Earth Science Frontiers ›› 2020, Vol. 27 ›› Issue (2): 254-275.DOI: 10.13745/j.esf.sf.2020.3.21

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The orogenic Au mineralization system and regional tectonic evolution in the Kalamaili area, East Junggar, Xinjiang.

GU Xuexiang,ZHANG Yongmei,GE Zhanlin,CHEN Weizhi,XU Jingchi,HUANG Gang,TAO Wei   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, China
    2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences (Beijing), Beijing 100083, China
    3. No.5 Gold Geological Party of Chinese People’s Armed Police Force, Xian 710100, China
    4. No.10 Gold Geological Party of Chinese People’s Armed Police Force, Kunming 650100, China
    5. Regional Institute of Shaanxi Bureau of Geological Exploration, Xianyang 712000, China
  • Received:2019-12-18 Revised:2020-02-22 Online:2020-03-25 Published:2020-03-25

Abstract:

 Au deposits, including the Jinshuiquan, Shuangquan, Nanmingshui, and East Sujiquan Au deposits in the Kalamaili area of eastern Junggar, Xinjiang, constitute a mineralization system related to the late Paleozoic collisional orogeny. The deposits are sandwiched between the regional Kalamaili and QingshuiSujiquan faults. Au mineralization is controlled by the subsidiary brittleductile faults in slightly metamorphosed, late Paleozoic volcanic sedimentary rocks, and typically occurs as mediumtosteep dipping auriferous quartz veins and surrounding altered rocks. Fluid inclusions, HOSPb isotopes, and hydrothermal zircon UPb dating indicate that the oreforming fluids are characterized by mediumtohigh temperature (mostly 240-330 ℃), low salinity (<6 wt% NaCleq), and CO2rich metamorphic water. The oreforming material was sourced from host volcanic sedimentary rocks. Fluid immiscibility (phase separation) and fluidrock interaction (wallrock sulfidation) are the principal mechanisms of Au deposition. The timing of mineralization was approximately 314 Ma, and  mineralization depths ranged from 7 to 15 km. From the Late Carboniferous to Early Permian, the transition of the tectonic system from compression to strikeslip or strikeslip extension in the study area resulted in the migration of deep metamorphic auriferous CO2H2ONaCl±CH4 fluids to shallower depths along NW to EWtrending strikeslip faults. Au precipitation in the subsidiary faults of the brittleductile transition zone or brittle deformation zone led to the formation of auriferous quartz veins and related altered rock ores.

Key words:  orogenic gold deposits, mineralization system, regional tectonic evolution, Kalamaili, eastern Junggar, Xinjiang

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