Mesozoic mesothermal Niuxinshan gold deposit, eastern Hebei Province, NE China

摘要

The Niuxinshan gold deposit occurs as gold-sulphide-quartz veins, mainly within Archaean am-phibolites and also within greisen zones of the Niuxinshan granite. The mineralizing fluids were characterized by H_2O-CO_2-NaCl fluids with low to moderate salinities of 3 to 11 wt.% NaCl equivalent and XCO_2 values of 0.1 to 0.4. Trapping P-T conditions of the fluids were 250 to 380°C and 1 to 3 kbar. δ~(13)C values of carbonates and fluid inclusion CO_2 in vein quartz are between -6.1 and -2.5 per thousand (PDB). Calculated δ~(18)O_(H2O) values of vein quartz and 5D_(H2O) values of sericite range from +3.9 to +7.1per thousand (SMOW) and from -26 to -20per thousand (SMOW), respectively. Measured δD_(H2O) values of fluid inclusions in vein quartz range from -85 to -64per thousand, suggesting that the fluids were derived from a magmatic source and mixed with meteoric waters.