Crust structure beneath Tengchong-Lincang region, Yunnan province, revealed by transform function

Based on three-component teleseismic records from portable digital seismic stations deployed in the Tengchong-Lincang region of Yunnan province, the S-wave velocity structure beneath 30 teleseismic stations are inversed by using the transform function method and SA technique. The result shows that in the region the S-wave velocities around the crust-mantle boundary and the velocity jump across the Moho discontinuity are clear, resulting in the mean thickness of the crust about 40 km with the tendency of northward increase. A common feature from the inversion result is that in the lower crust exists an obvious slow velocity zone about 10-20 km thick. Meanwhile, the velocity structure of the upper mantle below most stations is complex, suggesting that lithospheric deformation and material exchange between the crust and the upper mantle should exist near the India-Tibet collisional zone. Therefore, the presented result should provide new evidence for studying the lithospheric deformation and tectonic evolution around the Tengchong-Lincang region of the Southeastern Tibetan plateau, such as the proposed lower-crust channel flow model.