Chapter 14 Puzzling questions in the simple history of a continent
Publisher Summary This chapter describes the different aspects of the geology of Africa. The kinematics of the movement of Africa, relative to Europe, since the early Jurassic, is well known being constrained by the seafloor-spreading data of the north Atlantic. Applying the back-arc basin collapse model to interpret the geology of South Africa, the Cape supergroup of the Cape folded belt can be considered the shallow marine sedimentary cover of an island arc. The African margin south of the Cape was an active, not a passive margin, during the Palaeozoic. The subduction of ocean lithosphere down a northdipping Benioff zone under the active margin caused the formation of a back arc basin north of the Cape arc. It is found that during the late Palaeozoic, the floor of that back-arc basin was subducted down a Benioff zone dipping south under the arc. The glacio-marine sediments of the Dwyka group were laid down in this initially deep basin, before it was eventually filled up by the thick flysch-molasse sequence of the Karoo supergroup.