小江断裂带南段晚第四纪活动性研究

发布时间：2018-01-27 22:52

本文关键词： 青藏高原东南缘小江断裂带古地震滑动速率　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：青藏高原东南缘地区是青藏高原及周缘活动构造特征最复杂、强震活动性最频繁的区域,是青藏高原附近的研究热点。鲜水河-小江断裂带是东南缘地区重要的边界断裂带,在调节区域构造运动发挥着重要的作用。而小江断裂带位于鲜水河-小江断裂带的最南端,位于鲜水河-小江断裂带与红河断裂带交汇部位,是了解青藏高原东南缘运动学及动力学机制的重点地区。前人对小江断裂带主要的研究工作存在于断裂带中、北段,对于小江断裂带南段的研究工作很少。本文拟通过对小江断裂带南段进行详细的地质地貌研究,并辅以重点地区的古地震研究和滑动速率研究来对小江断裂带南段晚第四纪活动性进行探讨,得出的主要结论有:(1)小江断裂带南段从白云、落水洞、放马坪、龙潭,延伸到山花,并从山花一直往南,通过牛滚塘西侧山坡穿过红河河谷,全长约70km,总体走向北东20°左右,中间呈略为向东凸出的弧形。遥感影像数据上,小江断裂带南段的线性特性清楚,表现为一条连续贯通的、单一的断裂构造。(2)小江断裂带南段断错地貌现象丰富,出露了丰富的构造地貌现象,如地表破裂带、断层槽谷、断层陡坎、山脊位错、眉脊面、冲沟位错、断塞塘等,这些地貌现象表明小江断裂带南段强烈的活动,并具有原地多期次复发性。(3)在小江断裂带南段进行的古地震研究工作,发现了多次的古地震事件。其中落水洞探槽的古地震事件比较丰富,限定了三次事件,从老到新分别为12491±60 a BP和5627±21 a BP,5627±21 a BP和3908±38 a BP,3908±38 a BP和495±20 a BP。结合放马坪地区的年代结果,可以限定最新一次事件年代在495±20 a BP和574±36 a BP之间。根据有关历史地震资料,初步判定小江断裂带南段最晚一次地震事件发生在1606年11月30日,宏观震中位于放马坪至神仙洞水库之间,震级(M)为7.23-7.65。(4)在龙潭地区对典型的位错地貌进行滑动速率研究,测得小江断裂带南段的晚第四纪左旋滑动速率为7.02±0.20mm/a,与小江断裂带中、北段相似,说明小江断裂带的活动性向南不存被NW向断裂带阻挡而大幅减小,前人对小江断裂带的活动性低估了,小江断裂带向南仍是以单一的断裂调节着区域的顺时针旋转作用。通过本次的研究工作,发现小江断裂带南段是一条活动的晚第四纪断层,而且其速率7.02±0.20mm/a,远大于前人认识,同近年来一些GPS结果相似。这些GPS结果中这些滑动速率一直向南延伸,并且穿过红河断裂。本次对从山花往南的遥感影像进行解译,发现了部分断层迹象,大体可以认为小江断裂带南段没有终止于山花,而是继续往南穿过了红河断裂带,作为区域顺时针旋转的东边界,而不是前人认为的在红河以南以奠边府断裂带为东边界的结论。
[Abstract]:The southeast margin of Qinghai-Xizang Plateau is the most complicated area with the most active tectonic characteristics and the most frequent strong earthquake activity on the Qinghai-Xizang Plateau and its periphery. The Xianshuihe-Xiaojiang fault zone is an important boundary fault zone in the southeastern margin of Qinghai-Xizang Plateau. The Xiaojiang fault zone is located at the southernmost end of the Xianshuihe-Xiaojiang fault zone and at the junction of the Xianshuihe-Xiaojiang fault zone and the Honghe fault zone. It is a key area to understand the kinematic and dynamic mechanism of the southeast margin of the Qinghai-Tibet Plateau. The main research work of the Xiaojiang fault zone is in the northern part of the fault zone. There is little research work on the southern section of Xiaojiang fault zone. This paper intends to carry out a detailed geological and geomorphological study on the southern section of the Xiaojiang fault zone. The late Quaternary activity of the southern section of the Xiaojiang fault zone is discussed with paleoseismicity and slip rate studies in key areas. The main conclusions are as follows: the south section of the Xiaojiang fault zone falls from Baiyun to the water tunnel. Fangmaping, Longtan, extending to the mountain flower, and from the mountain flower straight south, through the western slope of Niuliangtang through the red river valley, the total length of about 70 km, the overall northeastward about 20 degrees east. On the remote sensing image data, the linear characteristics of the southern section of the Xiaojiang fault zone are clear, showing a continuous transfixion. The southern section of Xiaojiang fault zone is rich in fault geomorphology phenomena, such as surface rupture zone, fault trough valley, fault steep ridge, ridge dislocation, eyebrow ridge. These geomorphologic phenomena indicate the strong activity in the southern section of the Xiaojiang fault zone and the paleoseismological research in the southern section of the Xiaojiang fault zone. Many paleoearthquake events have been discovered, among which the paleo-seismic events in the trench of the falling water tunnel are abundant, which limit the three events. From old to new, it was 12491 卤60 BP and 5 627 卤21 BP, 5627 卤21 BP and 3908 卤38 BP, respectively. 3908 卤38a BP and 495 卤20a BP. The time of the latest event can be defined between 495 卤20a BP and 574 卤36a BP, according to the relevant historical seismic data. It is preliminarily determined that the last earthquake occurred in the southern section of the Xiaojiang fault zone on November 30th 1606, and the macro epicenter was located between the Yangmaping and Shenxiandong reservoirs. The magnitude M = 7.23-7.65. 4) the slip rate of typical dislocation landforms in Longtan area is studied. The left-lateral slip rate of the southern section of the Xiaojiang fault zone is 7.02 卤0.20mm / a in the late Quaternary, which is similar to that in the middle and northern part of the Xiaojiang fault zone. It shows that the activity of Xiaojiang fault zone is not blocked by NW fault zone, and the activity of Xiaojiang fault zone is underestimated. The south of Xiaojiang fault zone is still a single fault regulating the clockwise rotation of the area. Through this research work, it is found that the southern section of the Xiaojiang fault zone is an active late Quaternary fault. And its velocity is 7.02 卤0.20mm / a, which is much larger than that known by predecessors, and is similar to some GPS results in recent years, in which the sliding rates have been extending southward. And through the Red River fault. This remote sensing image from Shanhua to the south of the interpretation, found some fault signs, it can be considered that the southern section of the Xiaojiang fault zone did not end in Shanhua. Instead of the previous conclusion that the Fangbianfu fault zone is regarded as the eastern boundary in the south of the Red River, it continues to pass southward through the Red River fault zone as the eastern boundary of the region rotating clockwise.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315.2

【相似文献】