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Geochemical and isotopic constraints on the genesis of the Jueluotage native copper mineralized basalt

Eastern Tianshan, Northwest China

This study is part of a series of CET initiatives in China. Specifically, this project looks at a native copper mineralised basalt (NCMB) occurrence located in the Jueluotage Carboniferous Rift Belt, Eastern Tianshan, Xinjiang Uygur Autonomous region, Northwest China. The goal is to establish the geological, geochronological and geochemical architecture of the area and define its spatial and genetic relationships with a wide range of magmatic Ni-Cu-PGE systems. 

On the basis of recent geochemical and geochronological data, it is suggested suggest that the NCMB are associated with high iron tholeiitic basalts, which were sourced from a depleted continental lithosphere garnet-bearing peridotite mantle through fractional melting at a depth about 90~100km. The NCMB primary magma was 1) relatively low in silica and magnesium, 2) did not assimilate appreciable amounts of crustal material upon emplacement and crystallization, and 3) underwent only slight spinel and olivine mineral fractional crystallization during the magmatic evolution process. Our data support the hypothesis that NCMB magmatism was probably caused by lithosphere delamination in a post-collisional continental extensional environment. NCMB combined the Permian Cu-Ni mineralised mafic intrusions in Jueluotage area were probably successive magmatism and last about 40 Ma (307Ma~269Ma), while the latter mafic magmatism (290Ma~269Ma) were probably involved by lateral flow of Tarim Permian mantle plume (292Ma~272Ma). This study will bear significant implications on the understanding of the overall evolution of the lithospheric architecture in the area.