Metellogeneses In Relation To Central-Asia Style Orogeny Of Northern Xinjiang

Based on field investigation of large quantity of ore deposits and multidispline comprehensive research, the paper at first analyzed some basic geological problems puzzled division and selection of copper, gold and other orebelts in Xinjiang for a long time. According to cycle processes of plate tectonics, the major Cu, Ni, Cr, Au, Pb, Zn, Fe, W, Sn and rare metal deposits of Northern Xinjiang were divided into six tectonic stages, i.e. ore deposits in primary-rift stage, spreading oceanic stage, early transitional crust stage at the convergent plate boundary, late compressional continental margin stage at the convergent plate boundary, collision orogenic stage and extensional structural stage of post-collision. And then sub-division was made according to tectonic-formation association.The ophiolites in the Northern Xinjiang are mainly distributed around Junggar and are mainly Paleozoic in age. The geochemistry of the ophiolites suggests that they can be classified into three types, MORB-like, MORB+IAB and MORB+Transitional+IAB respectively, which record the magmatism related to the formation of middle-oceanic ridge, back-arc basins, from their initial rift stage to mature spreading.Based on petrology, geochemistry and metamorphism, the back-arc basin setting of Ashele-Kelang Devonian basins in Altay was fully proved, instead of former island arc or continental marginal rift setting.The paper suggested that Huangshan-Jinerqian Cu-Ni-bearing mafic-ultramaficintrusions(single grain zircon U-Pb age 285Ma) are products of mantle diapir under continental crust tensional setting after collision orogen stage instead of ophiolite suite, analyzed the distribution features of subaerial volcanic epithermal gold deposits in Northern Xinjiang and its implications to exploration for porphyry copper deposits, and then discussed the possible inherent linkage in orogin among the paleozoic ophiolite, "Alaska-type" ultramafic-mafic complex and alkaline-rich granitoids in Northern Xinjiang.The discovery of Tuwu-Yandong Large porphyry Cu deposits is the most important breakthrough for exploration in Xinjaing even in the whole China. The single grain zircon U-Pb age of ore-bearing porphyry is 356 Ma, K-Ar age of altered sericite is 341 Ma. The evolution and metallogeny of Dananhu-Tusuquan island and Aqishan-Yamansu back-arc basin at the south were discussed. We got great prospecting success at Kalatage acid alteration-Cu-Au mineralization target in the Paleozoic uplift at the south margin of Tu-Ha basin.The geology of Xinjiang is characterized by well developments of many ophiolite belts, high-alkaline intrusive rock belts, mafic-ultramafic complexes, and ductile-shear zones. Its basins bear abundant oil and gas, its orogenic belts team with abundant Cu, Ni, Au, Cr and Fe resources. Its volcanic-intrusive formation, metal deposit types and their association show some intimate similarity with the metallogenesis of Southeast Asia Cenozoic archipelago. Taking ore deposits and volcanic-sedimentary formation as guides to development stage and evolution of regional tectonics, the evolution model of Proterozoic Prime Tianshan ocean and Paleozoic Junggar archipelago-type collisional orogen at Xinjiang was suggested.