固物研究生论坛 - Tarim Large Igneous Province

The rising plume materials pond and spread beneath the lithosphere,and they produce a large volume of magma. The magma erupts to the surface at a short time to form the Large Igneous Province (LIP). Tarim LIP is located at the Northwest China which covers 250,000 km2~300,000 km2. Here a systematic and effective 3-D geodynamic model is implemented to constrain the Tarim LIP evolution. Our results show the following: (1) an ancient plume strongly eroding the Tarim craton can lead to the lithosphere thinning of about 50 km within 20 million years (Myr). The computed average melting extent is ~5%-8% that is consistent with the geochemical estimations. We infer that the excess temperature of Tarim plume is ~250 K. (2) The simulated pre-eruption topography is ~950 m between late Carboniferous and early Permian, that is consistent with stratigraphic records. We estimate the Tarim plume radius is ~200 km. (3) The high shear wave velocity anomalies derived from joint inversion in the middle-lower crust of Tarim craton suggests the high Fe, Mg mafic and ultra-mafic dikes intrude into the base of the crust and form the underplated magma chamber (4) Our parameters test and global plate reconstruction results show that high water contents and slow plate velocity are not necessary conditions to form the continental flood basalts.