Recent Developments Concerning the Geological History and Genesis of the Witwatersrand Gold Deposits, South Africa

A review of the Birimian Supergroup- and Tarkwaian Group-hosted gold deposits of Ghana

“…It is important to note that some gold mineralisation occurs within the quartz veins that cross cut the conglomerates, suggesting some gold remobilisation by fluids during deformation and metamorphism , similar to the modified placer mineralisation model for the Witwatersrand gold reefs of South Africa (e.g. Els, 1991;Robb et al, 1997;Frimmel and Minter, 2002;Hayward et al, 2005).…”

Recycling of Paleoplacer Gold through Mechanical and Postdepositional Mobilization in the Neoarchean Black Reef Formation, South Africa

“…The deposition of the BRF predates the 2.06 Ga Bushveld igneous event within the Kaapvaal Craton, where a series of initial rhyolitic extrusive rocks were followed by large-scale magmatism (Buick et al 2001). Magmatic underplating and intrusion of large amounts of melts into the lower to middle crust during the emplacement of the Bushveld Complex led to a notable thermal metamorphism and metasomatism in the BRF and other units of the Transvaal and Witwatersrand Supergroups (Frimmel and Minter 2002;Bose et al 2012). This tectonicthermal event significantly affected the central parts of the Transvaal Supergroup, as evident from the Transvaal Supergroup rocks that have subsided beneath the intruding Bushveld magmas.…”

Quartz-pebble-conglomerate gold deposits

“…The gold deposits located in this basin make up the largest known concentration of gold. Modified from Frimmel and Minter (2002) and Frimmel and others (2005a).…”

“…Barnicoat and others (1997) surmised that basinwide distribution of pyrophyllite, chloritoid, chlorite, and other assemblages resulted from acidic hydrogen metasomatism that also introduced the gold mineralization. Others have interpreted this assemblage to be a product of chemical weathering under acidic conditions (Frimmel and Minter, 2002).…”

“…Quartz-pebble-conglomerate gold deposits represent some of the largest gold depositories in the world; in fact, the Witwatersrand Basin represents the largest resource of produced gold in the world (for example, Frimmel, 2002Frimmel, , 2008Frimmel and Minter, 2002). Grains of native gold are found within coarse-grained sediment beds, either directly above erosion surfaces as heavy-mineral concentrates or at the top of individual beds left by winnowing.…”