Two fluid sources and genetic implications for the Hatu gold deposit, Xinjiang, China

• Hatu deposit is a structurally controlled orogenic gold system.
• C isotope data indicate a dominantly sedimentary source with a minor mantle addition.
• H–O isotope data suggest largely metamorphic water with minor magmatic water.
• S isotope values point to a heterogeneous sulfur source.
• He–Ar isotope data indicate a crustal source for much of the ore fluids.

The Hatu gold deposit is located in the West Junggar domain, Xinjiang, China. It contains 56 tonnes of gold. The deposit is hosted in the volcanic and sedimentary rocks of the Early Carboniferous Tailegula Group, and an ~ E–W trending ductile shear zone controls the mineralization. The gold mineralization is hosted in quartz veins and hydrothermally altered country rocks with < 3 vol.% sulfides developed along the faults. The fluid inclusions are characterized by the presence of dominant CO2 and minor CH4 fluid. The δ13CVPDB values of CH4 (− 18.7‰ to − 35.4‰) and CO2 (− 9.7‰ to − 13.9‰) in fluid inclusions from quartz and their ∆13CCO2–CH4 values (5.5‰ to 24.6‰) equilibrated at a temperature range from 299 °C to 1013 °C; these data indicate that the carbon had a dominantly sedimentary source with a minor contribution from the mantle. The oxygen and hydrogen isotope compositions (δ18O = 8.5‰ to 12.2‰, δD = − 87‰ to − 105‰) of water from fluid inclusions in quartz indicate that ore fluids comprised largely metamorphic water with a minor contribution of magmatic water. The δ34S values of sulfide from the mineral zones are between − 2.3‰ and + 2.5‰, with the exception of two values (− 9.7‰ and + 7.4‰), showing a heterogeneous sulfur source. Fluid inclusions in pyrite and arsenopyrite that are intergrown with auriferous quartz have 3He/4He ratios of 0.2 to 0.3 Ra, and their 40Ar/36Ar ratios range from 310 to 650, indicating a crustal source for much of the ore fluids. We propose that the Hatu deposit is a structurally controlled orogenic gold system which is characterized by two different fluids one dominantly derived from a crustal source with a minor component of mantle derived fluids.