Advances in the Study of Magmatic-type Cu-Ni Sulfide Deposits in the Eastern Tianshan, Xinjiang

1.Chinalco (Xiong′an) Mining Co.,Ltd.,Beijing,100082,China; 2.State Key Laboratory of Lithospheric and Environmental Coevolution,Institute of Geology and Geophysics,Chinese Academy ofSciences,Beijing,100029,China; 3.College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing,100049,China This study focuses four representative magmatic Cu-Ni sulfide deposits—Lubei, Tulaergen, Huangshandong, and Jingerquan—located within the Eastern Tianshan region along the southern margin of the Central Asian Orogenic Belt. The Eastern Tianshan region, located at the junction zone of the northern, central, and southern Tianshan tectonic units, underwent multi-cycle evolution from Paleozoic oceanic basin subduction and collisional orogenesis to late Paleozoic post-orogenic extension, accompanied by intensive magmatic activity that provided favorable conditions for Cu-Ni mineralization. These deposits are concentrated in three tectono-magmatic belts: the XiaoReqianzi-Danahu island arc, the Kanggur-Huangshan ductile shear zone, and the Central Tianshan composite continental margin arc. The ore-bearing mafic-ultramafic complexes commonly exhibit composite intrusive bodies with concentric zoning of lithological facies, where mineralization is concentrated in the ultramafic phase. The ores are characterized by pyrrhotite-pentlandite-chalcopyrite assemblages and have commonly experienced ductile shear deformation and superimposed hydrothermal alteration. The timing of magmatism and mineralization is tightly constrained to 285-275 Ma (early to middle Permian), corresponding to a post-orogenic extensional setting where asthenospheric upwelling induced partial melting of metasomatized mantle.