Peraluminous granites of East Tethys and their implication in Gondwana dispersion and Asian accretion

Abstract

Peraluminous granites are widely distributed in East Tethys. Among them, the Darongshan Granite in southeast Guangxi, the Lincang Granite in western Yunnan and the leucogranites in the High Himalayas are the most important. The granites are composed of cordierite-biotite granite, granitic porphyry (Darongshan), monzogranite (Lincang), or leucogranites (High Himalayas) with A/CNK values generally higher than 1.1 and high initial ratios of 87 Sr 86 Sr . The peraluminous granites are often associated with metamorphic rocks and migmatites which were sometimes predated by mylonites. Studies of tectonic settings and petrology, especially petrochemistry of the peraluminous granites indicate that they may be genetically related to the continent-continent collision. The Darongshan Granite might be related to the collision between two smaller continental blocks of the Asian Plate, while the Lincang Granite and the leucogranites in the High Himalayas should be related to the continent-continent collision between Indian Plate and Asian Plate. Three stages of formation of the peraluminous granites are distinguished: (I) mylonitization; (II) migmatization; and (III) magmatism.