Title:
Tuffs, tectonism and glacially related sea-level changes, Carboniferous-Permian, southern Namibia
Publication Year:
2000
Abstract:
The Carboniferous-Permian glacigene Dwyka Group in southern Africa has been widely regarded as amagmatic. Only in the higher parts of the Permian and subsequent younger strata has evidence of magmatism been recognised, particularly in the form of pyroclastic fallout ash beds. The source of these tuffs has been suggested to be Patagonia and West Antarctica, forming part of an extensive volcanic arc which lay some 1500 to 2000 km to the south and west in their pre-break-up Gondwana positions. Rhyolitic/dacitic and basaltic/andesitic tuff beds within the glaciomarine sediments of the Dwyka Group in Namibia reveal new evidence for an early onset of proximal bimodal volcanic activity in southern Africa. Contemporaneous tectonism is recorded by type-1 unconformities and systematic thickness changes across NW-SE trending extensional normal faults. We suggest that this tectonomagmatic period marks initial extensional events in southern Namibia and the Carboniferous-Permian volcanic trend appears to coincide with the position of the eventual Namibian continental margin. Keywords: Dwyka, glacial, glacio-eustatic, Gondwana, Karoo, Namibia, sea-level, volcanism.
Publication Title:
Palaeogeography, Palaeoclimatology, Palaeoecology
Volume:
161
Issue:
1-2
Pages:
127-150
Item Type:
Journal Article
Language:
en

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