The lithosphere-asthenosphere boundary revealed by S-receiver functions from the Hi-CLIMB experiment

Abstract

SUMMARY Detailed high-resolution images of the crust–mantle and lithosphere–asthenosphere boundaries (the Moho and the LAB, respectively) have been well observed by applying an S-receiver function technique to data collected by the Hi-CLIMB (Himalayan-Tibetan Continental Lithosphere During Mountain Building) experiment. The Moho depth variation in the range of ∼50–70 km is in good agreement with that from previous P-receiver function results. The significant variation in the LAB depth indicates that the subducting Indian lithosphere drops northwards from a depth of ∼80 km beneath the Himalayas to ∼130 km just north of the Bangong–Nujiang suture at ∼33.0 ◦ N, and undergoes a transition from low angle to flat subduction beneath the Yarlung–Zangbo suture. Our findings provide new seismic constraints on the 3-D subducting configuration of the Indian lithosphere beneath Tibet.