Zircon SHRIMP U-Pb age of volcanic rocks in E'erlongba Formation,eastern part of the Qiangtang basin,Qinghai-Tibet Plateau,China and its geological significance

A suite of volcanic rocks to volcaniclastic rocks overlie the Triassic E'erlongba Formation in the eastern part of Qiangtang basin, northern Xizang, China. The SHRIMP zircon U-Pb ages of the lower basalt from this strata can be categorized into two groups: 220.4±2.3 Ma and 241.4±3.6 Ma respectively. The former represents magma emplacement age of the E'erlongba Formation volcanic rocks in the eastern part of the Qiangtang basin region, while the latter is related to collision and uplift events during Middle Triassic period. Early stage sedimentation of basin evolvement during Mesozoic went through an overlapping process from continental to marine facies, sedimentary overlap started from the alluvial/fluvial facies, along with intrusion, eruption and pyroclaistic sedimentation, reflecting a upward deepened transgression sequence, which indicates a rift basin.