The Provenance of Selected Neoproterozoic to Lower Paleozoic Basin Successions of Southwest Gondwana: A Review and Proposal for Further Research

Abstract

A review and evaluation of existing provenance information together with their implication has been made of selected Neoproterozoic to Paleozoic successions of southwest Gondwana. This overview led to the identification of major underexplored areas of research and with often even basic issues still unresolved. Firstly, the data of U–Pb ages of detrital zircons needs to be adapted to the up-to-date knowledge of this methodological approach, which relates to sampling techniques, amount of grains and presentation of the data. Secondly, high resolution heavy mineral studies are nearly absent but powerful, especially in the identification of terrane boundaries and source compositions from active continental margins. Thirdly, the character of the geodynamic processes at the southern margin would be of importance, to differentiate the detritus derived from there from those related to the processes in the center of SW Gondwana, where allegedly the Kalahari, Congo and South American cratonic masses collided/interacted. Currently, it seems to be possible to argue that during the Neoproterozoic in the south of the Kalahari craton an active margin existed—of unknown distance to the modern continental margin. The central part of SW Gondwana is complex with an apparent minimum of three subduction zones to unify the Angola-Congo, South America and the Kalahari cratons, if they had been separated by oceanic crust. It is most probable that the tectonic regime changed from extensional to compressive during the Neoproterozoic, but how large had been the proposed oceanic basins and how was the proposed subduction zones orientated (if they have existed) is unknown. Subsequently, the area from central Argentina to southern Brazil and from the southern Gariep Belt to eastern South Africa have been covered with mainly recycled clastic successions of Cambro-Ordovican to Carboniferous ages. The western margin of Gondwana may have been affected by an active margin since c. 600 Ma until the Permian (or even today) interrupted by times of quiescence during the Upper Cambrian and Upper Ordovician to Lower Carboniferous.