摘要
柴达木盆地北缘断裂带是青藏高原北部的一条区域性活动断裂带,构成了柴达木盆地北部和祁连山的边界断裂,研究其第四纪晚期古地震活动对于理解柴达木盆地北缘断裂带地震复发周期、地震危险性等具有重要意义.通过地质考察、遥感解译、探槽开挖及OSL地质测年、古地震期次分析等,对柴达木盆地北缘断裂(锡铁山-阿木尼克山段)古地震事件进行了研究.研究表明:探槽剖面共揭露了 5次比较可靠的古地震事件,发震时间分别为:事件E1距今约60 a;事件E2 3.1±0.3～3.4±0.3 ka;事件E37.5±0.3～8.1±0.3 ka;事件 E4 10.1±0.4～11.4±0.4 ka;事件 E5 12.1±0.4～12.8±0.4 ka.利用古地震逐次限定法认为柴达木盆地北缘断裂(锡铁山-阿木尼克山段)地震复发周期为2.6～3.4ka.阿木尼克山段最新离逝时间为60年前,锡铁山段最新离逝时间为3.1±0.3 ka,分析认为柴达木盆地北缘断裂锡铁山段未来遭遇破坏性地震的可能性大于阿木尼克山段.该结果可以更好地了解柴达木盆地北缘断裂的古地震期次、复发间隔等,对地震预报预测及评价该断裂未来地震危险性具有一定的指导意义.
Abstract
[Objective]The northern margin fault zone of the Qaidam Basin is a regional active fault zone in the northern part of the Qinghai-Tibet Plateau,forming the boundary fault of the northern Qaidam Basin and the Qilian Mountains.Studying its late Quaternary paleoseismic activity is of great significance for understanding the seismic recurrence cycle and seismic hazard of the northern margin fault zone of the Qaidam Basin.[Methods]Through geological survey,remote sensing interpretation,trench excavation,OSL geological dating,and analysis of paleoseismic events,the paleoseismic events of the northern margin fault of the Qaidam Basin(Xitieshan-Amunikeshan section)were studied.[Conclusion]The study reveals that the trench profiles exposed five relatively reliable paleoseismic events,with occurrence times of approximately 60 years ago for Event El,3.1±0.3 to 3.4±0.3 ka for Event E2,7.5±0.3 to 8.1±0.3 ka for Event E3,10.1±0.4 to 11.4±0.4 ka for Event E4,and 12.1±0.4 to 12.8±0.4 ka for Event E5.Using the paleoseismic incremental limiting method,the seismic recurrence cycle of the northern margin fault of the Qaidam Basin(Xitieshan-Amunikeshan section)is estimated to be 2.6 to 3.4 ka.The most recent event departure time for the Amunikeshan section is 60 years ago,and for the Xitieshan section,it is 3.1±0.3 ka,suggesting a higher likelihood of destructive earthquakes in the future for the Xitieshan section compared to the Amunikeshan section of the northern margin fault of the Qaidam Basin.[Significance]This result can provide a better understanding of the paleoseismic events,recurrence intervals,and other aspects of the northern margin fault of the Qaidam Basin,which has guiding significance for seismic forecasting,prediction,and evaluation of future seismic hazards of this fault.
基金项目
青海省科技厅基础研究项目(2018-ZJ-746)
青海省地震灾害风险普查项目()
维普
万方数据