| 利用接收函数研究青藏高原东南缘的地壳上地幔结构 |
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| 引用本文： | 徐强,赵俊猛,崔仲雄,刘明乾.利用接收函数研究青藏高原东南缘的地壳上地幔结构[J].地球物理学报,2009,52(12):3001-3008. |
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| 作者姓名： | 徐强 赵俊猛 崔仲雄 刘明乾 |
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| 作者单位： | 1.中国科学院青藏高原研究所，北京 100085;2.东方地球物理公司研究院长庆分院，西安 710021 |
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| 基金项目： | 国家重点基础研究发展计划(973计划) |
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| 摘 要： | 本文使用位于青藏高原东南缘的25个地震台站的远震数据，采用P波和S波接收函数的方法研究了台站下方的Moho深度、泊松比以及地幔过渡带的厚度.计算结果表明：① 青藏高原东南缘的地壳厚度由松潘—甘孜地体和羌塘地体的约60 km，向邻区的印支地体以及扬子板块分别减薄为约38 km和约42 km； ② 羌塘地体的泊松比主要集中范围为0.25～0.28，地壳物质组分主要为中基性岩石，推测与下地壳镁铁质成分的增加有关.松潘—甘孜块体、印支块体和扬子板块的泊松比为0.25～0.26，主要为中酸性岩石组分.缺乏高的泊松比(≥0.30)分布表明青藏高原东南缘的地壳不存在广泛的部分熔融，但是不排除局部部分熔融的存在；③ 青藏高原东南缘的羌塘地体内存在一个比较明显的、异常变化范围为10～26 km的地幔过渡带增厚区域，其对应着地幔过渡带内100℃～260℃的温度降低，可以推断与此异常区域的地幔过渡带内存在俯冲的板块有关.
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| 关 键 词： | P波接收函数 S波接收函数 地幔过渡带 泊松比 |
| 收稿时间： | 2008-12-23 |
| 修稿时间： | 2009-11-23 |
Structure of the crust and upper mantle beneath the southeastern Tibetan Plateau by P and S receiver functions |
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| XU Qiang,ZHAO Jun-meng,CUI Zhong-xiong,LIU Ming-qian.Structure of the crust and upper mantle beneath the southeastern Tibetan Plateau by P and S receiver functions[J].Chinese Journal of Geophysics,2009,52(12):3001-3008. |
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| Authors: | XU Qiang ZHAO Jun-meng CUI Zhong-xiong LIU Ming-qian |
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| Institution: | 1.Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China;2.Changqing Division of BGP Geophysical Research Institute, CNPC, Xi′an 710021, China |
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| Abstract: | Combined P and S receiver functions from seismograms of teleseismic events recorded at 25 temporary broadband seismic stations in the southeastern Tibetan Plateau are used to map the Moho depth, Poisson's ratio and the thickness of the mantle transition zone. The main results are as follows:1] The crustal thickness gradually decrease from-60 km in Songpan-Ganze terrane and Qiangtang Terrane to-38 km in Indochina block and-42 km in Yangtze block. 2]The Poisson's ratios in Qiangtang terrane mainly range from 0.25 to 0.28, which indicate that the crust is mainly composed of intermediate and mafic rocks and may be caused by the increased mafic rocks in lower crust. But the Poisson's ratios range from 0.25 to 0.26 in Songpan-Ganze terrane, Indochina block and Yangtze block, which indicate that the crust is predominantly felsic and intermediate rocks. The lack of consistent high Poisson' s ratio (≥0.30) shows that widespread partial melt does not exist within the curst, but does not exclude the presence of local partial melt.3]There is an obvious thickened zone of the mantle transition zone compared with IASP91 standard value which varies from 10 km to 26 km in Qiangtang terrane. The anomaly suggests that the temperature is about 100℃ to 260℃ lower than global average value within the mantle transition zone,and it may be attributed to the presence of a subducted slab within the mantle transition zone. |
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| Keywords: | P wave receiver function S wave receiver function Mantle transition zone Poisson's ratio |
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