【作者】 杨明岭；

【导师】 陈汉林；

【作者基本信息】 浙江大学 ， 地质学， 2008， 博士

【摘要】 郭局子洼陷属于济阳坳陷车镇凹陷内部的一个洼陷。它北部埕南断层下降盘,呈典型的箕状凹陷沉积特征,从缓坡带到陡坡带发育各种类型的储集体和输导体系,具有良好的成藏条件,据第三次资源评价,郭局子洼陷远景资源量1.8×108t。目前仅探明了596万吨的石油地质储量,探井密度只有0.05口／km2,因此,郭局子洼陷极低的勘探程度蕴含着较大的勘探潜力。而且受埕南大断层活动的影响,古近系沉积时期,来自于呈子口凸起的物源沿埕南断层近源堆积,在陡坡带形成了一系列的洪积扇、扇三角洲、近岸水下扇、滑塌浊积扇,是研究断层伸展作用对断陷盆地扇体发育的典型地区。本文在大量岩芯观察、测井和录井资料分析和大量地震剖面解释的基础上,从郭局子洼陷的构造变形过程研究入手,分析了古近系沙河街组受构造控制的沉积特点。通过论文的研究,取得以下创新成果：1.提出了郭局子洼陷整体上经历了断陷一断拗一拗陷三个演化阶段。在沙四一沙三为断陷阶段,断层活动强烈,断块掀斜运动发育；沙二一东营期为断拗阶段,该期断陷稳定,水域扩大,凸起与凹陷的分隔性相对减弱；新进纪和第四纪为拗陷阶段,埋深整体加大。沙四段到沙一段为滚动半地堑主要发育时期,主要受边界犁式正断层的控制；东营组为复杂半地堑阶段,内部浅层断层发育,主要为同向断层。2.提出了郭局子洼陷断陷过程中的水平方向伸展量伸展率和垂直方向的断层落差,并分析了它们的随时间和空间变化规律。古近纪时期洼陷的南北向伸展量自西向东逐步减少,且南北向剖面平均总伸展量与近东西向剖面接近,约为3000m；而总伸展率上,南北向剖面的伸展率达到40%,东西向剖面的伸展率为17%。洼陷古近纪断层伸展活动有两个高峰期,第一次发生在沙四段到沙三中段,为强烈伸展运动阶段,伸展率为9—-17%,此时期总伸展率达到30%左右；第二次从沙二段开始到东营组活动强烈。而且还发现了伸展活动空间位置上是变化的,中部沙四段到沙三下段为初次伸展活动强烈阶段,向西部和东部发生强烈伸展的时间推移到沙三下、中段；二次伸展活动发生的时间次序正好与此相反,东、西部从沙二段开始较大的伸展率,直到东营组活动最为强烈,而中部只在东营组强烈伸展。断层落差分析发现洼陷在沙四、沙三下段一中段、东营组是三个构造沉降较快的时期,从沙四段到沙三段快速沉降时期的沉降中心存在向西迁移的变化；同时也发现洼陷北部沉降幅度为南部的10倍左右。3.提出了郭局子洼陷的地层在断陷过程中掀斜作用及其随时间和空间的变化规律。通过对南北向三条剖面测量,认为埕南断层的构造掀斜作用明显,特别是在沙三中下段,在有同向调节断层时,掀斜角最大达到15度,一般5～10度,远离埕南断层的南部缓坡带,掀斜角一般为1—3度,最高的为4度。4.提出了郭局子洼陷沉积特征的演化。沙四上时期整个郭局子洼陷整体水体较浅,为浅湖相沉积；物源区与沉积区的高差小,形成了小型的带状水下扇体。沙三时期,由于盆缘断裂的强烈活动,盆地开始处于断陷期沉积,洼陷的沉积中心位于靠近盆缘断裂一侧,总体为半地堑结构；物源以北部埕子口凸起寒武一奥陶系为主,石碳一二叠系、中生界次之；盆地与物源区高差加大,在湖盆北带及东部调节断层处,形成多期、多套水下扇沉积,扇间彼此相连,在洼陷中央,形成了湖底扇沉积；沙三中期形成了东部的湖缘峡谷,在峡谷的末端,形成了一定规模的浊积扇。沙三上时期构造活动减弱,气候开始向干旱环境过渡,由于物源区与沉积区高差逐渐变小导致北部水下扇的规模变小；洼陷中部此时仍处于半深湖,南坡发育三角洲沉积。沙二时期,盆缘断裂对沉积的控制逐渐减弱,地层总体显示透镜状分布,盆地中心厚南北两侧逐渐减薄,盆地进入断拗期沉积。沙一至东营期,气候潮湿多雨,湖盆再一次下沉,生物再次繁盛,是湖盆相对平坦期；在陡坡上发育了前扇三角洲及半深湖沉积；南坡地势平缓,发育三角州沉积体系。5.提出了洼陷的构造变形过程对盆地沉积具有重要的控制作用。洼陷的构造变形过程不仅对沉降中心的迁移具有控制,而且对沉积相带展布和对有利砂体分布也具有重要的控制。郭局子洼陷主要受埕南断层的控制,埕南断层在沙四段到沙三段的时期,断层活动向西迁移,导致了沉降中心的向西迁移；而断层的伸展作用导致了盆地与物源区高差加大,物源区岩石剥蚀产物被快速水流源源不断地带入湖盆,在湖盆形成多期、多套水下扇沉积；沙四晚期一沙三早期自西向东形成大35、郭4、郭6和郭1等水下扇体就是受到断层作用的控制；每一个快速构造沉降初期大都是大套近岸砂砾岩的发育期,如沙四早期和沙三早中期砂砾岩厚度大,岩性粗,近岸发育。论文取得的研究成果不仅对指导郭局子洼陷下一步油气勘探具有重要的意义,而且对我国东部断陷盆地沉积体系发育的构造控制作用研究也具有重要的参考价值。更多还原

【Abstract】 Guojuzi sag is one of sag within the of CheZheng depression of Jiyang depression.it’s northern Chengnan hanging-wall block is a typical of half garben sedimentary characteristics, and develop various types of reservoir and transporting system from the fault zone to slope, and has a good reservoir conditions. According to the third resource evaluation, the prospective reserve of Guojuzi sag has 1.8×108 tons of geological oil reserves. At present, only 5.96 million tons of geological oil reserves were proved and the density of exploration well is only 0.05 well/km2. Hereby, Guojuzi sag has a larger exploration potential. Because the impact from the activity of Chengnan fault, The sediment in Paleogene from Chengkouzhi uplift were accumulated along Chengnan fault and a series of alluvial fan, fan delta, inshore underwater fan, fluxoturbidite fan was growed in Guojuzi sag. And Guojuzi sag is a type region for studing the controlling of extension faulting on the development of sedimentary fan.Based on the large number of rock core observation, well logging, logging data analysis, and interpretation of seismic profiles, The dissertation studies the process of structural deformation in Guojuzi sag and the controlling of extension faulting on the development of sedimentation of Shahejie formation in Paleogene. The dissertation acquires the following innovations:1. Guojuzi sag has experienced three stages of evolution. From Shahejie fourth to third phase, The sag was controlled by faulting, and fault activity was very intense, and the block was tilted by fault movement. Shahejie second phase to Dongying phase, the sag was controlled by faulting and thermal subsidence. In this phase, the width of garben was stability, but the sag was enlarge with the expanding of water area, the separation between uplift and depression is relative weakening. From Neogene to Quaternary, the sag was controlled by thermal subsidence and the whole sag subsidenced. From Shahejie fourth phase to Shahejie first phase, the rolling half graben developed which controlled by the boundary listric fault. In Dongying phase, the sag was a complex half-graben, and a series of normal fault with same dipping was develop in upper layer.2. The dissertation has discussed quantity of extension in horizontal and fault displacement in vertical and has also analyzed their spatial and temporal change rule.In Paleocene, the quantity of extension of sag in direction of north-south is reducing gradually from west to east, and the total quantity of extension between north-south section and west-east section is close and is about 3000m. The ratio of extension, are reach to 40% in the north-south section, however, it is 17% in the east-west section. The extension during Paleocene have two intense period. The first period from Shahejie fourth phase to middle stage of Shahejie third phase is the intense extension period, and the extension ratio is 30%. The second period form Shahejie second phase to Dongying phase, the fault movement is also intense. The dissertation also found that the extension in different area is different. In the central of the sag, the time of intense extension is from Shahejie fourth phase to lower period of Shahejie third phase, but in the west part and the east part,The time which happen intense extension was from lower to middle period of Shahejie third phase. In contrast, secondary extension happen early at east and west part which began at Shahejie second phase, but in the central part, the extension happened until Dongying formation. The analysis of vertical displacement of faulting indicated that the fast tectonic subsidence happened in Shahejie fourth phase, lower-middle period of Shahejie third phase and Dongying formation. The subsidence center has happened westward migration from Shahejie fourth phase to Shahejie third phase. Moreover, the subsidence in north part of sag is about 10 times in south part of sag.3.The dissertation has put forward that the stratum of Guojuzi Sag has been tilted in the process of faulting and the spatial and temporal change of tilting. The measurement of the three north-south profiles indicates that tilting is most obvious in Chengnan fault, especially in the lower period of Shahejie third phase, angles of tilting are 5 to 10 degrees in general, but the biggest angle of tilting can reach to 15 degrees where the concordant adjustment-fault developed. In the South gentle slope which is away from the Chengnan fault, angles of tilting are 1 to 3 degrees and the biggest angle is 4 degrees.4.The dissertation has put forward the sedimentary evolution of Guojuzi Sag. In Upper period of Shahejie forth phase, Guojuzi Sag is shallow lacustrine sedimentation, water of overall Sag is shallow. Owing to small height difference between provenance and sediment trap, small size striatus subsea apron developed. In Shahejie third phase, since the intense movement of fault in the margin of sag, sag came into the stage of fault depression deposition. The depocenter of sag is near the side of fault and structure is half-graben. The main provenances is the Cambro-ordovician strata in the north Chengzikou uplift and scondary is the Permain-Carboniferous and Mesozoic strata. Owing to the obvious height difference between provenance and sediment trap, In the north part and eastern adjustment-fault belt, multi-phase, multi-series underwater fan developed, and fan was connected between each other. In central of sag, lake bed fan developed. In the east, the canyon developed in the margin of lake was formed and a certain of scale turbidities fan developed in end of the canyon in middle period of Shahejie third phase. In the middle peroid of Shahejie third phase, faulting became weak, the climate changed to be dry environment. Since height difference between provenance and sediment trap was gradually decreased, the size of northern subsea apron is turn to be smaller. In this period, the central of sag is still semi-deep lake, and there develop deltaic deposit in South slope. In Shahejie second phase, the controlling of faulting is gradually weakened. The strata are main show lenticular which is thicker in the central of sag and is gradually thinning in north and south part, and sag was controlled by the faulting and thermal subsidence. In Shahejie first phase to Dongying phase, the climate is rainy and humid, the lake sinking once again and biology became prosperous again. Fan delta and semi-deep lake sediments are develop in the steep slopes (fault zone), and southern gentle slope developed delta deposition system.5.The dissertation has also put forward that the tectonic deformed process of Sag is play a impotrant role on controling of depositional process of sag. The deformation process of sag not only controlled the migration of subsidencecenter, but also control distribution of sedimentary facieses and the distribution of sand bodies. Guojuzi sag was mainly controlled by Chengnan fault.In Shahejie fourth phase to Shahejie third phase, owing to the activity of Chengnan fault was migrated to west, the subsidence center was also migrated to west. Hence, the extension has resulted into the increase of height difference between provenance and sediment trap. The rocks of provenance was denuded and were continuously carried into lake by rapid stream, and multi-phase, multi-series underwater fan were developed in the lake. The subsea aprons are develop from west to east in upper peroid of Shahejie fourth phase to lower Shahejie third phase, such as Da35, Guo 4, Guo6 and Guol which are controlled by faulting. Every early stage of rapid tectonic subsidence are mostly the development of great suit of offshore sand gravel, such as sand gravel in upper Shahejie fourth phase and lower Shahejie third phase has large thickness, coarse granularity, and develop in offshore.The research results of this dissertation not only has important significance for guiding exploration activity of Guojuzi sag, but also has important reference for the research of tectonic control on depositional system of fault basin in Eastern China.更多还原