天津幅地区重力场与构造特征研究

发布时间：2019-04-02 16:02

【摘要】：天津幅地区1:100万比例尺图幅包括天津幅的整个地区,地理位置位于北纬36°~40°、东经114°~120°之间。天津幅地区西起太行山,东到渤海和山东莱州,北依燕山,南至泰安市,总面积约23.4×104km2。由于天津幅经历了多次构造运动与沉积演化,导致其周边隆起区与渤海湾盆地的沉积地层具有不同特征。天津幅地区的地球物理及地质工作程度高低不一,渤海湾盆地的研究程度相对较高,而在其他地区的研究程度则较低。目前为止,还没有系统利用天津幅已完成的重力资料对天津幅地区构造等进行系统研究。因此本文以重力资料为主,结合地质、地球物理等研究成果对天津幅的构造体系、沉积地层发育特征等进行研究。本文通过对天津幅地区重力资料的系统收集、整理及处理得到了布格重力异常资料,利用RGIS软件对布格重力异常进行了趋势分析、解析延拓、滑动平均滤波、水平一阶导数、垂向二阶导数等处理,同时结合研究区的构造地质、区域地质、地震测量、钻井勘探等研究成果对重力异常特征进行了综合研究,对研究区的局部重力异常成因进行了分析研究。认为研究区内太行山隆起、燕山褶皱带、鲁西南隆起以及鲁东隆起带内的局部重力高是由基底隆起引起,而局部重力低则是由中、新生界局部增厚引起;渤海湾盆地内的局部重力高一般是由基底局部隆起(断隆)引起,局部重力低则是由中、新生界凹陷(断凹)引起。本文根据重力场特征并结合前人相关研究成果推测出了天津幅地区断裂体系。天津幅地区主要发育NE(NNE)、NW及近EW向三组断裂,不同走向的断裂平面上交织成网格状。根据布格重力异常特征对天津幅地区进行了构造单元划分,可划分为太行山隆起、燕山褶皱带、渤海湾盆地、鲁西南隆起、鲁东隆起这5大一级构造单元,其中渤海湾盆地又进一步划分为2个隆起区、5个坳陷区共7个二级构造单元。同时,本文利用地震、钻井等研究成果,选择了能大体控制渤海湾盆地主要构造格局的6条重力剖面进行了拟合反演,通过定性与定量的解释,采用线性回归法计算获得了研究区内新生界底界埋深。结果表明:渤海湾盆地凸起区内新生界厚度较薄,主要为新近系和第四系,其最小沉积厚度约500m左右,最大厚度不到3000m;在凹陷区内新生界较厚,主要为古近系、新近系和第四系,平均沉积厚度超过3000m,在沉降中心处其厚度达8000m以上。
[Abstract]:The 1: 1 million scale map of Tianjin is located between 36 掳~ 40 掳N and 114 掳~ 120 掳E. The Tianjin area rises from Taihang Mountain to the west, to the Bohai Sea and Laizhou in the east, to Yanshan in the north and to Tai'an in the south, with a total area of about 23.4 脳 104km2. Because Tianjin has experienced many tectonic movements and sedimentary evolution, the sedimentary strata of its peripheral uplift area and Bohai Bay basin have different characteristics. The degree of geophysical and geological work in Tianjin area is different. The degree of study in Bohai Bay basin is relatively high, but the degree of study in other areas is lower. Up to now, there is no systematic study on the tectonics of Tianjin area by using the gravity data of Tianjin amplitude. Therefore, based on gravity data and combined with geological and geophysical research results, this paper studies the tectonic system of Tianjin amplitude and the characteristics of sedimentary strata development. In this paper, the Bouguer gravity anomaly data are obtained by systematically collecting, sorting and processing the gravity data in Tianjin area. The trend analysis of Bouguer gravity anomaly is carried out by using RGIS software, and the continuation, moving average filtering and horizontal first-order derivative are analyzed. At the same time, combined with the research results of tectonic geology, regional geology, seismic survey and drilling exploration in the study area, the characteristics of gravity anomaly are comprehensively studied. The cause of local gravity anomaly in the study area is analyzed. It is considered that the local gravity height in Taihang mountain uplift, Yanshan fold belt, southwest Shandong uplift and east Shandong uplift zone is caused by basement uplift, while local gravity low is caused by local thickening of Mesozoic and Neogene. The local gravity height in Bohai Bay basin is usually caused by the basement local uplift (fault uplift), while the local gravity low is caused by the Meso-Cenozoic sag (fault depression). Based on the characteristics of gravity field and previous research results, the fault system in Tianjin area is deduced in this paper. Three sets of faults, NE (NNE), NW and near EW, are mainly developed in the Tianjin area, and the fracture planes with different strike are interlaced into grids. According to the characteristics of Bouguer gravity anomaly, the tectonic units of Tianjin area can be divided into Taihang uplift, Yanshan fold belt, Bohai Bay Basin, Southwest Shandong uplift and East Shandong uplift, which can be divided into five first-order tectonic units: Taihang Mountain uplift, Yanshan fold Belt, Bohai Bay Basin, Southwest Shandong uplift and East Shandong uplift. The Bohai Bay basin is further divided into 2 uplift areas and 7 secondary tectonic units in 5 depression areas. At the same time, based on the research results of earthquake and drilling, six gravity profiles which can control the main tectonic pattern of Bohai Bay Basin are selected to fit and invert, and the results are explained qualitatively and quantitatively. The buried depth of Neozoic bottom boundary in the study area is calculated by linear regression method. The results show that the thickness of Neozoic in the bulge area of Bohai Bay basin is thin, mainly Neogene and Quaternary, the minimum sedimentary thickness is about 500 m, and the maximum thickness is less than 3 000 m. The Neozoic is thicker in the depression, mainly Paleogene, Neogene and Quaternary. The average sedimentary thickness is more than 3000m, and its thickness is more than 8000m at the center of subsidence.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P548;P312

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