Carpathian Journal of Earth and Environmental Sciences

Using temperature in microscope, composition and hydrogen and oxygen isotope testing, this study provides an in-depth analysis on fluid inclusions’ parameters of the Daxigou gold mine and the characteristics of the ore-forming fluid. The results show that the inclusions in the quartz which displays close relations with Daxigou gold mineralization contain three types of inclusions: gaseous inclusion, gas-liquid inclusion and liquid inclusion, of which the latter two types are most common. The homogenization temperatures of the inclusions are mainly concentrated in 175°C ~ 275°C, with the salinity of 2% to 7%, the fluid density of 0.804 ~ 0.959g/cm³, and the mineralization depth of 1.01 ~ 2.24km. The vapor in fluid inclusions is mainly composed of H₂O and CO₂; in fluid inclusions liquid, the main cations are Na+ followed by Ca²⁺, K⁺, and the anions are SO₄^2- and Cl^- followed by only traces of F^-. The δ¹⁸O water values in quartz are 2.1 ‰ ~ 5.8 ‰, and the δD values are -87‰ ～ -103.67%, reflecting the ore-forming fluids coming from magmatic water and atmospheric precipitation. By calculating the gas fugacity, gold in the Daxigou gold ore-forming fluids mainly migrates in the form of complex [Au (HS)₂]^-. The complex process and hydrothermal alteration are the major factors for gold precipitation and enrichment.