Ore genesis of the Tethyan Himalayan antimony polymetallic metallogenic belt: Constraints from isotope geochemistry

Abstract

The Tethyan Himalayan metallogenic belt is a significant product resulting from the collisional orogeny between the Indian plate and the Eurasian plate. The region experienced three intricate tectonic-magmatic-mineralization stages: the 59–49 Ma Au mineralization stage, the 43–36 Ma Pb–Zn mineralization stage, and the post-collisional (25–0 Ma) Pb–Zn–Sb–Au mineralization stage. Among these, the post-collisional stage represents the most intense period of Pb–Zn–Sb–Au mineralization in the Tethyan Himalayan region. During this period, about 170 Pb, Zn, Sb, Au and Ag deposits (mineral occurrences) with different sizes and complex types were formed. An extensive analysis of isotope geochemical data from antimony polymetallic deposits within the metallogenic belt led to a comprehensive evaluation of the ore-forming fluids and mineralization processes for various deposit types in the belt. The diverse metal element enrichments and various metal deposit types in the metallogenic belt were not formed from a single fluid source. Instead, the ore-forming fluids showed characteristics of fluid mixing from multiple sources. The composition of these fluids primarily comprises formation water, magmatic water, atmospheric precipitation, geothermal water, and metamorphic fluid. However, there were similarities between the different deposit types. Ore-forming materials predominantly come from the crust, although contributions from the mantle to varying degrees have been observed. Deep magmatic fluids or metamorphic fluids within rocks play a crucial role in the ore-forming process. Simultaneously, by establishing the internal relationship between tectonic–magmatic events and Pb–Zn–Sb–Au mineralization, detailed studies on the characteristics of the ore-forming fluid and the ore-forming process were conducted.