Fluid inclusion microthermometry on Archaean granites in the hinterland to the Welkom Goldfield, South Africa

The subsurface basement in the hinterland to the Welkom Goldfield comprises tonalitic and granodioritic gneisses, as well as massive, porphyritic adamellites and granites. These pervasively altered granites are enriched in both gold and uranium. The hydrothermal veins that cross-cut the granites and adamellites also exhibit gold and uranium enrichment. The origin and source of the fluids responsible for the observed alteration and associated mineral enrichments is considered relevant to the source of gold and uranium in the adjacent Witwatersrand sediments. 9 refs., 1 fig