NEW EVIDENCE FOR NEOARCHAEAN, HYDROTHERMALLY ALTERED GRANITES IN SOUTH-CENTRAL BOTSWANA

Recent drilling in south-central Botswana intersected hydrothermally a ltered dolerite and granitic rocks beneath Karoo strata on the western side of a domical structure. This structure occurs within the western part of the Kaapvaal Craton and is bounded to the west by the N-trend ing Palaeoproterozoic Kheis Belt. U-Pb dating of zircon and titanite f rom the cared granitic rock gives an age of 2928 +/- 4 Ma, which provi des a temporal correlation with hydrothermally altered racks along the northern margin of the Witwatersrand basin, South Africa. These hydro thermally altered rocks may form part of the source area for the Neoar chaean Witwatersrand gold deposits. The age also indicates that the Ka apvaal Craton extends as far west as Mabuasehube.