Ages of Lüliang Group and Its Metamorphism in Mt. Lüliang Region, Shanxi Province: Evidence from Single Grain Zircon U-Pb Dating

摘要

Presented in this paper are the newly obtained grain zircon U-Pb ages of volcanic rocks of the Luliang Group and associated Kuanping granitic migmatitic gneiss in Shanxi Province. The zircon U-Ph ages of bimodal volcanic rocks (basalt and rhyolite) of the Upper Luliang Group indicate that the rocks erupted at about 2100 Ma. So the Luliang Group was formed during the Early Proterozoic. In the area studied the second-stage metamorphism experienced by the Luliang Group is the dominant one which took place at about 1806 Ma, i. e., during the late Early Proterozoic.