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