Metallogenic epoch of the Shuangquan gold deposit in Qitai area, Xinjiang, China.

The Shuangquan gold deposit in Qitai County, Xinjiang, is located in east Junggar, which belongs to the Karamaili-Moqinwula mineralization belt (Ⅳ-grade metallogenic belt) of the Karamaili-Daerbute gold metallogenic belt (Ⅲ-grade metallogenic belt). In this paper, the laser microprobe 40Ar/39Ar isotopic dating was carried out on the alteration minerals of sericite and gold-bearing quartz veins in the Shuangquan gold deposit. The isochronic ages of three sericite samples are 269Ma±9Ma, 265Ma±2Ma and 260Ma±4Ma. A quartz sample returns an isochron age of 269Ma±8Ma. These results suggest that the main mineralization age of the Shuangquan gold deposit varies between 269Ma±9Ma and 260Ma±4Ma. During the large-scale continent-continent collision and the subsequent extensional tectonic movement in the early Carboniferous to late Permian, the east Junggar area underwent two large-scale fluid-thermal events which were recorded by isotopic ages of 310Ma and 260~270Ma, respectively. The former one represents an early ductile deformation and associated initial accumulation of metamorphic fluids, and its geodynamic background possibly belongs to post-collisional orogenic thrusting system. While the latter represents the main gold mineralization epoch and the formation of ore-controlling faults by brittle deformation, and its geodynamic background possibly belongs to post-collisional extension system.