藏南佩枯错地堑西缘岗彭庆断裂带活动特征及工程效应  

Activity characteristics and engineering effects of the Gangpengqing fault zone on the western margin of the Peiku Co graben in southern Tibet

作　　者：李蒙 Li Meng(China Railway First Survey and Design Institute Group Co.,Ltd.,Xi′an 710043,Shaanxi,China;Shaanxi Railway and Underground Traffic Engineering Key Laboratory(FSDI),Xi′an 710043,Shaanxi,China)

机构地区：[1]中铁第一勘察设计院集团有限公司,陕西西安710043 [2]陕西省铁道及地下交通工程重点实验室,陕西西安710043

出　　处：《地质学刊》2024年第2期115-124,共10页Journal of Geology

基　　金：国家重点研发计划项目(2021YFB2301302);西藏自治区科技厅重点研发计划项目(XZ202001ZY0011G);西藏自治区第一次全国自然灾害综合风险普查(2022年地震灾害部分)项目(XZLXBMC-2022-053)。

摘　　要：岗彭庆断裂带位于喜马拉雅山脉北侧、佩枯错—措勤裂谷西南侧,是马拉山东侧的控制性活动断裂带。通过区域地质背景分析、航空航天遥感技术、地面调查、物理勘探及槽探等方法,查明了岗彭庆断裂带的准确位置、空间展布特征,以及断裂组合、断裂深部结构等断层要素。结合断裂地貌实地测量及阶地、探槽古地震年代学测试分析,确定了该断裂带晚第四纪以来的活动性强弱、活动周期和活动速率。岗彭庆断裂带中北段表现为3条次级断裂,自西向东分别为F_(1)、F_(2)、F_(3),其中,F_(1)、F_(2)活动时间较早,为非全新世活动断裂;F_(3)活动时间较晚,为全新世活动断裂。F 3断层垂直滑动速率中等,晚更新世垂直滑动速率约为0.28 mm/a,全新世垂直活动速率为0.10~0.60 mm/a,断层活动周期为6000~8000 a,最新活动时间约为7000 a.BP。岗彭庆断裂带具有长期、分段和多期活动的显著特征,断层不同段落的地貌特征、空间展布形态和深部结构均有明显差异,这种差异带来的工程效应存在较大不同。藏南裂谷区该类型活动断裂普遍发育,研究成果可为藏南线性交通工程穿越该类型活动断裂的方案选择、工程设置及结构设计提供重要的基础支撑。The Gangpengqing fault zone,a controlling active fault zone on the east side of Mala Mountain,is located in the north of the Himalayas and the southwest of the Peiku Co-Cuoqin rift.In this paper,regional geological background analysis,space and aerial remote sensing technology,ground survey,physical exploration and trench exploration are used to find out the accurate location,spatial distribution characteristics,fault combination and deep structure of the Gangpengqing fault zone.Based on the field measurement of fault geomorphology and paleoseismic chronology analysis of terrace and trench,the activity intensity,activity period and activity rate of the fault zone since Late Quaternary are determined in this paper.The central and northern section of the Gangpengqing fault zone shows three secondary faults,F_(1),F_(2)and F_(3),respectively,from west to east.F_(1)and F_(2)are non-Holocene active faults with earlier active time,while F_(3)is a Holocene active fault with later active time.The vertical slip rate of F 3 fault is moderate,the Late Pleistocene vertical slip rate is about 0.28 mm/a,the Holocene vertical activity rate is about 0.10-0.60 mm/a,the fault activity period is about 6000-8000 a,and the latest activity time is about 7000 a.BP.The Gangpengqing fault zone is characterized by long-term,segmented and multi-phase activity.The geomorphic characteristics,spatial distribution and deep structure of different fault sections are obviously different,and the engineering effects resulted from such differences are quite different.This type of active fault is widely developed in the rift region of southern Tibet,and the research results can provide important foundation support for the scheme selection,engineering setup and structural design of linear traffic engineering across this type of active fault in southern Tibet.

关 键 词：断层特征 断层活动性 古地震 线性工程 岗彭庆断裂带 藏南 

分 类 号：P542.31[天文地球—构造地质学] P642.27[天文地球—地质学]