内蒙古乌海盆地内黄河隐伏断裂第四纪活动性研究

发布时间：2018-05-17 01:00

本文选题：乌海断陷盆地 + 黄河隐伏断裂　；参考：《中国地震局地壳应力研究所》2015年硕士论文

【摘要】：隐伏活动断层是指地表无明显位错标志、断裂主体部分隐伏于第四系松散层内的一类活动断裂,因地表没有错段痕迹而难以识别。隐伏活断层的活动不仅可能导致地震的发生,而且可能造成沿断层两侧人员伤亡与严重的财产损失。对于隐伏活动断裂的探测,浅层地震勘探与钻探相结合目前看来是比较有效地方法。但第四纪陆相地层相变复杂、横向连续相较差等特征,给地层等时面的确定与对比、断层多期活动识别带来了困难。利用地层多层次旋回的特点,逐次开展从大层序到小层序的钻孔地层对比,可以有效地避免地层对比的盲目性,降低对比的不确定性。乌海断陷盆地内黄河隐伏断裂早先是由航磁资料推测的,其位置非常靠近甚至穿过乌海市区。因此,在“乌海市城市活断层探测”项目中,将黄河隐伏断裂的探测作为重中之重。本文主要介绍运用深浅层地震勘探与钻孔联合剖面,来研究黄河隐伏断裂的上断点埋深及其晚第四纪活动性。在乌海盆地内布设的地震剖面揭示,黄河隐伏断裂并非是一条单一的断裂,而是由三条近平行近南北走向的分支断层(F3、F4、F5)共同组成。其中断层F3为E倾正断层,大约在在埋深8～10km处终止于W倾正断层F5上。断裂F4为一条向W倾的正断层,与断裂F3呈“Y”字形分布,大约在深度1.2-1.5km左右归并到向E倾的断裂F3上,二者组成断陷内部的一个沉降中心。在浅层地震勘探的基础上,分别沿X07、K2-2、K3、X09四条浅层地震测线,布设了乌兰乡、通达大街、岗德尔河和新园村4条联合钻孔剖面,其中通达大街钻孔用于探测断层F3,乌兰乡和新园村钻孔用于探测断层F4,岗德尔河钻孔用于探测断层F5。在每排钻孔实施过程中,钻孔的布设均采用“对折法”和“层位坡降法”相结合的动态分析方法,即在层位坡降有所增加的区段继续加密钻孔。钻孔过程中,实时记录下地层深度、岩性、结构、构造等信息,并及时采集用于测年的光释光和14C样品。后期,通过层序地层学、岩性岩相分析和第四纪年代测定等方法建立了各钻孔联合剖面。乌兰乡钻孔跨X07测线上两断点FPx06和FPx07布设,共布设100米钻孔4口,钻井编号自西向东依次2→3→4→1,孔间距分别为83m、30m、53m。钻孔过程中六个标志层(标志层①～⑥)在断层两侧断距依次为2.2m、2.0m、2.2m、3.6m、3.6m和6.1m。可能是由三次地震活动事件所导致,三次事件断距依次为2.2m、1.4m和2.5m。根据钻孔所揭露地层岩性特征、相序变化和地层沉积的旋回性特点,应用层序地层学理论,将地层向下而上分为5个准层序(Sq1-Sq5)和19个体系域进行从大层到小层的精细对比。最后得出黄河隐伏断裂分支断裂F4在晚更新世以来表现出3期活动特征,其上断点埋深约为26米,其最新活动时间大约为25Ka。同时乌兰乡钻孔剖面揭露断层F4晚更新世以来的三次活动事件,其垂直活动错距分别为2.2米、1.4米和2.5米,活动的时间依次是(25.6士0.11)Ka BP、(35.6士0.29)～(41.7士0.57)Ka BP、(58.25士7.13) Ka BP。通达大街的联合钻孔剖面共布设了4口100米钻孔,钻孔编号自西向东依次为1→3→4→2。根据地层旋回性自下而上将其分为了3个准层序和12个体系域,通过地层的精细对比,揭露了黄河隐伏断裂分支断裂F3的晚更新世两期活动事件。断层F3上断点埋深深度为50.5米,断层F3的最新活动时间大约为40Ka。地层中的两个标志层(标志层②和标志层①)在断层两侧的垂直落差,反映断层F3晚更新世以来的两次地震活动事件,其垂直断距分别为2.8m和2.0m,活动时间分别为(39.5土0.45)Ka BP和(11.1土1.21) Ka BP。钻孔ZK4在67.2m处穿过F3断层面。岗德尔河钻孔剖面由于钻孔位置距离东侧岗德尔山太近(小于1.5公里),第四纪地层多为岗德尔山山麓冲沟洪流沉积所形成的洪积物,因此沉积物中砾石含量很高。在此处布设的三口钻孔所揭露地层在50m以下全为砾石沉积,难以有效识别断层F5。新园村钻孔揭示该处100m以上地层未受断层F4扰动,100-120m地层表现出一定错位现象。
[Abstract]:Concealed active faults are a kind of active faults that have no apparent dislocation marks on the surface, and the main part of the fault is hidden in the loose layers of the quaternary system, which is difficult to identify because there is no trace on the surface. The activity of hidden active faults may not only lead to the occurrence of earthquakes, but also cause casualties along the two sides of the fault layer and the serious property loss. The detection of hidden active faults and the combination of shallow seismic exploration and drilling seem to be more effective methods at present. However, the phase transition of the Quaternary Continental strata is complicated and the lateral continuous phase is poor. It is difficult to identify and contrast the stratigraphic isochronous surface. The borehole contrast of the large sequence to the small sequence can effectively avoid the blindness of the stratigraphic contrast and reduce the uncertainty of the contrast. The the Yellow River hidden fault in the Wuhai faulted basin was early speculated by the aeromagnetic data, and its position is very close to even through the urban area of Wuhai. Therefore, in the "Wuhai urban active fault detection" project, it will be yellow. The detection of the hidden faults of the river is a heavy weight. This paper mainly introduces the use of deep shallow seismic exploration and borehole joint section to study the buried depth of the concealed fault in the Yellow River and its late Quaternary activity. The seismic profiles in the Wuhai basin reveal that the hidden fault in the Yellow River is not a single single fault, but is composed of three near leveling faults. The branch faults (F3, F4, F5) near the north-south direction are common. The fault F3 is E inclined fault, which terminates on the W tilting fault F5 about 8 to 10km at the depth of the buried depth. The fault F4 is a W inclined normal fault, and the fault F3 is "Y". On the basis of shallow seismic exploration, four shallow seismic surveys along X07, K2-2, K3, and X09, respectively, set up 4 joint drilling sections in uran Township, Tongda street, gang Del River and Xinyuan village, of which Tongda Street drilling is used to detect fault F3, uran Township and Xinyuan village boreholes are used to detect fault F4 and gang Del River drilling. In the process of detecting the fault F5. in each row of drill holes, the layout of the drill holes used the dynamic analysis method combining "the folding method" and the "layer slope method", that is to continue to encrypt the borehole in the section with the increase of the slope of the horizon. In the process of drilling, the information of the depth, lithology, structure and structure of the strata is recorded in real time and is collected in time. The light release light and 14C samples of the year were measured. Later, through sequence stratigraphy, lithology and lithofacies analysis and quaternary dating methods, various drilling joint sections were set up. The two broken points FPx06 and FPx07 were set in the X07 survey line of Ulan township. A total of 100 meters drill holes were set up, and the number of drilling numbers from west to East was 2 to 3 to 4 to 1, and the spacing of the holes was 83m, 30m, 53, respectively. In the course of M. drilling, the six mark layers (sign layer 1 ~ 6) are in turn 2.2M, 2.0m, 2.2M, 3.6m, 3.6m and 6.1m. may be caused by three earthquake events, and the three event interval is 2.2M, 1.4m and 2.5m. are based on the lithologic characteristics of the strata, the phase sequence change and the sedimentary cycle characteristics, and the application layer. The sequence stratigraphy theory divides the strata down into 5 quasi sequence (Sq1-Sq5) and 19 system domains for the fine comparison from the large to the small. Finally, it is concluded that the the Yellow River concealed fault branch fracture F4 shows 3 stages of activity since the late Pleistocene, and the depth of the breakpoint is about 26 meters, and the latest activity time is about 25Ka. and the drills of Ulan township. The hole section reveals three events of the fault F4 since the late Pleistocene, which are 2.2 m, 1.4 m and 2.5 m, respectively. The activity time is (25.6 st 0.11) Ka BP, (35.6 and 0.29) - (41.7 and 0.57) Ka BP and (58.25 7.13) (7.13) joint drilling section of Ka BP. Tongda street. In the East, 1 - 3 - 4 - 2. are divided into 3 quasi sequence and 12 individual regions based on stratigraphic cyclicity. Through fine contrast of the strata, the late Pleistocene two phase activities of the the Yellow River hidden fault branch fault F3 are revealed. The depth of the breakpoint depth of the fault F3 is 50.5 meters, and the latest activity time of the fault F3 is about 40Ka. strata. The vertical drop of two mark layers (sign layer 2 and sign layer) on both sides of the fault reflects the two seismic events of the fault F3 since late Pleistocene, whose vertical break distance is 2.8m and 2.0m respectively. The activity time is respectively (39.5 soil 0.45) Ka BP and (11.1 soil 1.21) Ka BP. drilling ZK4 through F3 broken layer at 67.2m. Because the location of the borehole is too close to the eastern gang of Del mountain (less than 1.5 km), the Quaternary strata are most of the flood deposits formed by the flood sediment in the foothills of the post Del mountain. Therefore, the gravel content is very high. The strata exposed here in three holes are all gravel below 50m, and it is difficult to effectively identify the new village of the fault in the fault. Boreholes reveal that the strata above 100m are not disturbed by fault F4, and 100-120m strata show a certain dislocation phenomenon.
【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】：P542

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