| 帕米尔及邻区地壳上地幔P波三维速度结构的研究 |
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| 引用本文： | 雷建设,周蕙兰,赵大鹏.帕米尔及邻区地壳上地幔P波三维速度结构的研究[J].地球物理学报,2002,45(6):802-811. |
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| 作者姓名： | 雷建设 周蕙兰 赵大鹏 |
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| 作者单位： | 1. 中国科学院研究生院,北京,100039;
2. 日本爱嫒大学地球科学系,日本松山市,790 |
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| 基金项目： | 国家自然科学基金项目 (4 973 41 5 0 ) . |
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| 摘 要： | 研究了帕米尔及邻区(65°E-80°E,30°N-45°N,深度0-2km)的P波三维速度结构. 所使用的59054条初至P波到时数据取自ISC的73个台站对5402个地震的记录报告,这些地震和台站都在研究区内. 以水平面上1°×1°和不等的深度间隔(随深度在20-90km之间变化)划分网格并设置初始三维速度模型,用近似弯曲快速射线追踪方法计算走时和射线路径,用LSQR方法进行反演. 反演结果的分辨率用检验板方法进行了讨论,并引入了定量描述还原程度质量的两个参数. 初步结果表明:(1)天山山脉的km深度处,在东部和西部各有一个明显高速区,而在74°E、41°N附近的低速区可能与天山地表大断层在该处被大幅错开相关. 在75°E附近的天山山脉下,波速在40-60km深度偏高,而在60-90km深度(或更深)又偏低,反映了天山下方构造和物性的复杂性. (2)在由帕米尔构造"结"南侧往北直至天山以北的速度纵剖面上,显示了印度-欧亚板块在帕米尔构造"结"地区的强烈碰撞挤压作用:在抬高地面形成高原的同时,也把浅部速度较低的地壳岩石层介质俯冲拖曳到了深部.
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| 关 键 词： | 帕米尔及邻区 三维速度结构 地壳上地幔. |
| 文章编号： | 0001-5733(2002)06-0802-10 |
3-D VELOCITY STRUCTURE OF P-WAVE IN THE CRUST AND UPPER-MANTLE BENEATH PAMIR AND ADJACENT REGION |
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| LEI JIAN-SHEZHOU HUI-LAN.3-D VELOCITY STRUCTURE OF P-WAVE IN THE CRUST AND UPPER-MANTLE BENEATH PAMIR AND ADJACENT REGION[J].Chinese Journal of Geophysics,2002,45(6):802-811. |
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| Authors: | LEI JIAN-SHEZHOU HUI-LAN |
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| Institution: | 1. Graduate School of University of Science and Technology of China, Beijing 100039, China;
2. Department of Earth Sciences, Ehime University, Matsuyama 790, Japan |
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| Abstract: | We have investigated the three-dimensional seismic velocity structure in the crust and upper mantle down to the depth of 210km beneath Pamir and adjacent regions （30°-45°N, 65°-80°E） with more than 59,054 P-wave arrival times from 5402 earthquakes recorded by 73 stations, collected from the bulletin of ISC. Travel times and ray paths were calculated with an effcient 3-D ray-tracing technique, and the inversion was conducted by the algorithm LSQR. The involved events and the stations are located within the studying area. We set up 3-D grid nodes with a horizontal spacing of 1°×1° and a vertical spacing of about 20-90km. The resolution of the inversion result has been discussed with checkerboard resolution tests, and two parameters have been introduced to quantitatively describe the recovered degree. The preliminary results are as follows: （1） At the depth of 10km beneath Tienshan Mountain, there is a visible higher velocity region at the east and west parts of it, but the lower velocity area in the vicinity of 74°E, 41°N may be correlated with a larger dislocation of the larger fault in the surface of Tienshan moutain. Near the longitued of 75°E of Tienshan, the velocity is a bit higher at the depth of 40-60km and a bit lower at the depth of 60-90km or more, which shows the complexity of the tectonic and material property under the Tienshan Mountain. （2） From the vertical profile of the velocity from south of Pmair knot to north of Tienshan, it shows that near pamir knot there exists an obvious collision between India and Eurasia plate: the plateau is formed by raised ground surface, the shallower crustal strata of slow velocities are subducted into deeper depth. |
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| Keywords: | Pamir and adjacent areas 3-D velocity structure Crust and upper-mantle |
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