• ISSN 2097-1893
  • CN 10-1855/P

嘉黎断裂带活动性研究进展

Research progress of Jiali fault activity

  • 摘要: 嘉黎断裂是一条横贯青藏高原东南部的大型走滑断裂,在印度和欧亚板块碰撞前后通过调整应力平衡发挥着重要作用. 本文根据前人对嘉黎断裂的研究成果,从地质学和地球物理学的角度,系统地总结分析嘉黎断裂带构造背景、壳幔结构、晚第四纪和现今的活动性质和速率. 基于地质学方法,搜集前人在测年方面的研究结果,限定断裂的活动年限以及活动速率. 同时在东段的北侧分支嘎龙寺附近,采用光释光测年法增加两个测年点,完善活动速度资料,并对断裂自西向东不同部位的走滑速率和错动断距进行对比分析. 基于地球物理学观测资料,分析地震活动性和壳幔物质的速度结构、各向异性等参数,利用波形拟合方法,新增18个3~5级地震的震源机制解. 结果表明,嘉黎断裂现今的构造变形主要表现为右旋走滑运动,但是在不同的分段具有显著的差异性,新生的西兴拉—达木分支是地震最活跃的区域. 在此基础上,探讨青藏高原的构造演化过程,分析东构造结地区构造运动的稳定性,为川藏铁路雅安—林芝段工程建设地质灾害风险评估提供必要参考资料.

     

    Abstract: The Jiali fault is a large strike-slip fault that traverses the southeast of the Tibetan Plateau. It played an important role as an adjustment fault for adjusting stress balance both before and after the collision of the Indian and Eurasian plates. Based on early publications about the Jiali fault, this study systematically summarizes and analyzes its tectonic background, crustal and mantle structure, properties and rates of activity in the Late Quaternary and the present from the perspectives of geology and geophysics. Based on geological methods, we collected results related to dating in order to constrain the active age and rate of the fault. We newly tested optical stimulated luminescence dating for two areas near the Galong Temple, the northern branch of the eastern section of the Jiali fault to complement the measurement of activity rate. We compared the strike-slip rate and dislocation distance for different segments along the Jiali fault from west to east. Based on geophysical observations, we analyze the seismic activity, crustal and mantle velocity and seismic anisotropy. Using waveform modeling method, we newly determined focal mechanisms of 18 earthquakes with magnitudes between 3 and 5. We found that the current tectonic deformation of the Jiali fault is primarily the right-lateral strike-slip. However, there are different features at different segments. The newly activated Xixingla-Damu branch is the most active segment. On this basis, we discussed the tectonic evolution process of the Tibetan Plateau, and analyzed the structural stability of the eastern Himalaya syntaxis, which is needed for the geological hazard risk assessment of the Sichuan-Tibet railway engineering construction at the Yaan-Linzhi branch.

     

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