• 责任者：Wang Xinsheng (National Earthquake Infrastructure Service ; Beijing 100036 ; China) ; Fang Jian
• 刊名：Chinese Journal of Geophysics
• 出版年：2013
• 卷期：56(11)
• 关键词：岩石圈 ; lithosphere ; 青藏高原 ; Qinghai-Tibetan Plateau
• 页码：p.3770-3778
• 图表：6 illus., 29 refs.
• 分类号：0400
• issnNo：ISSN0001-5733
• isbnNo：CN11-2074/P

     We obtained the beneath northeastern margin three of the dimensional velocity and density structures of Tibetan Plateau （TP） using gravity and seismic lithosphere  data, and discussed its geodynamic implication. Firstly, P wave velocity structures are determined by seismic tomography using P wave travel time data, and then converted to initial density model for the following gravity inversion. Subsequently, the density structures in lithosphere are inverted by Bouguer gravity anomaly. Our density model shows that the crustal density structures are critical for the occurrence of earthquakes as well as the lower crustal flow. The trend of density isopleths is coherent with that of surface fractures in the crust. However, it presents a clockwise rotation in the mantle. This phenomenon may indicate the decoupling between curst and mantle In 80-100 km depth, P wave velocity anomalies are significantly lower than density anomalies. This may demonstrate the partial melting and increase of rock water Content. The combined effects of the subduction of Indian plate and the obstruction force from Ordos and Alashan blocks made a strong tectonic squeezing, inducing the asthenosphere upwelling, and providing conditions for the crustal-mantle decoupling, partial melting, and reduction of the P velocity.