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Slip rates and paleoearthquakes along the east segment of the Guanggaishan–Dieshan fault zone, West Qinling Range, NW China
International Journal of Earth Sciences ( IF 1.8 ) Pub Date : 2020-10-31 , DOI: 10.1007/s00531-020-01947-0
Bo Zhang , Aiguo Wang , Daoyang Yuan , Qinjian Tian , Xiaofeng Liu , Long Zheng , Ming Wu

The WNW-trending GuanggaishanDieshan fault (GDF) is located in the West Qinling Range at a site of tectonic junction between the Tibetan plateau, the Sichuan basin and the Ordos block. Tectonically, this region is bounded by the East Kunlun fault to the southwest, the West Qinling fault to the north, and the Longmenshan fault to the southeast. The activity of the GDF is essentially related with the northeastward expansion of the Tibetan Plateau and associated strain partition between the East Kunlun fault and the West Qinling fault. This study reported the sense of fault movement, rate of fault slip, and the timing of three paleoseismic events on the east segment of the GuanggaishanDieshan fault (EGDF) with which no historical earthquake has been documented before. We focused our investigation on three branch faults in the central part of the EGDF using a range of study methods, e.g. structural mapping, paleoseismological trenching, unmanned aircraft vehicle photogrammetry, differential GPS survey, as well as radiocarbon and optically stimulated luminescence dating. Our new results highlighted: (1) the EGDF is dominated by the left-lateral sense of movement with a minor component of dip slip, (2) the range-bounding branch is characterized by a maximum left-lateral slip rate of 0.72 ± 0.34 mm/year and a maximum vertical-slip rate of 0.13 ± 0.03 mm/year, respectively. Kinematics of the EGDF is similar to many other active faults in the West Qinling Range, together they play a joint role in accommodating and transferring the residual left-lateral slip of the East Kunlun Fault. Three paleoseismic events were identified on the range-bounding fault based on two types of event markers: cut-cover relation and colluvial deposition. The ages of the most recent two events are estimated to be 2765–3320 cal. year BP and 12,775–13,005 cal. year BP and the age of the oldest event is as early as 18,495–32,950 cal. year BP. In contrast, there is no compelling evidence to show paleoseismic event along the rest two branches, and further work is needed to demonstrate this.



中文翻译:

西西北秦岭广盖山-叠山断裂带东段的滑移率和古地震

WNW趋势的广盖山叠山断层(GDF)位于西秦岭山脉,在青藏高原,四川盆地和鄂尔多斯地块之间的构造交界处。从构造上看,该地区的西南部是东昆仑断裂,北部是西秦岭断裂,东南部是龙门山断裂。GDF的活动本质上与青藏高原向东北扩展以及东昆仑断裂和西秦岭断裂之间的应变分布有关。这项研究报告了广盖山东段的断层运动感,断层滑动率以及三个古地震事件的发生时间叠山断裂(EGDF),以前没有记录过地震。我们使用一系列研究方法将研究重点放在了EGDF中部的三个分支断层上,例如结构测绘,古地震学开挖,无人机摄影测量,差分GPS测量以及放射性碳和光激发发光测年。我们的新结果突出显示:(1)EGDF以左侧运动感为主,且有少量滑移;(2)范围边界分支的特征是最大左侧滑移率为0.72±0.34毫米/年,最大垂直滑移率分别为0.13±0.03毫米/年。EGDF的运动学与西秦岭山脉的许多其他活动断裂相似,它们共同在容纳和转移东昆仑断裂带剩余的左侧滑动方面起着共同的作用。根据两种类型的事件标志物,在边界层断层上确定了三个古地震事件:切-盖关系和冲积沉积。最近两个事件的年龄估计为2765–3320 cal。年BP和12,775–13,005卡路里。BP年和最古老事件的年龄最早可追溯到18495–32,950 cal。年BP。相比之下,没有令人信服的证据表明其余两个分支都发生了古地震事件,需要进一步的工作来证明这一点。最近两个事件的年龄估计为2765–3320 cal。年BP和12,775–13,005卡路里。BP年和最古老事件的年龄最早可追溯到18495–32,950 cal。年BP。相比之下,没有令人信服的证据表明其余两个分支都发生了古地震事件,需要进一步的工作来证明这一点。最近两个事件的年龄估计为2765–3320 cal。年BP和12,775–13,005卡路里。BP年和最古老事件的年龄最早可追溯到18495–32,950 cal。年BP。相比之下,没有令人信服的证据表明其余两个分支都发生了古地震事件,需要进一步的工作来证明这一点。

更新日期:2020-11-02
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