Chinese Acad Sci, Inst High Energy Phys, Beijing, Peoples R China
; Univ Hong Kong, Dept Earth Sci, Hong Kong, Hong Kong, Peoples R China
One of the largest and most important metallogenic provinces in China is the East Tianshan, where seven major types of Late Palcozoic metal deposits have been recognized: (1) porphyry-type Cu-Mo-(Au) ore; (2) volcanic Fe-Cu; (3) orogenic lode gold; (4) magmatic Cu-Ni sulfide; (5) epithermal gold; (6) volcanic hydrothermal Cu; and (7) skarn Cu-Ag. Tectonically, the development of these Late Paleozoic mineral deposits was closely associated with subduction and closure of the ancient Tianshan ocean, lying between the Tarim craton and the Junggar-Kazakhstan composite block. In Late Devonian to Early Carboniferous time, the northern edge of the Tarim craton existed as a passive continental margin, whereas the ancient Tianshan oceanic crust was subducted beneath the southern margin of the Junggar-Kazakhstan block, resulting in the formation of the Dananhu-Tousuquan magmatic are and associated porphyry-type Cu-Mo-(Au) deposits. In Middle Carboniferous time, the ancient Tianshan oceanic crust began to subduct beneath the northern margin of the Tarim craton, leading to the formation of the Aqishan-Yamansu magmatic arc and associated volcanic Fe-Cu deposits. In the Late Carboniferous, the ancient Tianshan ocean closed, and a continent-arc collision occurred, leading to the formation of the Tianshan orogen. Following collision, an extensional event, associated with the emplacement of voluminous ultramafic-mafic complexes and formation of a number of large- to medium-scale magmatic copper-nickel ore deposits, occurred along the Kangger suture zone. In Early Permian time, East Tianshan entered into a post-collision stage associated with widespread emplacement of granitoid bodies and within-plate volcanism, which led to the formation of hydrothermal copper deposits, skarn-type Cu-Ag deposits, post-orogenic gold deposits, and epithermal gold deposits.