苏北盆地中新生代构造演化及其与油气的关系

发布时间：2018-06-23 23:34

本文选题：苏北盆地 + 中新生代　；参考：《长江大学》2015年硕士论文

【摘要】：苏北盆地经过近50余年的勘探研究,在地球物理、沉积、构造和油气方面取得了系列成果认识,主要还存在一下的一些问题：(1)成盆动力学机制尚不明确；(2)原型盆地类型及演化存在多种认识等。本文以苏北盆地为原型,依据现今地震、钻井等资料,开展地震资料的解释,重建现今构造格局。同时基于构造动力学背景分析,以对区内骨干剖面利用平衡剖面分析技术去还原、重塑该区中新生代不同关键时期的构造格局和盆地原型面貌,探讨差异构造演化特征。取得了如下几点认识：一、系统理清了苏北盆地成盆动力学背景早白垩世,苏北盆地所处的下扬子地块与周缘造山带的碰撞造山奠定了盆地的构造格局：南断北超以及自西向东构造由NE向→近东西向→NWW向的弧形展布。晚白垩世-古新世,太平洋板块向欧亚大陆之下俯冲的板块俯冲角度增大,太平洋板块的高角度潜没和回卷产生的地幔楔内,对流以垂向上涌为特征,使欧亚大陆东部地壳逐渐拉伸垮塌-变薄,同时由于印度板块与欧亚板块的碰撞,导致了中国东部处于SE-NW向的右旋张扭。二、建立起了苏北盆地构造格架纵向上将苏北盆地盖层划分为断拗期构造层、断陷期构造层、坳陷期构造层,其中断陷期构造层进一步划分出两个次级构造层。横向上各凹陷都表现为南断北超的箕状断陷特征,各凹陷的轴向与凹陷中古近系各沉降中心轴向大致相同。苏北盆地中以建湖隆起相隔,东台坳陷与盐阜坳陷中各凹陷均呈现右雁行式排列,其中尤以东台坳陷中各凹陷的雁行式排列最为明显。三、完善了苏北盆地构造单元划分,确立了断陷类型基于断陷期沉降幅度和后期改造强度,将断陷分为3种结构类型：裂陷型、断-拗型和断-翘型。裂陷型有高邮凹陷；断-坳型有金湖、溱潼凹陷；断-翘型断陷较多,包括洪泽、海安等凹陷。整体上苏北盆地受郯庐断层走滑作用,断-翘型较多。四、明确了断裂体系特征及对构造的控制作用综合考虑断层尺度、卷入断层变形的地层等因素综合分析基础上可将盆地的断层分为盖层滑脱型断层、基底卷入型主干断层和基底卷入型次级断层等三种类型,其中基底卷入型主干断层大多都是借助印支—燕山期区域性逆冲断层面发生反转位移而形成的NE—NNE向断层,对始新世断陷的凹陷或次凹边界断层起到控制作用。基底卷入型主干断层向深层延伸则可能与地壳深层的拆离断层连接构成更大尺度的连锁伸展断层系统,或在中地壳层软弱层中滑脱构成的地壳尺度的滑脱断层系统。五、确立了盆地构造演化期次及性质依据盆地盖层内部的角度不整合和盆地沉降、断层活动特征可将盆地分为晚白垩世-古新世、始新世和新近纪-第四纪等三期盆地。晚白垩世-古新世盆地发育大量基底卷入型小位移正断层,盆地沉降快速而均匀,显示地壳均匀裂陷伸展形成的坳陷、坳陷-断坳型伸展盆地特征；始新世盆地中的次级基底断层活动明显衰减,而主干断层强烈活动,盆地沉降差异明显,块断升降运动明显,显示地壳非均匀裂陷伸展造成的主干正断层、走滑正断层上盘断陷型伸展盆地特征；新近纪—第四纪断层活动基本停止,盆地整体缓慢沉降,显示后裂陷阶段由于热岩石圈冷却作用形成的热拗陷型盆地特征。六、阐明了盆地差异构造演化特征泰州组-阜宁组一段沉积期洪泽凹陷的伸展率最大,其次为高邮凹陷。整体上西部和中部各凹陷伸展率相对较大。沉积速率以金湖凹陷和高邮凹陷最大,海安和盐城凹陷相对较小。阜宁组二-四段沉积期,苏北盆地最大伸展率凹陷迁移至各中心部位,其最大伸展速率分布位于高邮凹陷-溱潼凹陷,各坳陷东西两侧伸展率相对减小。沉积速率以高邮凹陷最大。戴南组沉积期高邮凹陷的伸展率最大,其次为海安凹陷,再次为洪泽凹陷、溱潼凹陷。沉积速率亦以高邮凹陷最大。三垛组沉积期高邮凹陷的伸展率最大,盆地中高邮、海安、盐城凹陷伸展作用则减弱。七、建立起了盆地构造应力场数值模拟泰州组-阜宁组一段沉积期主张应力强度以洪泽凹陷最强,其次高邮凹陷,其中洪泽凹陷靠近断裂带附近主张应力强度最大,,高邮凹陷主张应力强度高值区主要集中于凹陷南部,金湖凹陷高值区域集中于金湖-宝应之间的区域。阜宁组二-四段沉积期主张应力强度以溱潼凹陷、高邮凹陷最强,溱潼凹陷主张应力高值区集中于西南部,由东北→西南呈现逐渐增强的趋势,而高邮凹陷主张应力强度高值区主要集中于凹陷南部,靠近模拟区域的边界呈现高值主要是边界效应的噪声,属于无效值。戴南组沉积期主张应力强度以高邮凹陷最强,高邮凹陷主张应力强度高值区主要集中于凹陷南部。三垛组沉积期主张应力强度以洪泽凹陷最强,洪泽凹陷靠近断裂带附近主张应力强度最大,断裂带中部最为明显,高邮凹陷主张应力强度高值区主要集中于凹陷南部。金湖凹陷高值区域集中于金湖-宝应之间的区域。
[Abstract]:After nearly 50 years of exploration and research, the North Subei basin has made a series of achievements in geophysical, sedimentary, tectonic and oil and gas fields, and there are still some problems: (1) the mechanism of basin dynamics is not yet clear; (2) the type and evolution of the archetypal basin have a variety of understanding. The interpretation of seismic data and the reconstruction of the present structural pattern are carried out. Based on the structural dynamic background analysis, the structure pattern and the prototype of the Mesozoic and Cenozoic Mesozoic and Cenozoic basins in the region are remodeled by the technique of equilibrium profile analysis, and the characteristics of the differential tectonic evolution are discussed. First, the system clarifies the early Cretaceous in the basin dynamic background of the northern Jiangsu Basin, and the collision orogeny of the lower Yangtze block and the perimeter orogenic belt in the North Jiangsu Basin laid the tectonic framework of the basin: the South fault and the west to the east structure from the NE to the near East-West to the NWW direction. The plate subduction angle of the subduction of the Eurasian continent is increasing, the high angle subduction of the Pacific plate and the mantle wedge in the rewinding of the Pacific plate are characterized by the vertical upwelling, which leads to the gradual collapse of the eastern Eurasian continental crust and the thinning of the earth's crust, while the collision between the India plate and the Eurasian plate leads to the right in the east of the SE-NW direction in the east of China. Two, the tectonic framework of Subei basin has been established to divide the caprock layer of Subei basin into the fault depression period structure layer, the fault depression period tectonic layer and the depression stage structure layer, in which the tectonic layer of the fault depression is further divided into two secondary tectonic layers. The center of each subsidence center in the middle Paleogene is roughly the same axis. In the northern Jiangsu Basin, the Dongtai depression and the Yanfu depression are all arranged in the right goose row, especially in the depression in the Dongtai depression. Three, the division of the construction unit of the northern Jiangsu Basin is perfected and the fault type is based on the fault depression. The period settlement amplitude and the later transformation strength can be divided into 3 structural types: rift type, fault depression type and broken and warping type. The rift type has Gaoyou sag, the fault depression type has Jinhu, the Qin Tong sag, and the fault and warp type fault depression is more, including the Hongze and Haian depression. The whole Subei basin is subjected to the Tan Lu fault strike slip, and the fault - warp type is more. Four, clear. On the basis of comprehensive analysis of the fault scale and the control of the structure, the basin's faults can be divided into three types, such as the cover layer slip fault, the basement involved main fault and the basement involved secondary fault on the basis of comprehensive analysis of the fault scale and the formation of the strata involved in the fault deformation, of which the main basement involved main faults are mostly borrowed. The NE - NNE trending fault occurred in the Indo branch - Yanshan regional reverse thrust fault, which controls the depression or subconcave boundary faults in the Eocene fault depression. The slip fault system of the crustal scale formed by the slippage in the weak layer of the middle crust. Five, the tectonic evolution period of the basin has been established and the nature of the basin is based on the angle unconformity and basin settlement within the caprock of the basin. The characteristics of the fault activity can be divided into the late Cretaceous - Paleocene, the Eocene and the Neogene - quaternary basins. The basin developed a large number of small displacement normal faults with basal involvement type in the Miocene basin. The basin subsidence was fast and uniform, showing the depression of the crust, depression and depression type extensional basins, the secondary basement faults in the Eocene basin were obviously attenuated, and the main faults were strongly active, the basin settlement difference was obvious, block and fall movement Obviously, it shows the main fault of the main crust caused by the unevenly split extension of the crust, the feature of the faulted extensional basin in the strike slip normal fault, the fault activity of the Neogene Quaternary period basically stopped, the whole basin subsiding slowly and the characteristics of the heat depression basin formed by the cooling of the thermal lithosphere in the stage of the post crack depression. Six, the difference of the basin was clarified. The tectonic evolution features the largest extension rate of the Hongze depression in the first section of the Taizhou formation and Funing formation, followed by the Gaoyou sag. The extensional rates of the depression in the western and central regions are relatively large. The deposition rate is the largest in Jinhu and Gaoyou depression, and the Haian and Yancheng depression are relatively small. The maximum extensional rate of the Funing formation in the two - four period and the maximum extension rate in the northern Jiangsu Basin The sag migrated to the central part of the Gaoyou sag - the Qin Tong sag, the East and west sides of the depression were relatively reduced. The deposition rate was the largest in the Gaoyou sag. The Gaoyou sag was the largest in the dentan depression, followed by the Haian sag, and the Hongze sag and the Qin Tong sag. The deposition rate was also Gaoyou. The sag is the largest. The extensional rate of Gaoyou depression in the three stack period is the largest, and the extension of Gaoyou, Haian and Yancheng depression in the basin is weakened. Seven, the tectonic stress field of the basin is set up to simulate the main tensile stress intensity of the Taizhou formation and Funing formation period, the strongest in Hongze sag, and the Gaoyou depression in Hongze depression near the fault zone. The stress intensity of the Gaoyou sag is mainly concentrated in the south of the sag, and the high value region of the Jinhu sag is concentrated in the region between Jinhu and Baoying. The main tensile stress intensity of the two - four section of the Funing formation is the Qin Tong sag, the Gaoyou sag is the strongest, and the high value area of the main tensile stress in the Qin Tong sag is concentrated in the southwest and East from the East. The north to the southwest shows a tendency to increase gradually, while the Gaoyou sag maintains that the high stress intensity area is mainly concentrated in the south of the depression. The boundary near the simulated area shows that the high value is mainly the boundary effect noise, which belongs to the invalid value. The main tensile stress intensity of the Dai Nan formation is the strongest in the Gaoyou sag, and the main tensile stress intensity area of the Gaoyou sag is the main area. It is concentrated in the south of the depression. The main tensile stress intensity in the three stacks period is the strongest in Hongze sag, the main tensile stress near the Hongze sag near the fault zone, the most obvious in the middle of the fault zone. The high value area of the main tensile stress intensity in the Gaoyou sag is mainly concentrated in the south of the sag. The high value region of the Jinhu sag is concentrated in the region between Jinhu and Baoying.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

【参考文献】