| 基于P波三重震相的下扬子克拉通地幔转换带顶部低速层初探 |
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| 引用本文： | 李国辉,眭怡,周元泽.基于P波三重震相的下扬子克拉通地幔转换带顶部低速层初探[J].地球物理学报,2014,57(7):2362-2371. |
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| 作者姓名： | 李国辉 眭怡 周元泽 |
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| 作者单位： | 1. 中国科学院计算地球动力学重点实验室, 北京 100049;2. 中国科学院大学地球科学学院, 北京 100049 |
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| 基金项目： | 国家自然科学基金(41074065,41274092)资助 |
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| 摘 要： | 本文基于中国地震观测台网记录到的震中距为10°~23°之间琉球俯冲区一个中深源地震的P波三重震相信息，研究了下扬子克拉通转换带顶部P波速度结构.通过射线追踪和理论地震图与观测地震波形的对比，发现下扬子克拉通下方的410 km间断面为一厚度20 km的梯度带，其上存在一由西南向东北变厚的低速层，厚度变化40~57 km，P波速度减低2.7%~4.5%.该低速层可以被认为是由于地幔橄榄岩部分熔融引起的.
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| 关 键 词： | 三重震相 410km间断面 低速层 上地幔 下扬子克拉通 |
| 收稿时间： | 2013-08-30 |
Low-velocity layer atop the mantle transition zone in the lower Yangtze Craton from P waveform triplication |
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| LI Guo-Hui,SUI Yi,ZHOU Yuan-Ze.Low-velocity layer atop the mantle transition zone in the lower Yangtze Craton from P waveform triplication[J].Chinese Journal of Geophysics,2014,57(7):2362-2371. |
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| Authors: | LI Guo-Hui SUI Yi ZHOU Yuan-Ze |
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| Institution: | 1. Key Laboratory of Computational Geodynamics, Chinese Academy of Sciences, Beijing 100049, China;2. College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | The P waveform triplications from the seismograms of a mid-deep earthquake at the Ryukyu subduction zone recorded by the Chinese Digital Seismic Network between the epicentral distances from 10° to 23° are used to study the upper mantle structure beneath the lower Yangtze craton. Comparing the observed seismograms with the synthetic ones from different models based on IASP91 earth model and using the ray-tracing method, we find that the 410 km discontinuity is a gradient zone with the thickness of 20 km and there is a low-velocity layer atop the discontinuity which becomes thicker from southwest to northeast beneath the lower Yangtze craton. The low-velocity layer is characterized by a thickness varied from 40 km to 57 km and P velocity decreased by 2.7%~4.5% and should be the result of partial melting of mantle peridotite. |
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| Keywords: | Seismic triplication 410 km discontinuity Low velocity layer Upper mantle Lower Yangtze craton |
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