摘要
在详细的野外地质调查基础上,通过开挖探槽剖面揭露了断层的基本性质,初步展示了西宁市北川河东岸断裂、南川河断裂和湟水河断裂的地表特征。结合前人的阶地测定年代结果初步判断,北川河东岸断裂错断相当于湟水河Ⅱ至Ⅲ级阶地,Ⅱ级阶地形成不晚于0.05 Ma,Ⅲ级阶地形成不晚于0.12 Ma,说明该断裂是晚更新世活动断裂;南川河断裂错断相当于湟水河Ⅳ、Ⅴ级阶地,Ⅳ级阶地形成不晚于0.54 Ma,Ⅴ级阶地形成不晚于0.78 Ma,说明该断裂是早中更新世活动断裂;湟水河断裂错断其Ⅱ、Ⅲ级阶地砾石层,说明该断裂是晚更新世活动断裂。这些断裂规模小、活动性弱,可能为盖层断裂。
In this paper, on the basis of detailed field geological survey, the features of the faults revealed by digging trenches, the surficial features of faults at the eastern side of Beichuan River, Nanchuan River and Huangshui River in Xining City are presented. Through the previous thermo-luminescent dating, we find that the fault at eastern side of Beichuan River cut the second-order to third order terraces crossed by fault; the third-order terraces formed 0. 12 Ma ago. It shows that this fault has been not active since late Pleistocene; Nanchuan River fault cut the four-order to fifth-order terraces crossed by fault, the four-order terraces formed 0.54 Ma ago. It shows that this fault has been not active since early Pleistocene; Huangshui River fault cut the second-order to third-order terraces crossed by fault. It shows thai this fault has been not active since late Pleistocene. Small scale and weak activity of those faults show that they possibly belong to superficial faults.
出处
《地震》
CSCD
北大核心
2005年第4期119-126,共8页
Earthquake
基金
中国数字地震观测网络工程城市活断层探测项目资助
关键词
活动断裂
西宁城市
探槽剖面
地表特征
Active fault
Xining City
Cross-section of trench
Surface features
