Tomographic structure of East Asia:Ⅱ.Stagnant slab above 660 km discontinuity and its geodynamic implications

作     者：Yongshun John Chen Shunping Pei 

作者机构：Computational Geodynamics Laboratory Department of Geophysics School of Earth and Space Sciences Peking University Beijing 100871 China Key Laboratory of Continental Collision andPlateau Uplift Institute of Tibetan Plateau Research Chinese Aeademy of Sciences Beijing 100085 China 

出 版 物：《Earthquake Science》 (地震学报（英文版）)

年 卷 期：2010年第23卷第6期

页      面：613-626页

核心收录：

学科分类：0709[理学-地质学] 0819[工学-矿业工程] 07[理学] 070801[理学-固体地球物理学] 0707[理学-海洋科学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0815[工学-水利工程] 0816[工学-测绘科学与技术] 0813[工学-建筑学] 0825[工学-航空宇航科学与技术] 0704[理学-天文学] 0814[工学-土木工程] 

基　　金：grants(B-11440134,S-12002006)to Dapeng Zhao from the Japan Society for the Promotion of Science Support for Shunping Pei came from a postdoct grant of Peking University supported by the National Natural Science Foundation of China(Nos.40125011,90814002 and 41074041) the Chinese Academy of Sciences(No.KZCX2-EW-QN102) 

主　　题：tomography stagnant slab mantle wedge 

摘      要：P-wave arrival times of both regional and teleseismic earthquakes were inverted to obtain mantle structures of East Asia. No fast （slab） velocity anomalies was not find beneath the 660-kin discontinuity through tomography besides a stagnant slab within the transition zone. Slow P-wave velocity anomalies are present at depths of 100-250 km below the active volcanic arc and East Asia. The western end of the flat stagnant slab is about 1 500 km west to active trench and may also be correlated with prominent surface topographic break in eastern China. We suggested that active mantle convection might be operating within this horizontally expanded ＂mantle wedge＂ above both the active subducting slabs and the stag- nant flat slabs beneath much of the North China plain. Both the widespread Cenozoic volcanism and associated extensional basins in East Asia could be the manifestation of this vigorous upper mantle convection. Cold or thermal alaomalies associated with the stagnant slabs above the 660-km discontinuity have not only caused a broad depression of the boundary due to its negative Clapeyron slope but also effectively shielded the asthenosphere and continental lithosphere above from any possible influence of mantle plumes in the lower mantle.