Miocene leucogranites, southern Tibet: geochemical characteristics and geodynamic significance

The Miocene granites of southern Tibet are mainly distributed in the Himalayas. The rock type is two-mica monzogranite, biotite monzogranite, tourmaline-muscovite granite. The major oxides composition of granites is of SiO2 65.66-75.35 wt%, Al2O3 13.09-15.76 wt% and K2O 3.42-5.92 wt% suggesting peraluminous and alkalic features. The samples mainly fall in S-type field with few in I-type field in the ACF plot. Miocene granites formed in the settings of large-scale extension and detachment in the post-collision stage of the Himalayas from evidence of existences of TTG Group, core complex and thrust instruction in this area.