断层泥电子自旋共振测年在杭州城市活动断层探测中的应用

Electron Spin Resonance Dating of Fault Gouge for Fault Activity in Hangzhou

  • 摘要: 断层泥电子自旋共振(ESR)测年现已广泛应用于断层最后一次活动时代的测定。在杭州地区,本工作系统地采集北东走向的萧山-球川断裂、北西走向的孝丰-三门湾断裂及东西走向的昌化-普陀断裂上的断层泥进行了ESR测年,并辅以断代地层的光释光(OSL)测年,用以确定断层最后一次活动时代。通过测年结果的统计分析,对同一条断层的同一段,断层泥ESR年龄远大于断代地层的OSL年龄。本工作推断,可能由于杭州地区晚更新世以来断裂活动性较弱,断层泥ESR测年结果并不能反映断裂的微弱活动,而是反映了断裂在第四纪较强活动的历史。

     

    Abstract: Electron spin resonance (ESR) dating was widely used in seismic risk assessment. We collected fault gouge samples for ESR dating and sedimentary samples relativing to fault activity for OSL to conclude the last fault movement for Xiaoshan-Qiuchuan Fault trending NE-SW, Changhua-Putuo Fault trending EW-SN and Xiaofeng-Sanmenwan Fault trending NW-SE in Hangzhou, China. However, ESR data were much older than the OSL data of the sediment which was moved by the same fault. It is predicted that ESR data of fault gouge may not represent the age of the last fault movement because of the weak fault activity since late Pleistocene in Hangzhou region, but it still represents the strong fault activity history in Quaternary.

     

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