The Galale skarn gold (copper) deposit in Tibet discovered by No. 2 Geological Party of Tibet in recent years is a deposit of a certain size and potential. In this paper, with the phlogopite from the Galale sharn gold-copper deposit as the study object and by using the method of ⁴⁰Ar/³⁹Ar isotopic dating, the authors determined the ore-forming age of the Galale sharn gold-copper deposit precisely. Phlogopite crystallized between the formation of garnet and diopside and the formation of pyrite and chalcopyrite, and was closely associated with garnet, tremolite and actinolite. Test results show that the ⁴⁰Ar/³⁹Ar plateau age of phlogopite from the Galale deposit is 85.41±0.64 Ma, consistent with the corresponding isochron age 85.9±2.4 Ma. It is thus inferred that mineralization might have been related to the magmatic activities induced by upwelling mantle caused by lithospheric delamination that occurred in the north of Lhasa block after the collision of Lhasa block with Qiangtang block.