郯庐断裂带苏皖段新构造活动规律

发布时间：2018-03-10 10:20

本文选题：郯庐断裂带苏皖段　切入点：活断层　出处：《合肥工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：郯庐断裂带苏皖段在白垩纪伸展活动中表现为北北东走向的大型正断层。这些正断层在江苏段自东向西分别简称F1、F2、F3和F4断层,它们控制发育了北北东向展布的东地堑、西地堑及两者之间的地垒。东地堑内部还出现了一条北北东向的F5断层。对于郯庐断裂带江苏段的野外地质调查表明,活断层广泛出现,F2、F3与Fs活断层以逆冲活动为主,而F1断层北段则呈现为逆右行平移活动。通过擦痕反演应力场表明,这些活断层是在北东东—南西西向挤压作用下活动,与现今的应力状态相似。依据活断层切割的最新地层时代及光释光测年结果,表明F1断层北段最新活动时代为全新世,F4断层北段在第四纪以来发生过活动,而其南段在第四纪以来没有明显活动,江苏段其余活断层的最新活动时代为晚更新世。活断层位移数据及第四系沉积特征显示,在时间上晚更新世为较强活动期,而空间上F2与F5断层的活动强度最大。实地调查表明,F1、F2、F3及F4活断层多为白垩系地堑边界正断层直接复活成因,具有不均一分段活动的特点。倾向多变的F5活断层则是利用东地堑边界断层的同向或反向正断层复活。郯庐断裂带主干脆性正断层进入嘉山盆地后,转变为两条断层,进入合肥盆地东缘后转变为一条断层,向南沿大别造山带东缘延伸。野外地质调查表明,郯庐断裂带安徽段活断层也是广泛存在,自北向南分别沿着嘉山盆地的东、西边界、合肥盆地东界与大别造山带东界分布。它们自北向南由北北东走向转为北东走向,倾向上与早期盆缘正断层倾向一致。这些活断层以逆右行平移活动为主,但显示了逆冲分量随着断层倾角变小而增大的现象。依据一系列擦痕实测数据的反演,显示这些活断层活动时的区域应力状态为北东东—南西西向挤压,也与现代应力状态一致。依据多种现象综合分析,本文认为郯庐断裂带安徽段活断层的最新活动时代应为中更新世,从而该段没有强震记录或小震群集现象。本次工作表明,区内活断层主体上是早期盆缘正断层直接复活成因。由于其第四纪期间有限的累计垂直位移分量,并没有改变白垩一古近纪盆地发育阶段的地貌格局。
[Abstract]:During the Cretaceous extensional activities, the Jiangsu and Anhui sections of the Tan-Lu fault zone were characterized by large normal faults in the NNE strike. These normal faults are referred to as F1F2F3 and F4 faults from east to west, respectively, in Jiangsu, which control the development of NNE trending eastern graben. There is also a NNE F5 fault in the east graben. The field geological investigation in Jiangsu section of the Tanlu fault zone shows that the active faults are mainly thrust activity. On the other hand, the northern segment of F1 fault shows an inverse right-lateral translation activity. The inversion of stress field by scratch indicates that these active faults are active under the action of NW-W compression. It is similar to the present stress state. According to the latest stratigraphic age of active fault cutting and the results of photoluminescence dating, it is shown that the latest active age of the northern segment of F1 fault is that the northern segment of the Holocene fault has been active since the Quaternary. The last active age of the rest active faults in Jiangsu is the late Pleistocene. The displacement data of the active faults and the sedimentary characteristics of the Quaternary show that the late Pleistocene is a strong active period in time. The active faults of F _ 2 and F _ 5 are the most active in space. The field investigation shows that the active faults of F _ 1, F _ 2, F _ 2, F _ 3 and F _ 4 are the direct resurrection of the Cretaceous graben boundary normal faults. The F5 active fault, which tends to be changeable, is reactivated by the same or opposite normal fault of the eastern graben boundary fault. The main brittleness normal fault of the Tanlu fault zone is transformed into two faults after entering the Jiashan basin, and the main brittleness normal fault of the Tanlu fault zone enters the Jiashan basin. After entering the eastern margin of Hefei Basin, the fault was transformed into a fault, extending southward along the eastern margin of the Dabie orogenic belt. Field geological investigations show that active faults in Anhui section of the Tanlu fault zone are also widespread, from north to south along the eastern and western boundaries of the Jiashan basin, respectively. The eastern boundary of Hefei basin and the eastern boundary of Dabie orogenic belt are distributed from north to south from north to south to north to east, which tend to be consistent with the early basin margin normal faults. But it shows that the thrust component increases with the decrease of fault dip angle. Based on the inversion of a series of measured data of scratch marks, it is shown that the regional stress state of these active faults is east-west compression. It is also consistent with the modern stress state. Based on the comprehensive analysis of various phenomena, this paper holds that the latest active age of the active faults in Anhui section of the Tanlu fault zone should be the Middle Pleistocene, so that there is no strong earthquake record or small earthquake cluster phenomenon in this section. The main body of active faults in the area is the direct resurrection of the early basin margin normal faults. Due to the limited accumulative vertical displacement components during the Quaternary period, the geomorphological pattern of the Cretaceous Paleogene basin development stage has not been changed.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P546

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