Geochemical characteristics and source of ore-forming fluid of Duolanasayi gold deposit, Xinjiang

The Duolanasayi gold deposit, 60 km NW of Habahe County in Xinjiang, is a medium-large scale gold deposit controlled by the coupled ore-forming processes involving brittle-ductile shearing, albitite veins, and post-stage magma solution. Fluid inclusion studies indicate that the homogenization temperatures range from 160°C to 315°C with the peak values of 220–300°C. Mineralization pressures are from 21.0 MPa to 64.5 MPa. Ore fluid inclusions contain Ca2+, K+, Na+, Mg2+; HCO3-, SO42-, HS-, F-, Cl- and Au+ (maximum: 5.3 × 10-6), and the mineralizing fluid is a H2O-CO2 system. Sulfur, hydrogen, oxygen and strontium isotopic compositions [graphic not available: see fulltext][graphic not available: see fulltext] suggest that the ore-forming fluid is the mixture of magmatic water, meteoric water, metamorphic water and formation water sealed in rocks and strata. It is mainly magmatic water in the early stage, and mixing fluid of water, meteoric water, metamorphic water and formation water that occurred in rocks and strata in the major mineralization stage. The ore-forming materials were derived from the upper mantle or lower crust.