摘要
嘉黎-察隅断裂带是喀喇昆仑-嘉黎断裂带的东段及其东延部分,其中南段主要是指东构造结顶部及东南的通麦-波密-察隅段,断裂位于构造强烈隆升的高山峡谷地貌区,植被茂密、断错地貌不清晰,且缺少第四纪沉积,阻碍了对该断裂带的空间几何展布和地震活动性研究。本文通过对嘉黎-察隅断裂带中南段的遥感解译和地质调查,以及断错地貌和晚第四纪湖相软沉积物变形构造的研究,结合古地震探槽和地质测年等手段,新识别出2次古地震事件,时间限定在16.13±1.06~15.66±0.92 ka和8630±600~9561±37 aB.P.。综合前人资料,分析认为嘉黎-察隅断裂带中南段晚第四纪以来可能发生了5次古地震事件,分别为16130~15660 a、11060±940 a、8630~9561 aB.P.、2780~2160 aB.P.和650 aB.P.,地震复发周期约为2000~5000 a。GPS数据表明,嘉黎-察隅断裂带中段和东南段水平滑动速率为1.3~2.0 mm/a和2~4 mm/a,挤压速率为2.5~2.9 mm/a和5.1~6.2 mm/a,为右旋挤压性质,均存在南北两支断层。断裂活动明显受控于青藏高原东向和绕喜马拉雅东构造结的顺时针旋转运动。嘉黎-察隅断裂带与龙门山断裂带均具有低滑动速率、长复发周期地震特征,考虑到喜马拉雅东构造结顶部目前仍处于较高的构造挤压状态,未来有发生M;≥7级地震的可能性。
The middle south section of the Jiali-Chayu fault is located in an intensive uplift alpine topography area. Due to the dense vegetation, unclear fault landforms, and lack of Quaternary sediments, which hinder understanding of the geometric distribution of fault and seismicity. Based on the remote sensing interpretation, faulted landforms and soft-sediment deformation structures in Late Quaternary lacustrine, and geophysical sections, paleoseismic trench, OSL and;C dating of sediment, at least two paleoseismic events were revealed with ages between 16.13±1.06~15.66±0.92 ka and 8630±600~9561±37 aB.P., respectively. According to the geological survey combined with the available data, at least five paleoseismic events occurred since the late Quaternary in the middle-south section of Jiali-Chayu fault.These were dated to 16130~15660 a, 11060 a, 8630~9561 a B.P., 2780~2160 a B.P.and 650 aB.P., with an earthquake recurrence period of about 2000~5000 a. GPS data show that the horizontal slip rates of the middle and southeast sections of the Jiali-Chayu fault are 1.3~2.0 mm/a and 2~4 mm/a, the compression rates are 2.5~2.9 mm/a and 5.1~6.2 mm/a. Both are dextral compression, and there are two faults in north and south. The fault activity is obviously controlled by the eastward escaping of the Tibetan Plateau and clockwise rotation around the eastern Himalayan syntaxis. The Jiali-Chayu fault is characterized by slow strain accumulation and long recurrence interval. Considering that the top of eastern Himalayan syntaxis is still in a high state of structural compression, there is a possibility of an earthquake(M≥7) in the future.
作者
钟宁
郭长宝
黄小龙
吴瑞安
丁莹莹
张献兵
李海兵
ZHONG Ning;GUO Changbao;HUANG Xiaolong;WU Ruian;DING Yingying;ZHANG Xianbing;LI Haibing(Key Laboratory of Neotectonic Movement and Geohazard,Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing100081,China;Key Laboratory of Deep-Earth Dynamics,Ministry of Land and Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2021年第12期3642-3659,共18页
Acta Geologica Sinica
基金
中国地质调查局项目(编号DD20190319,DD20190059)
国家自然科学基金项目(编号41807298)
中国博士后基金(编号2019M650788)项目联合资助的成果。
