Abstract:

Geochronology and petro-geochemistry of garnet-bearing granite from Wulan area of Urad Zhongqi are investigated, and its forming age and tectonic background are discussed. The age of garnet-bearing granite dated by SHRIMP U-Pb of zircons is (256.4±2.2) Ma, indicating that it was formed at the Later Permian. Petro-geochemical characteristics show that the granite is weakly peraluminous I-type ones formed in post-collision tectonic settings and its sources is  the greywacke in upper continental crust. The partial melting degree of the source rocks is lower. The granite was derived from interaction of an I-type granitic liquid as a result of strong with hydrothermal fluid during the magmatic stage. According to tectonic settings, forming conditions and emplacement times of garnet-bearing granites, it is referred that the suturing between the Northern margin of North China plateform and the Southern margin of Siberian plate in research area took place before 256.4 Ma.

Key words: SHRIMP U-Pb zircons age, I-type granites, geochemistry, Urad Zhongqi in Inner Monglia