ABSTRACT
The Niuxinshan gold deposit occurs as gold-sulphide-quartz veins, mainly within Archaean amphibolites and also within greisen zones of the Niuxinshan granite. The mineralizing fluids were characterized by H2O-CO2-NaCl fluids with low to moderate salinities of 3 to 11 wt.% NaCl equivalent and XCO2 values of 0.1 to 0.4. Trapping P-T conditions of the fluids were 250 to 380 °C and 1 to 3 kbar. δl3C values of carbonates and fluid inclusion CO2 in vein quartz are between -6.1 and -2.5‰ (PDB). Calculated δ18OH2O values of vein quartz and δDH2O values of sericite range from +3.9 to +7.1‰ (SMOW) and from -26 to -20‰ (SMOW), respectively. Measured δDH2O values of fluid inclusions in vein quartz range from -85 to -64‰, suggesting that the fluids were derived from a magmatic source and mixed with meteoric waters.
