Using tellus stream sediment geochemistry to fingerprint regional geology and mineralisation systems in Southeast Ireland

Abstract

Regional stream sediment geochemistry provides a useful tool for screening relatively large areas for anomalous metal concentrations. Large, open-source governmental datasets represent an affordable option for smaller companies to prioritise areas for follow-up. Equally, such datasets are useful in applied geochemical research. This study investigates recently released Tellus regional stream sediment analyses for Southeast Ireland, focusing on counties Wicklow, Wexford, and parts of Kildare, Carlow, Kilkenny and Waterford. The aim is to: i) apply trace element ratios and vectors to define and confirm key lithologies and types of mineralisation previously mapped in the study area, ii) provide a tool to reconstruct the geological setting at a 1:500k regional scale and iii) outline follow-up areas from a mineral exploration point of view. I demonstrate that governmental geochemical datasets can not only define anomalous areas per se, but also support the recognition of regional geological trends and the definition of a number of ore deposit styles. The Tellus dataset for Southeast Ireland, despite its low-density and regional nature, confirmed the regional geological setting albeit in limited detail. Geochemical vectors for Li-Cs-Ta (LCT) pegmatites in the Leinster Granite as well as Volcanogenic Massive Sulphide (VMS) mineralisation in the Copper Coast and Avoca areas, were established and support previous univariate anomaly detection studies. The workflow will be particularly beneficial in remote and poorly mapped areas where geochemical surveys can add additional value to support ongoing definition of stratigraphy, lithologies and anomalous metal abundances.