Geochemical exploration for gold in western Turkey: success and failure

Abstract

BLEG (bulk leach extractable gold) 180 μm stream sediment geochemical data over the Sogut–Eskisehir–Sivrihisar area in Western Turkey resulted in the discovery of the Turkmen base metal mineralization. The Sogut Sb–W–Au and Kaymaz Au–Ag deposits occur within a thrust belt but no mineralization has been reported previously between Sogut and Kaymaz. The BLEG Ag/Au ratio at Sogut is low (maximum 1.7), suggesting Ag-poor Pb–Zn mineralization, whereas the ratio at Turkmen is extremely high (maximum 86), indicating Ag-rich Pb–Zn mineralization. This Ag enrichment is further demonstrated by a soil survey data yielding up to 100 ppm Ag. Silver is a weak pathfinder for Au at Sogut, whereas As, Pb, Zn and Ag exhibit significant correlation with Au at Turkmen. As is also useful, being more mobile than Sb. Turkmen area exhibits abundant base metal enrichments in 180 μm stream sediment samples and Pb–Zn anomalies are consistently strong over its northeastern part. Although the BLEG sampling did not lead to the discovery of the small Kaymaz epithermal Au deposit, it appears to be a time- and cost-efficient stream geochemical technique for discovering relatively large primary geochemical haloes encompassing the large precious (Au, Ag) and base metal (Cu, Pb, Zn) deposits. Orientation studies of mineral deposits should be conducted to establish ancient to recent mineral productivity of the area under consideration before BLEG stream sediment surveying to decrease the percentage of failure in discovering precious and base metal deposits.