| 青藏高原及邻近区域的S波三维速度结构 |
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| 引用本文： | 周兵,秦建业.青藏高原及邻近区域的S波三维速度结构[J].地球物理学报,1991,34(4):426-441,T001. |
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| 作者姓名： | 周兵 秦建业 |
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| 作者单位： | 1. 成都地质学院, 成都 610059;
2. 加拿大多伦多大学 |
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| 摘 要： | 本文收集了WWSSN台网和我国台网中13个地震台站的长周期地震记录,用140条10-90s瑞利波频散曲线和作者提出的Tarantola-Backus面波频散层析成象方法,作了青藏高原及邻区的速度反演,得出该地区岩石层速度结构的三维图象.结果表明,1.在10-110km深度范围内,速度结构出现与大地构造特征相关的分区性,显示出四个构造单元:青藏块体、柴达木-巴颜喀拉-三江块体、塔里木块体和印度块体.2.高原内部,深度为10-70km内速度较低,莫霍界面呈不对称盆形分布,藏北那曲附近地壳厚度超过70km,高原边缘壳厚为45-50km,90-110km为高速异常,表明高原内部存在上地幔盖层.3.高原北部的班公湖断裂和东部的三江断裂系是该区重要的分界线,是岩石层结构存在明显差异的重要接触部位,可能是冈瓦纳古陆与欧亚古陆的缝合带.4.柴达木-巴颜喀拉-三江块体内部速度分布不均匀,地壳厚度由北向南从45km加深到60km;在深度90-110km存在一低速层.5.塔里木地块内速度随深度均匀增加,从地壳到上地幔110km内没有发现低速层.地壳厚度约50km.
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| 关 键 词： | 瑞利波 频散 横波速度三维层析成象 青藏高原岩石层结构 |
| 收稿时间： | 1989-10-04 |
THREE-DIMENSIONAL SHEAR VELOCITY STRUCTURE BENEATH QINHAI-TIBET AND ITS ADJACENT AREA |
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| ZHOU BIN ZHU JIE-SHOU.THREE-DIMENSIONAL SHEAR VELOCITY STRUCTURE BENEATH QINHAI-TIBET AND ITS ADJACENT AREA[J].Chinese Journal of Geophysics,1991,34(4):426-441,T001. |
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| Authors: | ZHOU BIN ZHU JIE-SHOU |
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| Institution: | 1. Chengdu College of Geology, Chengdu 610059;
2. University of Toroto, Canada |
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| Abstract: | Surface wave data, consisting of 140 individual dispersion curves, have been obtained from 13 stations located in and outside of the Qinhai-Tibet region of western China. Tomographic inversion of the data have yeilded a rather detailed structural model (10-110 km depth range) beneath the studied region. The results indicate as follows: (1) The study region consists of four distinct crust-mantle velocity substructures, each of which can be identified with one of the known tectonic units: Qinghai-Tibet block, Chaidamo-Bayarhar/Three River block, Ta-rim block and the Indian subcontinent. The average lithospheric velocity is lowest beneath the Qinhai-Tibet region and the highest beneath the Tarim block. (2) At the depth exceeding 70 km, the Moho discontinuity in north of Yarlung Zangbo river reaches the deepest point of a "basin" configuration, whose marginal depth is about 50 km. (3) The Tibetan crustal s'ruc-ture resembles a vertically stretched out model of the Indian subcontinent. (4) Pangong Lake Fault and Nujiang Jinsha River Fault are deep-rooted structural features along which the Moho discontinuity suffers a vertical offset, with ihe northeastern side being relatively shallower. (5) The velocity structure within the Chaidamo-Bayarhar/Three River block is laterally in-homogeneous. Ranging from 90 to 110 km, the upper mantle low velocity layer in this region is more prominent as well as shallower than that beneath the Qinhai-Tibet plateau- And (6) the velocity increases monotonically with depth beneath the stable Tarim Basin block where the crust is about 50 km thick. |
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| Keywords: | Tomography Dispersion Rayleigh wave Shear velocity Lithosphere |
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