Bulong quartz-barite vein-type gold deposit in the Xinjiang Uygur autonomous region, China

The Bulong gold deposit, located in Akqi County, Southwest Tianshan, China, is hosted in Upper Devonian fine-grained clastic rocks. Gold mineralization is controlled by a series of gently- dipping fracture zones. The δ34S values of pyrite range from 14.6 to 19.2‰ and those of barite from 35.0 to 39.6‰, indicating that the sulfur was probably derived from the surrounding sedimentary rocks. The 3He/4He ratios of fluid inclusions in pyrite are 0.24–0.82 R/Ra, the 40Ar/36Ar ratios vary from 338 to 471, and the 40Ar/4He ratios range from 0.015 to 0.412, indicating that the ore fluids of the Bulong gold deposit were mainly derived from the crust. The δ13CPDB values of fluid inclusions in vein quartz define a narrow range of −4.6 to −1.4‰. The δ18Ofluid values of 6.7 to 14.7‰, and δD values of fluid inclusions of between −70 and −55‰. The combined isotopic data imply that the ore-forming fluids of the Bulong gold deposit were mainly derived from basinal fluids, with some minor contributions from magmatic fluids and meteoric water.