Evolution of an Archaean intracratonic basin: A review of the Transvaal Supergroup lithostratigraphy in Botswana

Several lithostratigraphic and radiometric-dating studies over the last half century have generated a robust stratigraphic data set about the Transvaal Supergroup sedimentary deposits throughout southern Africa. The Transvaal Supergroup in southern Africa represents one of the best examples of a Precambrian intracratonic sequence, including one of the best preserved and extensive Archaean/Palaeoproterozoic carbonate platforms. Sediments of the Transvaal Supergroup are hosted on the Kaapvaal Craton in three areas of South Africa and Botswana. Critically, the smallest of the three Transvaal depocentres, the Kanye Basin (including the Molepolole-Mochudi sub-basin), is the least known, and the stratigraphic model is still incomplete. The Kanye Basin in southern Botswana exposes a mixed volcanic-sedimentary succession spanning from the Meso-Neoarchaean to the Palaeoproterozoic, including the complete sequence of the Lower Transvaal Supergroup (LTS) and the lower part of the Upper Transvaal Supergroup (UTS). Although no consensus has been reached so far, the deposition of the Transvaal-age sediments in Botswana likely followed the same thermal and tectonic processes recorded in South Africa, albeit diachronously. The initial stage of rifting was followed by sediments that formed in an epicontinental sea setting that recorded the deepening of the basin. The younger sequence records the reactivation of the extensional tectonics alternating with post-rift thermal subsidence.