Petrology and LA-ICP-MS zircon U-Pb age of the ore-bearing porphyry in the Walegen gold deposit at the juncture of the Qinling-Qilian-Kunlun orogens

The middle Triassic calc-alkaline arc magmatism and its related porphyry-skarn type Cu-Au, Cu-Mo and Ag-Pb-Zn polymetallic deposits are widespread at the juncture of Qinling-Qilian-Kunlun orogens. The Walegen Au deposit is a newly-discovered porphyry deposit. The host rocks of the Walegen deposit are quartz porphyry and granite porphyry, with the quartz porphyry more closely related to gold mineralization. The results of zircon U-Pb analysis by using LA-ICP-MS technique indicate that the granite porphyry was formed in middle Triassic (237Ma), and contained voluminous Paleozoic-Proterozoic inherited zircons. These characteristics are similar to characteristics of other porphyry Cu-Au deposits in this region. These data suggest that the magmas produced by northward subduction of Paleo-tethys ocean captured pre-Triassic crust and mantle materials, resulting in the arc magmatism and the formation of related porphyry-skarn deposit assemblage at the juncture of Qinling-Qilian-Kunlun orogens.