Seismic signature of the collision between the east Tibetan escape flow and the Sichuan Basin
作者单位：Deutsches GeoForschungsZentrum GFZTelegrafenberg14473 PotsdamGermany Freie Universitat BerlinGermany
会议名称：《中国科学院地质与地球物理研究所第十届(2010年度)学...》
会议日期：2011年
学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学]
基 金：support from the Chinese Academy of Sciences(KZCX2-YW-132) the National Nature Science Foundation o f China(#40721003 and #40830315)and the Deutsche Forschungsgemeinschaft the Graduate University of Chinese Academy of Sciences and the Chinese Earthquake Network Center
关 键 词：east Tibetan escape flow Sichuan Basin receiver function imaging mantle transition zone
摘 要：GPS displacement vectors show that the crust in east Tibet is being squeezed in an easterly direction by the northward motion of the Indian plate,and the Sichuan Basin is resisting this stream and redirecting it mainly towards *** Longmen Shan,containing the steepest rise to the high plateau anywhere in Tibet, results from the strong interaction between the east Tibetan escape flow and the rigid Yangtze block (Sichuan Basin),but the kinematics and dynamics of this interaction are still the subject of some *** herein present results from a dense passive-source seismic profile from the Sichuan Basin into eastern Tibet in order to study the deep structure of this collision *** P and S receiver function images we observe a sudden rise of the Lithosphere-Asthenosphere Boundary(LAB) from 120 to 150 km beneath the Sichuan Basin and from 70 to 80 km beneath eastern *** contrast,the depth of the crust-mantle boundary (Moho) increases from 36 to 40 km beneath the Sichuan Basin and from 55 to 60 km beneath eastern Tibet. The 410km discontinuity is depressed below eastern Tibet by about 30 km,although the 660 remains at nearly the same depth throughout the *** these observations,we conclude that the mode of collision that occurs between Tibet and the Sichuan Basin is very different to that found between India and *** southern Tibet,we observe in essence the subduction of the Indian plate,which penetrates northwards for several hundred kilometers under central *** very thin mantle part of the lithosphere beneath eastern Tibet may indicate delamination or removal of the bottom of the lithosphere by hot asthenospheric escape *** process leads to the exceptionally steep topography at the eastern Tibetan margin as a result of gravitational *** view is supported by the very unusual depression of the 410 km discontinuity beneath eastern Tibet,which could be caused by the dynamics of the sub-vertical downward asthenospheric f