Organic Matter and Mineralisation: Thermal Alteration, Hydrocarbon Generation and Role in Metallogen

A 'soft-rock' petroleum-type approach to exploration for 'hard-rock' minerals in sedimentary basins D. Taylor I. Introduction Several major groups of ore deposits are found as tabular, stratiform bodies or as cross- cutting but essentially stratabound deposits within sedimentary basins. Important exam- ples are oxide and carbonate ores of iron and manganese, copper and zinc-lead sulphides and gold-uranium deposits. Where the host basins have been strongly in- verted and deeply eroded and the mineralized horizons brought to outcrop, the laterally extensive nature of the mineralization usually results in outcrop or subcrop of the ore itself. Direct detection by geological or geochemical prospecting is then possible. Major deposits also occur in basins which have not been strongly deformed and deeply eroded as non-outcropping sub-horizontal sheets (Polish Kupferschiefer deposits of the fore-Sudetic Monocline) or linear belts (Vibumam Trend, Missouri, Admiral Bay, NW Australia). I believe that both the Polish Kupferschiefer and Admiral Bay de- posits were found by chance during oil and gas exploration, and deposits of this type are similar in attitude and dimensions to small-medium size oil and gasfields.