| 四川盆地西部及邻区地壳上地幔精细结构研究 |
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| 引用本文： | 李萍萍,程先琼,刘媛.四川盆地西部及邻区地壳上地幔精细结构研究[J].CT理论与应用研究,2018,27(2):145-153. |
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| 作者姓名： | 李萍萍 程先琼 刘媛 |
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| 作者单位： | 成都理工大学地球物理学院, 成都 610059 |
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| 基金项目： | 国家自然科学基金（41774095）。 |
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| 摘 要： | 为获得四川盆地及其邻区地壳和上地幔精细结构，并据此对该区域整体构造运动初步进行动力学解释，本研究采用接收函数、线性反演与H-kappa扫描相结合的方法，获得以下结论:研究区域地壳厚度东西向差异巨大，其厚度差高达29 km。四川盆地地表具有较厚沉积层，属于刚性块体。龙门山南段与四川盆地交接地区存在某些区域的波速比较高，推测这些地区可能存在地幔物质上涌导致地壳中铁镁质成分增加。松潘-甘孜地块的地壳厚度存在58~65 km的横向变化，中下地壳存在梯形低速层，可能由于青藏高原向东俯冲过程中遭遇四川盆地刚性块体的阻挡而引起该地块的挤压变形，该区域具有较高的波速比，综合分析推测其可能存在区域性的部分熔融。
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| 关 键 词： | 接收函数 H-kappa扫描 地壳厚度 波速比 |
| 收稿时间： | 2017-11-08 |
Fine Structure Research of Crust and Upper Mantle in Western Sichuan Basin and its Adjacent Regions |
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| Institution: | College of Geophysics, Chengdu University of Technology, Chengdu 610059, China |
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| Abstract: | This research make use of a large number of teleseism waveform record coming from 123 stations, for the purpose of knowing the crust and upper mantle subtle structure of Sichuan Basin and its adjacent area, furthermore getting more information about the plate movement such as its direction or the process, by means of the receiver function, linear inversion and H-kappa method, ultimately having a comprehensive analysis based on the previous results. there are the conclusions:The crust thickness of our research area vary enormously on the east-west direction, the subtraction between the maximum and minimum is 29 km.The average of the crust thickness in Sichuan Basin is 39.4 km, which exist huge deposits of sediments in the surface, and the lower wave velocity ratio, which is the ratio of the shear wave velocity and the longitudinal wave velocity, illustrating this ares is a kind of the rigid block. There are thicker crust in Longmen Shan fault. The transition region between the south-Longmen Shan fault and Sichuan Basin features higher wave velocity ratio, resulting from the mantle material up welling. Songpan-Ganzi block's crust thickness has lateral variations of 58~65 km, where there is a low velocity layer existing in the shape of trapezoid at the middle and lower crust. The area features higher average of the wave velocity ratio. It could be inferred that under the long-term pressure eastward from the Tibetan plateau, the Songpan-Ganzi block is squeezed and deforming. The crust in Western Sichuan Plateau is much thick, there may be partial melting area because of the higher wave velocity ratio. The average of crust thickness in Chuan-Dian block is 58.5 km.There is a low velocity layer at the middle crust. |
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