Using regional geochemical survey data to trace anomalous samples through geochemical genes: The Tieshanlong tungsten deposit area (Southeastern China) case study

Abstract

In order to determine and trace geochemical anomalies in soils, a tungsten (W) metallogene was constructed according to the idea of the gold (Au) metallogene previously developed. Based on the outcomes obtained for the Tieshanlong tungsten deposit area in southeast China from both three weathered profiles and a subset of data extracted from a regional geochemical survey database, a value of 40% of similarity between a W metallogene and an ideal ore was set as a criterion to individuate samples with potential W mineralization. Based on their W or Au metallogenes, a value of 70% of similarity was also chosen as the threshold criterion to locate samples with similar genes relative to a parent rocks or its weathered products. Based on the regional geochemical survey data available for the Tieshanlong tungsten deposit area, single elemental anomalies were determined and classified by means of the “seven levels' classification” method. Integrated anomalies were also determined and classified by using similarities (relative to their ideal ore) on W and Au metallogenes. Results indicate that the determined anomaly regions are well spatially consistent with the known deposits and that the metallogenes can be used to trace mineralized soil samples. Furthermore, the location of mineralized samples sourced by (altered) magmatic rock could be well pinpointed on geochemical genes, as well.It was also observed that a value of 80% similarity for a lithogene (a geochemical gene based on a sequence of eleven immobile elements) which, similarly to metallogene, allow to compares samples to a specific parent rock and its weathered products, may be too stringent in the case of sedimentary rocks (even if metamorphosed) due to their relevant geochemical heterogeneity.