An early Proterozoic three-stage rift system, Kaapvaal Craton, South Africa

Abstract

A three-stage model that constitutes a fully evolved rift system is proposed for a number of superimposed, early Proterozoic basins on the Kaapvaal Craton. Based on interpreted depositional systems and syndepositional tectonics, this model consists of three superimposed basins: 1. (1) a pre-graben stage that influenced the Dominion Group, Witwatersrand Supergroup, and Klipriviersberg Group of the Ventersdorp Supergroup 2. (2) graben development that superimposed the Platberg Group, Bothaville, and Allanridge Formations of the Ventersdorp Supergroup 3. (3) post-graben thermal subsidence that superimposed the Black Reef Quartzite Formation and the Chuniespoort/Ghaap Group of the Transvaal Supergroup. Oblique collision of the Kaapvaal Craton and Zimbabwe Craton is interpreted to have generated stresses that initiated the three-stage system. At different time intervals, compressional deviatoric stress appears to have replaced tensional stress and kept the system in operation. Tectonically, the system is analogous to the Baikal Rift System and the Pannonian Basin System while the general configuration of the superimposed basins is comparable to the North Sea Basin or the North China Basin.