New regional correlations between the Congo, Paraná and Cape-Karoo basins of Southwest Gondwana

Abstract

Pioneering stratigraphic correlations by J. Keidel and A. du Toit, in the first half of the twentieth century, first highlighted significant similarities between the age-rock sequences in southern Africa and eastern South America, supporting A. Wegener’s concept of a united Gondwana supercontinent. Based on subsequent field investigations and modern sedimentary basin analysis of the Congo Basin of central Africa and the Paraná Basin of southeastern Brazil, we revisit these early correlations and derive new paleogeographic reconstructions of the interior of southwest Gondwana. Following late Neoproterozoic-Early Cambrian amalgamation of Gondwana, earliest Paleozoic continental red-bed sediments were deposited regionally southward across the peneplained Central African and Kalahari Shields. Thereafter, Ordovician-Devonian subsidence along a vast shallow marine platform bordering the southwestern margin of Gondwana linked the Paraná Basin with the Cape-Karoo Basin of South Africa. Equivalent sequences are absent in the Congo Basin. In contrast, succeeding Carboniferous-Permian and Triassic successions are similar in all the Congo, Paraná and Cape-Karoo Basins, including thick transgressive glacial and deglaciation sequences overlain by progressively terrestrial and arid sediments, which suggest a single Central West Gondwana Basin (CWGB) complex. This late Paleozoic-early Mesozoic cycle of subsidence of the CWGB can possibly be linked to long wavelength flexure of Gondwana continental lithosphere related to the Mauritanian-Variscan and Cape-de la Ventana orogens along the northwestern and southern margins of the supercontinent, around ca. 300 Ma and 250 Ma, respectively. Following Jurassic-Cretaceous hot and arid sedimentation across southwest Gondwana culminated in widespread deposition of northerly-derived aeolian dunes, episodically interrupted by successive eruption of Large Igneous Provinces during the initial phases of Gondwana break-up (ca. 183 Ma and 132 Ma). This shared sedimentation and climatic history of the Congo, Paraná and Cape-Karoo Basins was then disrupted by the Early Cretaceous opening of the South Atlantic Ocean and the Kalahari epeirogeny, after which the Congo Basin survived and recorded intermittent phases of lacustrine and fluvial deposition.