Geological features and geochronology of the Jinshuiquan gold deposit in the east Junggar, Xinjiang

Located in the Kalamaili metallogenic belt in the east Junggar of Xinjiang, the Jinshuiquan gold deposit is a typical orogenic gold deposit which occurs along the secondary fault zone between the Kalamaili deep fault and the major disruption of QingshuiSujiquan. The mineralization timing has been unclear up till now. Zircon species in auriferous quartz veins of this study were initially determined by cathodoluminescence electron (CL) images, Back Scattered Electron (BSE) image and mineral inclusions before the performance of LA-ICP-MS U-Pb isotopic dating on these zircons. The trapped zircons are mainly in the columnar and long columnar forms, with clear shock bands, consisting of magmatic zircons and metamorphic zircons. These zircons are larger than hydrothermal zircons. LA-ICP-MS U-Pb dating on these trapped zircons yielded ²⁰⁶Pb/²³⁸U ages of 365~418Ma and 265Ma. The hydrothermal zircons are in short columnar, angular, double cone and irregular forms and usually contain inclusions such as inherited zircon core, apatite or gold bearing apatite, some with weak band of shock waves or even without shock bands. LA-ICP-MS U-Pb dating on these hydrothermal zircons yielded a weighted average ²⁰⁶Pb/²³⁸U age of 314.9 ±3.2Ma, indicating that early Late Carboniferous gold mineralization occurred during the transition from collisional orogenesis to post-collisional extension. The metallogenic epoch was later the epoch of ore hosting wall rock, i.e., the Jiangbasitao Formation (C₁j, ~343Ma) which coincides with the time frame (320~310Ma) limited by the summarized orderliness of regional tectonic evolution from the data obtained by previous researchers. Comprehensive studies suggest that the metallogenic process of the Jinshuiquan gold deposit can be divided into three periods:the formation of gold bearing fluid at the orogenic stage during 350~320Ma, the migration and emplacement of goldbearing hydrothermal fluid at 315Ma during compression to extension stage and the fracture and deformation of gold orebody at the Permian intracontinental deformation stage.