The granite units and their tectonic settings in the Gamba-Tingri zone, southern Xizang

The granites in the Gamba-Tingri zone are arranged into the Lhagoi Kangri tectonic-magmatic belt in southern Xizang. The rock types consist dominantly of porphyroid two-mica monzonitic granites, biotite monzonitic granites, monzonitic granites and gneissoid two-mica monzonitic granites. The granites may be grouped, on the basis of petrology, petrochemistry, geochemistry and contacts, into five units, all of which are incorporated into one supraunit, i.e. the Paikuco supraunit. The study of petrology, petrochemistry and geochemistry shows that all the granites within the supraunit are assigned to the S-type granites and comagmatic granites formed in the syn-collisional tectonic settings on passive continental margins.