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Deep deformation of Tengchaong volcano zone and its east neighboring zone in the SE Tibetan plateau

Yuan Gao ^1\  ^ Jianhui Tian1  Xinyi Li1  Yiwen Yang1  Ying Li1

Abstract

Tengchong volcano zone (TVZ) is in the SE margin of the Tibetan plateau, near to the east Himalaya tectonic knot. Its east neighboring zone is considered as the Sanjiang lateral collision zone between the India plate and the Eurasian plate, where is a crucial area for the study of the collision between the Paleotethys orogenic belt and the oblique subduction of the Neotethys. In order to studying the deep crustal deformation and low velocity mass movement in the middle-low crust, we adopted seismic data from three different temporary seismic arrays and regional permanent stations to obtain S wave velocity and azimuthal anisotropy in the depths from 3 km to 50 km. The results suggest that the low velocity (LV) materials from the Tibetan Plateau move generally southwards, with the fast velocity direction (FD) in N-S oriented. The geometry of the low velocity zone is along the Lijiang-Xiaojinhe fault (LXF) and the FD is influenced obviously by the LXF. The TVZ is at the west side of the LXF. In the south of Indochina block) and Baoshan block, near to the TVZ, the high velocity zone continues from the middle crust to the low crust. The FDs below TVZ shows NE oriented from 10 to 40 km. However the interesting is the low velocity body below TVZ seems to disconnect with the ascending material from the upper mantle, but is possible to connect to the LV materials from the Tibetan plateau in the middle crust. However, the further research is necessary.