Ore Forming Fluids of Several Gold Deposits in the Irtysh Gold Belt, Xinjiang, China

Abstract

The metallogenic environment of the Irtysh gold belt in Xinjiang is studied in detail. The metallogenic geological background, metallogenic conditions and ore-controlling factors of the gold deposits in eastern, central and western regions of the metallogenic belt are compared. The metallogenic structure of the Irtysh tectonic belt has the characteristics of diverging to the west and converging to the east. Composite ore controlling by ductile shearing and magmatic activity in Irtysh gold belt result in zoned and segmented distribution of gold mineralization. Through the fluid inclusion research and H-O-S isotope analysis, the evolution regularity of gold ore-forming fluids in the region was analyzed. Synchrotron radiation X-ray fluorescence was used to analysis the concentration of metal elements in a single fluid inclusion, explaining the occurrence and migration process of Au in hydrothermal fluid. The source of ore forming minerals in western gold deposit is more closely related to magmatic activity, and the structural metamorphism of eastern gold deposit has greater influence on mineralization. Metallogenic fluids of gold deposits are characterized by metamorphic water (and magmatic water) in the early stage and mixed with meteoric water in the late stage. And the metallogenic elements are enriched in CO2 rich fluid. The Au is mainly activated, migrated and enriched with the mixed fluid of magmatic hydrothermal, metamorphic hydrothermal and atmospheric precipitation in the medium-low temperature, shallow to medium-deep environment.