Eastward subduction of the Indian plate beneath the Indo-Myanmese arc revealed by teleseismic P-wave tomography

IF 1.2 4区 地球科学 Q3 Earth and Planetary Sciences
Yu Gao, Jiansi Yang, Yu Zheng
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引用次数: 0

Abstract

The deep structure of the eastward-subducting Indian plate can provide new information on the dynamics of the India-Eurasia collision. We collected and processed waveform data from temporary seismic arrays (networks) on the eastern Tibetan Plateau, seismic arrays in Northeast India and Myanmar, and permanent stations of the China Digital Seismic Network in Tibet, Gansu, Qinghai, Yunnan, and Sichuan. We combined these data with phase reports from observation stations of the International Seismological Center on the Indian plate and selected 124,808 high-quality P-wave relative travel-time residuals. Next, we used these data to invert the 3-D P-wave velocity structure of the upper mantle to a depth of 800 km beneath the eastern segment of the arcuate Himalayan orogen, at the southeastern margin of the Tibetan Plateau. The results reveal a high-angle, easterly dipping subducting plate extending more than 200 km beneath the Indo-Myanmese arc. The plate breaks off at roughly 96°E; its fragments have passed through the 410-km discontinuity (D410) into the mantle transition zone (MTZ). The MTZ beneath the Tengchong volcanic area contains a high-velocity anomaly, which does not exceed the Red River fault to the east. No other large-scale continuous subducted plates were observed in the MTZ. However, a horizontally spreading high-velocity anomaly was identified on the D410 in some regions. The anomaly may represent the negatively buoyant 90°E Ridge plate or a thickened and delaminated lithospheric block experiencing collision and compression at the southeastern margin of the Tibetan Plateau. The Tengchong volcano may originate from the mantle upwelling through the slab window formed by the break-off of the subducting Indian continental plate and oceanic plate in the upper mantle. Low-velocity upper mantle materials on the west side of the Indo-Myanmese arc may have supplemented materials to the Tengchong volcano.

远震P波层析成像揭示印度板块在印度-缅甸弧下向东俯冲
东俯冲印度板块的深部构造可以为印度-欧亚板块碰撞动力学提供新的信息。我们收集和处理了青藏高原东部的临时地震台站(台网)、印度东北部和缅甸的地震台网以及中国数字地震台网西藏、甘肃、青海、云南和四川的永久台站的波形数据。我们将这些数据与印度板块国际地震中心观测站的相位报告相结合,选择了124,808个高质量的p波相对走时残差。接下来,我们利用这些数据反演了青藏高原东南边缘喜马拉雅弧形造山带东段800公里深处的上地幔三维纵波速度结构。结果显示,在印度-缅甸弧下方有一个高角度、向东倾斜的俯冲板块,延伸超过200公里。板块在大约96°E处断裂;它的碎片穿过410公里的不连续带(D410)进入地幔过渡带(MTZ)。腾冲火山区下MTZ包含一条高速异常,该异常向东不超过红河断层。MTZ内未见其他大型连续俯冲板块。然而,在D410的一些区域发现了水平扩展的高速异常。该异常可能代表青藏高原东南缘负浮力90°E脊板块或经历碰撞和挤压的增厚分层岩石圈块体。腾冲火山可能起源于上地幔俯冲的印度大陆板块与大洋板块断裂形成的板块窗,由地幔上涌形成。印缅弧西侧的低速上地幔物质可能为腾冲火山补充了物质。
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来源期刊
Earthquake Science
Earthquake Science GEOCHEMISTRY & GEOPHYSICS-
CiteScore
1.10
自引率
8.30%
发文量
42
审稿时长
3 months
期刊介绍: Earthquake Science (EQS) aims to publish high-quality, original, peer-reviewed articles on earthquake-related research subjects. It is an English international journal sponsored by the Seismological Society of China and the Institute of Geophysics, China Earthquake Administration. The topics include, but not limited to, the following ● Seismic sources of all kinds. ● Earth structure at all scales. ● Seismotectonics. ● New methods and theoretical seismology. ● Strong ground motion. ● Seismic phenomena of all kinds. ● Seismic hazards, earthquake forecasting and prediction. ● Seismic instrumentation. ● Significant recent or past seismic events. ● Documentation of recent seismic events or important observations. ● Descriptions of field deployments, new methods, and available software tools. The types of manuscripts include the following. There is no length requirement, except for the Short Notes. 【Articles】 Original contributions that have not been published elsewhere. 【Short Notes】 Short papers of recent events or topics that warrant rapid peer reviews and publications. Limited to 4 publication pages. 【Rapid Communications】 Significant contributions that warrant rapid peer reviews and publications. 【Review Articles】Review articles are by invitation only. Please contact the editorial office and editors for possible proposals. 【Toolboxes】 Descriptions of novel numerical methods and associated computer codes. 【Data Products】 Documentation of datasets of various kinds that are interested to the community and available for open access (field data, processed data, synthetic data, or models). 【Opinions】Views on important topics and future directions in earthquake science. 【Comments and Replies】Commentaries on a recently published EQS paper is welcome. The authors of the paper commented will be invited to reply. Both the Comment and the Reply are subject to peer review.
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