Genesis of the ore-bearing porphyrite in Tiegelong, Gerze, Xizang

The ore-bearing rocks in Tiegelong, Gerze, Xizang consist of dioritie-porphyrite and quartz diorite-porphyrite which are assigned to the calc-alkaline and high-K calc-alkaline rock series characteristic of I-type granites. These rocks resulted from the tectonic settings of the Early Cretaceous Bangong Lake-Nujiang oceanic basin subduction. The rockforming magmas comprise oxidized magmas derived from the juncture of the crust and mantle and are highly contaminated by the crust-derived matter. There are gaps in rock type, petrochemistry, geochemistry and tectonic setting for the orebearing rocks from the Yulong and Gangdise porphyry belts and the copper-gold deposits in the study area, implying that the copper-gold deposits in the study area should belong to the "ialsnd-arc" porphyry-type copper-gold deposits varying from the "collision" and "post-collision" porphyry-type deposits in geodynamic setting and mineralization mechanism.