LA-ICP-MS Zircon U-Pb Dating of Gneissic Granitic Intrusive Mass in Wuqiagou on the Southern Margin of Altay Orogenic Belt and Its Geological Significance

Wuqiagou gneissic biotite adamellite and the gneissic fine-grained granite dike which spread along the tectonic lines in Wuqiagou of Fuyun County of Xingjiang, exposed on the southern margin of Altay orogenic belt, and the wall rock is Supute group biotite plagioclase gneiss. LA-ICP-MS zircon U-Pb dating analysis on gneissic biotite adamellite and gneissic fine-grained granite dike were carried out. The dating results show that the gneissic biotite adamellite granite's formation age is(393.5±4.5)Ma in Lower Devonian. By comparison of regional geological settings, this rock mass was formed by the collision orogenic stage. In contrast, the intrusion age of the gneissic fine-grained granite dike is(293.5±6)Ma, which just signifies the time limit of tectonic thermal event in this area. Tectonic deformation features show the close relationship between the gneissic granitic intrusive mass and sinistral ductile shearing of the tectonic lines. The deformation and metamorphism age and the time limit of sinistral ductile shearing in this region were presumably speculated.