【摘要】 乌兰乌拉湖-玉树断裂是巴颜喀拉地块与羌塘地块分界地带的一条重要活动断裂。该断裂东段晚第四纪以来活动强烈,断错地貌特征明显,为全新世活动的左旋逆冲断裂。利用后差分GPS对阶地与洪积扇断错地貌进行了精细测量,并结合碳十四(14C)和光释光(OSL)测年结果对地貌面年代进行限定,获得该断裂东段晚更新世晚期以来的垂直位错量为5.5～6.3m,平均垂直滑动速率为0.23～0.28mm/a;全新世以来的垂直位错量为2.2～4.3m,平均垂直滑动速率为0.40～0.63mm/a;晚第四纪以来的平均左旋滑动速率为4～6mm/a。为该断裂的地震危险性分析和相邻活动地块的运动学特征探讨提供了基础资料。更多还原

【Abstract】 Wulanwulahu-Yushu Fault is an important active fault at the boundary area between Bayankala block and Qiangtang block.The slip rate of this fault in the late Quaternary is of fundamental importance for analyzing the seismic hazards and kinematic characteristics of neighboring active blocks.Due to the limited field conditions,the study of the late Quaternary fault activity on the eastern segment of this fault is rare.On the basis of interpretations of remote sensing images and field investigation,the eastern segment of this fault is active since late Quaternary and the offset geomorphic features are prominent,displaying left-lateral and high-angle thrust faulting.Using the methods of detailed geomorphic mapping,geological survey,differential GPS survey,optically stimulated luminescence(OSL)dating and radiocarbon(\{14C\})dating,this paper makes an analysis of the late Quaternary geomorphic features and slip rate of the eastern segment of this fault.Four typical sites on the fault,including Xiabatang,Zhada,Shangbatang and southwest corner of Batang Basin,were selected for the field investigation.At Xiabatang,the vertical slip rate of the fault is 0.23～0.28mm/a since around 22～27kaBP,0.40～0.51mm/a since 4～5kaBP,and left lateral slip rate is 6.0mm/a since 27kaBP.At Zhada,the vertical slip rate is 0.23mm/a since around 24kaBP.At Shangbatang,the vertical slip rate is 0.45～0.63mm/a since around 6～9kaBP.At southwest corner of Batang Basin,the left lateral slip rate is 4.0mm/a since 150kaBP.The average vertical slip rate of the eastern segment of Wulanwulahu-Yushu Fault is 0.23～0.28mm/a since late Pleistocene,the average vertical slip rate is 0.40～0.63mm/a since early-mid Holocene,and the left lateral slip rate is about 4～6mm/a since late Quaternary.更多还原