喀喇昆仑断裂南段晚第四纪分段活动特征与扎西岗地表破裂带研究
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中国地质科学院地质力学研究所

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中国地质科学院地质力学研究所基本科研业务费项目(所科研56)。


Late Quaternary segmentation activity of the southern part of the Karakorum fault and a study of the Chaxikang surface rupture
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Institute of Geomechanics,Chinese Academy of Geological Sciences

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    摘要:

    青藏高原在近20-30年间发生了一系列大地震,引起了国内外学者的广泛关注。然而,高原上还存在一些规模巨大的断裂带,不仅具有较强的晚第四纪活动性,而且具有孕育和发生强震的构造条件。喀喇昆仑断裂是青藏高原西部的一条规模巨大的右旋走滑断裂,其中龙木错断裂以南的部分是活动性更为明显的段落,且曾发生过1883年普兰Ms 7.0大地震。查明断裂的分段活动特征和地表破裂,有助于理解断裂最新的变形行为并分析其发震习性。文中基于高分辨率遥感影像解译和野外地质调查,详细研究了喀喇昆仑断裂南段晚第四纪分段活动性和最新的扎西岗地表破裂带。结果表明断裂南段可分为拉达克-扎西岗段、昆莎-巴尔段和门士-公珠错段三个一级段落,分别表现为右旋走滑、右旋走滑拉分和右旋走滑兼马尾状正断。地震地表破裂带测得的最小水平位移为8-9m,结合~200km的破裂长度,推测此次地震震级可达~7.5级。喀喇昆仑断裂带在调节高原西部物质向东挤出的方式,由北西段的刚性块体运移方式,向东南段逐渐转化为较为分散的弧形正断和走滑变形。

    Abstract:

    Numerous large earthquakes have occurred in the Tibetan Plateau since the recent decades years, which has attracted widespread attention from scholars both domestically and internationally. However, there are some large-scale fault zones on the plateau, which not only have strong late Quaternary activity, but also have the tectonic conditions for generating strong earthquakes. The Karakorum fault is a large dextral strike-slip fault in the western part of the Tibetan Plateau, with the southern part of the Longmucuo Fault being the more active segment. The Perlan Ms 7.0 earthquake occurred in 1883 along this fault. It is helpful to understand the latest deformation behavior of the fault and analyze its seismogenic behavior by identifying the segmented activity characteristics of the fault and surface rupture. Based on high-resolution remote sensing image interpretation and field geological survey, the late Quaternary segmented activity of the southern section of the Karakorum fault and the Chaxikang surface rupture zone are studied in detail. The results show that the southern section of the fault can be divided into three primary segments: Ladakh-Chaxikang, Kunsha-Bar and Menshi-Gongzhu Co segment, which are respectively characterized by dextral strike-slip, dextral strike-slip tension and dextral strike-slip with with a horsetail normal fault. The minimum horizontal displacement measured at the surface rupture zone is 8-9m. Combined with the rupture length of ~200km, the magnitude of the earthquake is estimated to be ~7.5. The Karakorum fault zone, which regulates the material extrusion in the western plateau, gradually transforms from a rigid block migration mode in the northwest section to a more dispersed arc-shaped normal fault and strike slip deformation in the southeast section.

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  • 收稿日期:2023-05-29
  • 最后修改日期:2023-09-21
  • 录用日期:2023-09-25
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