{"title":"Eastward subduction of the Indian plate beneath the Indo-Myanmese arc revealed by teleseismic P-wave tomography","authors":"Yu Gao, Jiansi Yang, Yu Zheng","doi":"10.1016/j.eqs.2022.08.002","DOIUrl":null,"url":null,"abstract":"<div><p>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.</p></div>","PeriodicalId":46333,"journal":{"name":"Earthquake Science","volume":"35 4","pages":"Pages 243-262"},"PeriodicalIF":1.2000,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1674451922003494/pdfft?md5=cb671218c1faeb3d9359770dca73f3ec&pid=1-s2.0-S1674451922003494-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Earthquake Science","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1674451922003494","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"Earth and Planetary Sciences","Score":null,"Total":0}
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.
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.