| 青藏高原东缘的地壳流及动力过程 |
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| 引用本文： | 朱介寿,王绪本,杨宜海,范军,程先琼.青藏高原东缘的地壳流及动力过程[J].地球物理学报,2017,60(6):2038-2057. |
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| 作者姓名： | 朱介寿 王绪本 杨宜海 范军 程先琼 |
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| 作者单位： | 1. 教育部地球探测与信息技术重点实验室 成都理工大学地球物理学院, 成都 610059;2. 四川省地震局, 成都 610041 |
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| 基金项目： | 国家自然科学基金（40839909，40674040，41074062），中国地质调查项目（1212011220263）资助. |
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| 摘 要： | 黏滞性地壳流对地壳及上地幔变形作用及动力机制,是大陆新生代造山带的一个重要研究内容.青藏高原中下地壳存在部分熔融或含水物质的黏滞性流体,已为一系列地球物理及岩石学研究所证实.为研究青藏高原东缘地壳流的动力作用,本文用密集的被动源宽频带地震台的观测数据,反演了地壳上地幔精细速度结构和泊松比.研究表明,川西及滇西北高原的中地壳内普遍存在低速层,而高泊松比的地壳只分布在川西北地区.位于中地壳的黏滞性地壳流从青藏高原腹地羌塘高原流出,自北西向南东流入青藏高原东缘.这些黏滞性地壳流带动了上地壳块体水平移动,当它们受到刚强的四川盆地及华南地块阻挡时将发生分层作用,地壳流将分为二或更多分支不同方向的分流,向上的一支地壳流将对上地壳产生挤压,引起地面隆升,向下的一支地壳流将使莫霍面下沉加厚下地壳·黏滞性地壳流的运动在地壳中产生应变破裂发生强烈地震活动,地震的空间分布与震源机制也受到地壳流动力作用控制.
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| 关 键 词： | 青藏高原东缘 地壳速度结构和泊松比 中地壳黏滞性地壳流 地壳异常隆升及增厚 地震活动性 |
| 收稿时间： | 2016-11-14 |
The crustal flow beneath the eastern margin of the Tibetan Plateau and its process of dynamics |
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| ZHU Jie-Shou,WANG Xu-Ben,YANG Yi-Hai,FAN Jun,CHENG Xian-Qiong.The crustal flow beneath the eastern margin of the Tibetan Plateau and its process of dynamics[J].Chinese Journal of Geophysics,2017,60(6):2038-2057. |
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| Authors: | ZHU Jie-Shou WANG Xu-Ben YANG Yi-Hai FAN Jun CHENG Xian-Qiong |
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| Institution: | 1. Key Lab of Earth Exploration and Information Techniques of Ministry of Education College of Geophysics, Chengdu University of Technology, Chengdu 610059, China;2. Sichuan Seismological Bureau, Chengdu 610041, China |
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| Abstract: | In large continental orogens, an important topic is the behavior of deep crust and upper mantle deformation, and the dynamic mechanism of the viscous crustal flow.The partial melting or water-containing substances of viscous fluid in the middle and lower crust beneth the Tibetan plateau has been proven by a series of geophysical and petrological reserchs.For study on the dynamics of the crustal flow in the eastern margin of the Qinghai-Tibet plateau, weadopt the dense source of passive broadband seismic observation data to invert the fine velocity structure of crust and upper mantle, and the crustal Poisson's ratio.The results indicate that the viscous crustal flow in the eastern margin of the Tibetan Plateau drives crustal material around the strong rigid Sichuan Basin. Studies have shown that the viscous crustal flow in the eastern margin of the Tibetan Plateau is common in western Sichuan and northwest Yunnan plateau with the crust low-velocity layer, and the high Poisson's ratio of the crust only distributed in northwest Sichuan regions.The stream of viscosity crust flowed from the Qinghai-Tibet hinterland Qiangtang plateau, along the northwest to south east into the eastern margin of the Qinghai-Tibet plateau.The viscous crustal flow in the eastern margin of the Tibetan Plateau drives upper crustal block movement.When the viscous flow hits the obstruction of the Sichuan basin and South China block, delamination is likely to occur.These flows are divided into two or more branches with different directions.The upper part of viscous flow upwelling produces the pressure to intrude the upper crust, thereby uplifting the mountain ranges and high peaks. In contrast, the lower part of viscous flow down-welling produces the pressure to intrude the lower crust and upper mantle to deepen the Moho boundary, thereby causing the crustal thickening.The movement of viscous flow also producing of crust strain burst causes strong earthquake activity, and the spatial distribution and focal mechanism of earthquakes have also been controlled by crustal flow dynamics. |
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| Keywords: | Eastern margin of the Qinghai-Tibetan plateau Fine crustal velocity structure and Poisson's ratio Viscous crustal flow Crustal anomaly uplift and thicken Seismic activities |
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