Geochemical characteristics, zircon U-Pb age and metallogenic significance of Chalong granites in the Gangdise Belt of Tibet

The Chalong granite is located in volcanic magma arc of the Mid-Gangdise belt. The granite petrologically consists of biotite granodiorite and granodiorite; the zircon U-Pb age of fine-grained granodiorite is 89.88±0.55Ma (95% conf., n=24, MSWD=0.43) and that of medium-grained biotite granodiorite is 86.6±1.0Ma (95% conf., n=30, MSWD=0.64). Their petrochemical characteristics indicate that they are high-K calc alkaline peraluminous "Ⅰ" type granite. The REE distribution curves are right-inclines, and the magma experienced differentiation to some extent. The trace elements Ti, Nb and P are relatively deficient. The intrusive rock resulted from the unidirectional subduction of the Yarlung Zangbo River crust, was formed in the volcanic arc environment, and was the product of intermediate acid magma with crust mantle mixing Characteristics. The genetic type of Chalong magnetite mineral deposit closely related to the intrusive rock is skarn hydrothermal superimposition type. Chalong magnetite mineral deposit has a similar metallogenic geological background to the discovered deposits in the area.