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The Late Paleozoic layered or stratoid-layered basalts in western Guangxi have similar elemental and iso-topic compositions to Emeishan high-Ti basalts. Whole- rock Ar/39Ar and SHRIMP zircon U-Pb dating were carried 40 out for the representative basalt samples in three typical pro- files in the area. Three basalts from the upper segment of Yangxu profile and lower segment of Yufeng and Min’an pro- files yield the 40Ar/39Ar plateau ages of 253.6 ± 0.4 Ma(20BS-71),255.4±0.4 Ma (20BS-99)and 256.2±0.8 Ma (20BS-119),respectively. Twenty-three analyses on 23 zircons of the basalt from the upper segment of yangxu profile give a weighted mean 206Pb/238U age of 253.7±6.1 Ma with and MSWD=2.8. These new and published geochronological data for Emeishan large igneous province (LIP) indicate that the Emeishan LIP was initiated at ~260 Ma,voluminously erupted between 253 and 256 Ma,and possibly ended at ~251—253 Ma. The age (251—260 Ma) is generally consistent with that of the associated environmental deterioration and mass ex- tinction events at the end-Guadalupian and permo-Triassic boundary. These precise geochronological data provide im- portant constraints on the dominantly eruptive time of the Emeishan LIP and understanding of the distribution of Eme- ishan high-Ti basalts and its mantle plume dynamics.
The Late Paleozoic layered or stratoid-layered basalts in western Guangxi have similar elemental and iso-topic compositions to Emeishan high-Ti basalts. Whole-rock Ar / 39Ar and SHRIMP zircon U-Pb dating were carried 40 out for the representative basalt samples in Three typical pro-files in the area. Three basalts from the upper segment of the Yangxu profile and lower segment of Yufeng and Min’an pro- files yield the 40Ar / 39Ar plateau ages of 253.6 ± 0.4 Ma (20BS-71), 255.4 ± Twenty-three analyzes on 23 zircons of the basalt from the upper segment of the yangxu profile give a weighted mean 206 Pb / 238 U age of 253.7 ± 6.1 Ma (20BS-99) and 256.2 ± 0.8 Ma with and MSWD = 2.8. These new and published geochronological data for Emeishan large igneous province (LIP) indicate that the Emeishan LIP was initiated at ~ 260 Ma, voluminously erupted between 253 and 256 Ma, and possibly ended at ~ 251-253 Ma. The age (251-260 Ma) is generally consistent with that of the associated e nvironmental deterioration and mass ex-tinction events at the end-Guadalupian and permo-Triassic boundary. These precise geochronological data provide im- portant constraints on the dominantly eruptive time of the Emeishan LIP and understanding of the distribution of Eme-ishan high-Ti basalts and its mantle plume dynamics.