Lead isotope geochemistry of the Weishancheng gold-silver ore belt, Henan Province, China: Implications for ore genesis

The Weishancheng ore belt is located in Tongbai Mountains and consists of the Yindongpo large gold deposit, the Poshan and Yindongling large silver deposits and some small ore deposits or occurrences. All the ore deposits are stratabound and hosted in the Neoproterozoic Waitoushan Formation. These deposits have the very uniform lead isotope compositions, with (206)Pb/(204)Pb = 16.753 similar to 17.216, (207)Pb/(204)Pb = 15.417 similar to 15.638, and (208)Pb/(204)Pb = 38.251 similar to 39.050, which are close to those of the Waitoushan Formation while far different from other lithology units or batholithes in Tongbai region. Lead isotope geochemistry suggests that the ore metals were sourced from the Waitoushan Formation through metamorphic devolatilization. The Weishancheng gold-silver ore belt could be attributed to a typical stratabound orogenic-type metallogenic system. The ore-forming process occurred during the continental collision between the Yangtze and North China Blocks. The metamorphic devolatilization of the underthrust slabs induced the development of ore-forming fluid system, subsequently the intense water-rock interaction make the metallogenic materials in Waitoushan Formation were extracted, migrated and enriched in the carbonaceous sericite schist.