Geology and stable isotope geochemistry of the Shuangwang gold deposit in Taibai County, Shaanxi Province

Abstract：The Shuangwang gold deposit, located in the east of the Fengtai ore concentration area of West Qinling, is a large gold deposit of auriferous albite breccias type. The ore deposit occurs in the weakly metamorphosed upper Devonian Xinghongpu Group, dominated by calcareous siltstone, sericite silty slate and carbonate that comprise flyschoid formation. Gold mineralization is strictly controlled by auriferous breccia bodies. Pyrite is the most important ore sulfide, and the main wall-rock alteration is albitization. Systematic stable isotope analyses show that the ore-forming fluids of the early and the main stages came from mixed fluids and those of the late stage mainly came form magmatic hydrothermal fluids with the addition of a little meteoric water. Carbon was derived mainly from the great depth and partly from the dissolution of carbonate strata. Sulfur is the mixed sulfur of the crust and the magma. Lead mainly came from the upper crust with the mixture of a little mantle lead. Based on the regional geological-structural background, it is concluded that the mineralization of the Shuangwang gold deposit was related to the Late Triassic collision between the North China Plate and the Yangtze Plate. The early stage mineralization was mainly caused by hydrothermal metasomatism, and the main gold mineralization occurred at the hydrothermal filling stage after the blasting action. The Shuangwang gold deposit is genetically a cryptoexplosive breccia type gold deposit.