Detrital gold, heavy minerals and sediment geochemistry elucidate auriferous mineralization in southeast Ireland

Recently published Tellus geochemical data for sediment fines in SE Ireland show extensive Au anomalies in north Wexford, but few anomalies in Wicklow despite historical extraction from the Goldmines River. Discovery of bedrock sources is hampered by glacial dispersion and scarce bedrock exposure. Here we describe a novel approach to characterizing regional gold metallogeny which involves the synthesis of data sets from stream sediment surveys, analysis of heavy mineral concentrates (HMCs) and detrital gold. Mineralogical characterization of HMCs and 2160 gold grains from 40 localities in the auriferous region provides a clear indication of proximity of gold to source and genetic origins. Detrital gold in the south of the region (Wexford) is most likely derived from the widespread stratabound Au-As-Fe-S reported by exploration companies, whereas the distinctive Pb-Bi-As mineral inclusion signature in detrital gold from the Goldmines River area is suggestive of a magmatic influence. Combining data sets from the different techniques yields superior information than is possible using each approach in isolation.