摘要
在杭州地区,根据系统采集的萧山—球川断裂、孝丰—三门湾断裂和昌化—普陀断裂的断层泥ESR年龄,以及地层的光释光年龄的统计分析表明,对同一断层同一段而言,断层泥ESR年龄大于地层光释光所给出的断层最后一次活动时代,并不能反映杭州地区各个断裂最后一次活动时代,而是反映了断裂历次较强活动的历史.在距今100—58万年,各断裂均有活动;58—45万年断裂活动性减弱;45—20万年仅萧山—球川断裂活动;10万年以来杭州地区整体处于弱地震背景.以孝丰—三门湾断裂为界,萧山—球川断裂第四纪的活动具有鲜明的分段性.
This paper collected fault gouge samples systematically for ESR （electron spin resonance） dating, and sediment samples for OSL （optically stimulated luminescence） dating, along Xiaoshan-Qiuchuan fault, Xiaofeng-Sanmen fault and Changhua-Putuo fault. In the same fault outcrop, the ESR dated age of fault gouge is older than the time of last fault movement concluded from the OSL data of overlying strata and offset strata. Therefore, the ESR data of fault gouge colleted in Hangzhou region do not represent the time of weak fault movement in late Cenozoic, but represent the episodes of past strong fault movements. The episode of fault movement in late Cenozoic could be inferred according to the ESR data： during 1. 00--0. 58 Ma, there were strong fault movements along the Xiaofeng-Sanmen fault, Xiaoshan-Qiuchuan fault and Changhua-Putuo fault in Hangzhou region; 0.58--0.45 Ma, the movement of all faults became weaker and did not reset ESR signals; 0.45--0.20 Ma, there were strong fault movements along part of Xiaoshan-Qiuchuan fault; 0. 1 0.01 Ma, there were fault movements along the Xiaofeng-Sanmen fault only, but the fault movements were not strong enough to reset the ESR signal; since 0.01 Ma, the Hangzhou region tends to be stable. In addition, the XiaofengSanmen fault might demarcate the Xiaoshan-Qiuchuan fault into segments.
出处
《地震学报》
CSCD
北大核心
2008年第3期262-270,共9页
Acta Seismologica Sinica
基金
杭州市政府及杭州市地震局“十五”重大项目(HZZFCG-2005-A4)资助
