【作者】 李智武；

【导师】 刘树根；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2006， 博士

【摘要】 毗邻的沉积盆地与造山带是大陆构造的基本单元和形成于统一地球动力学系统中的一对孪生体。对于前陆盆地-造山带系统，二者间的耦合关系是通过其间的冲断带建立起来的。由于其重要的大陆动力学意义并富含油气，20世纪70年代以来前陆盆地和冲断带被给予了极大的关注。论文选择大巴山前陆盆地及毗邻的冲断带作为研究对象，以盆-山耦合研究思想为指导，通过地表地质的详细调查并结合钻井和地震资料，对其构造特征、沉积充填特征、沉降和隆升历史进行了详细解剖。在此基础上，重点讨论了中新生代大巴山前陆盆地和冲断带的形成和演化历史，并对其形成和演化机制进行了探讨。同时，对大巴山前陆盆地的含油气条件和有利勘探区域进行了初步分析。 大巴山冲断带位于四川盆地和秦岭造山带的过渡部位，向西与汉南-米仓山隆起、龙门山冲断带和松潘-甘孜褶皱带相连，东端止于黄陵隆起，总体上为一向南西凸出的弧形构造带。习惯上，以城口断裂为界，将大巴山冲断带分为北大巴山和南大巴山两个构造-地层单元。现已变形的南大巴山（包括米仓山）和四川盆地北部共同组成了本文讨论的中生代大巴山前陆盆地（T₃—K₁）。古生代至中三叠世晚期，南大巴山和四川盆地北部一直是特提斯秦岭洋南侧的被动大陆边缘。中三叠世末以来，伴随华南地块与华北地块间的碰撞拼合以及此后燕山期秦岭大型陆内俯冲，四川盆地北部和南大巴山响应于南秦岭造山带上地壳载荷发生挠曲沉降而演化成为陆内前陆盆地。早白垩世中晚期以来，随着南秦岭逆冲推覆构造的逐渐向南扩展，大巴山前陆盆地也逐渐卷入变形并随之抬升遭受剥蚀。晚三叠世至白垩纪期间的前陆盆地沉降和北东-南西向挤压变形发生于华南与华北地块碰撞拼接之后，表明成盆和造山事件具有陆内性质。 北大巴山以脆-韧性变形和发育厚皮构造为主要特征，由一系列北倾南倒的冲断层和不对称褶皱组成。南大巴山为一薄皮冲断楔，以脆性变形和类侏罗山式褶皱为主要特征，褶皱形态主要包括箱状褶皱、紧闭倒转-同斜褶皱和复杂闭合褶皱。按照断层和褶皱的组合特征，南大巴山可进一步分为叠瓦断裂带、断层-褶皱带和滑脱褶皱带三个次级构造带。叠瓦断层系、断层相关褶皱、反冲断层和冲起构造、（被动顶板）双重构造（或Ⅱ型三角带）等是南大巴山以及四川盆地东北部的主要变形样式。北东-南西向挤压和滑脱层是大巴山冲断带构造变形的主要控制因素。大巴山冲断带共发育四套主要的滑脱层：中下三叠统、志留系、中下寒武统和元古界顶部。大巴山冲断带正是南秦岭大型滑脱推覆构造向南扩展的过程中借助上述滑脱层由深到浅地顺层滑脱或向上切层逆冲形成的。 将详细的节理构造研究纳入区域构造演化的框架中，结合石英ESR测年、岩石声发射Kaiser效应等的研究表明，中新生代南大巴山主要经历了七期构造活动。按照节理的形成依次为：①早期平面X型节理（T₃-K₁早期）；②“断坪-断坡”型节理和早期剖面X节理（K₁早期）；③具逆冲趋势的纵节理（～132Ma）；④具走滑趋势的斜节理及横节理（～100Ma）；⑤右旋走滑趋势的纵节理（K₂-E）；⑥逆冲趋势的斜节理（～28Ma）；⑦左旋趋势的纵节理和正断趋势的纵节理（N-Q）。其中最为重要的是①、③和④期，代表了南大巴山褶皱形成的主要时期，最大构造应力（NE向）平均值为26.9MPa，最小构造应力（NW方向）平均值为6.6MPa。从印支晚期到燕山早期，南大巴山构造应力场发生了顺时针旋转。 大巴山前陆盆地由下向上依次充填了上三叠统须家河组、下侏罗统自流井组、中侏罗统凉高山组和沙溪庙组、上侏罗统遂宁组和蓬莱镇组和下白垩统，残余厚度逾7000m。主要发更多还原

【Abstract】 Sedimentary basin and adjacent orogenic belt are two basic tectonic units of continent and twins developed in a geodynamic system. A foreland basin is connected dynamically with adjacent orogenic belt through a structural belt referred as to fold-thrust belt or thrust belt. Owing to its great significance to continental dynamics and richness in hydrocarbon, the foreland basin-thrust belt system has been paid much attention to in the last three decades. That is the reason why I select Dabashan foreland basin and thrust belt, central China, as my thesis topic.In light of the idea of basin-orogenic belt coupling, I present new structural, sedimentary, subsidence and uplift data integrated into a regional Mesozoic stratigraphic and tectonic framework to provide a detailed picture of spatio-temporal variations in deposition, depocenter migration, and post-depositional deformation of the Dabashan foreland basin-thrust belt system. Moreover, the hydrocarbon potential of the Dabashan foreland basin is also discussed simply in this thesis.The Dabashan fold-thrust belt lies between the northeast Sichuan basin and the Qinling orogenic belt and is a southwestward verging structural belt, joined up with the Hannan-Micangshan dome, Longmenshan thrust belt and Songpan Ganzi complex to the west, terminating at Huangling dome to the east. Tectonically, from orogenic belt towards craton, the Dabashan thrust belt and adjacent region can be divided into three tectono-stratigraphic units by Chengkou fault and Tiexi-Wuxi concealed fault, namely the north Dabashan thrust-nappe belt (N. DBS), the south Dabashan foreland fold-thrust belt (S. DBS), and the Sichuan basin. The deformed north Sichuan basin and S. DBS constitute the Mesozoic Dabashan foreland basin (Late Triassic to Early Cretaceous) discussed in the thesis.The north Sichuan basin, together with the S. DBS, behaved as a passive margin south of the Qinling Tethys from late Paleozoic to Middle Triassic times and then evolved into a foreland basin in response to the amalgamation of the North and South China blocks along the Qinlig-Dabie orogenic belt since the late Late Triassic. Since the middle to late Early Cretaceous, with the edge of the South Qinling deformed belt advancing toward the foreland through time, previously-deposited proximal strata in the Dabashan foreland basin were deformed in the leading edge of the thrust belt, and then uplifted and eroded by subsequent subaerial processes. The subsidence of Dabashan foreland basin and coeval basin-margin compressional deformation from northeast to southwest during Late Triassic to Cretaceous times occurred after the westward progressive collision of the South China Block with North China Block, suggesting that the orogenic and basin-forming events were intracontinental in nature.The N. DBS is characterized by brittle-ductile deformation and basement-involved structure, composed of a suite of thrusts and associated asymmetric folds directed southwest. The S. DBS is a thin-skinned thrust wedge superposed by dextral transpression, characterized by brittle deformation and Jura-like folds, including box fold, tight overturned-isoclinal fold, and complex closed fold. The更多还原