New CO isotopic data on supergene minerals from the Skorpion and Rosh Pinah ore deposits (Namibia): Genetic and paleoclimatic constraints

The δ18O and δ13C compositions of Skorpion calcite indicate that the precipitating supergene fluids remained roughly unchanged, but that the bicarbonate from the host rock became prevailing. This suggests that calcite formation occurred at the beginning of the last late Miocene-Pliocene semi-arid period, when the host marbles were uplifted and karstified, thus promoting a higher bicarbonate contribution from dissolving host rock.