摘要
边坝-洛隆断裂为班公湖-怒江缝合带东南段的西界断裂,正在规划建设中的川藏铁路穿经了该断裂.研究该断裂的晚第四纪活动性对认识缝合带的发展演化历史以及青藏高原东南缘现今构造变形的动力学机制具有重要意义,也直接关系到川藏铁路的规划建设和工程地震安全.边坝-洛隆断裂沿线记录有1642-1654年洛隆M≥7地震和1791-1804年边坝M 63/4地震,然而,由于缺少明确的地质地貌证据,关于边坝-洛隆断裂是否为全新世活动断裂至今仍存在较大争议.基于遥感影像解译和野外地质地貌调查,结合^(14)C加速质谱(AMS)测年技术,笔者在八宿县城和洛隆县城一带获得了多个断错晚更新世-全新世地层的剖面,揭示边坝-洛隆断裂为一条全新世活动断裂,活动性质以左旋走滑为主,其最新一次活动发生在(3310±30)a BP之后,可能对应1642-1654年洛隆M≥7地震事件.调查结果也显示,边坝-洛隆断裂晚第四纪活动的地表形迹非常不连续,其几何展布与班公湖-怒江缝合带的早期边界断裂并不完全一致,似乎暗示缝合带晚第四纪以来的活动可能正在发生新的演化.
The Bianba-Luolong fault,which runs through the Sichuan-Tibet Railway under planning and construction,is the western boundary fault of the southeastern section of the Bangong-Nujiang suture.The Late Quaternary activity of the fault is of great significance for understanding the development and evolution history of the suture and researching the dynamics of the present tectonic deformation in SE Tibetan Plateau,and is also directly related to the planning and construction of the Sichuan-Tibet Railway and the safety of engineering earthquake.Historical records show that two large earthquakes,the 1642-1654 Luolong M≥7 earthquake and the 1791-1804 Bianba M 63/4 earthquake,have occurred on the Bianba-Luolong fault.However,whether the fault has been seismically active in the Holocene remains a subject of debate due to poor research and lack of reliable geologic and geomorphological evidence.In this study,we focus on the Late Quaternary activity of the Bianba-Luolong fault based on interpretation of remote sensing imagery,analysis of field fault outcrops,faulted landforms and chronological measurement of ^(14)C samples.It is suggested that the Bianba-Luolong fault is an active Holocene fault,and the main movement of the fault is sinistral strike-slip.Specifically,the latest faulting event occurred after(3310±30)a BP,which possibly corresponds to the 1642-1654 Luolong M≥7 earthquake.Survey results also show that the surface traces of the Bianba-Luolong fault activity is significantly discontinuous during the Late Quaternary,which is not completely consistent with the previous boundary fault of the Bangong-Nujiang suture,suggesting that the activity of suture zone may be undergoing a new evolution since the Late Quaternary.
作者
韩明明
陈立春
李彦宝
高帅坡
冯嘉辉
Han Mingming;Chen Lichun;Li Yanbao;Gao Shuaipo;Feng Jiahui(Institute of Geology,China Earthquake Administration,Beijing 100029,China;College of Earth Sciences,Guilin University of Technology,Guilin 541006,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2022年第3期757-765,共9页
Earth Science
基金
第二次青藏高原综合科学考察研究任务九专题项目(No.2019QZKK0901)
新建铁路川藏线昌都至林芝段地壳稳定性、活动断裂及对铁路影响评价专题项目(No.X-18-21)
中国地震局地质研究所基本科研业务专项(No.IGCEA1418)。
