Lithospheric structure below Dabie Shan, China

点击翻译按钮获取中文摘要

The aim of the proposal is to study the structure of the lithosphere and upper mantle in the Qinling-Dabie orogenic belt in China. Outcrop of ultrahigh pressure coesite-bearing eclogite indicates that during collision of lithospheric plates crustal rocks were subducted to large depths and then exhumed. Teleseismic earthquake records (S and P receiver functions) will used to study seismic discontinuities (Moho and lithosphere- asthenosphere boundary, 410 and 660 discontinuities) to obtain images of the geodynamic processes in the region. Thirty four seismic broadband stations of the Institute of Geology of the Chinese Seismological Bureau have been operating with support of the DFG within ICDP in the Dabie Shan region along a 500km long profile between the years 2001 and 2002. The data are stored in Potsdam. Results of a preliminary P receiver function study, which are published in China, show clearly the Moho reaching 42km depth below the center of the orogen. The main goal of the proposed study is to apply the S receiver function technique to map the lithosphere-asthenosphere boundary (LAB) across the Dabie Shan. This technique, although still new, has proven very useful for mapping the LAB at the Hawaiian and Iceland plume tracks (see enclosures). Also across the Tien Shan the LAB was clearly observed with this technique (Kosarev, personal communication). Knowledge about the structure of the complete lithosphere, not only the crust, will significantly improve understand of lithospheric collision processes.