Tectonic evolution stages of northern Xinjiang and tectonic types of porphyry-epithermal deposits

Abstract：The metallogenic ages of porphyry-epithermal deposits in northern Xinjiang are systemically summarized in this paper. Based on tectonic setting, the ore deposits can be classified into three types, i.e., ocean-continent subduction, collision orogen composed of collision sub-type and post-collision sub-type, and intra-continent. The main differences of the four type/sub-type deposits lie in metal element assemblages of the ore deposits and the associated deposit types in the same period. Ocean-continent subduction type porphyry deposits are mainly characterized by Cu-Au association, accompanied by VMS deposits as well as iron deposits related to submarine volcanism; collision type deposits and post-collision type deposits are characterized by Cu-Mo-Au association, accompanied by orogenic gold deposits; intra-continent type deposits are characterized by single metal element Mo (or Mo-Re association). Porphyry deposits and epithermal deposits belong to the same metallogenic system, but they do not coexist, and metallogenic age of the latter is later than the former by about 10Ma to 20Ma. The host rocks and metallogenic characteristics of different types of porphyry-epithermal deposits don’t show symbolic difference. Porphyry deposits in different metallogenic epochs show genetic and regional “isospatial metallogenesis” characteristics and zoned distribution; from early to late the deposits expanded gradually from the position close to the suture belt outwards, and from linear distribution to planar distribution.