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[SIT10-05] Where was the Permian Emeishan mantle plume in southwestern China?
Keywords:mantle Plume, Emeishan LIP, Permian
However, recent structural, petrological, sedimentological, and geochemical evidence, together with precise zircon U–Pb dating, does not support previous interpretations of a mantle plume beneath the Emeishan LIP. Recent data show that the apparent 1 km of domal uplift is an artifact of modeling multi-stage deformation. Furthermore, there is no distinct spatial pattern in Ti-enrichment, only with respect to lower (low-Ti) and upper (high-Ti) profile features. Additionally, the initial response of the lithosphere to mantle upwelling would have been a rift system. Rather than picrite lava, there are mafic–ultramafic intrusions and cumulative olivine phenocrysts with corrosion structures, which cannot be used as evidence of a high-temperature primitive magma. Precise U–Pb age data show that the basalts erupted over a period of 10–15 Myr, but large-scale eruptions occurred rapidly within a period of ca. 5 Myr. However, the record of paleobiological evolution shows that the mass extinction event did not coincide with the large-scale eruptions during the 5 m.y. interval.
The available evidence does not support the hypothesis of a mantle plume beneath the Permian Emeishan flood basalt province. As the Emeishan LIP formed during the assembly of the Pangea supercontinent, the large-scale upwelling of volcanic magma may be explained by horizontal flow of the asthenosphere and northward motion of the Yangtze plate.