A Weichselian deglaciation model applied to the Early Permian glaciation in the northeast Karoo Basin, South Africa

It generally is assumed that the Early Permian Gondwana deglaciation in Sou th Africa started with a collapse of the marine ice-sheet. The northeast pa rt of the Karoo Basin became ice-free as a result of this collapse. The deg laciation here probably took place under temperate glacial conditions. Thre e glacial phases have been identified. Phase 1: the marine ice retreat of 4 00 km over the northeast Karoo Basin, which may have been completed over a few thousand years. The glaciers grounded in the shallower areas around the shore of the basin. Phase 2: the smaller, now mainly continental ice-sheet here re-stabilised and remained more or less stationary for several tens o f thousand years. During this phase, between 50 and 200 m of massive glacio marine mud with,dropstones accumulated in the open, marine basin that becam e ice-free during Phase 1. Isostatic,uplift, as a response to the first rap id deglaciation phase, can be traced in the inland part of the region. Phas e 3: the final deglaciation may have taken 10 to 20 kyr. After this time no new ice sheet was built up over southern Africa. The entire Early Permian deglaciation of the northeast Karoo Basin was completed within thousands ra ther than millions of years. Phases 1 and 3 had lengths similar to typical Quaternary deglaciations, whereas Phase 2 was a long, stable phase, more si milar to a full Quaternary glaciation. Copyright (C) 2001 John Wiley & Sons , Ltd.