Abstract

Recent excavations at Coedmore Quarry, Durban, KwaZulu-Natal, have revealed the presence of tempestites and complex, large-scale deformation features in the Dwyka Group. The striated surface of the underlying Natal Group sandstone, upon which the Dwyka Group rests, is clear evidence of glacial erosion during the advance of a glacial ice sheet. However, the glaciation was interrupted by an interglacial (the Ethekwinian Interglacial) that probably resulted in a significant sea-level rise (±100 m). During the interglacial period, a sedimentary succession, characterized by resedimentation products, tempestites and relatively rare stadials (thin diamictites and varvites), was laid down. Subsequently, during a further glacial period, large-scale soft sediment deformations occurred in the region. We suggest that the deformed sedimentary sequence represents an olistostrome. This feature was most probably initiated by ice-push and/or earthquake activity at the basin margin, but reached its final position (at Coedmore) through gravity sliding into the main Karoo Basin, the Coedmore region may have been a localized palaeodeep (Coedmore Deep) within this part of the main Karoo Basin.

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