The Dominion Group, Witwatersrand Supergroup, and Ventersdorp Supergroup constitute a volcanosedimentary sequence that is famous for its fossil gold placers. It has been estimated that since gold-bearing conglomerates were discovered near Johannesburg (Fig. 4-1) in 1886, mines in the Transvaal and Orange Free State have produced more than 55 percent of all the gold ever mined in the world (Pretorius, 1976). The level of activity in this South African industry may be gauged from the fact that 300,000 workers develop 1000 km of underground tunnels at an average depth of 1650 m every year; 108 metric tons of ore are mined to produce approximately 700 metric tons of gold annually (Gay and Jager, in press).
KeywordsZircon Sedimentation Lithology Azimuth Sorting
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