A number of large - very large porphyry Cu-Mo-Au deposit was discovered in Tibetan plateau, which has rised widespread concern in recent years. It is commonly argumed that the periods of ore-bearing porphyries and porphyry deposits mainly composed of four stages in Tibetan Pleteau, i.e., 120 ~ 110 Ma, ~ 90 Ma, 54 ~ 45 Ma and 18 ~ 12 Ma of them, the ore-forming geological background of second stage (90Ma) porphyry deposits is still controversial and hotly debated. The zircon U-Pb and Molybdenites Re-Os ages are reported in this study, with the geodynamic setting in Balazha porphyry deposits in northern Lhasa terrane. LA-ICPMS U-Pb zircon dating of two granodioritic porphyry samples concordant 206Pb/238U age of 92.1 ± 1.2 Ma and 93.8 ± 1.2 Ma, respectively, which probably record the magmatic crystallization. Molybdenites Re-Os isotopic dating shows that the molybdenite is formed at 88.2 ~ 89.6Ma, which probably represent the age of mineralization of Balazha porphyry deposits. These geochemical features, combined with other characteristics of Late Cretaceous lavas in mid-northern Lhasa terrane, indicate that ~90Ma magmatism and mineralization did not result from melting of seafloor subduction or ocean ridge subduction of the Yarlung-zangbo Ocean, or from erther southward subduction of the Bangong co-Nujiang Ocean. This mineralization may be produced in collision process, which subduction closed of the Bangongco-Nujiang Ocean. So we suggest that ~90Ma magmatism in northern Lhasa terrane and its mineralization is formed in the collision of tectonic environment.