Arcbaean Baryte Deposits of Southern Africa

Abstract The major Southern African baryte deposits of Archaean age are of stratiform nature -and can be subdivided into two main groups. (1) Volcanogenic-exhalative deposits in the Swaziland Super-group of the Barberton greenstone belt, as well as possibly in similar rocks in Botswana and Zimbabwe. These deposits, with a strike length of up to 9 km, are frequently associated with sulphide mineralization. (2) Placer deposits in the Fig Tree Group of the Barberton belt. These formed through erosion of contemporaneous and/or mostly older volcanogenic-exhalative baryte deposits over a well-documented intraformational unconformity. The baryte beds contain notable quantities of detrital chromite as well as traces of detrital gold, molybdenite, and other heavy minerals. The zone extends over at least 12 km along strike of the schist belt and possibly up to 45 km if a number of minor occurrences of uncertain stratigraphic position are included. The various type of vein deposits found in greenstone belts and the intervening granite/ gneiss terrane are of little importance from a genetic or economic point of view. The stratiform baryte occurrences in greenstone sequences can be considered as good indicators for spatially related syngenetic base metal deposits.