怒江断裂带邦达断裂中段全新世活动证据及其古地震记录

Evidence of Holocene activity and paleoseismic records in the central section of Bangda fault in Nujiang fault zone

活动断裂带常是大地震的发震构造,并诱发地质灾害,产生黏滑位错和蠕滑变形,并形成断裂破碎带,进而对城市和工程安全直接造成威胁。因此,厘定活动断裂的空间几何展布、活动性对工程地质研究和防灾减灾具有重要的指导意义。通过遥感解译、错断地貌、槽探和14C测年,对怒江断裂带邦达断裂中段的发育分布特征与活动性进行了调查研究。结果表明:邦达断裂中段在1457±51 a BP/1598±47 a BP发生过古地震事件,为引发中强地震的全新世活动断裂。断裂活动主要受控于川滇菱形块体的南向逃逸挤出和印度板块NEE向直接挤压作用,表现为走滑兼有逆冲分量的高角度活动断裂。该研究为了解怒江断裂带邦达断裂中段活动性和工程抗震设防提供了基础资料。

Objectives:Active faults frequently cause earthquakes and geological disasters,produce stick slip dislocations and creep deformation,and form fault fracture zones,which directly threaten the safety of cities and projects.It is very important to determine the spatial geometric distribution,activity and avoidance distance of active faults,which can help us carry out engineering geological research and disaster prevention and reduction.Therefore,determining the spatial geometric distribution,activity and avoidance distance of active faults has guiding significance for engineering geological research and disaster prevention and reduction.Methods:Through remote sensing interpretation,faulty landform,trough profile and14C dating to research the distribution and activity of the central section of Bangda fault of Nujiang(River)fault.Results:The results show middle section of Bangda fault has occurred one earthquake event at 1457±51/1598±47 a BP,which can induce medium strong earthquakes.The fault activity is mainly controlled by the southward escape extrusion of the Sichuan—Yunnan diamond block and the direct extrusion of the Indian plate in the NEE direction.The central section of Bangda fault is high-angle Holocene active faults,with have a strike-slip and thrust components fault.Conclusions:This study provides basic data for understanding the activity of the east branch of the central section of Bangda fault of Nujiang(River)fault and the seismic fortification of engineering.