Citation: | LI Huaqin, WANG Denghong, REN Haitao, WANG Xiaodi, JIA Xiaohui, YANG Wenqiang, WANG Lei. Zircon SHRIMP U-Pb age of the layered mafic rock mass in Panxi area, Sichuan Province, and its geological significance[J]. Geological Bulletin of China, 2017, 36(5): 691-697. |
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.
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Distribution of the intrusive complex in western Panzhihua area
Microscope photos showing the features of the ore-bearing mafic-ultramafic rocks from the Baima ore district
Microscope photos showing the features of the ore-bearing mafic-ultramafic rocks from the Taihe ore district
Cathodoluminescence (CL) image of zircons from the Baima (a) and the Taihe (b) intrusive rocks and the 206Pb/238U apparent age of measuring points
Concordia diagram(a) and 206Pb/238U weighted average age(b) of SHRIMP U-Pb data of zircons from Baima intrusive rocks
Concordia diagram (a)and 206Pb/238U weighted average age(b) of SHRIMP U-Pb data of zircon from Taihe intrusive rocks