A Preliminary Study on the New Activity Features of the Lajishan Mountain Fault Zone in Qinghai Province
A Preliminary Study on the New Activity Features of the Lajishan Mountain Fault Zone in Qinghai Province
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发表时间：
2005
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通讯作者：
Yuan;Daoyang;Zhang;Peizhen;Lei;Zhongsheng;Liu;Baichi;Xiaolong
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作者：
Yuan;Daoyang;Zhang;Peizhen;Lei;Zhongsheng;Liu;Baichi;Xiaolong
拉脊山断裂带由拉脊山北方和南缘两条北东向凸起的弧形断裂组成，断裂长度分别为230 km和220 km。该断裂带位于NWW向右行走滑的热水日月山断裂带与NWW向左行走滑的西秦岭断裂带北方缘之间的大型挤压构造带和构造梯度带中，是一条重要的边界断裂带，将拉脊山南侧的西宁民和盆地与北方的循化-化隆盆地分隔开来。野外调查揭示的新活动的地质地貌证据表明，拉脊山断裂带的最新活动发生在晚更新世晚期（全新世早期仅有少数断裂段活动），以挤压逆冲为主，并伴有轻微的左旋走滑成分。上述运动可能导致了近20次5.0级左右的中强地震的发生。因此，拉脊山地区可作为反映构造运动和地震活动的地震构造窗。
The Lajishan Mountain fault zone consists of two NE-protruding arcuate faults, i.e. the northern and southern margin fault of Lajishan Mountain with the fault length of 230km and 220km respectively. The fault zone is located in the large-scale compressional structure zone and tectonic gradient zone in-between the NNW-trending right-lateral strike-slip ReshuiRiyueshan fault zone and the NWW-trending left-lateral strike-slip northern margin of west Qinling Ranges fault zone is also an important boundary fault zone, separating the XiningMinhe basin and the Xunhua-Hualong basin at the southern and northern sides of the Lajishan Mountain respectively. Geologic geomorphic evidences of new activity revealed by field investigations indicate that the latest movement of the Lajishan fault zone was in late Epipleistocene (only a few segments were active in early Holocene ) and is mainly of compressive thrusting with slightly left-lateral strike-slip component. The above movement has possibly resulted in the occurrence of about 20 moderate earthquakes of magnitude around 5.0.The Lajishan region can therefore be regarded as a seismotectonic window to reflect tectonic movement and earthquake activity.