A dinocephalian therapsid fauna on the Ecca–Beaufort contact in Eastern Cape Province, South Africa
- Authors: Modesto, S P , Rubidge, B S , de Klerk, William J , Welman, J
- Date: 2001
- Language: English
- Type: text , Article
- Identifier: vital:6999 , http://hdl.handle.net/10962/d1008355
- Description: Systematic exploration of outcrops of the lowermost Beaufort Group for fossils of the oldest terrestrial vertebrates of South Africa, known only from the Permian age Eodicynodon Assemblage Zone in Western Cape Province, has resulted in the discovery of a therapsid fauna in Eastern Cape Province that is dominated by advanced dinocephalians. The new discoveries include the skull and partial skeleton of a juvenile Anteosaurus, skull and skeletal elements of tapinocephalids, as well as the skull of a scylacosaurid therocephalian. The combined presence of advanced tapinocephalid dinocephalians, the anteosaur Anteosaurus, and scylacosaurid therocephalians suggests that the rocks of the lowermost Beaufort Group in the Eastern Cape Province can be assigned to the Tapinocephalus Assemblage Zone, rather than to the Eodicynodon Assemblage Zone, which appears to be restricted to the southwestern part of the Karoo Basin. This biozone identity permits the recognition of a younger age for the Ecca-Beaufort contact eastwards along the southern margin of the basin, thus demonstrating the diachronous nature of the Ecca-Beaufort contact in the southern Karoo.
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- Date Issued: 2001
Some geochemical constraints upon models for the crystallization of the upper critical zone-main zone interval, northwestern Bushveld complex
- Authors: Eales, Hugh V , Marsh, Julian S , Mitchell, Andrew A , de Klerk, William J , Kruger, Floris J , Field, Matthew
- Date: 1986
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/136044 , vital:37331 , https://doi.org/10.1180/minmag.1986.050.358.03
- Description: Ratios between elements Mg, Fe, Co, Cr, Ni, V, and Sc are consistently different in mafic rocks of the upper critical zone, and those above the Bastard unit. Within the 300 m section above the Merensky Reef, 87Sr/86Sr ratios increase from c.0.7063 to c.0.7087, irrespective of rock type. Decoupling of Mg/(Mg + Fe2+) ratios and the Ca contents of plagioclase, and wide variations in the proportions of anorthosite within the Bastard, Merensky, and Merensky Footwall units, are inconsistent with anorthosite formation by simple fractional crystallization of magma batches of limited volume.
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- Date Issued: 1986