The Cape Supergroup (Middle Ordovician-Lower Carboniferous) of South Africa: A review

Abstract The Middle Ordovician-Lower Carboniferous Cape Supergroup is a low-grade metasiliciclastic succession outcropping within the Cape Fold Belt spanning the southern periphery of South Africa. Deposits of the Cape Supergroup record a near unbroken ~110 to 140 My record of environmental change as South Africa migrated from low-subtropical to increasingly high-polar latitudes during the Palaeozoic and is an important anchor point in the correlation of similar aged West Gondwanan depocentres. Although of little importance economically, the rocks of the Cape Supergroup are host to several world-class fossil assemblages and palaeontological discoveries; many of which are exclusively known from South Africa or few locales elsewhere globally. Such assemblages include the Latest Ordovician Soom-Disa, Early-Middle Devonian Malvinoxhosan and Latest Devonian Witpoort biotas. Stratigraphically, deposits of the Cape Supergroup may be grouped into the Middle Ordovician-Lower Devonian Table Mountain, Lower-Middle Devonian Bokkeveld, and Middle Devonian-Lower Carboniferous Witteberg groups. The Middle-Upper Devonian Msikaba Formation is an assumed equivalent of the Witteberg Group (being separate from exposures in the Cape Fold Belt) in the vicinity of the KwaZulu-Natal and Eastern Cape provincial boundary. Variably these deposits accumulated in paralic to shallow marine environments that were punctuated at times by episodes of glaciation and subaerial alluvial sedimentation across the shallow western Clanwilliam and deeper eastern Agulhas sub-basins of the Cape Basin. Although the stratigraphy and sedimentology of these successions is reasonably robust and well-established, much of this information is exclusively from outcrops in the Clanwilliam Sub-basin. Major stratigraphic and sedimentological research awaits regarding deposits located in the Agulhas Sub-basin, whose geologic history is poorly understood. Deposits of particular interest include the Sardinia Bay Formation (Table Mountain Group) the Traka Subgroup (Bokkeveld Group), as well as most of the Witteberg Group. Further to this, better geochronological constraints for the Cape Supergroup are required, in part to understand its tectonic history, as well as its relationship with similar aged depocentres in West Gondwana.