Crustal Structures beneath West Qinling-East Kunlun Orogen and its Adjacent Area -Result of Wide-Angle Seismic Reflection and Refraction Experiment

A 637km long wide‐angle seismic reflection and refraction profile was carried out in the northeast margin of Tibet plateau, which crosses A'nyemaqen suture belt in the north‐south direction. The crust section obtained from the seismic data shows that the depth of the Moho is about 48‐51 km. The crust is slightly thicker in the south than in the north and it varies smoothly toward the north along the profile with different structures in the various tectonic blocks. The clearly identified overcritical reflections P3, P4 on the seismic record sections indicate that the lower crust features multi‐layer structure and strong reflectivity in this area. There are severe deformations on the interfaces of the crust, and low velocity distributions on the south of Aba arcuate fault and near A'nyemaqen suture belt. The low velocity zone in the mid and lower crust beneath A'nyemaqen suture belt may be explained as the extension of the suture belt into the crust. The crust structure from the West Qinling fold zone to Songpan‐Garze block is characterized by strong reflections from the mid and lower crust, and relatively weak Moho reflections on the seismic record sections.