Isotope Geochemistry of the Weishancheng Stratabound Gold-Silver Ore Belt, Tongbai County, Henan Province, China

The Weishancheng ore belt is located in Tongbai Mountains and consists of three stratabound deposits (Yindongpo large gold deposit, Poshan super-large silver deposit, and Yindongling large silver-dominated poly-metallic deposit) and some small ore spots. The orebodies are strictly hosted in carbonaceous strata of the Neoproterozoic Waitoushan Formation. The H-O-C isotopic system of the fluid inclusions from each deposit indicates that the fluids in the early and middle ore-forming stages came from the metamorphic devolatilization, and in the late stage, considerable meteoric water entered the fluid system. The C-S-Pb isotope geochemistry suggests that the metallogenic materials are derived from the rocks from the Waitoushan Formation. The K-Ar and 40Ar-39Ar dating results show that the metallogenesis of the Weishancheng ore belt occurred during 100–140 Ma, when a tectonic setting changed from collisional compression to extension. The Weishancheng gold-silver ore belt belongs to a typical stratabound orogenic-type metallogenic system in terms of the ore-forming fluid, metal source, and geologic characteristics. The ore-forming process took place under the continental collision setting between Yangtze and North China plates.