CSAMT constraints on the metallogenic mechanism of the Zhaishang gold deposit, West Qinling, China

Whether the ore-forming fluids and materials of Zhaishang Carlin/Carlin-like type gold deposit were derived from concealed Mesozoic intermediate-acidic intrusive rocks through deep faults is controversial. In this study, eight CSAMT profiles were used to investigate the electrical resistivity structure of this deposit using high-resolution 2-D inversion. A similar to 1 km wide high-resistivity (>3000 omega m) body was observed at the base of the resistivity model (similar to 600 m). Two slightly NE-dipping high-conductivity channels were also observed along two sides of the high-resistivity body that connected to the gold-bearing quartz veins at the surface. The data suggest that the high-resistivity body is a Mesozoic granite and the two high-conductivity channels are fault zone conductors, which may be the wings of an NE-trending anticline that formed under regional compressive stress during the Caledonian orogeny. Their reactivation during the Indosinian and Yanshanian periods likely formed conduits for rising deeply-sourced ore-forming fluids (likely magmatic water). These conduits also promoted ground and meteoric water infiltration and mixing with the rising fluids. Accordingly, at least some of the ore-forming fluids and materials in the Zhaishang deposit were derived from Mesozoic granites through concealed faults, which can provide new geophysical constraints for discussions of the deposit's metallogenic mechanism.