Three-dimensional geochemical patterns of regolith over a concealed gold deposit revealed by overburden drilling in desert terrains of northwestern China

摘要

Desert terrains are widespread in northwestern and northern China, and these areas present particular challenges for exploration. In recent years, partial extraction techniques have been proven to be effective in the search for concealed deposits in arid desert terrains in some cases. However, we still lack an understanding of the dispersion patterns of ore-forming elements in regolith. In this study, air reverse circulation drillings were used to create three-dimensional (3D) distribution patterns of elements in regolith over the Jinwozi gold deposit in China, which is covered by tens of metres of regolith, in order to trace the migration of elements and to understand the dispersion mechanisms. The 3D distribution maps of elements show that (1) coherent anomalies occur at different depths of transported cover over the ore body, (2) Au tends to be enriched in the top and bottom horizons and depleted in the middle horizon in the vertical direction, (3) the anomalous distribution of Au at the bottom is restricted to places at the interface of sediments and bedrock, and (4) the anomaly in the bottom sediments is confined to a width of tens of metres, whereas that in top soils is much wider and can extend up to several kilometres. In addition, close positive correlations were found between the As, Hg, and Au distributions. (C) 2015 Elsevier B.V. All rights reserved.