郯庐断裂带（张渤带以南）地震破裂综合分段研究

发布时间：2017-12-28 01:19

本文关键词：郯庐断裂带（张渤带以南）地震破裂综合分段研究　出处：《中国地震局地质研究所》2016年博士论文　论文类型：学位论文

【摘要】：郯庐断裂带是中国东部规模最大的一条板内断裂带,南起长江北岸的广济地区,向北经安徽、江苏、山东,跨越渤海,经东北三省,进入俄罗斯境内,在我国境内长达2400多公里,总体走向NNE。郯庐断裂带是一条性质多变、长期活动的断裂带,最早起源于中侏罗纪华南、华北板块碰撞中的转换断层模式,致使大别与苏鲁造山带左旋平移了350km;晚侏罗世初,郯庐断裂带再次左旋平移,其一步向北延伸,将华北板块的北边界左旋错移了约200km;共计左旋位移550km。断裂带的伸展活动始于早白垩世期间一直持续到古近纪,形成了我国东部“两堑夹一垒”构造格局。在西太平洋弧后扩张和印度板块向北推挤中的构造挤出作用产生的区域动力下,断裂带新近纪以来持续遭受着挤压,最大主压应力场方向为NEE向。地震是造成我国重大生命财产损失的最重要自然灾害之一,而郯庐断裂位于我国东部地区,人口稠密、经济发达,该断裂带上曾经发生过公元前70年安丘7级地震、1668郯城8.5级地震,如果未来该断裂发生一次7级地震,就会造成人民生命财产的更大损失,会对我国经济造成重创,可能导致经济增长的停滞。因此,多年来,该断裂带一直受到各级镇府、地震主管部门及地质学家的高度重视。八五以来,郯庐断裂带地质填图课题组通过系统的大比例尺填图,把北起潍坊南至泗洪全长约360km的活断层划分为3段,自北向南分别为安丘-莒县段,莒县-郯城段,新沂-泗洪段。2003-2006年宋方敏研究员等和2009-2013年王志才研究员等对安丘-莒县段的两期工作基本查明了安丘-莒县段的空间展布、几何结构以及最新活动特征。2013-2015年冉勇康、许汉刚研究员等在执行宿迁市活动断层探测与地震危险性评价项目中,对宿迁段郯庐断裂开展了大量的物探、钻探、探槽等工作。姚大全研究员等在苏皖交界地带也做了大量的野外地震地质调查与研究。近年来的研究已经扩展了郯庐断裂带活动断层的长度,仅陆地部分就达460km。加上张家口-渤海构造带以南莱州湾海域部分140km,总长达600km。早期的地震破裂分段性划分已经不适应当前认识的深度需要,更不能满足国家经济建设的应用需求。本论文依托国家自然科学基金项目:华北克拉通破坏区最新构造运动事件起始时间及其地震破裂样式研究。开展如下研究:(1)从室内资料的整理收集、航卫片解译以及地质图、地形图的阅读及理解的基础上,开展野外地质调查工作,主要对断错地貌的核验、测量,断层展布的确认、探槽点的选择及开挖工作、断层剖面的绘制、样品的采集,到室内处理及分析,对断层的几何学、运动学及活动时代整体理解认识,并在此基础上分析讨论了公元前70年安丘7级地震和1668年郯城8.5级地震的发震断层;(2)收集我国东部地区小震资料,进行小震精定位工作的开展以及震源机制解的获得,对获得的小震精定位分布特征进行分析,用以断层分段工作,对震源机制解资料理解郯庐断裂区域应力环境;(3)收集我国东部地区的地球物理探测结果,用于分析断层横向、纵向上物性差异,为郯庐断裂带的地震破裂分段提供物性上的约束;(4)对段落边界的地貌、构造特征进行分析。在前人研究的基础上,结合以上分析对郯庐断裂带活动断层进行了地震综合分段。(5)收集华北地区的GPS观测资料,绘制不同段落的GPS速度剖面,求取各段的现今应变滑移速率。结合断层最新活动时代、小震精定位获得的各段小震活动特征,对郯庐断裂带地震破裂各段地震危险性进行了定性的分析。本论文把郯庐断裂带分为五个独立的地震破裂段落:(1)莱州湾-昌邑段包括陆地上的昌邑-南流段和海域内的莱州湾段,总长210km,最新活动时代为全新世中后期,分析认为昌邑-南流段是公元前70年安丘7级地震的发震构造;该段与安丘-莒县段之间差异主要是最新活动时代不同,其次断裂带两侧电性结构存在横向上的差异。(2)安丘-莒县段包括安丘-孟疃段和青峰岭段,总长100km,最新活动时代为晚更新世中晚期-全新世早期。(3)莒县-郯城段,由土岭-陵阳段、石井-大店段、左山段、腾马-中华山段和华侨-窑上段5条长数十公里的次级断层呈右阶斜列组成,长约130km,见晚白垩世砂砾岩逆冲于全新世沉积物之上,并错断冲沟水系,断层剖面可见新鲜的断层泥。该段是1668年郯城8?级地震的地表破裂,早期研究认为该段有三次古地震事件,分别距今3500a、6000-7000a、10000a。该段现代小震密集成带展布,与北侧安丘-莒县段之间是8km宽的左阶阶区障碍体分割,也是胶辽断块与苏北-胶南断块的分界;与南侧的新沂段之间是3km宽的左阶阶区障碍体分割,且被NWW向的晚更新世苍山-尼山断裂横向切割,地貌上山脊高度明显降低二十多米。断层两侧物质与两边断裂段存在着横向上电性差异等多个分段标志。(4)新沂段从郯城麦坡至宿迁市,长约80km,近期的研究认为该段发生过五次古地震事件,时代分别为3.8ka以来、6.2-13.4ka、33.9-45.3ka、46.2-50.4ka和66.5-83.9ka。沿这一活断层段,现今地震微弱。该段和泗洪段的分段标志表现为最新活动时代不同、被中更新世深大断裂无锡-宿迁断裂横向切割以及断层两侧物质横向上存在电性结构差异。(5)泗洪段从宿迁市向南延伸,跨从重岗山西坡穿过,至淮河以北,长约80km,最新活动时代为全新世早期。沿该断层段,缺少现代小地震。最后,我们定性地分析了郯庐断裂带各地震破裂段的未来地震危险性。基于离逝时间越长未来发生地震的可能性越大、小地震越频发释放的应变能越多及GPS应变滑移速率越大反反映处于能量积累早期阶段的科学假设。利用最新活动时代约束了各地震破裂段的离逝时间,结合小震精定位资料,对各个段落进行分析,认为安丘-莒县段和泗洪段离逝时间最长,达10ka,这两段又缺乏小震活动,与当前科学认识的处于闭锁状态,因此,分析认为这两段未来地震危险性较大。如若这两段的GPS速度场获得应变滑移速率可靠的前提下,我们有理由相信泗洪段的闭锁程度更高,相对来说也更危险。存在问题:对各段的古地震序列研究较少,年代样品结果也存在不确定性,因此对古地震序列约束不够;由于东部地区改造严重,至今获得的可靠的断错地貌信息较少,因此对滑移量及滑移速率的研究也是不足的;至于郯庐断裂带地震破裂分段研究,由于对海域部分莱州湾的理解相对较少,现有资料条件下只能把莱州湾-昌邑部分总长210km作为一段,随着海域断层探测的发展,未来是不是可以对该段进一步划分。另外,新沂段和泗洪段的分段标志相对较少,也不能排除大的地震产生级联破裂致使两段全部破裂,段落的分段稳定性需要核验;当前对地震危险性只能定性的评价,如果能对不同段落系统的断错地貌学、古地震序列等定量研究,建立各段的地震复发模型,可以为未来地震危险性评价提供定量的数据支持。
[Abstract]:The Tanlu fault zone is the largest in eastern China in batten fault zone, south of the north shore of the Yangtze River Guangji area, north of Anhui, Jiangsu, Shandong, across Bohai, the northeast, into the territory of Russia, more than 2400 kilometers in China, the overall trend NNE. The Tanlu fault zone is a fault, long-term activities with changeable nature, originated in the early Jurassic in Southern China, North China plate collision in the transform fault model, resulting in the Dabie Su Lu orogenic belt left lateral 350km; Late Jurassic early again sinistral strike slip movement of the Tan Lu fault zone, the step extends to the north, will the north boundary fault of the North China plate left shifted about 200km; total sinistral displacement 550km. The extensional activities began in the early Cretaceous period until the Paleogene formation in eastern China "two cut clip first" structure. After the tectonic extrusion of the Western Pacific back arc expansion and the northward extrusion of the India plate, the fault zone has been continuously squeezed since the Neogene, and the direction of the maximum principal compressive stress field is NEE direction. The earthquake is one of the most important natural disasters in China caused a significant loss of life and property, and the Tanlu fault is located in the eastern region of China, densely populated and economically developed, the fault zone had occurred in 70 BC in Anqiu 7 earthquake, 1668 Tancheng earthquake of 8.5, if a 7 earthquake in the fault happen in the future that will cause more damage to people's life and property, will cause heavy losses to the economy of our country, may lead to stagnation of economic growth. Therefore, for many years, the fault zone has been highly valued by the governments at all levels, the Department of seismological authorities and geologists. 85, since the Tanlu fault zone geological mapping research group has made systematic large-scale mapping, the active fault 360km from North Weifang to Sihong has been divided into 3 segments, from north to south, Anqiu Juxian section, Juxian Tancheng section, Xinyi Sihong section. In the past 2003-2006 years, Song Fangmin, fellows and 2009-2013 years Wang Zhicai researchers have basically identified the spatial distribution, geometric structure and latest activities of the Anqiu Juxian section for the two phases of the Anqiu Juxian section. In the past 2013-2015 years, Ran Yongkang, Xu Hangang and other researchers carried out a lot of geophysical prospecting, drilling and exploration in Suqian section of the Tanlu fault in the implementation of Suqian active fault detection and seismic risk assessment project. Yao in the border of Jiangsu and Anhui Guinness researcher also made investigation and Research on the seismic geological mass. In recent years, the length of active faults in the Tanlu fault zone has been expanded, and the land part only reaches 460km. In addition, the Zhangjiakou Bohai tectonic belt is part 140km of the Laizhou Bay area south of the sea, and the total length is up to 600km. The segmentation of early earthquake rupture has not adapted to the deep needs of the current understanding, and can not meet the needs of the application of the national economic construction. This paper is based on the National Natural Science Foundation Project: the study of the beginning time of the latest tectonic events and the pattern of earthquake rupture in the North China cratonic area. To carry out the research as follows: (1) based on collecting data, aerial photo interpretation and indoor geological map, topographic map reading and understanding, to carry out geological survey work, mainly on the faulted landforms verification, confirmation, measurement, fault trenching point selection and collection, excavation work fault profile drawing, sample, indoor processing and analysis, the fault geometry, kinematics and overall understanding of the era of activities, and on the basis of the analysis discussed in 70 BC to 7 Anqiu earthquake and the 1668 Tancheng 8.5 earthquake fault; (2) collecting small earthquake data in eastern China and for seismic relocation work and focal mechanism solutions, to obtain characteristic andseismic localization analysis, by segment to the fault, the data of the focal mechanism solution to understand the Tanlu fault zone stress environment; (3) received The results of geophysical exploration in eastern China are used to analyze the lateral and vertical physical differences of faults, which provide physical constraints for the fragmentation of the Tanlu fault zone. (4) analyze the physiognomy and structural characteristics of the boundary of the section. On the basis of previous studies, combined with the above analysis, the seismic comprehensive segmentation of the active faults in the Tanlu fault zone is carried out. (5) collect the GPS observation data in North China, draw the GPS velocity profiles of different paragraphs, and obtain the current strain slip rates of each section. Combined with the latest active age of faults and the characteristics of small earthquakes acquired by precise location of small earthquakes, the seismic risk of each segment of the Tanlu fault zone is qualitatively analyzed. The Tanlu fault zone is divided into five independent seismic rupture paragraph: (1) the Gulf of Laizhou - Changyi section including land on the Changyi - South Stream Laizhou Bay, and sea areas within the length of 210km, the latest active period is late Holocene, analysis that Changyi - South stream segment is in 70 BC Anqiu earthquake 7 earthquake; the section between Anqiu and Juxian the main difference is the latest activity in different times, then both sides of the fault zone electrical structure differences horizontally. (2) Anqiu - Juxian - Anqiu section including Meng Tuan section and Qingfengling section, length of 100km, the latest active period is the early Late Pleistocene - holocene. (3) Juxian - Tancheng section, by Tu Ling - Ling Yang, Shijing Dadian, left mountain section, Ma Teng - Chinese and overseas Chinese - kiln upper Hill section of 5 long dozens of kilometers of secondary faults showed right stepping, about 130km, see the late Cretaceous glutenite thrust in Holocene sediment, and faulted gullies, fault profile visible fresh fault gouge. This section is the surface rupture of the 8 - grade earthquake in Tancheng in 1668. Early study found that there were three ancient earthquake events in this section, which were 3500a, 6000-7000a and 10000a respectively. The modern intensive small earthquake zone, and on the north side of Anqiu - Juxian section is Jiejie barriors segmentation of left 8km wide body, but also jiao-liao
【学位授予单位】：中国地震局地质研究所
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P315.2

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