Geogas prospecting for igneous ore deposits covered by regolith: The Zijinshan high-sulfidation epithermal Cu-Au deposit in the Cathaysia Block

Abstract

The mining industry faces a challenge due to the scarcity of outcrop or near-surface mineral deposits, necessitating the development of low-cost and efficient prospecting methods. Inductively coupled plasma mass spectrometry (ICP-MS) has been applied to geological sample analysis, and scientists have been gradually improving the method of geogas prospecting. As a result, geogas prospecting has shown promising results in detecting underlying concealed Au, U, and Cu-Ni deposits covered by Gobi sand and Quaternary sediments.To verify the effectiveness of this method for exploring underlying concealed mineral deposits developed in igneous covered areas, the Zijinshan high-sulfidation epithermal (HSE) Cu-Au deposit, a concealed mineral deposit in southeastern China, was selected as the experimental field. Our experiments revealed nanoscale particles composed of Au, Cu-Fe, and Cu-other elements in the geogas captured above the ore bodies of the deposit. Furthermore, Cu-nanoscale particles retain the isotopic composition of copper found in both the oxidation zone and deep copper ores. The geogas samples exhibited similar C1-chondrite normalized rare earth element (REE) distributions, with right-inclined REE patterns indicating significant enrichment of LREE relative to HREE, slightly negative δCe anomalies, and similar (La)N/(Sm)N and (Gd)N/(Yb)N ratios. These characteristics are similar to those of the gold ores, copper ores, altered rock, and bedrock near the ore bodies. These findings suggest that deep-penetration geochemical methods using geogas can be a valuable tool for uncovering underlying concealed mineral deposits in igneous covered areas.