Origin and Evolution of the Cape Mountains and Karoo Basin

It has been 25 years since the last major conference and excursion across the Cape-Karoo was held, the results of which were subsequently published in a small book. This new book emerged from a recent follow up Imbizo (= South African meeting, especially a gathering of the Zulu people called by the king or a traditional leader) and excursion. It presents the latest research on the geological, geochemical, geochronological, biological, and geomorphic evolution of the unique and largely untouched landscape of the Cape Mountains and the Karoo Basin, a region in South Africa that is currently being targeted for shale gas exploration and development. Featuring up-to-date graphics, maps, drill-core and seismic data, it offers the latest observations and synthesis, and highlights areas of ongoing research.§§Following the amalgamation of disparate continental fragments into the supercontinent Gondwana, a series of unique Paleozoic-Mesozoic sequences that form the Cape-Karoo system were preserved along the southernmost mountains of Africa. The sequences hold a unique fossil record of Gondwana's colonization, with early fish and amphibious tetrapods just prior to one of the world's best archived paleo-ice ages (Dwyka), and after which mammal-like reptiles, early flora and coevolving insects, and a large variety of dinosaurs evolved, as well as a unique terrestrial record of the Permo-Triassic boundary that has spurred a long tradition of discourse on the science of stratigraphy.§§Shortly before and after this rapid Paleozoic-Mesozoic transition, the Cape-Karoo sequences were deformed by thrusts and folds to form the linked Cape Fold Belt-Karoo foreland basin. During this process the early Karoo sequences were deeply buried and matured to form unconventional gas resources and, closer to the surface, coal. At the surface the Karoo deposition continued (with local concentrations of uranium) under increasingly hot and dry desert-like conditions until ca. 182 Ma, when it was penetrated at depth by large volumes of dolerite sills (whose thermal disruptions have in places depleted the gas resources) linked to the eruption of large basalt caps, part of the Karoo LIP (Large Igneous Province) when Africa started to break away from Gondwana as the southern Oceans opened.§§The book also considers a wider connection of the Cape-Karoo system to other basins in Central Gondwana, including South America, thus following in the footsteps of A.L. du Toit. Clearly, there is still much to be learned before shale-gas development can be considered, and this book provides valuable and timely perspectives. §§