
finer details of the differentiation process identified through trace element analysis and major element modelling
are presented here. Both crystal fractionation and assimilation trends are identified for the False Bay dolerites
during magma evolution. Crustal assimilation processes are only identified in samples with less than 5 wt% MgO.
This observation is consistent with trace elements and Sr and Nd radiogenic isotopes, while initial differentiation
(greater than 5wt% MgO) is characterised by pure fractional crystallisation. Initial variation in conserved trace
element ratios, prior to assimilation, is not correlated to differentiation and is assumed as a result of variations
within the enriched source rock.
KEYWORDS: dolerite dykes, trace element ratios, Sr and Nd isotopes, Gondwana rifting, differentiation
4

Evolution of Proterozoic mantle lithosphere: petrological and
geophysical evidence from the Kaapvaal – Namaqua boundary
D. Bell 1,3 , U. Weckmann 2 ,P. Janney 1 , M. de Wit 3
1. SESE, Arizona State University, Tempe, AZ, USA, David.R.Bell@asu.edu
2. GeoForschungsZentrum Potsdam, Germany, uweck@gfz-potsdam.de
3. AEON, University of Cape Town, South Africa, Maarten.deWit@uct.ac.za
ABSTRACT
The subcontinental lithospheric mantle (SCLM) beneath Proterozoic and Archean crustal provinces differs in
composition, temperature, and thickness. To shed light on the origins of these differences we combined
petrological data from xenocrysts, megacrysts, and xenoliths in kimberlites with a lithospheric resistivity model
derived from a new high-resolution magnetotelluric (MT) traverse, to examine the transition between Archean and
Proterozoic lithosphere at the SW margin of the Kaapvaal Craton. Highly resistive SCLM persists up to 100 km
west of the Brakbos fault zone, confirming inferences from garnet xenocrysts of craton-like mantle beneath
Proterozoic crust (Kobussen et al. 2008). Xenolith thermobarometry also suggests craton-like mantle temperatures
in this region prior to Mesozoic disturbance (Bell et al. 2003; Janney et al. 2010). Surface and body-wave seismic
tomography studies reveal craton-like high-velocity domains within the SCLM beneath the Namaqua Belt.
Average whole-rock Mg#, Al2O3 contents, and Os isotope model ages of Kaapvaal and Namaqua mantle xenoliths
differ, but many individual off-craton xenoliths overlap the cratonic population and suggest complex multistage
history. Clinopyroxene megacrysts from the Pofadder kimberlites suggest interaction of deep melts with mantle
lithosphere similar to that beneath the Archean craton at Kimberley. The MT study reveals prominent vertical
zones of low resistivity within the high-resistivity SCLM in the boundary region. These may be metasomatized
zones that formed during the focused ascent of melts generated beneath the SCLM and have been inferred from
xenocryst compositions (Begg et al. 2009). Some kimberlite eruptions occur earlier in the boundary region than
would be predicted from their broader regional eruptive patterns, trace elements suggest some have mixed source
regions, and evolved megacrysts indicate local magma infiltration to shallow levels. These results support models
of (1) melt-refertilized Archean SCLM beneath Proterozoic crust, and (2) the focusing of mantle–derived magmas
into ancient shear zones that serve as repeating loci of tectonic reactivation. This model allows for tectonic
obduction of relatively young Namaqua arc crust across subducting Archean SCLM during arc-continent collision,
as is presently observed in the Banda Arc (Fichtner et al., 2010) [335 words]
KEYWORDS: mantle, lithosphere, kimberlite, conductivity, megacryst, xenolith, subduction-accretion.
5

The stratigraphy of the lower and middle Karoo Supergroup,
north of Paterson, Eastern Cape, South Africa
Dawn E. Black 1 , P.W.K. Booth 2 , M.J. de Wit 3
1. NMMU, South Africa, dblack@geoscience.org.za
2. NMMU, South Africa, peter.booth@nmmu.ac.za
3. UCT, South Africa, Maarten.DeWit@UCT.ac.za
ABSTRACT
Strata of the Karoo Supergroup (Karoo Basin) in an area north of Paterson, Eastern Cape, South Africa, are being
mapped in order to better define the litho and chrono-stratigraphy of the Ecca and Beaufort Groups. The southeast
Karoo Basin displays a thick section of Karoo Supergroup sediments that record deepening and shallowing of the
basin throughout the Permian.
Fieldwork to date has shown that mainly thinly-bedded deltaic deposits (Prince Albert, Whitehill and Collingham
Formations) are overlain by thick deltaic units of sandstone and mudrock (Ripon, Fort Brown and Waterford
Formations). Stratigraphically upwards the deltaic deposits of the Ecca Group give way to mudrock and lesser
sandstones of the Beaufort Group that represent fluvial sedimentation in an inland sea, with a provenance in the
south and east.
Once fieldwork is complete detailed lithostratigraphic columns will be constructed and geological sections drawn.
Features such as sedimentary structures, unit thicknesses and mineralogy will provide the basis for the
reconstruction of the palaeo-environment. The sections produced will form the basis for correlating Karoo strata
with the western part of the basin, albeit that such long range correlations may not be accurate.
Radiometric age dating especially of zircons in tuffaceous beds which occur throughout the Ecca and Beaufort
Groups will be determined by mass spectrometry (U/Pb isotropic method). Samples collected and analysed should
provide improved time constraints of the Permian-Triassic boundary in the south-eastern Karoo Basin, and will add
to the existing chronostratigraphic data base for the Karoo Basin. This approach should make for improved
interpretations of paleao-environments which previously relied on lithostratigraphy, but can now be modified or redefined
through the chronostratigraphy.
An additional aim of this project is to give a measure of the extent of deformation of the rocks, especially at their
southernmost outcrops, and thereby provide a better understanding of the relationship between Cape Supergroup
rocks and those of the overlying Karoo Supergroup.
KEYWORDS: Stratigraphy, Karoo Basin, ashfall tuffs.
6

Investigating the accuracy of gravity field models using
Satellite Laser Ranging data
M. C. Botai 1, 2 1, 2
, W. L. Combrinck
1. Space Geodesy, Hartebeesthoek Radio Astronomy Observatory, South Africa, christina@hartrao.ac.za
2. Department of Geography, Geoinformatics and Meteorology, University of Pretoria, South Africa,
ludwig@hartrao.ac.za
ABSTRACT
Continuous observations of geodetic satellites using the Satellite Laser Ranging technique have provided
unprecedented opportunity in the long- to medium-wavelength gravity field modeling. As a result, numerous
gravity field models have been derived from these observations and have been made freely available to the science
community for research purpose. The accuracy of most of these models in terms of precise orbit determination is
currently at cm level. Improvement in the modeling of the long wavelength components of the Earth is anticipated
as quantitative and qualitative data (in particular from low earth orbit satellites) become available in the future.
Such expectations require that the accuracy and precision of existing gravity field models be assessed. The
validation of gravity field models in terms of satellite orbit determination is based on the difference between the
observed (SLR measurements) and the computed range. The resulting O-C range residuals can be considered as an
important index when determining the accuracy of the gravity models and hence the satellite orbits. In this
contribution we investigate the accuracy of ten selected gravity field models (both satellite-only and combined
models) analyzed using LAGEOS 1 and 2 data. Preliminary results show that the gravity field models developed
over the years have improved by a factor of 2 per year.
Keywords: Satellite Laser Ranging, LAGEOS, gravitational field, Global Geopotential Models.
7

Inferences of α-stable Lévy distributions in long-range
dependent geodetic data
O. J. Botai 1 , W. L. Combrinck 1, 2 1, 3
, V. Sivakumar
1. Department of Geography, Geoinformatics and Meteorology, University of Pretoria, South Africa,
joel.botai@up.ac.za
2. Space Geodesy Programme, Hartebeesthoek Radio Astronomy Observatory, South Africa,
Ludwig@hartrao.ac.za
3. National Laser Centre (NLC), Council for Scientific and Industrial Research (CSIR), Pretoria,
South Africa, SVenkataraman@csir.co.za
ABSTRACT
Recent analysis of geodetic data demonstrated that the oscillatory modes of geophysical signals exhibit self-similar
behaviour. This scaling behaviour could be viewed as a manifestation of scale-invariant non-linear dynamics
whose fractal structures and multi-fractal statistics are typical of a turbulent atmosphere and the Earth’s variable
interior and complex topography. In order to explore the characteristics of the underlying geophysical signals and
noise components in the geodetic data, assessing the stability of the inherent frequency distribution is often
required. In the research presented here, the properties of a long-range α-stable Lévy distribution with long tails
and infinite moments in geodetic data are investigated by way of statistically testing their distribution. The choice
of stable distribution is based on the ease with which the statistical properties of the non-Gaussian processes are
defined. Results show that the independent geophysical components reconstructed from geodetic data exhibit
distributions that have asymptotic power-law decay whose underlying process can be modelled as a long-range
dependent process with an α-stable Lévy distribution (i.e., the stable variates have small characteristic exponents).
This an important contribution to geodetic data analysis because if the frequency distribution of geodetic data is
inferred as stable, then the noise characteristics present in the data would be understood and modelled. In
particular, if the presence of an α-stable noise component is inferred, it could imply that such a noise component is
triggered by single extreme events which could be statistically modelled and therefore corrected.
KEYWORDS: Geodetic data, long-range, self-similar, random process, α-stable Lévy.
8

A high-power 2 crystal Nd:YLF laser at 1314 nm
R. C. Botha 1, 2, 3 , H. Strauss 2 , W. S. Koen 2 , C. Bollig 2 , W.L. Combrinck 1
1. Space Geodesy Programme, HartRAO, South Africa, roelf@hartrao.ac.za
2. Laser Sources Group, CSIR National Laser Centre, South Africa
3. Laser Research Institute, Stellenbosch University, South Africa
ABSTRACT
A new fundamental space geodetic observatory for South Africa has been proposed. Lunar Laser Ranging (LLR) is
one of the space geodetic techniques to be hosted on-site. LLR requires a pulsed laser that can operate at 100 to
400 mJ energy per ~ 20 pico-second pulses, at a pulse repetition frequency in the kHz region. It must also have
excellent beam quality at M 2 < 1.1. Since no commercial laser matching the exact specifications could be obtained,
it was decided to investigate into the possible development of such a laser.
The most feasible candidate for such laser parameters was found to be a crystal-based diode pumped system.
Nd:YLF was identified as a suitable candidate for the gain medium crystal. Investigating this material with is a 2crystal
system operating at 1314 nm rather than the usual 1053 nm, will be our last experimental setup. The
investigation primarily focuses on the power scaling of this material at this specific wavelength. A smaller (relative
to previous efforts) pump beam diameter of 1.0 mm is used to increase the efficiency. This however increases the
risk of thermal fracture. A total output power of this initial continuous wave laser is expected to be above 50 W.
KEYWORDS: High-power, pico-second, laser, ranging, lunar
9

Seismic Interpretation, Distribution, and Numerical Modelling
of Natural Gas Leakage in Block 2 of the Orange Basin,
Offshore South Africa
Donna Boyd 1 , Maarten de Wit 2 ,Zahie Anka 3 , Rolando di Primio 4
1. AEON, University of Cape Town, South Africa, boyd.donna@gmail.com
2. AEON, University of Cape Town, South Africa, maarten.dewit@uct.ac.za
3. GFZ German Research Centre for Geosciences. Potsdam, Germany, zahie@gfz-potsdam.de
4. GFZ German Research Centre for Geosciences. Potsdam, Germany, dipri@gfz-potsdam
ABSTRACT
300 2D seismic profiles and 10 wells were analysed from the study area of 18750 km 2 in exploration Block 2 of
the Orange Basin located offshore the South African continental margin. The aims of this study are to: (1)
characterize different natural gas leakage features present throughout the basin, and (2) understand the relationship
of natural gas leakage with structural and stratigraphic elements, and (3) quantify liquid/gas hydrocarbon
generation, migration and seepage dynamics through the post-rift history of the basin. Methane gas escaping across
the sea floor into the exosphere may contribute to Earth’s climate fluctuations. Since a significant volume of
escaping gas was cut off when at least half of identified structurally-controlled chimneys were sealed within the
Miocene sequence, retention of gas along this continental margin may have to be factored into global cooling
models.
KEYWORDS: volcanic continental margin, South Atlantic, Orange Basin, natural gas leakage, gas chimneys,
South Africa
10

Quaternary dune gastropods of the South African west coast:
Implications for climate change
Claire Browning 1 , Dr Dave Roberts 2 , Dr Fenton ‘Woody’ Cotterill 3 , Prof Chris Harris 4
1. Council for Geoscience, South Africa, cbrowning@geoscience.org.za
2. Council for Geoscience, South Africa, cbrowning@geoscience.org.za
3. AEON (UCT), South Africa, Fenton.Cotterill@uct.ac.za
4. Department of Geological Sciences (UCT), South Africa, Chris.Harris@uct.ac.za
ABSTRACT
Fossilized terrestrial gastropods are widespread in the geological record and can be used in the identification and
delineation of Quaternary geological formations in South Africa. They may also be used to determine the
environmental conditions at the time of death. Both the species composition and the stable isotopes are employed
in this regard. Some species, for example Trigonephrus globulus, are temporally distributed from the Miocene to
the present. Individuals of this species vary greatly in size over time, with fossil examples from certain horizons
being twice the size of present day specimens. The present distribution of T. globulus is along the West Coast of
South Africa within the Mediterranean, winter rainfall climatic regime. The climate along the South African
coastline is sensitive and diverse and climatic fluctuations would have played a role in the distribution and size of
gastropods within the dune system. Dune snails are thus good potential palaeo-environmental indicators.
Oxygen isotope analysis of both fossil material and host lithologies will be done in order to elucidate
palaeoclimatic information. Seasonal growth rings of calcareous shell material will also be sampled in order for
high resolution climatic data to potentially be obtained. Comparisons with other gastropod fossils within different
climatic regimes along the South African coastline could be drawn, i.e. Acatina zebra along the south-eastern
coast. A better understanding of dune gastropods as indicators of palaeoclimates along the West Coast will add to
our ability to understand and properly map the Quaternary deposits of South Africa as well as contribute to our
understanding of global climate change.
KEYWORDS: Climate change, dune gastropod, Quaternary, west coast South Africa, Trigonephrus globulus.
11

Structural features of the Bokkeveld Group (Cape Supergroup)
in the Eastern Cape, South Africa
Gideon Brunsdon 1 , P.W.K. Booth 2 , J.A. Mondon 3
1. NMMU, South Africa, gideon.brunsdon@nmmu.ac.za
2. NMMU, South Africa, peter.booth@nmmu.ac.za
3. NMMU, South Africa, jean-luc.mondon@nmmu.ac.za
ABSTRACT
Previous studies of the Bokkeveld Group focussed mostly on the sedimentation and sedimentary features of this
group with a view to interpreting the depositional environment. This study aims to contribute new information on
the structural features of the Bokkeveld Group north-west of Uitenhage in the Eastern Cape, where there is
evidence of folding and thrust faulting, similar to that occurring in the under- and overlying groups of the Cape
Supergroup.
Field work to date shows that predominantly argillaceous beds of siltstones and mudstones, with lesser arenites and
thin conglomerates make up the Bokkeveld Group. This group conformably overlies the Table Mountain Group of
predominantly arenaceous beds. Both groups have been folded into asymmetric anticlines and synclines, with a
prominent, south-dipping pervasive cleavage developed in the Bokkeveld Group. The fissile nature of argillaceous
beds on outcrop have required that very careful observations of the all important bedding-cleavage relationship in
the field are made, so that correct interpretations of facing direction of strata can be applied. Thrust faults showing
fore-and backthrusts in the Bokkeveld Group are interpreted to have formed during a main deformation phase of
the Cape Orogeny, during the Permian.
Samples of mainly argillaceous rocks have been collected and mineral compositions identified with the aid of a
petrographic microscope and a scanning electron microscope (SEM). Bedding in argillaceous shales of the Gydo
Formation shows a graded texture with layers of coarse grained silicate minerals alternating with fine grained
chlorite. Chlorite, muscovite and quartz make up the major minerals in the shales, and accessories include zircon,
Rare Earths minerals and opaques (iron ore).
In places bedding planes dip predominantly to the northeast, but this is probably a function of poor outcrop because
bedding does dip in the opposite direction elsewhere in the study area, indicating the presence of folding in the
Bokkeveld Group. A pervasive cleavage dips consistently to the southeast, and appears to be thrust fault related. It
is however possible that some of the cleavage development might also be closely related to folding in the
Bokkeveld Group. This relationship needs to be carefully verified through further microscopic studies. The results
of this study will inevitably point to the fact that strata have been disrupted by structures such as folds, thrust faults
and cleavages to the extent that the stratigraphic order of the Bokkeveld Group in this area will have to be reassessed.
KEYWORDS: Bokkeveld Group, cleavage, folded, faulted strata
12

An Investigation of Nickel Mineralization in the Northwestern
Part of the Barberton Greenstone Belt, South Africa
N. Chabangu, M. Tredoux, F. Madala
University of the Free State, P. O. Box 339, Bloemfontein, 9300, South Africa
chabangun@ufs.ac.za, mtredoux@ufs.ac.za, fulufhelomadala@yahoo.com
ABSTRACT
The scope of this research is to evaluate the most probable origin of the Bon Accord (BA) Nickel-Oxide body and
the possible mechanisms responsible for its formation, since it appears to be the only type of this deposit found in
the world. Its occurrence seems to be confined to the Bon Accord farm near Barberton in Mpumalanga, South
Africa. It may represent a very rare type of rock.
The Barberton Greenstone Belt (BGB) formed during the Archean Eon. It represents > 3.0 Ga rocks in a
greenschist facies belt which might contain remnants of ancient oceanic crust. The BGB consists of a strongly
folded, ENE-trending, mid-Archean (3.6-3.1 Ga), volcano-sedimentary remnant, entirely surrounded by a variety
of granitoids of the Kaapvaal Craton. Geophysical data has shown that the greenstone belt reaches a maximum
thickness of 7.5 km and on average 3-5 km.
The objectives of the study include researching the following:
1) The relationship between the Nickel-Oxide BA body and the associated low grade sulphide mineralizations.
2) The evaluation of the full set of major elements found in BA using modern methods and the implication of these
data for BA and its probable origin.
3) How the current data can be reconciled with previously proposed models for the formation of BA.
The work done to date:
Eleven samples were analysed, ten of these samples were collected from the BA body during this current research
program. The extra sample was derived from a previous research program and was donated to this study by Prof
Grant Cawthorn. The analysis done on the ten samples from BA, include mineralogical investigations, XRD, XRF
work while susceptibility readings were taken on all the eleven samples because of the high magnetic remanence of
BA. The work done until now also includes field trips to the BA deposit. A new geological map of BA and the
surrounding areas is currently under production. Future work includes sample analysis and interpretation using the
SEM, EMP and ICP-MS.
KEYWORDS: Barberton Greenstone Belt, Bon Accord, Nickel Oxide, Sulphides
13

Study of the geo-electrical anisotropy in the Cape Fold Belt
using magnetotelluric
X. Chen 1, 2 , U. Weckmann 1
1. Helmholtz Centre Potsdam – German Research Centre for Geosciences, Potsdam, Germany
2. Institute of Earth and Environmental Sciences, University of Potsdam, Potsdam, Germany
xiaoming@gfz-potsdam.de , uweck@gfz-potsdam.de
ABSTRACT
Within the framework of the German - South African geo-scientific research initiative Inkaba yeAfrica a series of
magnetotelluric (MT) field experiments were conducted along the Agulhas-Karoo Transect in South Africa. This
transect crosses several continental collision zones between the Cape Fold Belt, the Namaqua Natal Mobile Belt
and the Kaapvaal Craton. Along the Cape Fold Belt profile we can identify areas (> 10km) where MT sites exhibit
phases over 90 degrees. This phenomenon usually occurs in presence of electrical anisotropy. Due to the dense site
spacing we are able to observe this behaviour consistently at several sites.
With isotropic 2D inversion we are able to explain most features in the MT data but not the abnormal phase
behaviour. In order to explain the abnormal phase behaviour we have to include zones of electrical anisotropy.
Currently, we can use 2D anisotropic forward modelling to reproduce the general trend of phases leaving the
quadrant. To explain the MT data in more detail, 2D anisotropic inversion would be desirable. In this presentation
we focus on a spatially constraint 2D anisotropic inversion. In a first step, we use simple 2D models with
embedded zones of electrical anisotropy to study the general influence of anisotropy parameters. In a second step,
isotropic 2D inversion results are used as background models in which we include anisotropic zones in order to fit
the abnormal phase curves in the data. For these forward modelling studies we implemented the 2D anisotropic
code by Pek & Verner (1997) into the modular EM modelling and inversion software (Egbert, 2006; Egbert &
Siripunvaraporn, 2008). The modular system provides an ideal environment to implement this inversion scheme.
KEYWORDS: Cape Fold Belt, magnetotelluric, anisotropy, modelling, constraint inversion.
14

Exploring the Origin of Breccia Pipes in the Karoo Basin,
South Africa
Naledi Chere 1 Maarten De Wit 2 , Dave Reid 3
1. Geological Sciences Department & AEON, University of Cape Town, South Africa, chrnal001@uct.ac.za,
2. maarten.dewit@uct.ac.za, 3. dave.reid@uct.ac.za
ABSTRACT
In the Karoo Basin enigmatic pipes occur in the western sector of the sedimentary basin-here and elsewhere in the
Karoo Bain, the pipes are closely associated with the Mid Jurassic (~180Ma) Karoo Large Igneous Province. It has
been suggested that these pipes resulted from the interaction of hot igneous intrusions such as dolerite sills and the
surrounding sedimentary units. This project aims to test this model. 21 breccia pipes across Loriesfontein and
Calvinia in the Northern Province (South Africa) have been investigated. The pipes outcrop in the sediments of the
Ecca Group and occur as low lying circular hills (average height of 15 m) ranging from 20m to 80m in diameter.
The centre of the hills are characterised by rocks with calcite infill in the vesicles. The contact between the
vesiculated rock at the centre and the country rock is sharp in most pipes. The surrounding rocks either shallowly
dip (dip angles 5 to 10 degrees) towards or dome away the centre of the breccia pipe. The rocks display variation in
the degree of vesiculation (approximately a maximum of 20%) and calcite infilling across the breccia pipes but
long axes of the vesicles typically had a preferred orientation. Microscopic studies of the breccia matrix rock reveal
a mineral assemblage of predominantly calcite, quartz and plagioclase laths. The increased porosity of the rock due
to its vesicular nature makes them optimal groundwater targets in the Karoo Basin. The further aims of the research
are to (1) construct detailed geological maps of at least 10 pipes based on field work using the QuantumGIS
system, (2) Petrological analyses of breccia and host rock samples for mineralogy studies using conventional
optical microscopy and XRD (3) Bulk rock geochemistry of the samples ( XRF, ICPMS). On the basis of this data,
a possible model for the pipes will be constructed.
KEYWORDS: Vesicular breccia pipes, Karoo Sedimentary Basin, dolerite dykes/sills
15

The Geothermal potential of South Africa
New Challenges for Geoscientists
L. Chevallier 1 , C.Musekiwa 2
1. Council for Geoscience, South Africa, lchevallier@geoscience.org.za
2. Council for Geoscience, South Africa, cmusekiwa@geoscience.org.za
ABSTRACT
Research and exploration in geothermal energy effectively started in many countries more than 30 years ago. These
countries are now technologically well advanced and able to generate power or build thermal stations for a wide
range of applications.
Geothermal energy is now receiving scrutiny in South Africa and the geoscientific community is therefore facing a
major challenge. Indeed, South Africa is lagging behind in this technological field and researchers are acting in a
relatively unknown environment. However, if such research is to start now, it can utilise knowledge and
experiences gained from other organisations around the world.
The scope of the investigation should focus on which types of geothermal source can be targeted in South Africa
and for which type of application? A geothermal potential map will represent the first step towards resource
assessment and its applicability. Geology plays an essential role in defining the geothermal potential of a country.
Favourable geological conditions such as rock types, degree of fracturing, structural framework, deep groundwater
circulation, recent tectonics, heat flow or abnormal temperature gradient, must be present for these various
geothermal systems to occur.
South Africa shows some potential: granites with light abnormal heat flow, hot springs some of them exceeding
50°C, deep sedimentary basins with a thermal gradient above normal, proximity to the possible extension of the
rift system. The hot dry rock (HDR) technology, for instance, which has recently been successfully implemented
for production of electricity in other countries, represents a real challenge for application in South Africa.
The geothermal potential map of South Africa and the inventory of geothermal resources is the basic
tool for a long term geothermal exploration programme in the country. The initiative nevertheless needs
to be driven by extensive national and international collaboration in order to deliver leading expertise
and solutions.
KEYWORDS: Geothermal potential map, geothermal energy.
16

The morphology and development of palaeo-terraces of the
Orange River in the Hopetown-Douglas-Prieska area
Clark, J.H.A 1 , MacDonald, N. 1 , Holmes P.G. 2 , Gauert C. 1
1. Dept. of Geology, University of the Free State, Bloemfontein, R.S.A., johnsupermanclark@gmail.com
2. Dept. of Geology, University of the Free State, Bloemfontein, R.S.A., holmespg.sci@ufs.ac.za
3. Dept. of Geology, University of the Free State, Bloemfontein, R.S.A., gauertcdk@ufs.ac.za
ABSTRACT
The field study was carried out along the Orange River between Hopetown-Douglas-Prieska. This
geomorphological study obtained information on river morphology and terrace development along the Orange
River and how the findings relate to previous work. The methods used in the study were sampling techniques,
satellite imagery, field sketches and photographs of the river terraces, notes on the geology, pebbles, gravels and
sediments were obtained and GPS positions.
There were six localities having different geomorphology investigated between Hopetown and Prieska. All six
localities displayed different fluvial sediment deposits. Pump Station differed from the Orange-Vaal Confluence
which in turn differed from the Wouterspan locality both in terms of geomorphology as well as sediment deposits.
Various river terraces were identified at all localities which showed different physiognomy.
At the Pump station only fine sediments were deposited, Bucklands displayed pebbles and fine sediments and
Wouterspan was mainly made up of pebbles and minor fine sediments. The different terrace deposits are dependent
on climate variations over geological time, by bedrock and by elevation gradient. Climate changes from wetter to
drier climatic phase’s affects river flow, causing the velocity of water to decrease and making it impossible for
pebbles to move downstream whereas fine sediments can still move. A difference in bedrock causes a change in
hardness, resulting in a change in erosional development. A change in elevation gradient will cause a change in
erosive action. A steeper gradient will cause higher erosion and a more incised river valley whereas a flatter
gradient will cause a more meander type river course.
The Pump Station on the Orange River, northwest of Hopetown is more incised and has a steeper gradient
compared to the Orange-Vaal confluence. The different factors cited above led to the formation of the different
deposits found along the Orange River in the Hopetown-Douglas-Prieska area.
KEYWORDS: Orange River, geomorphology, river morphology, river terrace,
17

Evaluation of GRT scale coefficients as an indicator of PPN
formalism test accuracy
W.L. Combrinck
Hartebeesthoek Radio Astronomy Observatory (HartRAO) Space Geodesy programme, South Africa,
ludwig@hartrao.ac.za
ABSTRACT
Parameterised Post Newtonian (PPN) parameters γ and β (which should equal unity if general relativity is valid)
are estimated through the analyses of four years of LAGEOS 1 and LAGEOS 2 data. To reduce the possibility of
possible imprinting of general relativistic effects which could be contained in the gravity model used, several low
order spherical harmonic coefficients are solved in the orbit estimation and propagation process. After convergence
is reached, the solved PPN parameters γ and β are kept fixed at their solved values and scaling coefficients are
introduced to explore the possibility of open parameter space in the accelerations due to the Schwarzschild field,
frame dragging and de Sitter (geodesic) precession. It is found that some parameter space is available in the radial
acceleration component, which could be taken up by including post Post-Newtonian components of general
relativity, or it could be due to some other radial acceleration component that is not adequately modeled. The
inclusion of scale coefficients in the least-squares process proves to be a valuable tool in evaluating the solutions
for γ and β . A comparison with results obtained for the PPN parameters by other authors utilising different
techniques such as VLBI and radar measurements to planets and probes are made.
KEYWORDS: Love number, elasticity of Earth, satellite laser ranging
18

Geoecodynamics and geobiological fingerprints of the
Kalahari epeirogeny: linking tectonism, drainage, and
phylogeography
F.P.D. Cotterill 1,2 , M.J. de Wit 1
1 AEON - Africa Earth Observatory Network
Department of Geological Sciences, University of Cape Town, Rondebosch 7701, South Africa
2 Department of Molecular and Cell Biology, University of Cape Town, Rondebosch 7701, South Africa
ABSTRACT
This paper summarises recent progress in geoecodynamics research on landscape evolution of the Kalahari Plateau.
Expanding the scope of geobiology, the theory and methods of geoecodynamics quantifies the tenures of geobiotic
entities in landscapes, within the framework of geomorphological and geospheric evolution. Geoecodynamics
centres on deciphering phylogeographic records of stenotopic species; molecular dating of DNA sequences
constrains timings of speciation and dispersal events in these biotic indicators, and quantifies each event as an
individualistic response to disruption of a landform. Our studies of biotic indicators reveal how geobiological
signatures across Africa’s Kalahari plateau can decipher the tempo and mode of late Cenozoic landscape evolution.
We demonstrate that this novel methodology obtains spatio-temporal constraints on episodes of tectonism.
Quantified geobiological signatures revealed in these biotic indicators of landscape evolution constrain where and
when both the drainage and biogeography of the Kalahari plateau changed. We interpret these signatures, preserved
in the biosphere, to reflect impacts of deep geosphere processes on landscapes; so these tight links between biotic
and palaeo-drainage dynamics constitute synergistic responses to the pulses of tectonics that altered river topology
and lacustrine environments. A synthesis of these biotic histories reveals how biodiversity dynamics responded to
changes in depocentres and drainage nets. We employ a synthesis of phylogeographic evidence to tighten spatiotemporal
resolution on these events. It enables us to map where and when geospheric processes impacted on earth
surface processes. In combination, phylogeography and molecular dating of biotic indicators confers both
geochronological resolution, and spatial precision, to quantify geobiological events as fingerprints of tectonic
pulses. This narrative of geobiological history is interpreted to reflect recurrent epeirogeny across the African plate,
which has reconfigured the Kalahari Plateau through the Plio-Pleistocene. Its unprecedented spatio-temporal
resolution quantifies a southwest spreading propagation of tectonics, to constrain the rate of individuation of the
Kalahari subplate.
KEYWORDS: Kalahari epeirogeny, tectonism, speciation, fishes, phylogeography, molecular clocks, drainage
evolution, African biogeography, geomorphology, molecular dating
19

A Lunar Geotechnical GIS as an aid for exploration and
settlement construction
Leon Croucamp 1, Ludwig Combrinck 2, Marius de Wet 3
1. University of Stellenbosch, South Africa, lcroukamp@sun.ac.za
2. HartRAO, South Africa, ludwig@hartrao.ac.za
3. University of Stellenbosch, South Africa, mdw1@sun.ac.za
ABSTRACT
We present the case for a Lunar Geotechnical GIS and the Earth based methods and instruments required to
support a geo-referenced framework for such a GIS.
During discussions with various role-players (NASA/ESA/etc) it was determined that the Lunar community have
the need for a Lunar GIS system as well as a Space Geodesy system to create a single world-wide (lunar-wide)
geo-referenced framework for the moon. Initially the biggest user of such a system would be the Constellation
Programme (CxP) of NASA plus other space faring nations of the world who are currently undertaking satellite
missions to the moon and are planning future missions. The Moon will eventually become a springboard for future
missions to Mars and beyond, in addition it will play a significant role as laboratory for the determination and
creation of better technologies for space travel and space material manufacturing.
A new space geodesy site is being developed at Matjiesfontein and will be known as the Matjiesfontein
Observatory (MO). This observatory will house the various Satellite Laser Ranging and Lunar Laser Ranging
instruments to track the GPS/GNSS/GALILEO type systems placed in orbit around the earth. Tracking of orbiters
around the moon (such as Lunar Reconnaissance Orbiter) and interplanetary probes will also be supported. The
most recent launch of a satellite to the moon was on Friday 1 October 2010 by China. The ability to track these
satellites accurately is vital to create a geo-referenced framework for the correct referencing of any data collected
on the moon, be it geotechnical, geochemical or other.
KEYWORDS: GIS, Geotechnical, Lunar, Space Geodesy
20

Low-δ 18 O magmas of the Cretaceous Koegel Fontein Complex,
South Africa
Catherine Curtis 1 , Chris Harris 1 , Coenraad de Beer 2 , David Reid 1 , Robert B. Trumbull 3 ,
Rolf Romer 3
1. Department of Geological Sciences, University of Cape Town, Rondebosch, South Africa
2. Council for Geoscience, Bellville, South Africa
3. GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, Germany
ABSTRACT
Koegel Fontein is a relatively unstudied, Cretaceous, large, silicic complex associated with the opening of the
South Atlantic. This paper reports O,- H-, Nd-, Pb- and Sr-isotope data for the complex. O- and H-isotope ratios for
Koegel Fontein are unusually low (δ 18 O 6‰) for quartz and quartz
phenocrysts and low δ 18 O values for feldspar separates have been hydrothermally altered. Koegel Fontein has the
lowest known magmatic δ 18 O values in Southern Africa. O- and Sr-isotope assimilation models and the initial Srisotope,
Pb-isotope and εNd results rule out assimilation as a possible mechanism for the generation of the lowδ
18 O magmas.
We suggest that the source of the low-δ 18 O magmas is low-δ 18 O crust, hydrothermally altered before the
emplacement of the Koegel Fontein Complex. Hydrothermal alteration did occur synchronously with the
emplacement of the complex. The hydrothermal fluid responsible was meteoric in origin with a calculated δ 18 O
value of -9.9‰.
KEYWORDS: Koegel Fontein, Cretaceous, Silicic Complex, Stable Isotopes, Radiogenic Isotopes, Low d18O
Magmas
21

Cosmogenic nuclide-based perspectives on long-term
landscape evolution models and short-term soil erosion rates
in southern Africa
J.E. Decker 1* , S. Niedermann 2 , M.J. de Wit 3
1. AEON and Department of Geological Sciences, University of Cape Town, Rondebosch 7700, South Africa,
geojedenator@gmail.com
2. Deutsches GeoForschungsZentrum, 14473 Potsdam, Germany, nied@gfz-potsdam.de
3. AEON and Department of Geological Sciences, University of Cape Town, Rondebosch 7700, South Africa,
Maarten.DeWit@uct.ac.za
*Present address: Petroleum Agency SA, 7 Mispel Road, Tygerpoort Building, Bellville 7789, South Africa,
deckerj@petroleumagencysa.com
ABSTRACT
Southern Africa’s landscape is characterised by a high plateau (elevation > 1,000 m) bound by escarpments and
extensional continental margins, and the region has been influential in the development of geomorphological
theory. The abundances of cosmogenic noble gas nuclides ( 3 He, 21 Ne and 38 Ar) in pyroxene separates from 22
Early Jurassic (~183 Ma) Karoo dolerite surface samples from southern Africa indicate minimum exposure ages
that range from ~20 ka to ~500-700 ka. Corresponding maximum erosion rates range from ~0.6 m/Myr to ~20
m/Myr, with most values < ~4 m/Myr. This data implies a decline in denudation rates over time, as these recent
surface process rates are too low to account for the form of topographic features. Low maximum erosion rates are
interpreted as weathering rates, but do not correlate with lithological and present-day climatic variables. However,
dolerite weathering rates are similar to theoretical basalt weathering fluxes modelled as a function of present-day
temperature and run-off. Regional discrepancies between measured and model values may be interpreted as an
indication of a variable late Quaternary palaeoclimate. Dolerite weathering rates are also similar to stratigraphically
determined Holocene denudation rates, suggesting that denudation has been weathering-limited over this time
period. Finally, if Karoo dolerite maximum erosion rates are interpreted as soil production rates, it is estimated that
modern rates of soil erosion in southern Africa are up to two orders of magnitude higher than rates of soil
production, implying that modern land-use practices are unsustainable.
Key words: cosmogenic nuclides, Karoo dolerite, landscape evolution, soil erosion, noble gases
22

Fate of soil organic matter in South African crop and pasture
land
C.C. du Preez 1 , W. Amelung 2
1. Department of Soil, Crop and Climate Sciences, University of the Free State, P O Box 339,
Bloemfontein 9300, Republic of South Africa, dpreezcc@ufs.ac.za
2. Department of Soil Science and Soil Ecology, Rheinische Friedrich-Wilhelms-Universität Bonn,
Nussallee 13, Bonn, Germany, wulf.amelung@uni-bonn.de
ABSTRACT
Organic matter influences properties of mineral soils disproportionately to the quantities present. It is thus not
surprising that organic matter is regarded as the most important indicator of soil quality and health. Soil with good
quality and health usually promotes sustainable land use in agriculture. A proper knowledge on the fate of organic
matter in agricultural soils is therefore essential in the design of management practices enhancing sustainable land
use. Several studies were conducted over the past 10 years to establish the fate of organic matter in South African
crop (0-98 years old) and pasture (0-31 years old) land. These studies were done in three agro-ecosystems
dominated by plinthic soils (clay ~ 14%), namely Harrismith (MAP ~ 625 mm and MAT ~ 13.8°C), Kroonstad
(MAP ~ 563 mm and MAT ~ 16.6°C), and Tweespruit (MAP ~ 516 mm and MAT ~ 15.9°C). Representative soil
samples were collected for analyses. The concentrations of organic carbon and nitrogen were determined in bulk
soil, particle size separates, and water-stable aggregate classes. In addition, lignin derived phenols and amino
sugars as markers for plant and microbial residues were measured. Long-term cultivation of native grassland
reduced organic matter in bulk soil by 60%, reaching equilibrium after 30 years. Losses of organic matter occurred
from all particle sizes, with increasing rates as particle size increased. Aggregates decreased in size into finer
classes. However, organic matter contents decreased in all aggregate classes, but fastest in the 2.8 to 8.0 mm class.
Increased ratios of phenolic acids to aldehydes suggested that side chains were increasingly oxidized. Amino sugar
analyses suggested that fungal residues were better preserved than bacterial residues, while microbial residues
declined by 60%. It appears that these losses and changes in organic matter cannot easily be rectified by the
conversion of crop to pasture land.
KEYWORDS: aggregate size, amino sugar, microbial residue, phenolic aldehyde
23

Observational studies to mitigate seismic risks in mines:
a new Japanese - South African collaborative research project
R J Durrheim 1,3,4 , H Ogasawara 1,2 , M Nakatani 1,5 , Y Yabe 1,6 , A Milev 1,4 , A Cichowicz 1,7 , H
Kawakata 1,2 , H Moriya 1,6 and the SATREPS 1 research group
1 JST-JICA Science and Technology Research Partnership for Sustainable Development
2 Ritsumeikan University, Japan
3 University of the Witwatersrand, South Africa
4 Council for Scientific and Industrial Research, South Africa
5 Earthquake Research Institute of the University of Tokyo, Japan
6 Tohoku University, Japan
7 Council for Geoscience, South Africa
ABSTRACT
Mining-induced earthquakes pose a risk to workers in deep South African mines, while natural earthquakes pose a
risk to people living close to plate boundaries. We introduce a 5-year Japanese - South African collaborative
project entitled "Observational studies to mitigate seismic risks in mines" that commenced in 2010. The project,
which seeks to develop human and instrumental capacity in South Africa, will build on previous studies carried out
by Japanese and South African seismologists in deep gold mines. Some aspects of the study will also cast light on
the mechanisms that generate tectonic earthquakes.
The project has five major work streams:
1. Determination of rock properties. We intend to map the rock mass and collect rock samples to probe mechanical
properties in both the impending seismic sources and surrounding host rock. Measurements of basic parameters
(elastic constants, fracture strength and elastic wave velocities) will be made in both South Africa and Japan,
while more advanced experiments (temporal changes in the micro-fracturing activity and the physical properties
during fracture process) will be conducted in Japan.
2. Sensitive close monitoring. We seek to investigate the preparation processes preceding earthquakes, and
especially the occurrence of forerunners. However, quasi-static stress changes and high-frequency seismic
waves decay very rapidly with distance. Consequently, arrays of instruments designed to monitor subtle change
associated with preparation of earthquakes must be installed as close as possible to the likely source region.
3. Seismic hazard assessment methods. We will rigorously test seismic hazard assessment methods currently used
in South African mines. We will also apply the stress inversion method that was recently used by Japanese
seismologists to delineate the fine detail of stress distribution
4. Strong ground motion monitoring. The evolution of fault rupture has not yet been monitored in situ at scales
greater than the centimetre dimension of a laboratory rock sample. Consequently, it is not known how rupture
evolves or how strong ground motion is generated in great tectonic earthquakes. In order to improve mine
design strategies and the effectiveness of support elements and systems, we have to clarify the geometrical
attenuation of strong motion and the site amplification factor at the stope.
5. Upgrading of the South African National Seismological Network (SANSN) in the mining districts. Large
earthquakes (M>4.0) occur several times a year in mining districts and sometimes cause damage to surface
structures. However, these important earthquakes are inadequately recorded by either the sparse SANSN or
mine networks that are equipped with short period geophones. This limits an accurate evaluation of the faulting
process of such big earthquakes.
A program of exploratory drilling began in 2010 to delineate the fault zones that the mining face will approach in
2012-2013. Additional holes will be drilled in 2011 to install sensors.
KEYWORDS: seismic hazard, mine seismology, rockbursts, deep gold mines
24

Dating Archean sedimentary processes and rates in the
Moodies Basin, Barberton Supergroup, Barberton Greenstone
belt
J. Engelhardt, C. Heubeck, J. Kirstein, M. Gröschke
Department of Geological Sciences, Freie Universität Berlin, Berlin, Germany, jfengel@web.de>
ABSTRACT
The Moodies Group (ca. 3.23 Ga) is the youngest sedimentary sequence of the Barberton Greenstone Belt (BGB).
Within its approximately 2.5 km–thick sandy and conglomeratic stratigraphic column, abundant sedimentary
structures, e.g., crossbedding, ripple marks and desiccation cracks record alluvial, fluvial, deltaic and shallow
marine environments. Petrography and sedimentary style clearly indicate a synorogenic setting of the Moodies
Basin, and much its sediments may have been deposited within a short time, raising the tantalizing possibility of
preserving a high-resolution time signal of the Archean surface record.
We mapped at 1:2000 scale the Moodies Lava (MdL), a unique 10-60 m thick effusive basaltic flow rock that
forms a distinctive marker unit throughout the BGB in the middle Moodies Group. The MdL overlies large-scale
cross-bedded coarse-grained sandstones interpreted as an offshore subaqueous dune field, and in places also an
enigmatic discontinuous cobble and boulder conglomerate that may reflect a sudden base-level fall. The lava is
strongly altered in most places and consists of a nearly homogeneous mass of illite, sericite, chlorite and very-fine
grained quartz in thin section. Ghost phenocrysts of feldspar, however, are recognizable in well-preserved samples.
In the eastern part of the Saddleback Syncline, the unit can be subdivided in two members representing individual
effusive events, separated by shales and cherts 8 to 15 m thick. Amygdules are common towards the top of the
MdL; the rare presence of pillow lavas attests to a submarine origin. The lower MdL shows magnetite-rich zones
and overlies banded magnetic shale in at least one site. A thin tuff unit overlying the MdL be datable, yield a direct
age of the Moodies Group, and constrain duration of Moodies sedimentation.
Keywords: Barberton Greenstone Belt, Moodies Group, sedimentology, volcanism.
25

Comparing 1960’s Karoo basin seismic data with recent data
(Inkaba yeAfrica Line), to identify and correlate Karoo seismic
stratigraphy on a more regional basis
1 Lynise Esterhuizen, 2 George Smith
1 Department of Geological Sciences, University of Cape Town, Rondebosch 7701, South Africa
lynise04@hotmail.co.za,
2 Department of Geological Sciences, University of Cape Town, Rondebosch 7701, South Africa
george.smith@uct.ac.za
ABSTRACT
The project entails comparing 1960’s Karoo basin seismic data with recent data (Inkaba yeAfrica Line), to identify
and correlate Karoo seismic stratigraphy on a more regional basis.
Due to the recent interest in shale gas exploration in the Karoo basin of South Africa, there is an interest in reinterpreting
old 1960's seismic lines of SOEKOR (now archived by PASA). This project entails comparing these
lines with a recent Inkaba yeAfrica near vertical reflection line across the southern Karoo Basin (Lindeque, 2008),
and tying the reflections to the known litho-stratigraphy, based on outcrop mapping and borehole data. It forms
part of a shale gas project to identify the location and depths of the Whitehill and Prince Albert Formations. The
differences in appearance and quality between the old and new data are outlined.
The old Karoo seismic images are of poor quality, but were enhanced by two-dimensional convolutional filtering.
Thereafter, the sections were re-interpreted using the recent seismic data and existing well-data as a guide.
The Inkaba yeAfrica seismic line shows much deeper penetration, with depths of up to 50km through the crust and
across the Moho. The older data only shows the upper most crustal layers down to approximately 10km.
The comparison of the two sets of data shows the differences in processing and how seismic acquisition quality has
improved since the early 1960's. The data also indicate where the old data can still be of good use after significant
but time-consuming enhancement using modern filtering techniques.
Reference:
Lindeque, A.S, 2008, Deep Crustal profile across the southern Karoo Basin, South Africa, Unpublished Masters Thesis in the
Department of Geological Sciences, University of Cape Town
KEYWORDS: Karoo basin, seismic data, image enhancement
26

Development of a Science and Technology Train
C.J.S. Fourie 1
1 Department of Environmental, Water and Geosciences, Faculty of Science, Tshwane University of
Technology, Pretoria, South Africa, E-mail:fouriecjs@tut.ac.za
ABSTRACT
The proposed Science and Technology (S&T) Train facility will promote research, science advancement,
accumulation of scientific knowledge, service delivery of a geoscientific nature in rural areas and training as its
main objectives. It will attempt to reach South Africans from all walks of life, but special attention will be given to
rural areas and communities.
Similar to a research vessel at sea, this facility will move across South Africa by rail. Although this facility will
concentrate on the geological sciences in its beginning, it will be developed to accommodate other scientific
disciplines, due to the modular nature of the train. As a mobile science and science centre entity, it will promote
science awareness, by hosting science exhibitions on board that will move with the train from town to town. More
children and adults will be reached who would otherwise not have had the means or opportunity to view these
science exhibitions.
Training of students (to PhD level) through Research and Mapping of areas visited by the Science and Technology
Train will contribute directly to education and economic development of the rural areas in South Africa. The
Science and Technology Train will create an avenue for international research consortiums (e.g. Inkaba yeAfrica
and SAMTEX) to make direct contributions towards the training of South Africans, while creating opportunities
for their own students. This will improve the understanding of the resources of South Africa.
Services by the Science and Technology Train will be geared as training and service delivery. Day to day
problems of rural communities and municipalities, such as clean drinking water, sources of suitable local building
materials and the placement of waste sites and cemeteries will also be addressed from this facility.
The train can provide access to a post box of the Department of Home Affairs, making it possible for persons in the
rural areas to do applications for documents (I.D., birth certificates etc.). The contents of the post box will be
delivered to the Department upon the return of the Geo-Science Train to Pretoria, approximately once every 3
months. Funding should be from government and industry. The first step in creating this facility is to move the
old donated rolling stock to the workshop at Koedoespoort in Pretoria.
KEYWORDS: Science and Technology Train, Education, Training, Rural Communities, Service Delivery.
27

Model-enhanced Geothermobarometry of mafic dikes of the Henties Bay
Outjo dike swarm, Etendeka Igneous Province, Namibia
O. Frei 1 , A. Renno 1 R.B. Trumbull 2
1. TU Bergakademie Freiberg, Institute of Mineralogy, Freiberg, Germany, frei@mailserver.tu-freiberg.de
2. GFZ German Research Centre for Geosciences, Potsdam, Germany, bobby@gfz-potsdam.de
ABSTRACT
The Henties Bay – Outjo dike swarm is one of largest Mesozoic dike swarms along the western coast of southern
Africa. It represents magmatic remnants of the Cretaceous opening of the South Atlantic during Gondwana
breakup. At least parts of the dikes are interpreted to have functioned as feeder channels for Etendeka lavas. The
dike swarm is situated in the Damara belt between the Kalahari and Congo Shield and extends about 400 km
inland, more or less perpendicular to the coastline. Although the dikes cover a complete tholeiitic differentiation
trend from picritic, basaltic to andesitic and more felsic composition, the most prominent rock type is a basaltic
dolerite, comprising plagioclase, clinopyroxene, olivine and Fe-Ti oxides. The texture is intergranular to
subophitic. Rudimentary quenching features are visible, such as plagioclase glomerophyres. Chromian spinel
occurs rarely. However, if it is present, then very abundant and often hosted in olivine crystals. In addition to an
oscillatory zoned plagioclase microphenocryst generation, olivine crystals partly resemble a cumulate texture and
therefore appear to be formed before the dike emplacement as well.
Comparing the olivine and whole rock Mg content clearly indicates that most of the olivines are too low in Mg
to have crystallized from melts with the composition of the host rocks. In other words, the rocks are too rich in
magnesium to be in equilibrium with the olivine phenocrysts, which we attribute to olivine accumulation. This has
severe implications for magma classification and for geochemical or geothermometric interpretations since the
whole rock compositions do not equal the melt composition. In particular, the mere Mg-rich character of the
picritic samples does not qualify them as near-primary magmas. This is further supported by the plagioclase
microphenocrysts, proving crustal fractionation.
To better understand the magmatic history of these samples a combination of forward and inverse modeling
was used, with focus on the Mg-rich dikes of mafic. First, model melt compositions have been calculated by
subtraction of olivine until equilibrium between olivine crystals and bulk composition was achieved. Since the
olivine population shows a range of forsterite contents, a set of melt-olivine pairs for each sample was calculated
and using these, a range of olivine-melt equilibrium temperatures were calculated. According to this, the observed
olivines crystallized from magmas with up to 11.5 % MgO at temperatures from about 1000 to 1280 °C. Since
olivine appears to be the liquidus phase in the rocks, the crystallization depth is less than about 30 km, or to 8 kbar
(based on phase relations for dry tholeiitic basalt). Forward modeling using the COMAGMAT program tested
fractional crystallization at different pressure scenarios until the predicted mineralogy fit best the observations.
These models confirm fractionation and crystallization in the upper crust. Despite the petrographic indication of
olivine as the liquidus phase, the Ca-Mg variations of the magmas suggest either non- peridotitic origin or early
fractionation of clinopyroxene, which is, however, not recorded in the rocks. Trace element modeling is planned to
further constrain crystallization processes, especially with respect to possible involvement of clinopyroxene.
KEYWORDS: Namibia, Large Igneous Province, dolerite dykes, geothermobarometry, olivine.
28

Genetic aspects of the PGE-bearing MG Chromitite layers of
the Bushveld complex - are those the world-class PGE ore
bodies of the future?
Gauert, C.D.K
Dept. of Geology, University of the Free State, Bloemfontein, R.S.A., gauertcdk@ufs.ac.za
ABSTRACT
Traditionally UG2 chromitite layer and Merensky Reef (MR) have been mined for platinum, whereas the MG1 as
well as the LG6 layers for chrome. This is due to the higher PGE and base metal sulphide content of the former and
the large chrome concentrations of the latter. Lately mining companies took interest in the so far neglected PGEs in
the LG6 and MG1, mostly as by-products to chrome.
A closer look at whole rock and PGE geochemistry, cumulate textures, and cumulus mineral chemistry at selected
intersections both in the eastern as well as the western Bushveld Complex indicates a lateral homogeneity of the
observed features.
Highest total PGE concentrations of more than 5000 ppb are measured in the MG1, whereas PGE enrichment
above 3000 ppb was also achieved in the MG2, MG3 and MG4. This applies both to the Tweefontein as well as to
the Kroondal sections indicating a relative homogeneous effectivity of enrichment processes in laterally over wide
distances separated layers both of the western and eastern Bushveld Complex.
Variable incompatible trace element ratios indicate mixing of liquids of distinct magma lineage below and above
the MG2, a phenomenon which is observed both at Kroondal and Tweefontein.
Although the MG chromitite layers due to their stratigraphic and absolute vicinity to UG2 and MR and their
regular intersection in exploration programmes, would be an easy target to mine, extraction seems to be not yet
feasible due to the still existing more feasible upper layers, i.e. UG2 and MR. Extraction as by-product to chromite
is aggravated by the abundance of chromite causing difficult flotation, and the complex liberation textures in
interstices, requiring a very fine grain size to grind down to.
Scavenging of PGEs by exsolved sulphide globules from the magma at the elevation of the MG layers and the
LG7/6 was deteriorated by hampered magma mixing due to missing density contrasts between resident and
subsequent magma pulses. Thus PGE concentrations in the above layers are still regarded as sub-economic,
although this status might change with time.
KEYWORDS: Bushveld Complex, MG chromitite layers, magma mixing, cumulus minerals, PGE-bearing
potential.
29

Improvements to Southern African
geomagnetic field and secular variation descriptions
from different modelling techniques
A Geese 1,2 , P Kotzé
3 , M Korte 2
1. TU Braunschweig, Germany, a.geese@tu-bs.de
2. GFZ German Research Centre for Geosciences, Germany, monika@gfz-potsdam.de
3. Hermanus Magnetic Observatory, Republic of South Africa, pkotze@hmo.ac.za
ABSTRACT
Over the Southern African area, the changes of the Earth's magnetic field are striking but cannot be described by
global field models. In the frame of the Inkaba ye Africa project, five subsequent regional magnetic field surveys
were conducted between fall 2005 and fall 2009 over South Africa, Namibia and Botswana in order to monitor
these field variations. At 21 field stations measurements were taken during all five campaigns, more than forty
stations were visited alltogether. The data were used in two different modeling approaches: On the one hand,
accurate epoch-based field models were constructed based on a polynomial spatial fit. Furthermore, a continuous
model covering the timespan from 2005.0 to 2010.0 relying on harmonic splines allows for a detailed description
of the temporal evolution. Both models offer new insights in the field's behaviour on a regional scale. A
comparison of the two regional models to the global field model GRIMM-2 highlights their enhanced accuracy that
is required to understand the underlying driving processes.
KEYWORDS: Regional modelling, magnetic field, secular variation, Southern Africa
30

Growth and dispersal of a southeast African large igneous
province
K. Gohl 1 , G. Uenzelmann-Neben 2 , N. Parsiegla 1,3
1. Alfred Wegener Institute for Polar and Marine Research, Germany, karsten.gohl@awi.de
2. Alfred Wegener Institute for Polar and Marine Research, Germany, uenzel@awi.de
3. now at: RWE Dea AG, Germany, nicole.parsiegla@rwe.com
ABSTRACT
The Mozambique Ridge (MOZR) and the Agulhas Plateau (AP) are prominent bathymetrically elevated rises off
south-eastern Africa connected by a rise of less bathymetric expression. Intuitively, this observation would imply
that the plateaus and rises underwent a related crustal formation. Deep crustal ocean-bottom seismometer data and
a multichannel seismic reflection profile from the southern MOZR show evidence for its predominantly oceanic
crustal origin with excessive volcanic eruption and magmatic accretion phases. The lower two-thirds of the crustal
column exhibit P-wave velocities of more than 7.0 km/s, increasing to 7.5-7.6 km/s at the crustal base. These
velocities suggest that the lower crust was accreted by large volumes of mantle-derived material to form an overthickened
equivalent of an oceanic layer 3. When comparing the velocity-depth model and the observations of the
seismic reflection data with those of the AP, a resemblance can be established which concludes that a greater
Southeast African Large Igneous Province (LIP) must have formed between 140 and 95 Ma in phases of highly
varying magmatic and volcanic activities. The timing, size, and formation history of the Southeast African LIP is
almost analog to that of the Kerguelen-Heard Plateau, which provokes speculation about related processes of
periodic magma generation at that time.
KEYWORDS: Agulhas Plateau, Mozambique Ridge, seismics, geodynamics, magmatism
31

New tools for hydrologic research at Sutherland Observatory,
western Karoo: superconducting gravimetry and satellite
gravimetry
A. Güntner, Ch. Förste
GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, Germany, andreas.güntner@gfzpotsdam.de
ABSTRACT
The existence of water and its distribution are of major importance for the environmental well-being and
economical prosperity of a region. Semi-arid areas such as the western Karoo depend on the availability of
groundwater. Therefore it is of essential interest to gain comprehensive information on the groundwater recharge
and discharge. The goal of this project is to improve the understanding of hydrological processes in the western
Karoo on different spatial and temporal scales by deploying gravity observations and gravimetric/hydrological
modelling. Investigation of the interrelation between hydrology and geodesy is done by the following worksteps:
(1) a 4-D simulation of the influence of water storage changes on the superconducting gravimeter installed at the
Sutherland Observatory SAGOS, (2) measuring and modelling of the water storages at the Sutherland site; namely
groundwater, soil moisture and snow, (3) transformation of the changes in water storage to a gravimetric signal,
and (4) comparison between the measured gravity change by the SG and the estimated hydrological gravity
response.
On a regional scale, the hydrological effects on gravity can be assessed by comparison of GRACE satellite gravity
data with regional-scale hydrological models that integrate information from the small-scale monitoring and
modelling at the Sutherland and other test sites. The results will help for an improved local and regional
quantification of hydrological dynamics and thus establish additional means for the management of the valuable
resource water.
KEYWORDS: Hydrology, superconducting gravimeter, GRACE, groundwater management
32

Tracking geobiological linkages between speciation and landscape
evolution through space and time – Are plants timekeepers of
formative events in the geomorphic history of the Cape Fold Belt?
V Hoffmann 1,2 , F.P.D. Cotterill 2 , G.A. Verboom 3
1. Botany Department, University of Cape Town, South Africa, vera.hoffmann@uct.ac.za
2. Africa Earth Observatory Network (AEON), Department of Geosciences, Department of Molecular and Cell
Biology, University of Cape Town, South Africa, fenton.cotterill@uct.ac.za
3. Botany Department, University of Cape Town, South Africa, tony.verboom@uct.ac.za
ABSTRACT
The southern tip of the African continent (the Cape Floristic Region) hosts a diverse and highly endemic flora,
whose distribution coincides closely with the Cape Fold Belt (CFB) of mountainous terrain. The geomorphological
evolution of the CFB is poorly understood, not least because the region awaits low temperature thermochronology
studies. Moreover, despite several theories that focus on palaeo-climatic forcing, the causes of “hyper-endemism”
of the Cape flora remain enigmatic. Most recently, Cowling et al. (2008) hypothesized that the geomorphological
evolution of the CFB could have driven pulses of speciation since the Mid-Cenozoic, such that the origin of new
landscapes fostered the origin of local endemics restricted to habitat patches which are characterized by particular
lithological/edaphic conditions. Teasing apart these environmental controls will enable us to test the spatial and
temporal aspects of ‘substrate-tracking’ by plants through a timescale of geomorphological evolution. This study
uses a cross-disciplinary synthesis of time-calibrated plant phylogenies, detailed spatial distribution maps of
individual taxa and fine-scale lithology/climate datasets to evaluate geobiological history of selected fynbos clades;
our key question asks whether formative events in the geomorphological evolution of the CFB created new
opportunities for speciation events and/or range expansions for these Cape plant species. The ability to date these
events with a molecular clock on plant phylogenies can not only resolve the turnover of floral habitats, but is
expected to provide novel insights into first appearances of particular geomorphological conditions in the CFB.
KEYWORDS: Cape Floristic Region, Cape Fold Belt, geomorphology, speciation, molecular dating
33

Some aspects of late magmatic replacement phenomena
developed in the layered sequence exposed at Northam
Platinum mine
S. Jack 1 , DL Reid 2 , C. Van Jaarsveld 3
1. University of Cape Town, Department of Geological Science, South Africa, jcksiy001@uct.ac.za
2. University of Cape town, Department of Geological Science, South Africa, David.reid@uct.ac.za
3. Northam Platinum Pty Ltd
ABSTRACT
Iron rich ultramafic pegmatites (IRUP) are due to a post magmatic event that affected the cumulate horizons of the
Rustenburg Layered Suite in the Bushveld Complex. It has been proposed that the IRUP bodies are products of a
complex replacement process perhaps involving a ferrobasaltic melt derived by liquid immiscibility in the Upper
Zone. Transport of ferrobasaltic melt from the Upper Zone to parts of the Upper Critical Zone lead to disruption of
the layered sequence that hosts PGE mineralization in the Merensky Reef and UG2 Chromitite. Large distributions
of IRUP in some mine sequences are suggested to have migrated through weak zones (e.g. faults and fractures), but
also by reaction infiltration through certain lithologies such as plagioclase rich cumulates (norites and
anorthosites).
The present study is being conducted at Northam Platinum Mine, where access to underground exposures and drill
core was made possible by the management. Good exposures of IRUP development occur in the footwall drives of
many levels, where the noritic footwall of the UG1 chromitite has been extensively replaced. The aim of the study
is to characterize IRUP petrographically, mineralogically and geochemically, so we can understand their nature,
distribution controls and origin, as well as their role in mobilization of Platinum Group Elements (PGE). Major and
trace element analysis were obtained using X-ray Fluorescence (XRF) and mineral analysis data obtained from the
Electron Microprobe (EMP).
KEYWORDS: ultramafic; pegmatite; Bushveld.
34

Investigation of the behaviour of platinum group elements
(PGE), in synthetic sulphide systems
Kennedy, B. 1 , Tredoux, M. 2
1. Dept. of Geology, University of the Free State, Bloemfontein, R.S.A., kennedybia@gmail.com
2. Dept. of Geology, University of the Free State, Bloemfontein, R.S.A., mtredoux@ufs.ac.za
ABSTRACT
The research aims to verify whether the binding mechanism of PGE in a magmatic environment is primarily a
chemical or physical/-mechanical process. The existence of small Pt clusters (10-100 atoms) within a monosulphide
phase would inevitably prove that an initial primary mechanical binding process is dominant and this
possibility was investigated.
Several experiments were conducted using variable quantities and ratios of Pt, As, Cu and Fe to mimic the manner
in which Pt binds in a high pressure, high temperature and highly reducing magmatic environment. The
experiments were done using a silica-vacuum technique. The samples were cooled down at different tempos to
ensure that various formation conditions were achieved. This was done to test if the same results (clusters) would
be obtained in every case, for if so a physical model is very probable.
The charges were made into polished sections which were analysed using several analytical methods including oremicroscopy
and SEM. It was found that the Pt forms Pt2As3 clusters within the mono-sulphide (crystalline) phase
of both slowly and faster cooled monsters. The presence of the clusters (10-100 atoms) in the faster cooled
monsters confirms that they must form as a primary phase. This behaviour cannot be explained by sub-solidus
immiscibility properties as has been suggested as an explanation for the frequent presence of PGE minerals in base
metal sulphide minerals.
Preliminary results seem to indicate that Pt as a proxy for the PGE forms clusters of about 10-100 atoms during the
early stages of magma differentiation, probably due to their siderophile behaviour. The clusters can easily be taken
up into an immiscible sulphide fraction or in oxide or silicate phases. This mechanism may explain the high
enrichment of PGE in cumulus (olivine and chromite) phases of the Bushveld Igneous Complex.
KEYWORDS: PGE, experimental petrology, PGE clusters
35

The design of a pressurised clean water supply system for the
Science and Technology Train
K. Khoele 1,2 , CJS Fourie 2 , M. Ranyaoa 1
1. Department of metallurgical Engineering, Faculty of Engineering at Tshwane University of
Technology, South Africa, khotsokhoele@gemail.com, ranyaoams@tut.ac.za
2. Department of Environmental, Water and Earth Sciences, Faculty of Science at Tshwane University
of Technology, South Africa, fouriecjs@tut.ac.za
ABSTRACT
The Science and Technology (S&T) Train will be a self sustaining entity. At any given time at least 50 persons
will be on board. A clean supply of water is essential to the facility. This design project will be the development
of a system that will use a 40 000 litre stainless steel water tanker as a base. The purpose of the project is to
establish the best approach to pressurise the water supply to the coaches of the train (4 Bar) and how to treat the
water supply to be safe for drinking water, using as inline water purification and filtering system.
Different design configurations will be investigated, by employing different pressure pumps and different filters for
purification. This will be done to find the best cost effective and lowest maintenance options. An investigation
will also include the usage of solar power to drive the system.
KEYWORDS: S&T Train, pressure pump, inline water purification, water filter
36

Southern Africa’s Geomagnetic Field Secular Variation
since 2005
P B Kotze(1), M Korte(2), M Mandea(2,3)
(1) Hermanus Magnetic Observatory, Box 32, South Africa, pkotze@hmo.ac.za
(2) GFZ German Research Centre for Geosciences, Potsdam, Germany
(3) IPGP, Paris, France
ABSTRACT
It is well known that secular change is a comparatively local phenomenon and that it does not proceed in a
regular and uniform pattern all over the Earth, giving rise to regions where the field changes more rapidly than
elsewhere, like for instance southern Africa.
As part of a cooperative project between Germany and South Africa, called Inkaba ye Africa, the COMPASS
(COmprehensive Magnetic Processes under the African Southern Sub-continent) program aims to study the
geomagnetic field and in particular its evolutionary behaviour. Secular variation observations over southern
Africa, including countries like South Africa, Namibia, and Botswana, have been conducted since 2005 as part
of this collaboration between the Hermanus Magnetic Observatory (HMO) in South Africa and the German
Research Centre for Geosciences in Germany.
For this purpose a total of 40 repeat stations were identified, separated by distances ranging between 300 and
400 km. These stations form part of a network of 75 repeat stations, established by the HMO during the last 60
years, and visited at regular intervals of 5 years till 2000. Due to the rapid secular variation change over this
area, it was necessary to conduct annual surveys at a reduced number of repeat stations. The stations were also
selected to form two independent sets of 20 beacons each, enabling one to visit these at alternative years
respectively.
During these field surveys 2 teams, consisting of both HMO and GFZ observers, using similar DI Flux
theodolites and fluxgate variometers, obtained geomagnetic field data over southern Africa. These
measurements were processed to remove daily variations etc. and then modelled using various techniques like
polynomial fitting and spherical cap harmonics to derive geomagnetic field models for southern Africa.
Results will be shown and compared with other global field models such as GRIMM and IGRF11.
KEYWORDS: geomagnetic field modelling, secular variation
37

Effect of long-term residue management on organic matter in a
Plinthosol cropped annually with wheat
E. Kotzé 1 , C.C. du Preez 2
1. Department of Soil, Crop and Climate Sciences, University of the Free State, P.O. Box 339, Bloemfontein,
Republic of South Africa, kotzee@ufs.ac.za
2. Department of Soil, Crop and Climate Sciences, University of the Free State, P.O. Box 339, Bloemfontein,
Republic of South Africa, dpreezcc@ufs.ac.za
ABSTRACT
Understanding the role of organic matter in maintaining a healthy soil is essential for developing ecologically
sound agricultural practices. A long-term trial at the ARC-Small Grain Institute near Bethlehem in the Eastern
Free State, South Africa offered the oppurtunity to establish the role of various agricultural practices on some soil
fertility indicators in a Plinthosol, and to establish whether differences in wheat grain yield could be attributed to
changes in the fertility indicators. The trial has been running since 1979 and the treatments that were applied are
two methods of straw disposal (burned and unburned) x three methods of tillage (ploughing, stubble mulch and no
tillage) x two methods of weed control (mechanical and chemical). Soil samples were collected at various depth
intervals every 10 years since the trial has commenced in 1979, and various fertility indicators were then analyzed
and compared. Organic C and total N were used as indices of organic matter. The different tillage practices had a
larger effect on organic matter than either straw burning or weeding method, especially in the upper 100 mm soil.
No tillage and to a lesser extent mulch tillage, especially when combined with chemical weeding were more
beneficial to soil organic matter than when ploughing was combined with mechanical weeding. The combination
of no tillage and chemical weeding is therefore recommended to maintain and even increase the organic matter
content of this Plinthosol when cropped annually with wheat. The response of soil enzymes to organic matter
changes as a result of residue management is being investigated now.
KEYWORDS: organic matter, plant nutrients, straw disposal, tillage practices, weed control methods.
38

Overview and preliminary results of magnetotelluric
experiments across the southern Barberton greenstone belt
S. Kuetter 1,2 , U. Weckmann 1 , X. Chen 1,2 , M. de Wit 3 , N. Ebel 4 , D. Eydam 1 , R. Klose 1 ,
B. Lob 5 , S. McLennan 6 , P. Sass 1 , G. Schmidt 1 , E. Witbooi 4
1. Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Germany,
kuetter@gfz-potsdam.de, xiaoming@gfz-potsdam.de, uweck@gfz-potsdam.de
2. Institute of Earth and Environmental Sciences, University of Potsdam, Germany
3. AEON – Africa Earth Observatory Network, University of Cape Town, South Africa,
Maarten.DeWit@uct.ac.za
4. Technical University of Berlin, Germany
5. Tshwane University of Technology, South Africa
6. University of Cape Town, South Africa
ABSTRACT
The Barberton greenstone belt (BGB) is one of the oldest and well-preserved tectonic remnants from the Archean,
possibly originating from continental collision. The identification of several Archean suture zones has led to a
controversial discussion about the onset of present day plate tectonics. Hence, examining the deep roots of these
suture zones will help to understand the tectonic evolution of the BGB and the role of plate tectonics on Early
Earth.
Within the framework of the German-South African geo-scientific research initiative Inkaba yeAfrica two high
resolution magnetotelluric (MT) field experiments, Barberton 1 and ELIBABA, were carried out in April/May
2009 and in July/August 2010 in the Barberton/Badplaas area (eastern Mpumalanga, South Africa). A 110 km long
profile and several shorter profiles with almost 200 MT sites provide a good areal coverage of the Barberton
sutures and the complex geological structures. We acquired 5-component MT data in a period range from 0.001 s
to 1000 s to resolve the deep roots of the BGB.
Because of nearby mining activities and the DC railway line connecting Johannesburg with Maputo, the natural
electromagnetic field variations are overprinted by these strong cultural electromagnetic signals. Improving the
data quality by applying, e.g., the remote reference technique is therefore a crucial task. For the first experiment we
have to rely on magnetic observatory data from Hermanus and Sutherland (South Africa). MT data at two reference
sites in the Little and Great Karoo were recorded during the second experiment.
We will present data examples from both experiments and preliminary two-dimensional inversion models of the
crustal electrical conductivity distribution. While the comparatively younger formations towards NW and the SE
exhibit extremely high resistivities, we observe intermediate resistivities for formations of the BGB. High electrical
conductivities down to the mid crust seem to correlate with the location of known faults in the area.
KEYWORDS: Magnetotellurics, Barberton Greenstone Belt, Crustal structure, Lithospheric structure, Archean
tectonics
39

Quantification of the soil-plant carbon stock in the Weatherley
catchment eight years after conversion from grassland to
forestry
R.M. Lebenya 1 , C.W. van Huyssteen 2 , C.C. du Preez 3
1. Department of Soil, Crop and Climate Sciences, University of the Free State, P.O. Box 339, Bloemfontein
9300, Republic of South Africa, r.lebenya@yahoo.com.
2. Department of Soil, Crop and Climate Sciences, University of the Free State, P.O. Box 339, Bloemfontein
9300, Republic of South Africa, vhuystc@ufs.ac.za
3. Department of Soil, Crop and Climate Sciences, University of the Free State, P.O. Box 339, Bloemfontein
9300, Republic of South Africa, dpreezcc@ufs.ac.za
ABSTRACT
The Weatherley catchment was dominated by grassland before being converted to commercial forestry in 2002.
Three tree species were planted: Pinus patula, Pinus elliotii, and Eucalyptus nitens. A baseline study was
conducted before planting to quantify the soil organic matter content in the different soils and to characterize the
grassland vegetation and its biomass yield. Twenty five sample sites were selected and two control sites outside the
afforested area. Four replicates were taken at each site. Organic carbon and total nitrogen were determined on all
soil samples. The bulk densities of these soil layers were also quantified for every site. A linear decrease from
0.015-0.020 Mg m -3 to 0.005 Mg m -3 organic carbon was observed from the surface to a depth of 650 mm followed
by a uniform decrease to 0.003 Mg m -3 at 1150 mm. The total organic carbon content to a depth of 1200 mm for
the different soil groups and tree species areas were: 111, 85, 97, and 88 Mg ha -1 for soil groups A, B, C, and H
respectively; and 90, 93, 74, and 75 Mg ha -1 for the P. Patula, P. Elliottii, E. Nitens areas, and control sites
respectively. Carbon sequestration efficiency by the grassland in the catchment was estimated to be 2.1 kg C ha -1
yr -1 mm -1 rain. The present study is conducted eight years after afforestation of the catchment. The first objective is
to quantify whether the soil-plant carbon stock in the Weatherley catchment have changed significantly after eight
years of afforestation. The second objective is to establish whether changes in soil-carbon stock in the Weatherley
catchment are related to either tree species or soil types. It is hypothesised that the soil-plant carbon stock will
increase on account of afforestation of grassland.
KEYWORDS: forestry, grassland, nitrogen, organic carbon, vegetation
40

Can base metal sulphides be used as a proxy for platinumgroup
mineral flotation of UG2 ore?
Lekgetho T.B. 1,2 , Chetty D. 2 , Tredoux M. 1
1. Geology department, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa,
thelmal@mintek.co.za
2. Mineralogy division, Mintek, Private Bag x3015, Randburg, 2125, South Africa.
ABSTRACT
Exhaustion of shallow Merensky Reef (MR) resources led to increased attention towards the Upper Group 2
chromitite (UG2), following the metallurgical advances in its processing by the 1970s. Both MR and UG2 are
recovered by sulphide flotation regardless of their different compositions. In this research project, mineralogy was
used to optimise the platinum group minerals (PGM) beneficiation of UG2 ore by investigating whether flotation
of the base metal sulphides (BMS) can be used as a proxy to predict the flotation behaviour of the PGM as done
conventionally in the industry. The mineralogy and chemical composition of the primary feed, various concentrator
cells and primary tailings of a UG2 concentrator plant were analysed using a mineral liberation analyser (MLA),
X-ray diffraction (XRD), wavelength dispersive-X ray fluorescence (WD-XRF), inductively coupled plasmaoptical
emission spectroscopy (ICP-OES) and LECO combustion.
The PGM (~80% PGE-sulphides), BMS and silicates showed positive response to sulphide flotation. However, the
BMS and PGM indicated negative correlation in grain size distribution as well as significant difference in grain
size range (BMS range from 1µm to >45µm, while the PGM range between 1µm and 15µm). Mineral association
and liberation thus played a major role in the flotation of the PGM, as most of the PGM lost to the tailings in the
samples studied were not fully liberated and were associated with the BMS that are attached to the gangue.
The study has shown that BMS flotation cannot be used as a proxy to predict the PGM flotation, as the PGM
appear not to be wholly dependent on the BMS flotation. Liberating the PGM by finer grinding and floating the
material in particle size classes may optimise recovery of the PGM.
KEYWORDS: Platinum-group minerals (PGM), base metal sulphides (BMS), UG2 flotation, mineral liberation
analyser (MLA).
41

Investigation of the crust in the Southern Karoo using the seismic
reflection technique
L. Loots 1,2 , R.J. Durrheim 2,3 , T. Ryberg 4
1. Council for Geoscience, South Africa, lloots@geoscience.org.za
2. University of Witwatersrand, South Africa
3. CSIR, South Africa, rdurrhei@csir.co.za
4. GeoForschungsZentrum Potsdam, Germany, trond@gfz-potsdam.de
ABSTRACT
A deep seismic reflection survey was conducted in September 1992 as part of the National Geophysics
Programme. The data were re-processed at GFZ using ProMax TM . The 100.5 km profile (running from Beaufort
West in the north to Klaarstroom in the south along the N12 national road) presents a high quality seismic image of
the crust down to the Moho. The profile traverses the southern Karoo Basin and the northern part of the Cape Fold
Belt (CFB). The upper crust is characterized by strong reflectors that dip gently to the south up to where the CFB
starts. The reflections are produced by the bedded strata of the Karoo and Cape Supergroups. The Karoo and Cape
Supergroups are separated by an unconformity, which has a very strong seismic signal. The upper and the lower
crust are also separated by an unconformity which can be traced from the north of the profile to where the Cape
Fold Belt starts. The lower crust is not very reflective, but is likely part of the Bushmanland sub-province of the
Namaqua-Natal Mobile Belt. It is also here that the most probably source for the Beattie magnetic anomaly (BMA)
is hosted. A ~10 km wide, highly reflective zone coinciding with the location of the BMA occurs at a depth of 7 –
15 km. The seismic fabric of the lower crust exhibits both northerly and southerly dips. A strong continuous
seismic signal can be seen at 20 – 25 km from the north of the profile at a depth of ~ 37 km. This is interpreted to
be the boundary between the crust and the mantle. All this preliminary results are in accord with other published
results.
KEYWORDS: Seismic reflection, crust, Beattie magnetic anomaly, Moho.
.
42

Integrated Interpretation of the Deep Crustal Geophysical
Profile Across the Southern Karoo Basin and Beattie Magnetic
Anomaly, South Africa
A. Lindeque 1,2 , M.J. de Wit 2 , T. Ryberg 3
1. Currently at the Alfred Wegener Institute for Polar and Marine Research, Am Alten Hafen 26, 27568
Bremerhaven, Germany ansa.lindeque@awi.de
2. AEON - Africa Earth Observatory Network and Department of Geological Sciences, University of
Cape Town, Rondebosch 7701, South Africa
3. GeoForschungsZentrum Potsdam, Germany, trond@gfz-potsdam.de
ABSTRACT
Between 2004 and 2007, several geophysical experiments were conducted along transects on the southern margin
of Africa as part of the Inkaba yeAfrica initiative. One of these, the Agulhas-Karoo (AK) transect, crosses
prominent tectonic features such as the Paleozoic-Mesozoic Karoo Basin, Paleozoic Cape Fold Belt Front and
Beattie Magnetic Anomaly. The acquired geophysical data provide the opportunity to adjust the last published
crustal model of 1993, based on sparse gravity and magnetic data, with a one derived from the joint interpretation
of archive data (surface geology, aeromagnetic data, nearby deep boreholes, teleseismic receiver functions,
regional seismic reflection profiles), and the acquired high-resolution geophysical data (impedance spectroscopy
measurements on borehole samples, near vertical reflection data (NVR), shallow P- and S-wave velocity data, wide
angle refraction data and magnetotelluric data), at the centre 100 km of the western AK-transect. The integrated
model differentiates four components in the ~42 to 45 km thick crust: (1) the ~2 to 5 km thick folded Karoo
Supergroup with low-angle thrust faults rooted in a zone of local, resting paraconformably on (2), the ~2.5 to 12
km thick non-folded sandstone/shale Cape Supergroup (CSG) - represented by a distinctive band of horizontal
reflectors ending in a flat base, or seismic unconformity, separating it from (3), the ~13 to 21 km underlying midcrust
with a distinct north dipping seismic fabric, interpreted as ~1.2 Ga Mesoproterozoic Namaqua-Natal
Metamorphic Belt (NNMB). The NNMB continues below the CFB tectonic front, possibly to the continental
margin and contains the two-part BMA. The BMA is constrained to a ~10 to 12 km wide northern zone, and a ~5
to 7 km wide southern zone, both at ~7 to 8 km below surface, continuing for a depth of ~5 km. The BMA source
is interpreted to be a Namaqua-like massive to disseminated, deformed/metamorphosed strataform sulfide ore
body. A mid-crustal detachment interpreted as a thrust or shear plane, separates the mid-crust from component (4),
the highly reflective ~10 to 24 km thick lower crust, interpreted as older Palaeo-Proterozoic NNMB basement, and,
a ~2 to 5 km thick highly reflective layer, sub-parallel to a clear Moho, interpreted as mafic underplating. The
model presents evidence in support of a thin-skinned tectonic thrust model for the evolution of the flat-based CFB
and shows no significant fore-deep stratigraphic thickening in the Karoo Basin towards the CFB front. The tectonic
model suggests a Meso-Proterozoic collision orogen setting, overprinted by a mid-Phanerozoic thin-skinned fold
and thrust belt coupled to the far-field accretion/subduction margin to the south.
KEYWORDS: Seismic Reflection, crust, Beattie Magnetic Anomaly, Karoo Basin, Cape Fold Belt, South Africa,
Namaqua Natal Metamorphic Belt
43

Influence of long-term wheat residue management on soil
fertility indicators of an Avalon soil at Bethlehem
P.F. Loke 1 , E. Kotzé 2 , C.C. du Preez 3
1. Department of Soil, Crop and Climate Sciences, University of the Free State, P.O. Box 339, Bloemfontein,
Republic of South Africa, lokepf@yahoo.com
2. Department of Soil, Crop and Climate Sciences, University of the Free State, P.O. Box 339, Bloemfontein,
Republic of South Africa, kotzee@ufs.ac.za
3. Department of Soil, Crop and Climate Sciences, University of the Free State, P.O. Box 339, Bloemfontein,
Republic of South Africa, dpreezcc@ufs.ac.za
ABSTRACT
Awareness of the environmental aspects of soil quality and crop production has been increasing in recent years,
which has led to renewed interest in crop residues as a source of soil organic matter (SOM) and nutrients. Some
residue management practices have been examined since 1979 in a long-term wheat trial at the ARC-Small Grain
Institute near Bethlehem on an Avalon soil. This trial provides thus an excellent opportunity to evaluate the longterm
effects of residue management on some soil fertility indicators and hence wheat response. The treatments that
were applied are: straw disposal (burned and unburned), tillage (ploughing, stubble mulch and no-tillage) and weed
control (chemical and mechanical). Soil samples were collected every 10 years at depth intervals of 0-50, 50-100,
100-150, 150-250, 250-350 and 350-450 mm, and analysed for various soil fertility indicators. In 1999 tillage
influenced SOM more than straw burning or weeding method, particularly in the upper 100 mm soil. No- and
mulch tillage, especially when combined with chemical weeding increased SOM more than when ploughing was
combined with mechanical weeding. Soil acidification was suppressed by burning and a combination of mulch or
no-tillage with chemical weeding. P, K, Cu, Fe, Mn and Zn were higher in the burned plots than in unburned. This
was also true for no- and mulch tillage in the upper 150 mm soil compared to ploughing. Grain yield did not
correspond with the higher organic matter and pH resulting from mulch and no-tillage. This could be attributed to
low availability of nutrients in the upper 150 mm soil. The 30 year measurements confirm to a large extent the
results of 1999.
KEYWORDS: nutrients, organic matter, soil acidity, straw disposal, tillage
44

Facies architecture and reservoir quality of Fan B, Permian
Laingsburg Formation, southwestern Karoo Basin, South
Africa
D. Lombard 1 , D. Mikeš 2 , P. Carey 3
1. Department of Geology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa,
15956717@sun.ac.za
2. Department of Geology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, South
Africa, mikes@sun.ac.za
3. University of Western Cape, Private Bag X17, Bellville 7535, South Africa, pcarey@uwc.ac.za
ABSTRACT
In recent years hydrocarbon exploration companies have shifted their attention to slope areas and associated
depositional environments. Slope fans develop at the base-of-slope and downlap onto the basin floor. Slope fans
are characterized by channel-levee complexes and are predicted to be dominated by mud-rich systems. The proven
and prolific Gulf of Mexico, offshore Angola, Nile and Niger delta slope reservoirs stands testament to the great
potential contained within slope hydrocarbon reservoirs.
Presently while the Karoo Basin is strongly compacted, it can nevertheless be used as an outcrop reservoir analog.
Facies outcrop characterization studies provides a means to obtain vertical and lateral attributes of strata and their
bounding surfaces, help reduce uncertainty in lithology prediction, and bridge the gap between wireline logs and
seismic scales of resolution.
The main aim of this study is to provide a clear understanding and description on reservoir heterogeneity in terms
of facies, porosity and permeability variations, within Fan B (base-of-slope) of the Laingsburg Formation based on
petrographic data. The objectives of the study are to 1) determine lateral continuity and vertical connectivity of
sedimentary units, 2) mitigate the effect of baffles and barriers to oppose flow capabilities, 3) describe textural and
compositional characteristics 4) establish the distribution of diagenetic alterations and their impact on reservoir
quality.
A sedimentological and stratigraphical study will be undertaken, which will include the description of facies and
depositional elements within the upper, middle and lower parts of Fan B. Descriptions will include lithotype,
sedimentary structures, bouma divisions, bounding surfaces and connectivity, thicknesses, net-to-gross ratios, grain
size, geometry, process of deposition and interpretation, identification of baffles and barriers to oppose flow,
construction of sedimentary logs, and hand sampling from surface outcrops. The various samples taken at the
different locations will be subjected to XRD, thin-sectioning, and SEM analyses. The XRD will be used to
quantitatively identify minerals in rock samples. XRD provides reliable mineralogical abundance data and allows
for accurate calculations to be made from mineralogical constituents that make up the rock. Thin sections will be
used to determine mineralogical and textural features, including porosity and connectivity of pore spaces.
Descriptions will include the degree of sorting, mean grain size of samples, grain shape, mineral constituents,
mineral alterations, dominant cements, and compaction effects. SEM will be used to provide valuable insight on
the structure of major diagenetic products effecting pore spaces and pore throats at pore/ grain scale.
The expected outcomes/- deliverables of the study include 1) sedimentological and stratigraphical model 2)
reservoir characteristic and comparison of lower, middle and upper fan facies, 3) development of 2D or 3D model
from outcrop profiles, 4) unravelling the main controls on mud-rich fans and 5) reservoir implications of outcrop
and petrographical characteristics, and possible application to other similar depositional settings.
KEYWORDS: Karoo Basin, slope turbidite channels, reservoir quality, diagenesis
45

Structural and geophysical transect across an archean suture
zone, Barberton Greenstone Belt
Scott MacLennan 1 , Ute Weckmann 2 , Oliver Ritter 3 Maarten De Wit 4
1. AEON, UCT, GFZ, South Africa, scottangusmac@gmail.com
2. GFZ, Germany, uweck@gfz-potsdam.de
3. GFZ, Germany, Oliver.Ritter@gfz-potsdam.de
4. AEON, UCT, South Africa, Maarten.dewit@uct.ac.za
ABSTRACT
In 2009 a magnetotelluric field campaign was carried out in the southern part of Barberton Greenstone Belt. The
profile was positioned at right angles to the NE-SW structural grain of the Greenstone Belt. While initial results
showed that there are vertical zones of high conductivity that correspond to major Archean shear zones, the data
quality was poor. A second field campaign August 2010 was conducted to collect more robust data.
Previously the southern extent of the Moodies- Inyoka fault system was investigated using structural techniques,
with a particular focus on the Stolzberg layered ultra mafic complex, which lies directly adjacent to the Moodies
fault. This serpentinised ultramafic complex has a complicated history and the less resistant serpentinite units have
many different generations of deformation. The serpentinites are now composed of many separate blocks, which
are separated by fault surfaces. These surfaces show a multitude of slickenfibres of different orientations. A series
of abandoned Asbestos mines within these serpentinites serves as an ideal location to study this deformation in
detail, owing to the excellent exposure. This analysis revealed that the deformation in this ultramafic unit was not
uniform, where the south western extent of the complex showed more strike slip motion, while in the north east
low to high angle reverse faults dominate. This change happens on the km scale. The data are not well constrained
though, showing low precision. This is attributed to the ease in which these serpentinites are deformed, creating
complex structural patterns.
Samples of major lithologies and rocks associated with shear zones from within the greenstone belt were collected
to test their electrical conductivity. This data will be used to constrain some of the modeling results from the
magnetotelluric survey and attempt to determine which material is responsible for the high conductivities observed
within these Archean suture zones.
KEYWORDS: archean, tectonics, magnetotellurics, serpentinites
46

Mineralogical and geochemical investigations of the nickel Bon
Accord deposit, Barberton, South Africa
Fulufhelo Madala1, Marian Tredoux2
1. University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa, fulufhelomadala@yahoo.com
2. University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa, mtredoux.sci@ufs.ac.za
ABSTRACT
The Barberton greenstone belt in the Mpumalanga, South Africa, covers an area of some 6 000 km to the south-east
of the town of Nelspruit. The Bon Accord Ni-oxide deposit is located in the central-east of the belt. It is extremely
Ni-rich and contains high levels of the PGEs and Sb. The host rock of BA consists of ultramafic rocks of the 3.2 Ga
Onverwacht Group belonging to the Jamestown ophiolite complex. The BA deposit has a unique mineralogy of rare
Ni-rich minerals, such as liebenbergite (olivine), trevorite (spinel), willemsite (talc), nimite (chlorite), and
bonaccordite (borate).
This study obtained mineralogical and geochemical data on eight samples supposedly taken of the Bon Accord body
and surrounding rocks. Four samples were positively identified as Bon Accord material and one probably represents
the host rock. Two samples were identified as belonging to the overlying Moodies Group and one sample represents
a hematitic rock and probably comes from an Fe-rich body close to Bon Accord.
KEYWORDS: Bon Accord
47

Hydrogeological Conceptual model development in
the vicinity of the Superconducting Gravimeter,
Sutherland, South Africa
Gaathier Mahed* 1,2 , Andreas Güntner 3 ,Theresa Blume 3 Maarten de Wit 1 and
Mouctar Doucoure 1
1) African Earth Observatory Network (AEON), University of Cape Town, South Africa,
Gaathier@gmail.com
2) Department of Geological Sciences, University of Cape Town, South Africa,
Gaathier@gmail.com
3) GFZ German Research Centre for Geosciences, Potsdam, Germany, Section 5.4
ABSTRACT
Stable isotope data stemming from streamflow, rain as well as groundwater was used in order to better
understand the hydrogeology of the vicinity of the Superconducting Gravimeter in Sutherland, South
Africa.. This was done in conjunction with the macro chemistry of the previously mentioned waters in
order to better understand the hydrogeochemistry of the area. The aforementioned information is
complimented with the interpretation of drilling logs and field geological data. Lastly the addition of
soil moisture information and interpretation of tracer experiments performed in the near-surface vadose
zone aids in completing the conceptual model and gives greater insight into recharge and groundwater
behaviour in the area.
KEYWORDS:
48

Seismicity and Seismic Hazard Assessment of the arid western
regions of South Africa: a Neotectonic Perspective
H R Malephane 1 , R J Durrheim 1, 2 1, 3
, M A G Andreoli
1. University of Witwatersrand, South Africa, hlompho.malephane@students.wits.ac.za
2. Council for Scientific and Industrial Research, South Africa, rdurrhei@csir.co.za
3. South African Nuclear Energy Corporation, South Africa, marco@necsa.co.za
ABSTRACT
There are two nuclear reactors in South Africa, a research reactor at Pelindaba near Pretoria and a powergenerating
reactor at Koeberg near Cape Town. High level radioactive waste (HLW) in the form of spent fuel is
currently stored in the designated spent-fuel pools on the Koeberg site. The shorter lived, low- and intermediatelevel
waste (half-life ≤31 years) is sent to the Vaalputs National Radioactive Waste Disposal Facility in the
Northern Cape Province, currently managed by the South African Nuclear Energy Corporation (Necsa). In
addition, the South African government is currently formulating plans to construct additional nuclear power
stations to meet future demands for energy. According to the Radioactive Waste Management Policy and Strategy
for the Republic of South Africa it is prudent to begin gathering the data needed to assess future HLW disposal
sites, and explore other options like the reprocessing of spent nuclear fuel.
Site selection criteria for a nuclear waste disposal site include proximity to settlements, agricultural potential of
land, geological stability and seismic activity. This study will make a detailed investigation of the seismic activity
in the arid western region of South Africa, as this region is likely to prove suitable, in principle, for the disposal of
radioactive waste. It is planned to expand and link the existing seismic network at Vaalputs to the National
Seismograph Network stations which should improve the sensitivity and location accuracy of the Bushmanland
region.
The current Necsa seismic database shows that the Vaalputs site is seismically stable, yet there has been sporadic
seismic activity in Namaqualand with swarms in 1996, 2001, and again (near Augrabies) in 2010. The network will
be used to assess the reliability of the reported magnitudes, to define active faults and seismotectonic zones, and to
derive seismic source mechanisms. This will yield more accurate seismic hazard assessments.
KEYWORDS: nuclear waste disposal, South Africa, seismicity, neotectonics, seismic hazard assessment
49

The role of footwall reconstitution in the genesis of Merensky
reef types at Northam Platinum Mine
Moses Takalani Mandiwana 1 , D. Reid 2 , C. Van Jaarsveld 3
1. Department of Geological Sciences, University of Cape Town, South Africa, mndmos001@uct.ac.za
2. Department of Geological Sciences, University of Cape Town, South Africa, david.reid@uct.ac.za
3. Northam Platinum Pty Ltd, South Africa, charl.vanjaarsveld@norplats.co.za
ABSTRACT
In spite of their variations in absolute grain size and modal mineralogy, the pegmatitic harzburgites, pyroxenites
and melanorites in the P2 and Normal Merensky reef types at Northam Platinum mine share many similarities. The
stratigraphic horizon equivalent to the P2 reef type is preserved along strike at the Normal reef elevation, where the
original P2 cyclic unit is preserved. Interaction between the P2 cyclic unit norites and the Merensky magma
resulted in replacement by the pegmatitic lithologies listed above and represents an example of footwall
reconstitution. A similar process acting to reconstitute the 4X cyclic unit to produce the Normal reef type is
therefore worthy of consideration.
This project focuses on investigating the P2 cyclic unit at both reef elevations to identify the mineral-magma
interactions that produced the mineralised pegmatitic horizons that form the footwall to the Merensky chromitite
(4A unit). Results will be utilized to gain an insight to the possible origins of the similar lithologies that now
occupy the 4X cyclic unit.
Our approach has been to examine the Normal and P2 reef exposures underground and collect samples for detailed
mineralogical and geochemical analysis. Core obtained from exploration and cover drilling has also been selected
to augment the collection with the unreplaced P2 cyclic unit. Laboratory methods include Optical Microscopy,
XRF and EPMA for comparison of textures, whole rock geochemistry and mineralogy.
KEYWORDS: Normal Merensky Reef; P2 Merensky Reef; P2 Cyclic Unit; 4X Cyclic Unit; Pegmatitic;
Reconstituted Footwall; Merensky (4A) chromitite; 4X chromitite
50

Carbonate alteration of dolerite intruding coal seams: Natural
carbon sequestration during fossil fuel combustion?
Reginald T Mathivha 1 , J. Vogeli 2,3 , D. Reid 4
1. Department of Geological Sciences, University of Cape Town, South Africa, mthreg003@uct.ac.za
2. Centre for Minerals Research, Department of Chemical Engineering, University of Cape Town,
vgljac001@uct.ac.za
3. Department of Geological Sciences, University of Cape Town, South Africa, vgljac001@uct.ac.za
4. Department of Geological Sciences, University of Cape Town, South Africa, david.reid@uct.ac.za
ABSTRACT
Recent investigations of Karoo dolerite intrusions into coal seams have revealed the operation of what seems to be
a natural carbon sequestration process perhaps significant in our understanding of industrial methods designed to
curb the buildup of greenhouse gases in the atmosphere.
Significant carbonation of the dolerite intrusions in the vicinity of coal points to redox reactions driven by
magmatic temperatures, abundant fluids and geological time scales. A principal aim of the current study is
determine whether the carbonates are derived from reactions involving olivine, pyroxenes and feldspars that
constitute the original magmatic assemblage. An insight to these reactions could aid in devising possible industrial
processes that could be applied.
Acid leaching and gasimetry analysis have been done in order to determine the amount of CO2 in the samples.
Optical microscopy, QEMSCAN, XRD and EMP techniques has been used to determine the textural relations,
carbonate - silicate interactions, mineral structure and compositional patterns.
While it is clear that Karoo dolerite has the potential to absorb significant carbon dioxide (25-35%) given the right
circumstances and environment, alternative but mineralogically similar reservoir materials are abundantly available
in the form of mine tailings.
KEYWORDS: Dolerite Dyke, carbon sequestration
51

.
.
The design of a Stirling engine system for the Science and
Technology Train
T. Matsepe 1,2 , CJS Fourie 2 , L. Beneke 1
1. Department of metallurgical Engineering, Faculty of Engineering at Tshwane University of
Technology, South Africa, tebohomatsepe@yahoo.com, benekelw@tut.ac.za
2. Department of Environmental, Water and Earth Sciences, Faculty of Science at Tshwane University
of Technology, South Africa, fouriecjs@tut.ac.za
ABSTRACT
The Science and Technology (S&T) Train will need a constant electrical power supply. Although it is possible to
use a diesel generator system to maintain a constant electricity supply, it will result in an unnecessary use of diesel
and pollution. Alternative ways of electricity generation was investigated and it was decided that the best
alternative solution will be a Stirling motor that uses solar energy. The diesel generator system will only be used as
a backup system.
A design model of an Alpha V-type Stirling Engine has to be done and built, to supply approximately an amount of
100kw of electrical power, for household purposes on the Science and Technology Train. It is a double acting,
twelve cylinder engine with the hot cylinders and pistons at ninety degrees out of phase with cold and hot sides (six
cylinders each side). According to the Stirling thermodynamic cycle studies, an efficiency of more that 30% can be
achieved (in our design 33%), therefore an amount of 300kw plus is predicted to be captured from a source of heat.
The source of heat for this system is a solar parabolic dish collector, with the receiver that has been designed
purposely for better capacity and large amount of heat capturing. The collector is a super corrosive resistant
stainless steel tank filled with salt, with a heat exchanger and a synthetic oil fluid inside. The concentrated radiation
will then be transmitted to the oil in the receiver and some be kept as a thermal energy storage, from which it can
be drawn for use at night and, or cloudy days. The thermal energy storage will be achieved by pumping the heated
fluid to an insulated storage tank.
The receiver will be absorbing the incoming solar radiation, converting it into heat, and transferring this heat to a
fluid (synthetic oil) flowing through to the reservoir and finally to the engine. Cold Water will be used to cool the
cold side of the cylinders, thus absorbing some of the heat energy from the working fluid. The energy shall be
disposed to heat water in the geysers, by running it through a heat exchanger.
KEYWORDS: S&T Train, Stirling Engine, parabolic dish, salt heat exchanger,
52

Characterization and quantification of preferential flow in
fractured rock systems, using resistivity tomography
F May 1 , D Mikeš 2 , A Rozanov 3 , R Bugan 4 , N Jovanovic 5
1. University of Stellenbosch, South Africa, fabianmay@gmail.com
2. University of Stellenbosch, South Africa, mikes@sun.ac.za
3. University of Stellenbosch, South Africa, dar@sun.ac.za
4. Council for Scientific and Industrial Research (CSIR), South Africa, rbugan@csir.co.za
5. Council for Scientific and Industrial Research (CSIR), South Africa, njovanovic
ABSTRACT
This study is part of a broader scope project focussed on the development of improved process-based estimates of
groundwater recharge. The proposed study will be conducted in the Kogelberg Biosphere Reserve, which is
located east of Cape Town in the Palmiet river basin, just north of Bettys Bay (South Africa). This catchment area
is typified by groundwater recharge mechanisms in a fractured rock environment. Various studies are being
conducted as part of this broader scope study, with the end result being an improved process-based recharge model
for the Kogelberg Biosphere Reserve, but more generally for the Table Mountain Aquifer type in the region.
The focus of the study is to develop an improved methodology on quantifying preferential flow in fractured rock
environments. It is envisaged to better understand and quantify the role of preferential flow in recharge estimations
using a geophysical method, i.e. resistivity tomography. Resistivity tomography is a non-invasive geophysical
method which determines the subsurface resistivity distribution by making measurements on the surface. The
method is relatively inexpensive and the ground resistivity can be related to various geological parameters. These
geological parameters can be used to identify the subsurface geology as well as the fluid content, porosity and
degree of water saturation in the rock.
The aim of the investigation is to take snap shots of the subsurface by using resistivity tomography to identify
preferential pathways. Resistivity changes in the subsurface are influenced by the movement of the wetting front
during and after rainfall. Therefore, resistivity measurements will be taken at 2 hour intervals to produce profiles
of the subsurface before, during and after rainfall events.
The anticipate end result would be to differentiate/indentify fast flowing (by-pass through fractures) and slow
flowing (water in matrix) conduits.
KEYWORDS: Resistivity, Preferential Flow, Fractured systems, Recharge,
53

Topographic imprint of Geomorphology in southern Africa
Ch. Mielke 1 , M. J. de Wit 2
1. AEON, Department of Geological Sciences (UCT), South Africa, chmielkepju967@yahoo.de
2. AEON, Department of Geological Sciences (UCT), South Africa, maarten.dewit@uct.ac.za
ABSTRACT
The geomorphology of southern Africa has been a subject of debate for over a hundred years (Penck 1905, du Toit
1933, King 1945 and 1967, Partridge and Maud 2000 and Burke 2009). Most of these studies attempt to
differentiate landscape elements based on assumed contiguous weathering surfaces (e.g. King, 1967) or delineation
of geomorphological provinces according to river base-levels (e.g. Partridge et al. 2010).To date there is still no
agreement about the origin or values of these features (Decker 2010).
Global digital elevation models have become valuable for quantitative geomorphology, and it is now possible to
use these models to test links between geological processes, geomorphology and their impact on the topography
across the African Plate. The SRTM-V4 data set produced by CIGAR (Jarvis et al. 2009), from the Shuttle Radar
Topographic Mission, presents a new tool for the geomorphometric characterisation of the African landscapes.
Statistical analysis of geomorphometric parameters such as the hypsometric integral, slope and the terrain
ruggedness index in combination with geological data will provide a more robust base for a reappraisal of the
landscape of southern Africa.
KEYWORDS: Digital Elevation Models, Geomorphology, African Plate
54

Karoo sequence stratigraphy and facies modelling for
improved reservoir characterisation and upscaling
Mikes, Daniel 1
1 Department of Earth Sciences, Stellenbosch University, South Africa, mikes@sun.ac.za
ABSTRACT
The overall aim of this project is to better understand the internal architecture of deltaic systems and the main research
question concentrates on the response of the deltaic depositional system to internal and external forcing. Sedimentary
systems are traditionally described using well-established techniques on three discrete scales: (1) Bedding analysis; (2)
Facies analysis ; (3) Basin analysis. But to date there is no adequate method for describing 4D behaviour of a
sedimentary system. It seems that the third spatial dimension might be a critical factor in addressing the issue. Our pilot
studies of physical experiments show that 1D/2D sections from an artificial delta system show great variability and
ambiguous interpretation, but they give us insight into proper interpretation of the rock record in the field.
The focus in the fieldwork has been on the Pienaarsfontein se Berge, presumably exhibiting a sequence of 13
depositional cycles deposited by shelf-edge and shelf-margin deltas. These depositional cycles consist of a variety of
facies resulting from tidal, wave, current, storm and gravity processes. The existing facies models seem to be
inappropriate, simply because they assume the passive margin terminology of a continental shelf – continental slope –
oceanic basin. The Tanqua Depocenter is an intracratonic basin and seems to form a transition from shelf – shelf-margin
–slope – continental basin.
By (re)constructing an adequate facies model for this depositional system we intend to demonstrate three things: (1)
existing facies models are inadequate and (2) adequate facies models are unique. By doing so we will also demonstrate
that proper analysis of a sedimentary system is still the crucial and most powerful tool of a sedimentologist. The pilot
study shows that this approach is promising.
We will use the results from this study to improve on the building of a geological model, fundamental element in a
reservoir modelling study, in its turn crucial to the production estimate. We will implement our findings into an
upscaling procedure that we propose and will test against existing upscaling procedures on a producing reservoir.
Numerous students involved in Inkaba will continue to work on different aspects of this work, largely falling into three
categories: (1) conceptual facies models for sedimentary systems, (2) geometrical geological models, (3) reservoir
characterization for use in upscaling and flow simulation.
KEYWORDS: sedimentary systems, geometrical geological models, upscaling, reservoir characterisation
55

The Mineralogy and PGE Geochemistry of the Middle Group
Chromitite Seams of the Western Bushveld Complex at
Kroondal Mine
Milanzi, K.S.R. 1 , Gauert, C.D.K., Mphatse C.T.
University of the Free State, P.O. Box, 9300, South Africa
kenzolanzi@gmail.com, Gauertcdk.sci@ufs.ac.za, thibos4geology@yahoo.com
ABSTRACT
This investigation serves to establish textural and geochemical relationships between chromitites and PGEs in the
Middle Group chromitite layers MG1 to MG4 in selected drillholes of Xstrata’s Kroondal Chrome Mine. The
project forms part of Inkaba phase 2 sub-programme “Platinum value chain”. Total PGE concentrations in the
chromitite layers UG6 to MG4 range from 1400 to 3500 ppb, as determined by fire assay/ICP-MS finish, with
highest concentrations of more than 5000 ppb being measured in the MG1 at Kroondal. This applies both to the
Tweefontein as well as to the Kroondal section indicating a relative homogeneous effectivity of enrichment
processes in laterally over wide distances separated layers both of the western and eastern Bushveld Complex.
Rock textures show a permanent change from intercumulus to cumulus plagioclase textures between the MG2 and
MG3 forming meso- to adcumulates, however cumulus plagioclase at Tweefontein already occurs at the elevation
of MG1 (to be checked and adapted). The modal mineral proportions show a change from pyroxene to plagioclasedominance
already at a stratigraphic elevation shortly above the MG2.
Decreasing Mg# and increasing V/Cr ratio upwards in the cumulate sequence indicates nearly almost ‘closed
system’-conditions, whereas incompatible trace element contents upwards increases steadily.
Chondrite-normalised (Anders and Grevesse, 1988) PGE patterns range from 1 to 10 and show a continuous
increase from Au to Rh, compared to MR and UG2.
Results indicate that PGE enrichment in between periods of sole appearance of plagioclase on the liquidus strongly
coincides with intervals of chromite precipitation and only to a lesser degree of limited sulphide exsolutions.
Tredoux et al’s (1995) PGE-cluster model in an S-poor environment appears a viable explanation for the PGE
mineralization in the MG chromitite layers.
KEYWORDS: Middle Group Chromitite, Platinum Group Elements, Kroondal, Western Bushveld
Complex
56

Palaeoclimate and ecosystems of the Pleistocene in South
Africa as archived in the Kalkop Crater Lake deposits
P Mthembi 1 , D Roberts 1 , C Harris 2 , M De Wit 2 , R Smith 3
1. Council for Geoscience, South Africa, pmthembi@gescience.org.za, droberts@geoscience.org.za
2. University of Cape Town, South Africa, Chris.Harris@uct.ac.za, Maarten.DeWit@uct.ac.za
3. Iziko South African Museum, South Africa, rsmith@iziko.org.za
ABSTRACT
Both cosmic impact and endogenic Crater Lake deposits of various ages occur in South Africa. Impact cratering is one
of the fundamental surface forming and modifying processes on all solid bodies on the solar system. In South Africa,
impact craters include the Palaeoproterozoic Vredefort Structure in the Witwatersrand basin, Early Cretaceous
Morokweng crater in North West Province, Middle Pleistocene Tswaing crater north northwest of Pretoria and Kalkkop
crater in the South-Eastern Cape dated by U-series to ~250 ka (Middle Pleistocene).
The main focus for this project is the Kalkkop impact crater situated south of Graaff Reinet town and formed in Permo-
Triassic lower Beaufort strata of the Karoo Supergroup. The crater is 0.64 km in diameter, smaller than Tswaing crater
at 1.13km. Drill cores show that the Kalkkop Crater Lake deposits mainly comprise finely laminated carbonate with
thin debris flows, underlain by a breccia succession formed during the impact. The latest core was drilled in mid-1992
and this 89 m long core will be studied in detail.
Ancient crater lakes deposits, like those formed in the Kalkkop crater, whether formed by impacts or endogenic
processes provide rare long and high resolution records of fluctuating palaeo-environments and are used as a tool to
investigate the link between terrestrial/atmospheric palaeodata and marine record to supplement, refine regional and
broader models of palaeoclimate and ecosystem evolution. Therefore the aims of the study is to extract palaeodata,
with emphasis on critical time intervals, like past warm periods as an analogue for present and future regional/global
climate change to inform policy-making in terms of prevention, mitigation and adaptation and develop the site to
enhance its value in terms of ecotourism and education. These will be done by geological mapping of the area,
combined with sedimentological, palaeontological and stable isotope studies of existing drilled bore holes.
KEYWORDS: South Africa, impact cratering, Kalkkop crater, paleodata, stable isotopes
57

A proposal for the determination of intercontinental plate velocities in
Africa to support the establishment of the African Geodetic Reference
Frame (AFREF)
C. Munghemezulu 1 1, 2
, W. L. Combrinck
1. Department of Geography, Geoinformatics and Meteorology, University of Pretoria, South Africa,
s27201211@tuks.co.za
2. Space Geodesy Programme, Hartebeesthoek Radio Astronomy Observatory, South Africa,
Ludwig@hartrao.ac.za
ABSTRACT
We propose to derive a velocity field map over the African continent derived from Global Navigation Satellite
System (GNSS) station coordinates as determined in the International Terrestrial Reference Frame. Such a velocity
field map will contribute towards a better understanding of the current intercontinental sub-plate movement and
will therefore support the future establishment and maintenance of a unified geodetic reference frame for Africa.
This work will be incorporated into the African Geodetic Reference Frame (AFREF) project as supported at
HartRAO; it will entail densification of the GNSS network in Africa, data processing, archiving, GNSS station
metadata log files maintenance and development of a software system for managing these activities. Data will be
processed with the GAMIT GPS software and estimated parameters will be utilised to describe crustal motion as a
function of time to enable the development of datum transformation parameters for different countries on the
African continent.
KEYWORDS: Global Navigation Satellite Systems, geodetic reference frames.
58

Economic benefits of varying maize production strategies
under various seasonal rainfall scenarios
in the Modder River catchment, South Africa
K.M. Nape 1,2 and A.S. Steyn 1
1. Department Soil, Crop and Climate Sciences, University of the Free State, South Africa,
dr.bean@webmail.co.za
2. Agricultural Research Council – Institute for Soil, Climate and Water, South Africa
ABSTRACT
The Modder River catchment is characterised by high rainfall variability which leads to a mismatch between water
demand by crops and water supply by rainfall. It is understood that farmers aim to employ a farming system that
maximizes production and minimizes risk whilst making a profit. Reducing the risk associated with rainfall
variability could have significant impacts on crop production. The main objective of this study was therefore to
investigate the economic benefits of different maize production strategies using a crop model against the backdrop
of various seasonal rainfall scenarios.
Seasonal rainfall totals were calculated from 1950-1999 for selected quaternary catchments within the Modder
River catchment for two 3-month periods (October, November, December and January, February, March)
comprising the maize growing season. Each 3-month period were subsequently categorized as above-normal (AN),
near-normal (NN) or below-normal (BN). A crop model (APSIM) was used to simulate maize yields under various
management strategies (i.e. choice of cultivar, plant density, planting dates, fertilizer application and weeding
frequency) for all the seasons. The simulated maize yields were analysed in order to determine the economic
benefit of applying different management decisions.
During above-normal rainfall seasons (AN-AN) the best practices involved a plant density of 21 000 plants/ha, a
fertiliser application of 50 kg/ha N and weeding twice for a crop planted during 16-30 November. This would lead
to a 50% probability of obtaining a profit of R2 319/ha. During dry seasons (BN-BN) the most productive
combination included a plant density of 12 000 plants/ha, fertiliser application of 35 kg/ha N and weeding twice for
a crop planted during 1-15 November. This would lead to a 50% probability of obtaining a mere profit of R497/ha.
The results indicate that management strategies guided by seasonal rainfall forecasts could aid in achieving
sustainable rainfed maize production.
KEYWORDS: maize production strategies, seasonal rainfall scenarios; crop model
59

An Investigation of the Trace Element Compositions of Gold
from the Zimbabwe and South Africa : Implications for tracing
the source of archeological gold
Robert Netshitungulwana 1 , M. Tredoux 2 , L. Jacobson 3
1. Council for Geoscience, South Africa, robertn@geoscience.org.za
2. University of Free State, South Africa, mtredoux@ufs.ac.za
3. McGregor Museum, South Africa, jake@museumsnc.co.za
ABSTRACT
The early Bantu farmers who settled in southern Africa were involved in trading and metal technology, and the
history of mining for metals like iron, copper, tin and gold in southern Africa spans at least the past 2000 years.
The main aim of the research was to test the viability of using gold chemistry to compare the composition of gold
ores in South Africa and Zimbabwe with those of the archaeological gold artefacts in Thulamela, Mapungubwe,
Bosutswe and Great Zimbabwe. Samples from Archaean greenstone belt in South Africa and Zimbabwe, as well as
samples from ores associated with the Witwatersrand Supergroup, were used in the study.
Trace element signatures were determined by laser ablation inductively coupled plasma mass spectrometry (LA-
ICP-MS), a technique whereby low concentration (down to low ppb levels) can be detected. In addition, Ag
concentrations (wt. %) were determined using scanning electron microprobe, so that Ag could be used as an
internal standard during the LA-ICP-MS runs to give semi-quantitative data. The most commonly occurring
isotopes in gold, namely, 56 Fe, 59 Co, 60 Ni 63 Cu, 66 Zn, 75 As, 188 Os, 105 Pd, 195 Pt, 202 Hg, 107,109 Ag, and 204, 206,207,208 Pb
and 209 Bi, were used to construct the signatures, using their intensities in the mass spectra in counts per second
(cps). Isotopic ratios were used to compare the gold ores with the gold artefacts.
The results show some variations in the signatures of gold from the greenstone belts and the Witwatersrand Basin.
The 107 Ag and 202 Hg cps in gold from the Witwatersrand Basin are high compared to the greenstone belts. These
differences have implications for the various models of gold deposition in these environments, pointing to different
geochemical histories. Multivariate correspondence analysis plots for the major gold deposits show the wide group
of the Barberton samples with little or no distinctive characteristics compared to the Zimbabwean gold samples.
The Witwatersrand gold plot differently to the Barberton greenstone belt but closely related to the Zimbabwean
greenstone belts. The ratio plot of 56 Fe (10 5 )/ 107 Ag versus 202 Hg (10 5 )/ 107 Ag shows that archaelogical gold artefacts
differ completely from the natural gold, indicating that the gold could not merely have been gold-worked, as has
been suggested. This suggests that gold from any one archaeological site could not be related to any particular or
even regional source. The problem could be associated with the possibility of mixing of gold from multiple
sources, recycling, contamination in melting, and trade in items.
KEYWORDS: Archaeology, Gold, Trace element analysis, Southern Africa, Zimbabwe
Netshitungulwana Robert. 1 received his Bachelor of Science (Honours) (BSc.H) degree
in Geology from the University of Venda, South Africa in 2003. He is currently doing his MSc.
Degree at the University of Free State, South Africa, with research interest geared towards
“trace elements geochemistry in southern African gold and artefacts”. He has done
geochemical fieldwork, compiling geochemical maps and data interpretation in South Africa
and internationally with Council for Geoscience, South Africa.
. 1 Department of Geology, University of Free State -Bloemfontein , SA
Email: robertn@geoscience.org.za / Mobile +27 73 339 9917
60

Sequence Stratigraphic Characterisation of Petroleum Reservoirs in
block 11B/12B of the Southern Outeniqua Basin, South Africa
E.Nformi 1 , P. Carey 2 ,
1. University of the Western Cape, South Africa, E-mail: 2801278@uwc.ac.za
2. University of the Western Cape, South Africa, E-mail: pcarey@uwc.ac.za
ABSTRACT
Deep water depositional systems are the one type of system that cannot be easily reached, observed and studied in
the modern environment, in contrast to other siliclastic and carbonate reservoir systems (Weimer and Slatt, 2004).
Going past conventional routes of exploration, this study uses the invaluable tool of sequence stratigraphy to
effectively prognose the huge, vast, unique and unexplored potential of the Southern Outeniqua Basin.
Using standard sequence stratigraphy techniques, including amongst others (seismic analysis/interpretation, cores,
and logs) and the Wheeler diagram, lithology constrains and time relationships between basin margin and basin
axis depositional packages is established.
This established relationship for the deepwater Southern Outeniqua Basin and the landward-adjacent Pletmos
Basin is hereby used in predicting the location of reservoirs in this frontier basin and thus prospectivity in the
undrilled areas by correlation (in time) with the landward-adjacent Pletmos sub-basin.
Seismic, log and core data analyses and interpretation have been used to match shallow water and deepwater
depositional packages thus predict reservoir location in the deepwater Southern Outeniqua basin. A close look at
systems tracts, their geometries and lithologies shows how sequence stratigraphy can be used to foretell reservoir
location and contents (Neal et al., 1993).
Sequence stratigraphy has proven and is proving successful in screening for reservoirs in frontier basins and the
Southern Outeniqua Basin hasn’t proven it wrong nor made the exception.
KEYWORDS: Sequence stratigraphy, Wheeler diagram, frontier basin, depositional package, deepwater
61

High-precision steering and pointing control of a satellite/lunar
laser ranging telescope
G.L. Nickola 1 and W.L. Combrinck 2
1. University of South Africa (UNISA) and Tshwane University of Technology, South Africa,
lnickola@unisa.ac.za
2. Hartebeesthoek Radio Astronomy Observatory (HartRAO) Space Geodesy programme, South Africa,
ludwig@hartrao.ac.za
ABSTRACT
A Satellite Laser Ranging System (SLRS) enhanced for Lunar Laser Ranging (LLR) is being developed as part of
geodetic instrumentation to be located at a new fundamental space geodetic station for South Africa.
The project under discussion here, will involve the development of high-precision steering and pointing control for
the LLR telescope. The role of the pointing system is to safely point the telescope towards the desired target and to
track the target in spite of internal and external disturbances. With the need for high-precision accuracy and
regulation, feedback control is required. The basis of a telescope’s closed-loop system consists of continuously
comparing the actual pointing direction to the desired pointing direction and feeding back any difference to the
drive system for correction.
An emphasis on safety aspects will be the most important design consideration of all. This will include hard-wired
safety interlocks as well as software protection for humans as well as the equipment. The mechanical design of the
telescope will determine some of the control design criteria. Compensation for mechanical behaviour will be
required in the control software.
National Instruments (NI) LabVIEW is a graphical programming language that is ideal for use in developing
engineering applications. LabVIEW programs use virtual instruments which have the look and feel of physical
systems or instruments. A working model using LabVIEW and an NI CompactRIO interface will be developed. NI
9514 motion control modules with encoder feedback will be used for control of the telescope’s two axes (azimuth
and elevation). An NI 9401 8-channel input/output module will be used for other circuitry. Vagon AC-drive units
with 3-phase asynchronous motors will be used to drive the model.
KEYWORDS: lunar laser ranging, telescope control.
62

Site characterisation:
Astronomical seeing from a turbulence-resolving model
M. Nickola 1,2 , I. Esau 3 , G.D. Djolov 2 , W.L. Combrinck 1 and R.C. Botha 1
1. Hartebeesthoek Radio Astronomy Observatory (HartRAO) Space Geodesy programme, South Africa,
marisa@hartrao.ac.za
2. University of Pretoria (UP), Department of Geography, Geoinformatics and Meteorology, South Africa,
george.djolov@up.ac.za
3. Nansen Environmental and Remote Sensing Center (NERSC), Bergen, Norway
igor.ezau@nersc.no
ABSTRACT
A Lunar Laser Ranging (LLR) system is to form part of geodetic instrumentation to be located at a new
fundamental space geodetic observatory for South Africa. LLR requires optical seeing (or astronomical seeing)
conditions at ~ 1 arc second resolution level in order to deliver usable data. Site characterisation should include a
description of astronomical seeing for various locations on-site as well as atmospheric conditions.
Atmospheric turbulence degrades astronomical seeing. In-situ methods of determining astronomical seeing are
difficult, time-consuming and costly. We propose the use of a turbulence-resolving model to determine and predict
astronomical seeing at a site.
Large Eddy Simulation NERSC (Nansen Environmental and Remote Sensing Centre) Improved Code (LESNIC) is
a turbulence-resolving simulation code with which to model atmospheric turbulence. It has been used to compile a
database of turbulence-resolving simulations, referred to as DATABASE64. This database consists of a collection
of LESNIC runs for a stably stratified planetary boundary layer (SBL) over a homogeneous aerodynamically rough
surface.
Results from DATABASE64 for the nocturnal boundary layer are employed to render profiles of the vertical
C profiles). Seeing parameter values are also obtained by making use of
2
distribution of optical turbulence ( N
2
DATABASE64 results. The C profiles and seeing parameters values obtained from DATABASE64 results are
N
compared with observational results that have been published in the literature. These values obtained are
consistent with results from field campaigns as reported in the literature.
Turbulence-resolving models, such as LESNIC, show potential for delivering and predicting profiles and
parameters to characterise astronomical seeing, which are essential prerequisites for establishing an LLR system at
the most suitable site and most suitable on-site location.
KEYWORDS: astronomical seeing, atmospheric turbulence, LESNIC, LLR.
63

Low Enthalpy Geothermal Energy purification of Acid Mine
Drainage, and storage of potable water in the deep gold mines
of South Africa
1 T.Ntholi, 2 M.de Wit
1. AEON- University of Cape Town, South Africa, thakane.ntholi@gmail.com
2. AEON- University of Cape Town, South Africa, maarten.dewit@uct.ac.za
ABSTRACT
The total volume of interconnected voids beneath the Witwatersrand, as a result of more than a century of deep
gold mining, is ≈ 6x10 6 -9x10 6 ML, at least double the volume of the Vaal dam. Most Witwatersrand mines
experience undesired water inflow from overlying aquifers. Operating mines invest resources to pump out the
water but abandoned mines are left to fill. The inflowing water evolves into acid mine water (AMW) as a result of
acid mine drainage (AMD). The AMD results from the hydrolysis and oxidation of pyrite and other sulphide
minerals, producing high acidity, sulphate ions and dissolution of heavy metal ions from their host minerals. The
AMW will continue to fill the mines until it eventually intersects the overlying water table and contaminate ground
water. In the East and Far West Rand, AMW is already decanting into natural rivers systems while in areas like the
Central Rand, it will do so in the near future.
We explore the viability of an in-situ, geothermally driven AMW purification system that can treat the AMW
within the mines before it reaches the water table. With such a scheme the voids can be allowed to naturally fill up
with water without posing a threat to the fresh ground water resources. The mines can then be used as underground
water reservoirs for the Gauteng region. The added benefit is that residual gold and other metals could be
chemically recovered from this system, and there will be no evaporation loss from this water reservoir.
The Witwatersrand basin has low geothermal gradient ≈18⁰C/km. The mines reach depths up to 4000m, and the
available geothermal energy is near renewable if exploited carefully. Whilst this low enthalpy geothermal energy
may not be high enough for electricity generation, it is enough to drive localised chemical purification systems.
KEYWORDS: Gauteng, deep gold mines, geothermal energy, Acid Mine Drainage, Geochemistry, fresh water
reservoirs
64

Correlation between agronomic and environmental
phosphorus analyses of selected soils
M.M. Nthejane 1 , C.C. du Preez 2 , C W van Huyssteen 3
1. Department of Soil, Crop and Climate Sciences, University of the Free State, P O Box 339, Bloemfontein
9300, Republic of South Africa, mabatho@rocketmail.com
2. Department of Soil, Crop and Climate Sciences, University of the Free State, P O Box 339, Bloemfontein
9300, Republic of South Africa, dpreezcc@ufs.ac.za
3. Department of Soil, Crop and Climate Sciences, University of the Free State, P O Box 339, Bloemfontein
9300, Republic of South Africa, vhuystc@ufs.ac.za
ABSTRACT
Phosphorus from cropped soils is regarded as a major contributor to the eutrophication of water. The challenge is
therefore to manage soil phosphorus so that crop productivity is maintained and if possible increased without
severe pollution of water. Many reliable soil phosphorus tests have been developed from a crop nutritional
viewpoint. This is not the case from a water protection angle, mainly due to a lack of suitable soil phosphorus tests
for this purpose. This study thus aimed to establish whether alignment between the many agronomic and few
environmental soil phosphorus tests are possible. Bulk soil samples from orthic A horizons were collected in three
distinct cropping areas in the Free State Province of South Africa. The areas are Jacobsdal (MAP ~ 250 mm and
soil pH >7), Bloemfontein (MAP ~ 500 mm and soil pH ± 6), and Ficksburg (MAP ~ 750 mm and soil pH

Mineralogical, geochemical and structural characteristics of
quartz-arenites of the middle Witteberg Group (Cape
Supergroup) near Kirkwood, Eastern Cape, South Africa
Wernich C. Olivier 1 , P.W.K. Booth 2 , C.R. Anderson 3
1. Nelson Mandela Metropolitan University, South Africa, wcolie4@gmail.com
2. Nelson Mandela Metropolitan University, South Africa, peter.booth@nmmu.ac.za
3. Nelson Mandela Metropolitan University, South Africa, Callum.anderson@nmmu.ac.za
ABSTRACT
A study of Late Palaeozoic Witteberg Group rocks (Cape Supergroup) near Kirkwood, Eastern Cape was carried
out to determine the viability of extracting silica for solar cell production. Mineralogical, geochemical and
structural analyses of selected outcrops of quartz-arenites showed that source rocks in the study area do not possess
the appropriate chemical attributes to warrant extraction of silica. Despite this finding the study presents valuable
information on strata composition and structural data which are compared and interpreted with known regional
structural patterns of the Cape Fold Belt in the Eastern Cape.
Samples from the Witpoort Formation were analyzed using petrographic light microscopy, scanning electron
microscopy and X-ray fluorescent spectroscopy. Analyses indicate that samples are composed almost entirely of
quartz, with accessory biotite, muscovite, sericite, baryte, apatite, rutile and monazite. Haematite occurs most
frequently along fractures, and is more prevalent in the Rooirand Member than the Perdepoort member, giving the
former a reddish brown colour on outcrop. The presence of chemical impurities is thought to be partly controlled
by the original depositional environment, namely, near-shore and beach environments. However, certain
impurities, especially Fe, were most probably emplaced during episodes of faulting related to the Cape Orogeny.
Rocks in the study area display a range of fold styles, mostly showing northward vergence. Low angle thrust faults
dip south and some thrusts dip north. In general, the orientation of fore-thrusts and folds in the study area indicate a
northward-directed compression event during the Late Palaeozoic. This pattern conforms to the structural
development in other parts of the Cape Fold Belt in the Eastern Cape. The south-dipping normal faults and strikeslip
faults that formed during the Mesozoic break-up of Gondwana transect all other structures in the study area.
KEYWORDS: Cape Fold Belt, deformation, silica.
66

A new approach to upscaling in reservoir modelling
A.O. Onaneye 1 , W.A. Sonibare 2 , D. Mikeš 3
1. Dept of Earth Sciences, Stellenbosch University, South Africa, alfred.onaneye@gmail
2. Dept of Earth Sciences, Stellenbosch University, South Africa, shoniwas@yahoo.com
3. Dept of Earth Sciences, Stellenbosch University, South Africa, mikes@sun.ac.za
ABSTRACT
Why do we need a geological based reservoir model?
Reservoir engineers over the years use upscaling as a tool in simulating reservoir performance and optimizing oil
recovery. Upscaling in concept is all about averaging and replacing a number of heterogeneous fine grids with a
homogenous block. A lot of upscaling procedures have been proposed, but many of them are complex, speculative
and often based on stochastic realizations. Therefore, they lack an approach that is simple and straightforward in
incorporating heterogeneities from the geological record down to the simulation phase.
Hence, we propose an approach that focuses on building our geological model in a fashion that it incorporates
heterogeneities on the one hand and also integrate the geological model into a new upscaling approach on the
other. Reservoir heterogeneities are known to be controlled by the arrangement of various hierarchies of
sedimentary facies and internal bounding surface. To this end, a hierarchical procedure would be a natural way to
build and upscale a geological-based reservoir model in a deterministic manner. In this regard, we initiate a fourstep
upscaling procedure: (1) Model construction: Assignment of flow cells and flow unit, (2) Parameter
assignment: Calculation of capillary pressure and relative permeabilities of laminae, (3) Micro simulation: Steady
state flow simulation on flow cells, and (4) Macro simulation: Assignment of the ensuing effective phase
permeabilities and capillary pressure to the flow units. The flow cell and flow unit are the key elements in this
procedure, while the laminae is the REV (Representative elementary volume) for the flow cell.
Implementation of this new upscaling approach should improve translation of the geological model into
reservoir model, capture necessary geological details and reflect reservoir heterogeneity. This approach lends itself
a simple and straightforward procedure to upscale all scales of heterogeneity for a full field flow prediction and
development plan.
KEYWORDS: Geological model, Reservoir heterogeneities, Upscaling, Reservoir simulation.
67

Petrophysical evaluation of the Albian Age Gas Bearing Sandstone
reservoirs of the O-M field, Orange Basin South Africa
Opuwari, Mimonitu 1 , Paul Carey 2 , Escordia de Poquioma 3
1.
Department of Earth Sciences, University of the Western Cape - Cape Town, SA -
mopuwari@uwc.ac.za, opusabem@gmail.com
2.
Department of Earth Sciences, University of the Western Cape - Cape Town, SA - pcarey@uwc.ac.za, paulcarey@live.com
3.
ABSTRACT
Petrophysical Evaluation of the Albian age gas bearing sandstone reservoirs of the O-M field,Orange basin has been
performed. The main goal of the research is to evaluate the reservoir potential of the field through the integration and
comparison of results from core analysis,production data and petrography studies for the evaluation and correction of
key petrophysical parameters from wireline logs which could be used to generate an effective reservoir model.A total of
ten (10) wells were evaluated and twenty eight sandstone reservoirs were encountered of which twenty four are gas
bearing and four are wet within the Albian age depth interval of 2800 to 3500m. six lithofacies (A1,A2,A3,A4,A5 and
A6 ) were grouped according to textural and structural and grain size .This study identifies the different rock types that
comprise reservoir and non reservoirs. Pore throat was estimated with the application of the winland’s method for
assessment of reservoir rock quality on bases of pore throat radius.Results from the winland method presents five
petrofacies (mega porous,macro porous,meso porous,micro porous and nanno porous).The best petrofacies is the mega
porous rock type which corresponds to lithofacies A1 and A2. The nanno porous rock type corresponds to lithofacies
A6 and was classified as non reservoir rock. The volume of clay model from log was taken from the gamma-ray model
corrected by the Steiber equation which was based on the level of agreement between the log data and the X-Ray
Diffraction clay data. The field average grain density of 2.67 g/cc was determined from core data and was used to
estimate porosity from the density log. Reservoir rock properties are generally good with reservoir average porosities
between 10 – 22 %, and permeability ranges from 6 to 1000mD. Log calculated water saturation models were calibrated
with capillary pressure and conventional core determined water saturations, and the Simandoux shaly sand model best
agree with capillary and conventional core water saturations and was used to determine field water saturations. The
study also revealed quartz as being the dominant mineral in addition to abundant chlorite as the major clay mineral. The
reservoirs evaluated in the field are characterized as normally pressured with an average reservoir pressure of 4800 psi
and temperature of 220 o F. An interpreted field aquifer gradient of 0.44 psi/ft (1.01 g/cc) and gas gradient of 0.09 psi/ft
(0.2 g/cc) were obtained from repeat formation test measurements.
KEYWORDS: Petrophysical, Gas Bearing Sandstone, O-M field, Orange Basin
68

Paleonenvironmental reconstruction of the Tanqua Basin, SW
Karoo, South
M Patel 1 & D Mikeš 2
1. Stellenbosch University, South Africa, malikahpatel@gmail.com
2. Stellenbosch University, South Africa, mikes@sun.ac.za
ABSTRACT
Deltaic build-out into the south-western Karoo Basin represents the last major phase of Ecca deposition. This study
focuses on the Ecca Group of the Tanqua depocentre which consists of a progradational siliciclastic succession
from submarine fan, prodelta, delta front to delta plain systems. The deltaic system has only been studied by few
and then only regionally. This study therefore focuses on the nature of the deltaic depositional environment and its
evolution through time. A detailed facies analysis is conducted to build a suitable facies model for the Tanqua
depocentre, which will then be used as a comparative study with existing facies models.
The Kookfontein formation is comprised of 13 cycles, dominant processes operating on the Tanqua submarine
slope vary temporally and spatially, which directly influences the distribution of facies and architecture. Cycles 1-
3 have been studied in detail. Cycle 1 is dominantly composed of thin-bedded, very fine grained- graded sandstone
and siltstone (heterolithic sst) interbedded with fine siltstones and mudstone facies consisting of four thickening
and coarsening-upwards units which is capped by a thinning and fining-upward unit. Cycle 2 attains an average
thickness of 30m, exhibiting a profile which generally coarsens and thickens upwards whilst the top most layers
have a thin, fining- upwards sequence. Cycle 3 exhibits a more symmetrical profile with units of mudstone (siltyclaystone)
and heterolithic very fine grained sandstone.
These cycles which characterise the proximal pro-delta/distal delta front deposits often contain distal distributary
mouth bar deposits as well as slumped units. Large-scale failure events and slumps observed within cycles 2 and 3,
typically occur in a lower to base of slope setting, but which has been demonstrated within the study area to occur
on the mid to upper slope.
KEYWORDS: Facies analysis; deltaic succession; Tanqua Depocentre; southwest Karo
69

Towards a magmatic reaction model for iron-rich ultramafic
pegmatites in the Rustenburg Layered Suite
David L. Reid 1 , I. Veksler 2 , J. Jakobsen 3 , R. Trumbull 4
1. Department of Geological Sciences, University of Cape Town, South Africa, david.reid@uct.ac.za
2. GFZ German Research Centre for Geosciences, Potsdam, Germany, veksler@gfz-potsdam.de
3. GFZ German Research Centre for Geosciences, Potsdam, Germany, jakob@gfz-potsdam.de
4. GFZ German Research Centre for Geosciences, Potsdam, Germany, bobby@gfz-potsdam.de
ABSTRACT
Iron-rich ultramafic pegmatite (IRUP) occurs as irregular bodies replacing the layered sequence associated with the
Merensky Reef and has fascinated workers with their unusual mineralogy, geochemistry and morphology. A
simple magmatic origin is precluded by the extreme iron-rich composition and the highly irregular morphology, the
latter also being inconsistent with injection as a crystal mush. Most workers have proposed some sort of
replacement origin, involving a ferrobasaltic melt reacting with cumulate assemblages to produce the range of
lithologies present in the IRUP bodies (olivine - clinopyroxene ± plagioclase ± magnetite)
Ferrobasaltic magmas are thought to be responsible for the Upper Zone of the Rustenburg Layered Suite and
certain highly differentiated melt fractions are thought to have migrated to the Critical Zone, causing replacement
and disruption of the Merensky Reef, the UG2 chromitite and elsewhere in the layered sequence exposed in the
platinum mines. Liquid immiscibility in the ferrobasaltic system is known to result in separate ultraferrous and
felsic melts, the former being perhaps capable of migrating through and reacting with country rock of variable
compositions to produce IRUP assemblages. The main question has been the composition of this ultraferrous melt
and recognition of its reaction products in the rock record.
While it is possible to characterize the starting materials (pre-exisiting layers of plagioclase - orthopyroxene ±
olivine ± chromite cumulates) and the final products (IRUP suite), the lack of recognisable introduced reactant
preserved in exposures examined requires an inductive approach. The most common lithology in the layered series
is norite (sensu lato) and shows transformation to a wehrlite, often with a transition zone of olivine-gabbro or
troctolite.
We are currently pursuing a mass balance approach to estimate the composition of the introduced ultraferrous melt
(UFM) and the residual melt (RM) that would satisfy the reaction equation below:
NORITE + UFM = OL-GABBRO + WEHRLITE + RM
Other approaches involve trying to derive possible ultraferrous melt compositions from liquid immiscibility
experiments, and studies of melt inclusions in suitable minerals.
KEYWORDS: IRUP, Merensky Reef, magmas, ultraferrous, UFM, RM
70

Climate/sealevel fluctuations along the Southern
African West Coast: regional and global context
D Roberts 1
1. Council for Geoscience, South Africa, droberts@gescience.org.za
ABSTRACT
Long term global trends in Cenozoic climatic/oceanographic evolution are mediated by fundamental
geological processes such as the changing configuration of landmasses. These in turn have major
impacts on ecosystems at all scales. However, the underlying forces driving some global trends remain
obscure. Whereas the Oligocene lowstand can be attributed to the final separation of Gondwana
landmasses allowing free flow of the Antarctic Circumpolar Current, neither the subsequent Early-
Middle Miocene recovery, nor the early Piocene warm period have obvious main causes.
Superimposed on these fundamental (global) trends are regional events such as tectonism, which
impinge on local climate and relative sea levels. The South African west and southern coasts form an
ideal field laboratory for studying late Cenozoic climatic/oceanographic histories because of the
extremely rich palaeorecord contained in the onshore littoral and fluvio-estuarine deposits, as
represented in a large number of well studied sites. The manner and extent to which they link with the
regional and global record may illuminate some of these important issues. In particular, many new
dates of major events based on palaeontology, radiometric methods, palaeomagnetics and luminescence
have provided fresh insights into the chronological sequence of events. Regionally, the southern
African subcontinent represents a passive intraplate, trailing edge setting, which is also removed from
glacial influence and has experienced no Cenozoic volcanic activity. Rates of vertical crustal motion
are consequently low and late Cenozoic shoreline datums chiefly reflect glacio-eustatic sea level
history. The tectonic stability of this region is therefore highly favourable for the study of glacioeustatic
sea level fluctuations. However, some authors have suggested otherwise, positing that the
region has undergone sharp and asymetric periodic uplift in the Neogene and the evidence cited for this
viewpoint is critically reviewed. This paper is essentially a critical review of the literature, but includes
some unpublished novel observations.
Keywords: Sea level; climate; late Cenozoic; southern Africa; chronology
71

Denudation rates and geomorphic evolution of the Cape
Mountains determined through cosmogenic dating using
10 Be and 21 Ne in quartz
1 T.Scharf, 2 A. Codilean, 3 M.J de Wit, S. 4 Niedermann,
1. AEON-University of Cape Town, South Africa, taryns1@gmail.com
2. Earth Surface Geochemistry, GFZ, Potsdam, Germany, codilean@gfz-potsdam.de
3. AEON-University of Cape Town, South Africa, maarten.dewit@uct.ac.za
4. Inorganic and Isotope Geochemistry, GFZ, Potsdam, Germany, nied@gfz-potsdam.de
ABSTRACT
The Cape Mountains, consisting of resistant quartzite, sandstones, as well as argillaceous material, form a
distinctive high relief area in comparison to the adjacent Karoo region to the north. The river systems draining the
southern ranges of the mountain system consist almost exclusively of short, near-linear rivers that have cut down
into the resistant rocks of the mountain ranges, leaving behind incised meanders and abandoned river terraces
within steep sided canyons.
The origin and timing of this Cape landscape remains unresolved. Fission track data suggests that the region was
largely exhumed in the Cretaceous, followed by possible further uplift in the Cenozoic. Whether this second-order
uplift took place continuously as an isostatic phenomenon, or as isolated tectonic uplift events, is unknown.
Previous cosmogenic data further inland of the Cape Mountains have yielded low recent erosion rates (

Environmental changes in Lake Tswaing during the last 84 ka
BP
Frauke Schmidt 1 , Hedi Oberhänsli 2 , Heinz Wilkes 3
1. Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum GFZ, Germany, fschmidt@gfzpotsdam.de
2. Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum GFZ, Germany, oberh@gfz-potsdam.de
3. Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum GFZ, Germany, wilkes@gfz-potsdam.de
ABSTRACT
The lacustrine sediments from Lake Tswaing provide the longest continuous record of palaeoenvironmental change
from the southern African subcontinent. The lake formed in an impact crater by the inflow of groundwater and
precipitation and at present, the lake is a highly saline and anoxic environment partly due to enhanced evaporation
during the dry winter months. For a comprehensive understanding of the climatic influence on the evolution of the
lake environment and for insights into the adaption of the lake organisms to the extreme and changing
environmental conditions during the last 84 ka BP, the organic matter in a 35 m long sediment core from Lake
Tswaing was investigated by several geochemical methods.
Lipid biomarkers, i.e., organism-specific chemical compounds, and their stable carbon and hydrogen isotopic
signatures provided information about the dominant organisms and the environmental conditions in Lake Tswaing.
The total organic carbon (TOC) content varied strongly throughout the core ranging from 0.3% up to 9.8% TOC.
Hydrogen isotopic composition of plant-derived n-alkanes indicated that low TOC contents corresponded to dry
climatic conditions which reduced the allochthonous input and the productivity in the lake. In general, algae and
bacteria were the predominating organisms in Lake Tswaing. Both groups showed strong variations and a temporal
succession in response to changing nutrient conditions in the lake during specific intervals; e.g., dinoflagellates
were most prominent in the time before 66 ka BP followed by an period with higher bacterial activity. Alkenoneproducing
algae appeared between 37 and 31 ka BP and showed strong shifts in their abundance which is possibly
related to salinity effects and will be further investigated.
KEYWORDS: Tswaing Crater Lake, palaeoenvironment, organic matter, lipid biomarkers.
73

Structural mapping and analysis of Rietvlei silica mine with
associated alteration zones and their relationship to the
Rustenburg fault
W. Sebone 1 , W. Colliston 2
1. Department of Geology, University of the Free State, P.O. Box 339, Bloemfontein 9300, Republic of South
Africa, wsebone@gmail.com
2. Department of Geology, University of the Free State, P.O. Box 339, Bloemfontein 9300, Republic of South
Africa, colliswp@ufs.ac.za
ABSTRACT
The hard mature quartzites of the quarry Rietvlei silica mine is located on one of Magaliesberg mountain ranges.
This rocks marks the floor of the Bushveld Complex and outcrops as prominent mountain ranges of the
Magaliesburg formation in the Western Transvaal supergroup. The quartzite varies from coarse-grained to finegrained,
and each with distinct alteration characteristics that are primarily controlled by variation in
mineralogy/composition. The structures were mapped out, their spatial orientations were also measured and plotted
on to the mine plan. Local structures include shear zones and joints, however detailed characteristics of the former
are not fully recorded. Three sets of joints can be distinguished based on their geometry and have general strikes of
NNW-SSE (which is a dominant pattern) and NNE-SSW. The dominant pattern is that of the former. The joints
also range from being vertical-subvertical and horizontal-subhorizontal. The joints appear to be all of the same age
and are tension joints. The quartzite layer dip gently to the north and part of the range has been offset by fault
activity, probably by the Rustenburg mega-structure, which is a NNW-SSE striking dextral strike-slip fault zone.
This fault may be somewhat coincident with the local structures, and therefore it is for this reason that the author
investigates the controls of alteration within the quartzite, the structural history of the study area and the
relationship between local structures and the Rustenburg fault.
KEYWORDS: quartzite, silica mine, Magaliesberg, Rustenburg
74

Rich Ultramafic Pegmatite replacement bodies, Bafokeng
Investigation of the Merensky Reef and the associated Iron
Rasimone Platinum Mine, Rustenburg, South Africa
Olaotse Shadi 1 , D. Reid 2
1. Department of Geological Sciences, University of Cape Town, South Africa. shdola001@uct.ac.za
2. Department of Geological Sciences, University of Cape Town, South Africa. David.reid@uct.ac.za
ABSTRACT
Iron Rich Ultramafic Pegmatite replacement bodies (IRUP) are abundantly distributed throughout the Rustenburg
layered mafic sequence of the Bushveld Complex and have been encountered at Bafokeng Rasimone Platinum
Mine (BRPM) during underground operations. In the NW sector of BRPM North Shaft, extensive IRUP
replacement of the Merensky Reef and underlying footwall norites cause physical displacement and redistribution
of the PGE.
The current study focuses on the replacement phenomena observed in the Merensky Reef sequence adjacent to a
large IRUP pipe with the aim to track the mineralogical and geochemical changes associated with the
transformation. In addition the study also address structural implications linked to the replacement bodies observed
at the mine.
A sample traverse was conducted from unreplaced reef, through a zone of mixing into the centre of the IRUP pipe.
Field characteristics shows that IRUPs preferentially replaces leucocratic lithologies and they occur in close
proximity to areas marked by extensive faulting and folding. Systematic chemical analysis conducted along the
transition shows that the IRUP is more evolved with a higher Fe content whilst depleted in Mg relative to the
norites.
KEYWORDS: IRUP; Merensky reef; mineralogical; geochemical; textural; characterization
75

Monitoring the 2-D urban heat island
for Bloemfontein, South Africa
P.E. Snyman and A.S. Steyn
Department of Soil, Crop and Climate Sciences, University of the Free State, South Africa,
2004168643@ufs4life.ac.za
ABSTRACT
The urban heat island (UHI) is the phenomenon where a city’s temperatures are warmer than those of the
surrounding countryside. It owes its existence to the contrasting surface areas since the materials used in build-up
environments are prone to retain more heat and thus warm up the air as this heat is re-radiated. The UHI is
responsive to the city size and anthropogenic activities. The objectives of this study included determining the
spatial extent and intensity of the Bloemfontein UHI as well as its diurnal variation.
Temperature sensor were placed inside Davis radiation screens and connected to HOBO U12 data loggers. 28
Sensors were subsequently mounted at a height of 2 m above the ground at various locations in and around the city.
The loggers were programmed to record the temperature readings at hourly intervals for a period spanning 14 July
to 16 August 2010. In addition, temperature data were also obtained from 5 permanent weather stations in the area.
Hourly averages and temperature anomalies were calculated for all the sensors. These hourly anomalies were
plotted on a map of the city and visually analysed to determine the position of the observed hotspots and cold
pools. Areas of intense temperature gradients were also identified.
The results revealed a well-developed UHI over even a relatively small city like Bloemfontein. The UHI is more
intense during the night and early morning hours when it exhibits a horseshoe shape running through the city centre
and the higher lying ground in the immediate vicinity. The strongest temperature gradients were observed to the
eastern side of the city with an observed temperature difference of up to 7.9 ºC between the city centre and the
surrounding countryside at 00:00 GMT.
KEYWORDS: urban heat island, temperature, Bloemfontein
76

Deterministic approach to geological and petrophysical
modelling of field analogue data: A case study of Tanqua-
Karoo (Kookfontein Formation) deltaic sequence, SW Karoo
Basin (South Africa)
W.A. Sonibare 1 , D. Mikeš 2 , A.O. Onaneye 3
1. Dept of Earth Sciences, Stellenbosch University, South Africa, shoniwas@yahoo.com
2. Dept of Earth Sciences, Stellenbosch University, South Africa, mikes@sun.ac.za
3. Dept of Earth Sciences, Stellenbosch University, South Africa, Alfred.onaneye@gmail.com
ABSTRACT
In recent years, the use of three-dimensional digital computer models to characterise and manage hydrocarbon
reservoirs with regards to resource evaluation and fluid flow prediction has become a widely accepted technique
within the oil industry. These geological reservoir models are often stochastically derived from sparse subsurface
datasets with poor resolution and inability to properly capture all scales of heterogeneity particularly small-scale
heterogeneities. The resultant models are not robust in terms of realistic geological and sedimentological
information. They lack accurate prediction of sediment-body geometry, internal facies architecture and spatial and
temporal distribution of facies and their petrophysical values (i.e. porosity and permeability). Therefore, central to
the success of any reservoir management technique (be it net-to-gross estimation for resource evaluation or
upscaling of petrophysical properties in a reservoir simulator to predict field-scale fluid flow behaviour) is the
accurate construction of a facies-dependent geological model.
At the exploration and development stage of an oilfield when there exists little geological information,
reconstruction of 3D stratigraphic and geometric elements from well-exposed outcrops could be a valuable tool.
This study, therefore, presents an outcrop analogue study of the excellently exposed Permian Kookfontein deltaic
succession in almost seven type-localities (Katjiesberg, Syfer, Skoorsteenberg, Bitterberg, Vaalberg
Pienaarsfontein and Roosterberg ) with a lateral extent of about 72 km. Quantitative outcrop data will be analysed
using facies, petrographic thin-section, gamma-ray log and photopanel analyses. A facies-dependent geological
model will be constructed hierarchically honouring all scales of heterogeneity. Modelling of petrophysical
properties will be based on the established facies distribution in our geological model, and performed in two steps:
(1) estimation or measurement of porosity values from thin-section analysis, and (2) grain size-based empirical
modelling of permeability values using Kozeny-Carman and Berg predictive methods. A correlation will then be
established between Kozeny-Carman and Berg models. This deterministic procedure will allow evaluation of the
relationships between depositional and diagenetic controls on the distribution of petrophysical properties in our
study area.
KEYWORDS: Geological and Petrophysical modelling, Field analogue data, Permian Kookfontein deltaic
succession, Kozeny-Carman and Berg models.
77

Statistical Downscaling of Climate Change Projections to
daily temperatures within the Upper Olifants River Catchment,
South Africa
A.S. Steyn
Department of Soil Crop and Climate Science, University of the Free State, South Africa,
steynas@ufs.ac.za
ABSTRACT
Climate change could have far reaching consequences for all spheres of life. Continued greenhouse gas (GHG)
emissions at or above current rates will cause further warming and induce further changes in the global climate
system. This is particularly true for southern Africa where an ever-increasing population is already causing an
increase in the demand for fresh water and much of the agricultural food production depends on rain. Global
Circulation Models (GCMs) are the main source of climate projections under varying GHG emission scenarios.
However, agrohydrological application models often require information at a network of point locations, implying
the need to downscale the GCM output. Downscaling approaches have subsequently emerged as a means of
employing large-scale atmospheric predictor variables (such as the 500 hPa geopotential heights) to develop
station-scale meteorological series. Variables such as daily minimum and maximum temperature, which are not
always accurately represented by the GCMs, can be derived using statistical approaches to build relationships
between the required forecast parameter and variables that are simulated more accurately.
Previous investigators have used the statistical downscaling model (SDSM) to downscale climate projections of
daily rainfall over North America and Europe. A similar methodology was adopted to downscale daily temperature
projections under the A2 and B2 emission scenarios at five selected quaternary catchments (QCs) within the Upper
Olifants River catchment in South Africa. Results include a list of the predictors variables identified as well as the
projected changes in minimum and maximum temperatures for the future climate as expressed in terms of several
delta-statistics (i.e. changes between the future time period and the current baseline period). The fact that the
downscaling procedure provides similar results for the A2 and B2 scenarios suggests that it is at least to some
extent robust and stable.
KEYWORDS: Statistical downscaling; climate change; temperature
78

Downscaling climate change scenarios to daily maximum
temperatures over Bloemfontein, South Africa
P.C. Tharaga and A.S. Steyn
Department of Soil Crop and Climate Science, University of the Free State, South Africa,
2005162884@ufs4life.ac.za
ABSTRACT
Climate change refers to a change in the state of the climate that can be recognised by changes in the mean and/or
the variability of its properties and that continues for an extended period, typically decades or longer. Climate
change may be limited to a specific region, or may occur across continents or the whole planet. Global Circulation
Models (GCMs) are the main source of climate projections under varying greenhouse gas emission scenarios, but
their output needs to be downscaled before it can be interpreted for point stations. The main objective of this study
was to downscale and quantify the projected changes in maximum temperatures that can be expected in
Bloemfontein within the 21 st century.
A statistical downscaling model (SDSM) was employed. SDSM reduces the task of statistical downscaling into the
following discrete steps: quality control, predictor screening, model calibration, generation of ensembles of future
data for the baseline climatic period using observed predictors, statistical analysis, generating of ensembles of
future weather data using GCM-derived predictors, and time series analysis. The model was calibrated and tested
with the use of observed datasets of daily temperature as the predictand and normalised NCEP variables as the
predictors. SDSM was then used to construct downscaled daily temperature projections under the A2 and B2
emission scenarios as obtained from the HadCM3 model. The projected changes for the future climate were
assessed by means of delta statistics.
Predictor screening revealed that the most important predictors for maximum temperature were mean sea level
pressure and 500 hPa height, probably because of the relationship to column thickness (which were not available as
a predictor variable). Wind direction was also included as a predictor variable because of its apparent influence on
temperatures in mid-latitudes. Preliminary results of the downscaling model will be presented.
KEYWORDS: climate change, statistical downscaling, maximum temperature
79

New insights on the role of a mantle plume in South Atlantic
breakup
R.B. Trumbull, J.K. Keiding, I.V. Veksler
GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany, bobby@gfzpotsdam.de,
jakob@gfz-potsdam.de, ilya.veksler@gfz-potsdam.de
ABSTRACT
There is controversy surrounding the existence and possible role of a deep-seated mantle plume associated with the
Paraná-Etendeka large igneous province. Observational evidence is limited to the erupted and intruded magmatic
rocks of mantle derivation: flood basalts, central complexes and mafic dyke swarms. Key information needed is
pressure-temperature conditions of mantle melting (how hot? how deep?) and composition of primary magmas.
Estimating primary magma compositions from geochemical models based on mineral and rock data is subject to
large uncertainties because rocks are often poor proxies for melt compositions. Preferable is direct analysis of melt
inclusions trapped within early-formed crystals and isolated from the rest of the magma during ascent and eruption.
Here we present data from melt inclusions and host olivines from the Henties Bay-Outjo (HOD) dyke swarm and
Tafelkop lavas in the Etendeka province of NW Namibia. The prime target for this study are dykes of high- MgO
(picritic) compositions, which are thought to be plume-derived, and are therefore of considerable significance for
understanding mantle dynamics and magmatism in this province.
Preliminary microprobe results show that olivines with 85 mol.% forsterite or higher are common in the HOD
dykes, while olivine in the lavas analyzed are less magnesian (Fo78 or lower). We reconfirmed extremely Mg-rich
olivines (up to Fo93.4) that were reported by Thompson and Gibson (2000) from SW of the Brandberg Complex,
and we have discovered more localities with exceptionally Mg-rich olivines (up to Fo93.6), so the distribution of
such high-Mg olivines appears to be larger than previously thought. Most olivines with Fo >85 are too Mg-rich to
be in equilibrium with the whole-rock composition, indicating that the grains are entrained xenocrysts which
crystallized from an earlier, much more magnesian melts.
Most important is the finding that melt inclusions are abundant in the xenocrysts with Fo > 90, so we have access
to melt compositions from which these enigmatic olivines formed. The inclusions range in size from 10-70
microns, are typically round in shape and are partly or completely crystallized, with Al-rich clinopyroxene , Al-rich
orthopyroxene, and spinel (chromite). Trapped melts are tholeiitic picritic basalts with maximum 17.5 wt. % MgO.
Olivine-melt themometry using these compositions yields estimates of mantle potential temperature of 1520°, in
contrast to the 1700°C proposed by Thompson et al. (2000) based on whole-rock models and more in line with
petrologic estimates for plume temperatures in Hawaii and Iceland. Further analysis of trace element compositions
from these inclusions will give potentially important information on magma type and mantle source composition.
Reference: Thompson, R. N. & Gibson, S. A. (2000). Transient high temperatures in mantle plume heads inferred
from magnesian olivines in Phanerozoic picrites. Nature 407, 502-506
KEYWORDS: Etendeka Province, mantle temperature, olivine, melt inclusions
80

A PGE-rich rock type from the Barberton greenstone belt,
South Africa
Tredoux, M. 1 , Chabangu, N. 1 , Wildau, A. 1 , Miller, D.E. 2 and Madala. F. 1
1. Geology Dept, Univ. of the Free State, PO Box 339, Bloemfontein, 9300 South Africa; mtredoux@ufs.ac.za
2. C.M.E., Univ. of Cape Town, Rondebosch, 7701 South Africa; embo@telkomsa.net
ABSTRACT
The mafic and ultramafic rocks of the Barberton greenstone belt can be interpreted as the remnant of an Archean
ophiolite, named the Jamestown complex. Ultramafic rocks of the lowermost stratigraphic unit of this ophiolite is
exposed in the northwestern flank of the belt. All the contacts are sheared; its geochemistry shows a severe
depletion in the LILEs, and Sm-Nd and Pb-Pb systematics point to ~3.5 Ga as the most likely time for the
depletion. This rock is therefore interpreted as the depleted upper mantle restite from which the overlying
komatiites were extracted at an Archean ridge system. In 1920, a very Ni-rich body (>30% NiO, whole rock),
containing unusual Ni minerals such as trevorite and nepourite, was discovered embedded in the ultramafite. It has
been described as an oxidized meteorite or of a deep mantle origin, potentially from the D” layer. Investigation of
sub-mm sized phases in the trevorite has indicated the presence of Fe-Ni alloy, and metallic Si. The body is highly
enriched in the PGE (PGEtot > 5000 ppb).
KEYWORDS: Archean, ophiolite, PGE.
81

Palaeoceanographic changes identified using seismic and
radiogenic isotope data from the Mozambique Ridge, SW
Indian Ocean
Gabriele Uenzelmann-Neben 1 , Michael K. Watkeys 2 , Warren Kretzinger 2 , Martin Frank 3
and Lasse Heuer 3
1. Alfred-Wegener-Institute for Polar and Marine Research, Am Alten Hafen, 27568 Bremerhaven, Germany,
Gabriele.Uenzelmann-Neben@awi.de
2.School of Geological Sciences, University KwaZulu-Natal, Private Bag X54001, Durban 4000, Republic
of South Africa, Watkeys@ukzn.ac.za, 202521809@uknz.ac.za
3. IfM-Geomar, Leibniz Institute of Marine Sciences at the University of Kiel, Wischhofstr. 1-3, 24148 Kiel,
Germany, mfrank@ifm-geomar.de
ABSTRACT
Seismic reflection data from the southern Mozambique Ridge, SW Indian Ocean, show indications for a
modification in the oceanic circulation system. In the absence of an age-depth model based on a drill site we used
information gathered from the study of radiogenic isotopes of ferromanganese nodules and crusts. Those were
recovered via dredges from the Mozambique Ridge to gain knowledge on the origin of the modifications of the
oceanic circulation system, which is documented in the distinct change in reflection characteristics. This is found to
have occurred at 9 Ma.
KEYWORDS: Mozambique Ridge, seismic data, reorganisation of circulation system, isotopic signatures of water
masses, NADW.
82

A framework for soil-based wetland research in South Africa
C.W. van Huyssteen
Department of Soil, Crop and Climate Sciences, University of the Free State, P.O. Box 339, Bloemfontein
9300, Republic of South Africa, vhuystc@ufs.ac.za
ABSTRACT
Wetlands are protected through legislation, but the legislation fails to adequately define these wetlands, stating
only that wetlands are transitory between terrestrial and aquatic ecosystems. Current indicators use soil
morphology, topography, and vegetation to delineate wetlands. These indicators are, however, not based on
comprehensive soil-based research. Limited attempts have been made, but were usually an outcome of other
studies. The aim of this paper is to elucidate soil-based wetland research and the opportunities that exist for future
studies in this regard.
An initial attempt was made in the Grabouw district, based on one year’s soil water measurement. The 160 ha
Weatherley catchment houses 29 measurement sites that have been monitored since January 1997. The catchment
was coved by grass until September 2002, when the catchment was planted with commercial forest. Twenty six
neutron access tubes were monitored for five years In the Cathedral Peak VI catchment, 2000 m above sea level
with basalt parent material and an annual rainfall of 1300 mm. In the Two Streams catchment were monitored at 24
neutron probe and 14 tensiometer sites, in well drained soils from sandstone parent material and an annual rainfall
of 1200 mm. Ad hoc measurements have also been made in the St Lucia, northern Maputaland Coastal Aquifer,
and Bokong (Lesotho) wetlands.
Concerted and coordinated soil-based measurements are required to adequately quantify soil wetland indicators
that can be used for delineation. This will ensure adequate protection of these valuable ecosystems whilst still
allowing other land use practices on the remaining land.
KEYWORDS: hydric soils, redoximorphic features, reduced conditions, water saturation
83

The development and evaluation of solar desalination
technology
DM van Tonder 1,2 , CJS Fourie 1
1. Department of Environmental, Water and Earth Sciences, Faculty of Science at Tshwane University
of Technology, South Africa, dvtonder@geoscience.org.za; fouriecjs@tut.ac.za
2. Council for Geoscience, Environmental Division, Pretoria, South Africa
ABSTRACT
South Africa has limited water resources and many parts of the country have limited access to water. Almost all of
its national available water resources (98%) already allocated. Predictions suggest that South Africa would have a
serious water allocation problem in the very near future. In the semi-arid to arid regions of the country significant
salt loading in groundwater occurs where anthropogenic influences can be excluded. Other areas are heavily
impacted by mining, which results in the degradation of surface and ground water quality, specifically with respect
to salinity and acidification. The energy crisis in South Africa has highlighted the need for alternative energy
sources. Although solar energy has been utilsed to some extent in South Africa, the full potential for alternative
uses of solar power has not been exploited. Desalination has become an accepted water treatment process around
the world and is becoming a price-competitive option. Distillation involves heating a liquid until it vaporizes, and
condensing the vapor and collecting it in a separate container. The most widely used solar desalination system is a
simple solar still. The main disadvantage of the current simple solar still is its low yield efficiency, which rarely
exceeds 50% of the input volume (10-20 l) during a day. Research on alternative designs within the South African
context and particularly on increasing the effectiveness of solar distillation technology is lacking. This study will
focus on the development of an alternative solar desalination technology which will endeavour to improve the
effectiveness of solar distillation and its application for rural water supply (to be distributed by the Science &
Technology Train) by utilising solar heating panels as an alternative heat source. The project will also be applied
in the mining industry in an attempt to provide an alternative, cost effective and sustainable way of improving the
water quality in mining impacted areas. The proposed solar desalination technology will attempt to effectively
eliminate all waterborne pathogens, salts, and heavy metals. The proposed project has the following steps: (a) the
development of a laboratory set-up for testing the efficiency of the removal of salts and heavy metals from brackish
drinking water and mine water, (b) the evaluation of the effectiveness and application limitations of the proposed
solar distillation method and (c) the evaluation of the potential for a pilot solar desalination system.
KEYWORDS: Solar, desalination, distillation, water quality, sustainable
84

Investigation of the potential for mineral carbonation of South
African PGM tailings
1 J. Vogeli, 2 D.L. Reid, 1 M. Becker, 1 J. Broadhurst, 1 J-P. Franzidis
1 Minerals to Metals Initiative, University of Cape Town, Rondebosch, 7700, SA, vgljac001@uct.ac.za
2 Department of Geological Sciences, University of Cape Town, Rondebosch, 7700, SA
david.reid@uct.ac.za
ABSTRACT
Increasing atmospheric CO2 concentration is currently of considerable concern in terms of global warming. A
possible technology that can contribute to the reduction of CO2 emissions is its sequestration by mineral
carbonation. In this study, tailings from several different platinum mines in South Africa will be mineralogically
characterised and their potential for mineral carbonation reviewed. Mg and Ca-rich minerals (plagioclase, olivine,
orthopyroxene, clinopyroxene) present in the tailings are good candidates for mineral carbonation, which mimics
natural weathering processes in which these minerals react with gaseous CO2 to form Ca or Mg carbonates. Since
the reaction is influenced by particle surface area, the ultra fine grained nature of the PGM tailings provides
another reason for the promise of PGM tailings for mineral carbonation. A preliminary ranking of the tailings
samples and their efficacy for mineral carbonation has been developed according to whether the samples showed
harzburgtic (eg. Northam Platinum mine), pyroxenetic (eg. BRPM) or noritic mineral assemblages. This
information and understanding will assist in identifying opportunities and guiding the development of engineered
facilities for the sequestration of CO2 by means of mineral carbonation.
KEYWORDS: global warming, mineral carbonation, PGM tailings
85

Records of Late Quaternary environmental changes
preserved in eolian and fluvial sediment geoarchives
of the SW-Kalahari, South Africa
J. Völkel 1 , K. Hürkamp 1 , K. Heine 2 , O. Bens 3 , M. Leopold 1 , J. Winkelbauer 1
1. Technische Universität München, Department of Geomorphology and Soil Science,
85350 Freising - Weihenstephan, Germany, geo@wzw.tum.de
2. University of Regensburg, 93040 Regensburg, Germany, klaus.heine@geographie.uni-regensburg.de
3. Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences,
14473 Potsdam, Germany, oliver.bens@gfz-potsdam.de
ABSTRACT
Precipitation in southern Africa – tropical summer rains in the north and the east and extratropical winter rains in
the southwest – is strongly influenced by the seasonal shift of the Intertropical Convergence Zone (ITCZ). Little is
known so far about the displacement since the Last Glacial Maximum (LGM; ~22-18 ka BP). Geomorphological
and sedimentological field work and laboratory analyses were carried out on fluvial, colluvial and eolian
geoarchives (valley, pan and terrestrial slope sediments, as well as dunes) in the catchment of the southern lower
Molopo River within the southwest Kalahari and were paleoclimatically interpreted. This area is very suitable for
terrestrial research on paleoclimatic and environmental change. Here dunes and pans coexist as major Kalahari
geomorphological types in an ideal way with the Molopo River valley, including different fluvial sediment facies
interbedded with slope and eolian sediments, as well as the confluence of the Molopo and Orange River systems.
The results are discussed in the context of existing literature about terrestrial and marine southern African
paleoenvironmental geoarchives. Literature evaluation, earlier research, results of field trips in 2009, as well as first
sediment age determinations support the hypothesis of a contemporaneous southward shift of the ITCZ during the
LGM along with a northward relocation of the westerlies. As a result, the southwest Kalahari (~25°30’S) was
influenced by summer and winter rains during the LGM. This leads to new ideas about the reconstruction of glacial
climate circulation patterns over the southern African subcontinent and is of major importance for modelling of
past and future climate scenarios.
KEYWORDS: ITCZ, paleoclimate, geoarchives, SW-Kalahari, Molopo River
86

Defining the Kaapvaal Craton boundary - new electrical
conductivity images
U. Weckmann 1 , O. Ritter 1 , M. Becken 1,2 & M. de Wit 3
1 Helmholtz Centre Potsdam - German Research Centre for Geosciences GFZ, Potsdam, Germany
2 University of Potsdam, Institute of Geosciences, Potsdam, Germany
3 AEON – Africa Earth Observatory Network, University of Cape Town, Cape Town, South Africa
ABSTRACT
Within the framework of Inkaba yeAfrica several MT field experiments were conducted along the Agulhas-Karoo
Transect in South Africa. This 650 km long transect is designed to cross several continental collision zones, in
particular the boundary of the Kaapvaal Craton with the Namaqua Natal Mobile Belt.
MT data from 120 sites along the northernmost section were inverted to obtain a two dimensional electrical
conductivity image on a lithospheric scale. The most intriguing feature of the inversion model is the distinct
difference between relatively high conductivities of the metamorphic rocks of the mobile belt und the extremely
resistive rocks of the Kaapvaal Craton. The area of the craton transition is characterized by resistive blocks
extending into the Earth’s mantle intersected by zones of higher conductivity which seem to correlate with thrust
and fault systems of the Gordonia Subprovince and the Marydale Terrane. Both tectonic units are believed to have
experienced a similar stress field compared with the adjacent Kaapvaal Craton.
Based on the electrical conductivity imaged in the Gordonia Subprovince, the Marydale Terrane and parts of the
Eastern Namaqualand, we would either define the craton boundary to be located approximately 80 km farther SW
than existing tectonic models suggest or rocks in this region are more related to those of the Archean Kaapvaal
Craton in terms of their composition than to rocks of the Namaqua Natal Mobile Belt.
KEYWORDS: Magnetotellurics, Kaapvaal Craton, Namaqua Natal Mobile Belt, electrical conductivity image
87