PERALUMINOUS GRANITES OF EAST TETHYS AND THEIR IMPLICATION IN GONDWANA DISPERSION AND ASIAN ACCRETION

Peraluminous granites are widely distributed in East Tethys. Among the m, the Darongshan Granite in southeast Guangxi, the Lincang Granite in western Yunnan and the leucogranites in the High Himalayas are the mo st important. The granites are composed of cordierite-biotite granite, granitic porphyry (Darongshan), monzogranite (Lincang), or leucograni tes (High Himalayas) with A/CNK values generally higher than 1.1 and h igh initial ratios of Sr-87/Sr-86. The peraluminous granites are often associated with metamorphic rocks and migmatites which were sometimes predated by mylonites. Studies of tectonic settings and petrology, es pecially petrochemistry of the peraluminous granites indicate that the y may be genetically related to the continent-continent collision. The Darongshan Granite might be related to the collision between two smal ler continental blocks of the Asian Plate, while the Lincang Granite a nd the leucogranites in the High Himalayas should be related to the co ntinent-continent collision between Indian Plate and Asian Plate. Thre e stages of formation of the peraluminous granites are distinguished: (I) mylonitization; (II) migmatization; and (III) magmatism.