Impact structures and deposits of South Africa

Abstract Abundant evidence of impact cratering is found on the surfaces of all solid bodies in the solar system, although on Earth this evidence is more restricted owing to the effects of an active geosphere. Investigating impact structures on Earth is important not only from the perspectives of understanding Earth’s geological history and the economic significance of some impact structures, but also because of the demonstrable threat large impacts pose to life on Earth. Besides the formation of a crater, the transfer of exceptional amounts of energy into Earth’s crust during an impact creates distinctive deformation features and rock types that aid in identifying impact sites, including where the original crater form has been lost through erosion or is deeply buried. South Africa contains a small but diverse sample of impact structures in which impact processes can be investigated. The country´s four confirmed impact structures – Tswaing, Kalkkop, Morokweng and Vredefort − have ages between ~200 000 years and 2023 million years, and diameters that range from