Tarim Large Igneous Province Caused by a Wide and Wet Mantle Plume

Large igneous provinces (LIPs) can form by interactions between a hot mantle plume and the lithosphere. The Tarim LIP between similar to 300 and 280 Ma, located in Northwest China, has been investigated by geochemistry and sedimentology studies. However, the factors controlling Tarim LIP formation and the ancient Tarim plume characteristics remain unclear. Here, a series of 3-D geodynamic models are combined with geological observations to constrain the Tarim LIP evolution and the features of the related Tarim plume. Our results show that (1) an ancient plume produced abundant melts attributed to decompression melting, excess temperature, high water contents, and slow plate motion velocities to form the banded Tarim LIP. (2) The simulated pre-eruption topography coincides with the stratigraphic records from the late Carboniferous to early Permian. Specifically, the swell area of pre-eruption topography is sensitive only to the plume radius and enables us to constrain the ancient mantle plume size well. (3) Based on the volcanic activity and pre-eruption topography, we infer that the ancient Tarim plume had a very large radius of similar to 200 km, a high excess temperature of similar to 250 K, and a high water content of similar to 5 wt.%. (4) Our parameter tests and global plate reconstruction results show that high water contents and slow plate motion velocities facilitate continental flood basalts to form with thick lithosphere. Our geodynamic modeling not only provides new constraints for the Tarim LIP evolution but also first quantificationally demonstrates that water in the mantle plays a key role in continental flood basalt formation.