基于青衣江变形河流阶地研究龙门山断裂带南段的构造活动性

发布时间：2018-04-24 22:18

本文选题：龙门山断裂带南段 + 芦山MS.地震　；参考：《地震地质》2016年03期

【摘要】：龙门山断裂带南段第四纪沉积差,断层出露不明显,晚第四纪构造活动性资料零星。为了提高对龙门山断裂带南段构造活动性的认识,探索芦山地震的发震构造,文中在分析龙门山断裂带南段的地貌以及构造演化的基础上,对跨盐井-五龙断裂、大川-双石断裂和芦山盆地的青衣江不同段的6级河流阶地进行了差分GPS连续测量和细致研究,结合对高分辨率航拍影像的地质解译,得到了龙门山断裂带南段青衣江各段的河流阶地横剖面,通过不同河段河流阶地的对比分析,建立了龙门山断裂带南段青衣江河流阶地纵剖面。通过对河流阶地的变形分析,发现龙门山断裂带南段晚第四纪以来,盐井-五龙断裂的平均垂向断错速率为0.6~1.2mm/a,大川-双石断裂没有明显的垂向活动,芦山地震的发震断层控制的山前褶皱最新活动。结合龙门山断裂带南段的地壳深部结构资料和芦山地震的精定位余震资料等,认为芦山地震的发震构造不是大川-双石断裂,而是龙门山断裂带南段的山前盲逆断层和反冲断层。
[Abstract]:The Quaternary sediments of the southern section of the Longmenshan fault zone are poor, the faults are not obvious, and the late Quaternary tectonic activity data are sporadic. In order to improve the understanding of tectonic activity in the southern segment of the Longmenshan fault zone and to explore the seismogenic structure of the Lushan earthquake, based on the analysis of the geomorphology and tectonic evolution of the southern section of the Longmenshan fault zone, the paper deals with the trans-Yan-Wulong fault. The 6 grade river terraces of different sections of Qingyi River in the Dachuan-Gemini fault and the Lushan Basin have been continuously measured by differential GPS and studied in detail, combined with the geological interpretation of high resolution aerial images. The river terrace cross section of Qingyi River in the south section of Longmenshan fault zone is obtained. The longitudinal section of Qingyi river terrace in the south section of Longmenshan fault zone is established through the comparative analysis of river terraces in different reaches. Through the deformation analysis of the river terrace, it is found that since the late Quaternary, the average vertical fault rate of the Yan-Wulong fault is 0.6 ~ 1.2mm / a, and there is no obvious vertical activity of the Dachuan-Gemini fault. The seismogenic fault of the Lushan earthquake controls the latest activity of the front fold. Based on the deep crustal structure data of the southern segment of the Longmenshan fault zone and the precise location aftershock data of the Lushan earthquake, it is considered that the seismogenic structure of the Lushan earthquake is not Dachuan-Gemini fault. It is the front blind thrust fault and recoil fault in the south section of Longmenshan fault zone.
【作者单位】：中国地震局地震预测研究所地震预测重点实验室;中国地震局地质研究所活动构造与火山重点实验室;
【基金】：中国地震局地震预测研究所基本科研业务专项(2013IES010101,2014IES010104);中国地震局地质研究所基本科研业务专项(IGCEA1416)共同资助高分光学遥感地震构造提取示范应用项目(31-Y30B09-9001-13/15-07)
【分类号】：P315.2

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