Velocity Anomalies Around the Mantle Transition Zone Beneath the Qiangtang Terrane, Central Tibetan Plateau From Triplicated P Waveforms
Abstract The Qiangtang terrane exhibits many unique features compared with surrounding areas in the Tibetan plateau. It has been largely remodeled by the northward downwelling of the Indian lithosphere and the vertical upwelling of the Eurasian asthenosphere. Here, we investigate the P‐wave velocity...
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| Format: | Article |
| Language: | English |
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American Geophysical Union (AGU)
2022-02-01
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| Series: | Earth and Space Science |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2021EA002060 |
| _version_ | 1811275076164648960 |
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| author | Guohui Li Ling Bai Heng Zhang Qiang Xu Yuanze Zhou Yuan Gao Mujiangshan Wang Zihao Li |
| author_facet | Guohui Li Ling Bai Heng Zhang Qiang Xu Yuanze Zhou Yuan Gao Mujiangshan Wang Zihao Li |
| author_sort | Guohui Li |
| collection | DOAJ |
| description | Abstract The Qiangtang terrane exhibits many unique features compared with surrounding areas in the Tibetan plateau. It has been largely remodeled by the northward downwelling of the Indian lithosphere and the vertical upwelling of the Eurasian asthenosphere. Here, we investigate the P‐wave velocity around the mantle transition zone (MTZ) beneath the Qiangtang terrane using high‐frequency triplicated waveforms recorded by the China Digital Seismic Network. We found a low‐velocity layer (LVL) atop the MTZ and a high‐velocity anomaly (HVA) in the lower part of the MTZ. They are characterized by thickness of 36 km with velocity drop of −2.0% and 155 km with velocity increment of 1.2%, respectively. The 410 and 660 km discontinuities are depressed by different depths of 12 and 30 km, suggesting a thickened MTZ. In combination with previous multi‐disciplinary observations, we infer that the LVL is a hydrous partial melt affected by dehydration and high temperature, and the HVA is due to water and low temperature conditions. The downwelling cold continental lithosphere may have accumulated in the lower MTZ and induced the hydrous hot MTZ materials to upwelling until the shallow depths of the upper mantle beneath the Qiangtang terrane. |
| first_indexed | 2024-04-12T23:31:32Z |
| format | Article |
| id | doaj.art-75f617f21cdc421aaad6c25fec7a0d2d |
| institution | Directory Open Access Journal |
| issn | 2333-5084 |
| language | English |
| last_indexed | 2024-04-12T23:31:32Z |
| publishDate | 2022-02-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Earth and Space Science |
| spelling | doaj.art-75f617f21cdc421aaad6c25fec7a0d2d2022-12-22T03:12:16ZengAmerican Geophysical Union (AGU)Earth and Space Science2333-50842022-02-0192n/an/a10.1029/2021EA002060Velocity Anomalies Around the Mantle Transition Zone Beneath the Qiangtang Terrane, Central Tibetan Plateau From Triplicated P WaveformsGuohui Li0Ling Bai1Heng Zhang2Qiang Xu3Yuanze Zhou4Yuan Gao5Mujiangshan Wang6Zihao Li7Key Laboratory of Earthquake Prediction Institute of Earthquake Forecasting China Earthquake Administration Beijing ChinaState Key Laboratory of Tibetan Plateau Earth System Resources and Environment Chinese Academy of Sciences Beijing ChinaState Key Laboratory of Tibetan Plateau Earth System Resources and Environment Chinese Academy of Sciences Beijing ChinaState Key Laboratory of Tibetan Plateau Earth System Resources and Environment Chinese Academy of Sciences Beijing ChinaKey Laboratory of Computational Geodynamics College of Earth and Planetary Sciences University of Chinese Academy of Sciences Beijing ChinaKey Laboratory of Earthquake Prediction Institute of Earthquake Forecasting China Earthquake Administration Beijing ChinaSchool of Software Tsinghua University Beijing ChinaLiaoning Earthquake Agency China Earthquake Administration Shenyang ChinaAbstract The Qiangtang terrane exhibits many unique features compared with surrounding areas in the Tibetan plateau. It has been largely remodeled by the northward downwelling of the Indian lithosphere and the vertical upwelling of the Eurasian asthenosphere. Here, we investigate the P‐wave velocity around the mantle transition zone (MTZ) beneath the Qiangtang terrane using high‐frequency triplicated waveforms recorded by the China Digital Seismic Network. We found a low‐velocity layer (LVL) atop the MTZ and a high‐velocity anomaly (HVA) in the lower part of the MTZ. They are characterized by thickness of 36 km with velocity drop of −2.0% and 155 km with velocity increment of 1.2%, respectively. The 410 and 660 km discontinuities are depressed by different depths of 12 and 30 km, suggesting a thickened MTZ. In combination with previous multi‐disciplinary observations, we infer that the LVL is a hydrous partial melt affected by dehydration and high temperature, and the HVA is due to water and low temperature conditions. The downwelling cold continental lithosphere may have accumulated in the lower MTZ and induced the hydrous hot MTZ materials to upwelling until the shallow depths of the upper mantle beneath the Qiangtang terrane.https://doi.org/10.1029/2021EA002060Tibetan PlateauQiangtang terranemantle transition zoneseismic triplicationlow‐velocity layerhigh‐velocity anomaly |
| spellingShingle | Guohui Li Ling Bai Heng Zhang Qiang Xu Yuanze Zhou Yuan Gao Mujiangshan Wang Zihao Li Velocity Anomalies Around the Mantle Transition Zone Beneath the Qiangtang Terrane, Central Tibetan Plateau From Triplicated P Waveforms Earth and Space Science Tibetan Plateau Qiangtang terrane mantle transition zone seismic triplication low‐velocity layer high‐velocity anomaly |
| title | Velocity Anomalies Around the Mantle Transition Zone Beneath the Qiangtang Terrane, Central Tibetan Plateau From Triplicated P Waveforms |
| title_full | Velocity Anomalies Around the Mantle Transition Zone Beneath the Qiangtang Terrane, Central Tibetan Plateau From Triplicated P Waveforms |
| title_fullStr | Velocity Anomalies Around the Mantle Transition Zone Beneath the Qiangtang Terrane, Central Tibetan Plateau From Triplicated P Waveforms |
| title_full_unstemmed | Velocity Anomalies Around the Mantle Transition Zone Beneath the Qiangtang Terrane, Central Tibetan Plateau From Triplicated P Waveforms |
| title_short | Velocity Anomalies Around the Mantle Transition Zone Beneath the Qiangtang Terrane, Central Tibetan Plateau From Triplicated P Waveforms |
| title_sort | velocity anomalies around the mantle transition zone beneath the qiangtang terrane central tibetan plateau from triplicated p waveforms |
| topic | Tibetan Plateau Qiangtang terrane mantle transition zone seismic triplication low‐velocity layer high‐velocity anomaly |
| url | https://doi.org/10.1029/2021EA002060 |
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