贺兰山西麓断裂活动性质的研究

发布时间：2018-05-22 13:36

本文选题：贺兰山西麓断裂 + 构造地貌　；参考：《中国地震局地壳应力研究所》2015年硕士论文

【摘要】：贺兰山西麓断裂位于南北带最北端,阿拉善块体与鄂尔多斯块体的交界处。其中巴彦浩特断裂是贺兰山西麓断裂最活动的一段,是一条右旋走滑兼有正倾滑的全新世活动断裂。根据影像解译及野外考察,断裂线性地貌清晰,陡坎发育,最新活动中断错的冲沟、河流阶地及洪积扇,为定量研究断裂提供可靠依据。根据3个探槽揭示的事件对比分析,确定4次古地震事件,分别为1.65-5.52 Ka之间、5.5-8.8Ka之间、8.8-11.66Ka、11.OKa-21.51Ka。根据断错地貌及相关沉积物年龄,获得断裂全新世平均水平位移10.1m,平均水平滑动速率1.37±0.1mm/a；晚更新世晚期平均水平位移13.1m,平均水平滑动速率1.09±0.2mm/a,表明断裂进入全新世活动有增强趋势；晚更新世以来的垂直滑动速率为0.64mm/a；而通过陡坎形变法确定断层的滑动速率为0.7mm/a。利用时间可预测模型和地震矩率释放法分别得到地震复发周期为3420a和3190a。此外通过阶地横剖面和年代数据确定断层上盘河流的下切侵蚀速率为0.27mm/a,此速率小于断层上盘的抬升速率。
[Abstract]:The west foot fault of Helan Mountain is located at the northern end of the north and south belt and the junction of Alashan block and Ordos block. The Bayanhaote fault is the most active fault in the western foothills of Helan Mountain, and it is a Holocene active fault with a right-lateral strike-slip and a positive dip slip. According to the image interpretation and field investigation, the linear geomorphology of the fault is clear, the steep ridges are developed, the gullies, river terraces and alluvial fans with the latest activity interruptions are developed, which provides a reliable basis for the quantitative study of faults. According to the comparison and analysis of the events revealed by the three channels, four paleoearthquakes are determined, which are between 1.65-5.52 Ka and 5.5-8.8 Ka, 8.8-11.66 Ka and 11.OKa-21.51 Ka. respectively. According to fault geomorphology and related sediment age, the average horizontal displacement of Holocene is 10.1 m, the average horizontal slip rate is 1.37 卤0.1 mm / a, the average horizontal displacement of late Pleistocene is 13.1 m, and the average horizontal sliding rate is 1.09 卤0.2 mm / a, which indicates that the activity of fault entering Holocene is increasing. The vertical slip rate since the late Pleistocene is 0.64 mm / a, while the fault slip rate is 0.7mm / a determined by the steep-ridge deformation. The recurrence periods are 3420a and 3190a, respectively, using the time-predictable model and the seismic moment rate release method. In addition, it is determined by terrace cross section and age data that the down-cut erosion rate of the upper face of the fault is 0.27 mm / a, which is less than the uplift rate of the upper face of the fault.
【学位授予单位】：中国地震局地壳应力研究所
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.2

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