3-D S Wave Crustal Velocity Structure Beneath the Ne Tibetan Plateau - Constraints from Receiver Function And Deep Seismic Sounding

The growth model of the Northeastern Tibetan Plateau has been controversial for a long time as the absence of reliable crustal structure model. To research the variation of crustal thickness and velocity structure of the NE Tibetan Plateau, we integrated the teleseismic receiver functions inversion results and several 2-D S-wave velocity models from deep seismic sounding data, and interpolated a 3-D S-wave crustal velocity structure of the NE Tibetan Plateau. The model shows remarkable velocity variation between different tectonic blocks and stepwise thickening crust in the NE Tibetan Plateau. Moreover, there is strong lateral heterogeneity in the same tectonic belt. Several typical 2-D velocity profiles extracted from the 3-D model show the prominent differences in the distribution of crustal low-velocity zones below the orogenic belts. The discontinuous distribution feature of crustal low-velocity zones indicates that the thickening of crust in the NE Tibetan Plateau is not dominated by the lower crustal channel flow. Combined with other research results, we hold that the NE Tibetan Plateau is accommodated by the horizontal shortening of the overall crust during the process of extrusion and shortening, while the crustal low-velocity zones play an important role in the process of mountain building.