Velocity structure of the mantle transition zone beneath the southeastern margin of the Tibetan Plateau
Velocity structure of the mantle transition zone beneath the southeastern margin of the Tibetan Plateau
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青藏高原东南缘地幔过渡带的速度结构
DOI：
10.1016/j.tecto.2017.08.009
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发表时间：
2017-11
期刊：
影响因子：
2.9
通讯作者：
Qinghui Cui
中科院分区：
文献类型：
--
作者：
Guohui Li;Ling Bai;Yuanze Zhou;Xiaoran Wang;Qinghui Cui
由中国数字地震台网（CDSN）记录的发生在印缅俯冲带（IBSZ）的三次中深度地震的垂直分量地震图中，清晰地观察到与410 km不连续（410）有关的纵波三次。一个普遍存在的低速层（LVL）位于地幔过渡带（MTZ）的顶部。LVL厚度为25 ~ 40 km，与标准地球模型IASP91相关的纵波速度衰减范围约为−5.3% ~−3.6%。在剖面II和剖面III之间观察到LVL速度衰减的突变。我们认为，青藏高原东南缘的地幔结构主要受青藏高原向北的东南挤压和印度板块向南的东俯冲控制，而不受峨眉山地幔柱的影响。我们认为llvl是由俯冲的印度板块和停滞的太平洋板块释放的水和/或其他挥发物引起的部分熔融，而不是由上升流或峨眉山地幔柱的残余引起的。在542 ~ 600 km深度处，还发现了一个高速异常，范围约为1.0% ~ 1.5%，为MTZ内俯冲太平洋板块的残余提供了额外的证据。
P-wave triplications related to the 410 km discontinuity (the 410) were clearly observed from the vertical component seismograms of three intermediate-depth earthquakes that occurred in the Indo-Burma Subduction Zone (IBSZ) and were recorded by the Chinese Digital Seismic Network (CDSN). By matching the observed P-wave triplications with synthetics through a grid search, we obtained the best-fit models for four azimuthal profiles (I-IV from north to south) to constrain the P-wave velocity structure near the 410 beneath the southeastern margin of the Tibetan Plateau (TP). A ubiquitous low-velocity layer (LVL) resides atop the mantle transition zone (MTZ). The LVL is 25 to 40 km thick, with a P-wave velocity decrement ranging from approximately − 5.3% to − 3.6% related to the standard Earth model IASP91. An abrupt transition in the velocity decrement of the LVL was observed between profiles II and III. We postulate that the mantle structure beneath the southeastern margin of the TP is primarily controlled by the southeastern extrusion of the TP to the north combined with the eastward subduction of the Indian plate to the south, but not affected by the Emeishan mantle plume. We attribute the LVL to the partial melting induced by water and/or other volatiles released from the subducted Indian plate and the stagnant Pacific plate, but not from the upwelling or the remnants of the Emeishan mantle plume. A high-velocity anomaly ranging from approximately 1.0% to 1.5% was also detected at a depth of 542 to 600 km, providing additional evidence for the remnants of the subducted Pacific plate within the MTZ.
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影响因子：
5.3
作者：
He, B;Xu, YG;Wang, Y
通讯作者：
Wang, Y
影响因子：
5.2
作者：
F. Tajima;S. Grand
通讯作者：
F. Tajima;S. Grand
影响因子：
5.3
作者：
S. Oreshin;L. Vinnik;S. Kiselev;S. S. Rai-S.;K. Prakasam;A. Treussov
通讯作者：
S. Oreshin;L. Vinnik;S. Kiselev;S. S. Rai-S.;K. Prakasam;A. Treussov
影响因子：
--
作者：
Wei Gao;E. Matzel;S. Grand
通讯作者：
Wei Gao;E. Matzel;S. Grand
影响因子：
2.8
作者：
KENNETT, BLN;ENGDAHL, ER
通讯作者：
ENGDAHL, ER