Carbon, oxygen and sulfur isotope characteristics and their constraints on mineralization in Qianchuiliu gold deposit, Jiaodong Peninsula

The Qianchuiliu gold deposit, newly discovered in recent years on the northeastern margin of the Jiaolai Basin, is a pyrite-carbonate vein-type gold deposit. Unlike the previously known altered-rock and quartz-vein-type gold deposits, its gold mineralization is closely associated with pyrite mineralization and ankerite alteration. Together with the nearby Liaoshang and Xilaokou deposits, it forms a pyrite-carbonate vein-type gold metallogenic belt. The Qianchuiliu deposit contains approximately 13.5 tons of Au reserves, with an average grade of 3.47g/t. Seventeen gold orebodies have been identified, dominated by pyrite-sericite-altered granitic breccia and pyrite-carbonate vein types. The mineralization can be divided into three stages: the pyrite-sericite stage, the gold-pyrite-ferrodolomite stage, and the dolomite stage, with the main mineralization corresponding to the gold-pyrite-ferrodolomite stage. Dolomite from the dolomite stage shows δ13CV-PDB values of -3.9‰ to -3.3‰ (average -3.6‰) and δ18OV-SMOW values between 9.1‰ and 10.5‰ (average 10.1‰), exhibiting varying degrees of depletion relative to the marble of Jingshan Group. In-situ sulfur isotope analyses of pyrite from the three mineralization stages yield δ34S values ranging from 10.2‰ to 10.7‰ (average 10.4‰), suggesting a mixed magmatic-hydrothermal and upper crustal Jingshan Group signature. Considering regional geological events such as Pacific Plate subduction, asthenospheric upwelling, and the tectono-magmatic evolution of the Jiaolai Basin, the Qianchuiliu pyrite-carbonate vein-type gold deposit likely formed from deep-sourced, ore-bearing hydrothermal magma derived from metasomatized, enriched mantle material. During its ascent, the fluid assimilated components from the Jingshan Group, forming a crust-mantle mixed-source fluid. Ultimately, within the detachment structures along the basin margin, abrupt changes in physicochemical conditions-such as steep structural angles and rapid temperature drops-led to gold precipitation, forming the pyrite-carbonate vein-type gold deposit.