Three-dimensional computer-assisted basin modelling to generate exploration target areas: an example from the late Archaean-early Proterozoic Transvaal Supergroup, South Africa |
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| Authors: | B F F Reczko L A G Antoine P G Eriksson |
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| Institution: | (1) Department of Geology, University of Pretoria, Pretoria 0002, South Africa, ZA;(2) BPI Geophysics, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa, ZA |
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| Abstract: | Second- and third-order fault-bounded Precambrian basins frequently host deposits of the sedimentary massive sulphide group.
Three-dimensional geometric modelling of the thickness of preserved basin-fill successions of the Transvaal Supergroup, using
DATAMINE software, and residual gravity modelling of the contemporary basement floor, help delineate areas of exploration
potential in this unit. Two main depositional axes are tentatively identified for the basal volcano-sedimentary protobasinal
Transvaal successions. A sheet-like geometry was indicated for the succeeding Black Reef sandstones and Chuniespoort Group
chemical sedimentary rocks. The uppermost Pretoria Group thickness model delineates eastern and western second-order basins
separated by a central submerged palaeohigh. A similar isopach pattern is noted for the thick shales of the Silverton Formation
in this group, with, in addition, a well-defined third-order basin in the northwest of the western second-order basin. The
residual gravity model indicates two linear palaeovalleys adjacent to this western basin, one coincident with one of the axes
inferred for the protobasinal rocks. The fault-bounded second- and third-order basins and depositional axes postulated here
are consistent with known geological data and suggested sedimentation models. Cumulative distortions implicit in the DATAMINE
computer modelling technique are reduced when the method is applied on the basin-wide scale, enabling identification of regional
exploration target areas rather than immediate prospecting targets.
Received: 14 August 1996 / Accepted: 13 March 1997 |
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