乌兰巴托以西断裂活动时代的光释光年代学研究

摘要

蒙古乌兰巴托周边发育了多条活动断裂.以乌兰巴托以西的Emeeh和Hustai断裂为例,对相关断层开挖探槽,进行年代学研究.结果表明,Emeeh断裂以走滑运动为主,根据剖面错断地层和其上覆、下伏地层的光释光年代学研究结果,推断出该断层最新活动时间介于距今(9.6±1.0)ka和(11.3±1.3)ka之间；对Hustai断裂开挖的新鲜剖面显示其为正断层,通过分析错断地层和其上覆堆积物的光释光定年结果,推断该断裂最新活动时间介于距今(0.87±0.08) ka和(24.2±4.9) ka之间,且可能更接近距今(0.87±0.08)ka.%Several faults are developed around Ulaanbaatar city.In this study,optically stimulated luminescence(OSL)dating is applied to the Emeeh and Hustai Faults in the west of Ulaanbaatar,in order to evaluate the hazards around Ulaanbaatar.Totally,two profiles are studied:the profile ET for the Emeelt Fault and the profile KI for the Hustai Fault.The fault-related sediments in the two profiles are dated by OSL dating to infer the date of the past fault activities.The OSL dating results for samples from profile ET suggest that the age of the last fault movement is between 9.6±1.0ka and 11.3± 1.3ka.The deformed strata and the Heilu soil in the fault scarp on the Hustai Fault suggest a maximum age of 24.2±4.9ka and a minimum age of 0.87±0.08ka for the faulting.