Genesis of adakitic porphyry and tectonic controls on the Gangdese Miocene porphyry copper belt in the Tibetan orogen
西藏冈底斯中新世斑岩铜矿带：埃达克质斑岩成因与构造控制

Most porphyry Cu deposits, a main source of base metals, occur in continent and island-arcs. Cu-bearing felsic magmas were widely regarded to be derived from the basaltic paternal magma that was formed by melting of the mande wedge, metasomatized by hydrous fluid released from the subducted oceanic slab and then evolved by crystal fractionation with or without assimilation. However, the data we present here indicate that a Miocene porphyry Cu belt with large mineral potential occurs in the Tibetan collisional orogen, and Cu-bearing porphyries show the geochemical characteristics of adakites, which were mainly derived directly from the thickened mafic lower-crust or the subducted New-Tethyan oceanic slab. The porphyry Cu systems developed during post-collisional extension after rapid uplift of the Tibetan plateau before 13 ~ 18 Ma ago. Like arc-transverse faults in arc settings, SN-trending normal faulting systems across the Tibetan orogen resulted in rapid rising and localization of adakitic porphyry magmas and sufficiently separating of large-volume Cu-bearing fluids from the magmatic-hydrothermal systems.