Zircon SHRIMP U-Pb age of the layered mafic rock mass in Panxi area, Sichuan Province, and its geological significance

In this paper, based on the application of SHRIMP zircon U-Pb dating method, the authors studied the age of the orecontaining layered basic-ultrabasic rocks in western Panzhihua area, with the U-Pb ages of zircons from the Baima layered gabbro body being 258±2Ma (95% confidence) and those of zircons from the Taihe layered gabbro body being 262±2Ma (95% confidence).These data show that both Baima and Taihe ore-bearing gabbros in western Panzihua metallognetic belt were formed in Late Perm-ian.The age information also suggests that the time gap between the intrusion of the layered gabbro body and the eruption of the Emeishan basalt (peak at 250Ma) was only about 5~10Ma, and both the intrusive rocks and the basalts should have resulted from mag-matic activities at different stages.Considering the spatial relationship between the layered gabbro body and the Emeishan basalt and consulting the above age dating results, it is suggested that both the mafic ultramafic rocks and the basalts were formed at the end of the late Paleozoic period and associated with the Emei mantle plume activity.