【作者】 孙冬胜；

【导师】 赵重远； 刘池阳；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2001， 博士

【摘要】 渤海湾盆地油气资源丰富，勘探和研究程度较高，有关伸展构造的研究论著甚丰，但仍存在不少研究薄弱或困惑人们的构造问题。本文以对大量地球物理资料的研究为基础，结合盆地及邻区丰富的地质构造研究成果及测试数据，以冀中坳陷中区为解剖对象，重点研究该区不同时期、不同类型伸展构造的形成背景，变形特征和演化过程。 从地壳伸展的动力来源出发，将伸展构造的类型划分为热力、区域应力及重力伸展三种类型。这三种伸展构造类型在冀中坳陷中部地区反映清楚，现象丰富，堪称伸展构造的“博物馆”。 在中生代中期强烈的左旋剪切挤压环境中，太行地区岩浆活动达到高潮。在热力作用下，阜平及赞皇两个穹隆状变质核杂岩体形成并快速隆升。现今在核杂岩体上部存在的残山盖层，说明其上原来覆盖有大面积的沉积盖层，该区当时位于前侏罗纪北北东向大型冀西复背斜的西翼。在核杂岩体地表出露的环带状韧性剪切带，反映了核杂岩体的强烈隆升及大规模的侧向拆离伸展，从而构成典型的岩浆侵入-热力穹隆-核杂岩三位一体和热力隆升、岩体剥蚀和侧向拆离三个有机相联、有序发展的演化过程。通过区域构造环境、岩浆岩同位素年龄、地温梯度及卷入拆离滑覆构造地层等综合分析，认为核杂岩体大规模的侧向拆离伸展期，发生在强烈隆升之后的晚白垩世。太行核杂岩体的拆离伸展，在其东侧冀中中区形成了西张东压、西断东隆的构造环境。即西部保定-石家庄断陷带为后缘伸展断陷区，而东部今冀中坳陷东缘和沧县隆起西部为前缘挤压逆冲推覆带，二者之间为过渡区。 西部保定-石家庄断陷以太行山东麓断裂(太东断裂)为界，呈西断东超的箕状结构，沉积地层厚度达6000m。东部前缘挤压带总体呈从西向东逆冲叠覆的叠瓦状结构。该带在早第三纪伸展环境中，向西反转滑覆形成了一系列前第三纪异地岩块。据此，提出了任丘潜山可能为异地岩体的初步论断。中部过渡带构造变形较弱，结构简单，其深部拆离滑覆面在地震剖面上有较清楚的表现。 早第三纪为渤海湾盆地在区域剪张应力作用下发生强烈伸展裂陷及盆地形成的主要阶段。伸展构造体系由拆离断层、生长(伸展)断层和横向构造带组成。本文详细地讨论和总结了在伸展裂陷过程中，三者在变形特征、地质作用等方面的差别。在地壳脆性域的伸展变形，主要通过基底拆离断层及基底生长断层的有机结合而实现，其中前者贡献量远远大于后者。横向构造带在区域差异伸展过程中，起着调节或转换作用。 中区东部一系列侧接的边界断层，发育在早期核杂岩体侧向拆离伸展过程中形成的前缘挤压逆冲带上，属正反转构造。本文以其中的马西断裂为例，详细解剖了基底生长断层的分断性及特征、伴生构造、平移距离、活动期次及演化等。太东断裂属典型的基底拆离断层，于早期核杂岩拆离伸展期形成，在早第三纪早期持续活动并率先进入强烈的伸展阶段，但沙四期后活动性趋于减弱。 两类断层控制的凹陷结构形态、沉积方式及含油气潜力差异较大。后者为规模较大的长条状 西北大学博士学位论文断陷，物源供给充足，沉积以冲洪积或河流相侧向加积为主，烃源岩发育差，且地温梯度低，不利于烃源岩向油气转化；而前者为规模有限的碟形断陷（洼槽），但多为深水环境沉积，烃源岩发育，且地温梯度高，利于油气生成，是主要的生油洼槽。 冀中拗陷差异伸展明显，横向构造带发育，两个一级横向构造带将冀中拗陷分为南、中、北三个结构有别和抽气赋存条件不同的构造区。这两个横向构造带分别为北侧的徐水－安新－文安调节转换构造带和南侧的衡水变换断裂构造带。本文对其特征、形成演化及改造作了深入研究。 早、晚第三纪之间，由于沧县隆起不均衡抬升，导致饶南地区发生大型拆离滑覆，所形成的滑覆构造系，东界始于沧西断裂，向西延至蠢县斜坡的肃宁－饶阳－东里满一线，北界受留北断层控制，南至衡水横向构造带。南北长约 65km，东西宽 30kin，总面积达 1950 km‘。本文从拆离滑覆面、两套差异变形系统、地层缺失及重复、前缘及后缘变形特征、地温场特征等方面，确定了饶南大型拆离滑覆构造的存在。指出原来解释的地震T。面（沙三段底）为一构造面，在该构造面之下，变形复杂，由于大量的韧性剪切带的存在，形成许多构造拆离透镜体：而上部变形相对简单，形成背、向斜相间的构造格局。空间上，拆离滑覆构造具有东西分带，南北分区的特点。 饶南大型拆离滑覆构造是一种新的重力滑动构造类型。其运动轨迹类似于昆虫前行时的“沼曲蠕动”方式逐步向前推进和应力传递。其后缘既是最强烈的伸展区，也是最强烈的挤压区，二者相伴而生。措皱变形在根部强，而向前缘逐渐减弱，且发生的时间依次变新，致使滑覆构造的前缘几乎无明显变形，与滑覆区外呈渐变过渡关系。现有的重力滑动模式则以后缘明显扩展，前缘强烈挤压，二者之间为变形较弱或几乎无变形的过渡带。 造成该区与典型重力滑动模式变形特征不同的原因是作用的物质条件不同。饶南地区为尚未成岩和成岩程度不高的?更多还原

【Abstract】 research data, there are still many puzzling urgent tectonic atderns about Babiima hasin. Based on integration of stacks of geophysical data, tectonic achievements and testing data of the basin and its neighborhoods, evolutive settings, deformation characteristics and evolutive processes of different extensional structural types in different tectonic periods of the middle area of Jizhong depression , are focused on in this paper.According to crust extansional dynamic resource. extensional structures are divided into three types, which are well developed and exhibited clearly in the middle area of Lizhong doression. which should be honored "extensional structural museum".Under middle Mesozoic strong sinistral shear compressive back magamatic activity -in Taihang mountain area culminated. Fuping and Zanhuang dome-like metamorphic assemblages formed and uplifted quickly with thermal process. Nowdays, the remained mountain-cover over the dome denoted large area of deposit cover that lay at the western wing of pre-Jurassic large complex Jixi anticline striking NNE at the beginning. Circum- metamorphic-assemblage tenacitive shear zone on earth surface indicates its violent uplift and large scale lateral extensional detachment. And thus resulted in three-in-one of magma intrusion-thermal vault-metamorphic assemblage and three interdependent evolutive processes of thermal-uplifting, petrographic-eroding and lateral-detaching. By integratedanalysis of regional tectonic settings, magma isotope ages, geothermal gradient and strata involvecyn the detachment,the conclusion has been reached that the assemblage detached laterally on large scale in late Cretaccous after its violent uplift, leading to the tectonic environment of extending in the west anding in theeasCto which corresponded^ by western rifting and eastern uplifting, namely, trierifted zone acted as the rear extensional zone, yet the eastern zone from today’s eastern fringe of Jizhong depression to the western fringe of Cangxian uplift played the role of front compressed thrust zone, and between the both zones is transitional zone.Thejyesteni zone bounded by Taihang fault appeared halfgraben-like with rifting in the west and t, in which sediment thickness comesto 6000m. The eastern cornpresseo^zone presented nappe thrusting from west to east in which a series of pre-Cenozoic allochthony block came into being because of decollement westward by inverted tectonic movement in the Cenozoic extensional settings. Supported by this thought, the original idea that Renqiu buried hill possibly is an allochthony block is reached. Deformation in the transitional zone is less strong and leaded to simple structures, and its detachment faces are fairly clear on seismic profiles basinwhich extended under regional ext^hgar stress, ExlsusJomLsttUCtural systems are composedb^jjfitachnienl faults. and The differences in deformative characteristics, geological functions etc. of this three factors are discussed and summed up in detail. Extensional deformations occurring in brittle crust area depend on close combinative action of basement detachment faults and basement growth faults, and devotion of the former is far more than of the later. The transverse zones adjust or transform regional extension diversity.A. series of overlapping bounding faults of the eastern middle area belonging to positive invertedsttjjcjujje were developed hasprHfln^Ihe-fronL thrust zonelvhich was-fjanned during early period of metamorphic assemblages lateral detachment process. Based on the example or Maxi fault, basement growth tauTts^s segmentation features, associated structures, the horizontal displacement distances, the active stages and the evolution etc. are analyzed thoroughly in this paper. Taidong fault as a typical basement detachment fault, formed during early processes of the metamorphic assemblages detaching, acted continuously in early Cenozoic and extended violently above all, and weakened after Es4obviously. The, fggjier is like a dish with limited scale, deep-wat更多还原