The discovery of the Early Triassic A-type granite in Gadasu, Jarud Banner, Inner Mongolia, and its geological significance

Gadasu A-type granite has the miarolitic structure and graphic and creep textures as well as chemical characteristics of rich silica and alumina and poor iron, thus belonging to high potassium calcalkaline series aluminum. Light rare earth curve is included to the right. The rock has rich Ga, Nb, U, poor Ba, Sr, Ti, 10⁴Ga/Al ratios of 2.64~3.18, Y/Nb ratios of 1.72~2.03, and Nb/Ta ratios of 5.99~5.99, indicating A2 type granite. Zircon U-Pb emplacement age shows that the rock mass has the age of 249.0±2.7 Ma. The authors thus infer that the granite was formed in the environment of late stage stretching and pull-apart of the Xing-Meng orogenic belt after the closure of the paleo-Asia Ocean in Triassic.