扬子板块海相中古生界盆地的递进变形改造

印支—早燕山期由于古特提斯洋盆的关闭,扬子板块大陆边缘受到了挤压与碰撞作用,在板内形成了江南-雪峰基底拆离体(A带),从SE向NW方向的大规模水平推挤作用使扬子板内中古生界盆地发生了由强及弱的递进(衰减)变形改造。在其前缘形成了高角度冲断层-断弯褶皱带(B带)、逆掩断层-断展褶皱带(C带)、滑脱断层-滑脱褶皱带(D带)、共轭冲断层-膝折褶皱带(E带)和古隆起-单斜带(F带);在其后缘则形成了滑覆断层-滑脱褶皱带(G带)。不同的构造变形区带具有不同的水平位移量、压缩变形量,不同的逆冲断裂、褶皱的空间配置和不同的构造圈闭类型、保存条件,因而控制了不同类型的油气聚集与分布。     

鄂尔多斯盆地西南缘断层相关褶皱与油气圈闭构造

通过对鄂尔多斯盆地西南缘三岔－演武地区野外调查和地震剖面分析,用断层相关褶皱理论对油气储集构造进行了研究。提出在盆地西南缘由断层转折褶皱形成油气圈闭构造的两种类型：（1）缺失前翼膝折带的断层转折褶皱;（2）完整结构的断层转折褶皱。     

塔里木盆地北缘库车前陆褶皱──冲断构造分析

库车前陆褶皱－冲断带是以断坪－断坡式的台阶状逆断层作为滑动机制的盖层薄皮推覆构造，它们在剖面上形成一个向南变薄尖灭的推覆构造楔，底部沿脱面在北侧深南侧浅，推覆变形也是自北向南传递。依据其构造形态和变形特点可分为五个构造亚带：（1）南天山前缘楔状构造带；（2）库姆格列木－依奇克里克断层扩展褶皱构造带：（3）吐格尔明－吉迪克断层弯曲褶皱构造带：（4）秋里塔格断层扩展褶皱与断层弯曲褶皱叠加构造带；（5）库车－亚肯生长断层弯曲褶皱构造带。     

乍得Bongor盆地反转构造特征及形成机制：来自地震剖面及沙箱模拟实验的证据

结合区域地震剖面解析和沙箱模拟实验,探讨分析了乍得Bongor盆地反转构造特征及其形成机制。结果表明：（1） Bongor盆地中发育三种典型的反转构造类型：挤压反转单斜构造、挤压反转向斜构造和挤压反转背斜构造。该类反转构造 一部分具有反转断层相关褶皱样式,主要沿高角度边界断层和基底地垒边界断面发育,形成演化与断裂活动息息相关,另 一部分呈散花状背斜构造样式,属于地层纵弯上拱褶皱,主要发育于斜坡断阶带之间;（2） 区域剥蚀作用对盆地反转构造 演化具有重要的影响,其对盆地内深部地层反转褶皱发育具有促进作用,为深部构造圈闭形成提供条件,而对浅部地层的 反转褶皱发育则表现出阻碍或破坏作用,不利于浅层构造圈闭的形成。     

东濮凹陷古近系伸展褶皱及形成机理

东濮凹陷是一个新生代裂陷盆地,古近纪为裂陷期,形成各种各样的褶皱构造及具有潜力的圈闭构造。本文在地震资料解释基础上,对东濮凹陷褶皱类型进行划分,讨论褶皱形成机制和油气地质意义。东濮凹陷古近纪褶皱,按照褶皱轴向与断层走向关系分为纵向、横向和斜向褶皱;按照褶皱与断层的成因联系,可划分为断弯褶皱、断展褶皱和变换褶皱等。褶皱作用分三个时期,即始新世、渐新世和始新世–渐新世。褶皱的形成机理为顺层剪切滑动和切层剪切滑动。褶皱的形成与断层紧密相关,是断面形态、断层多期活动和断层位移变化的结果。东濮凹陷油气圈闭与褶皱存在直接或间接的关系。     

东营凹陷伸展断弯褶皱的构造几何学分析

东营凹陷是渤海湾盆地南部一个典型的中新生代半地堑盆地。本文通过对横穿东营凹陷的地震反射剖面进行精细的构造解析,发现这个半地堑盆地的伸展构造具有明显的膝折变形特征,基本上符合伸展断弯褶皱模型。由此运用伸展断弯褶皱理论,同时按照平衡剖面原理,详细恢复了东营凹陷伸展构造的发育过程。经过对盆地内部构造变形的反复拟合和测算,我们确定了东营凹陷伸展断弯褶皱的构造几何学特征及其运动学过程,揭示出东营凹陷各主要裂谷阶段的地壳水平伸展量,并且将其中的背斜解释为上凹与上凸断层转折组合所形成的一个伸展背斜构造。同时采用构造几何学方法推断在白垩纪末期该地区曾经历过大约1750m厚的剥蚀作用,总伸展量可达25km。     

挤压断裂构造样式地震解释

挤压构造的动力学为板块与板块碰撞形成造山带,在造山带一侧或造山带内部形成挤压型盆地,这些盆地在挤压应力作用下,形成叠瓦逆冲、复合逆冲、多层次滑脱逆冲、多产状逆冲断裂构造组合。文中对与挤压逆冲有关的褶皱构造样式——断弯、断展、断滑褶皱构造进行了描述,指出在加强非背斜构造样式勘探的同时,也应加强背斜构造样式的勘探。油气资料显示80%～90%的油气生产来自背斜构造样式的油气田,面积大、幅度高的挤压构造是形成大、中型油气藏的地质条件。     

库车坳陷克依构造带坎亚肯背斜变形序列及其ESR年代

基于对库车褶皱逆冲带坎亚肯褶皱发育的小尺度构造的特征和相互叠加、切割关系的分析,认为该构造形成于新生代,经历了三个阶段,即平行层面的挤压缩短作用阶段、弯滑与弯流褶皱作用阶段和逆冲断层改造作用阶段.断层滑动数据反演和古应力恢复的结果表明,控制整个变形过程的构造应力场最大主应力方向σ1(即构造缩短方向)集中分布在NNW-SSE向.断层面上薄层方解石晶体的ESR测年结果显示,断层活动时间不晚于2.1Ma.该区这一构造变形发生在上新世末以前,是在同一稳定应力场下同一次构造挤压产生的渐进式序列变形结果,对于克依构造带的构造圈闭最终定型起着决定性作用.     

伸展断层相关褶皱的几何学分析及其在车镇凹陷中的应用

本文总结了伸展断层相关褶皱的发育类型,主要包括伸展断层传播褶皱与伸展断层转折褶皱(也叫断弯褶皱)等.伸展断层传播褶皱多形成在较陡的正断层之上,正断层向上传播使断层顶部地层弯曲,进而形成一个伸展的断层传播褶皱,其发育模式与三剪变形发育模式一致.车镇凹陷是渤海湾盆地南部一个典型的中新生代半地堑盆地.本文通过对横穿车镇凹陷的...     

贝尔凹陷苏德尔特构造带的形成与演化

苏德尔特构造带是海拉尔盆地贝尔凹陷的重要油气聚集带之一。使用平衡剖面技术和基于斜向剪切模型的人字形桁架法对苏德尔特构造带及其两侧的贝西断陷和贝中断陷进行了详细的构造几何学和运动学解析,认为在南屯期近SN向伸展,形成近EW向断陷盆地群之后,又叠加了大磨拐河组早期的短时间NW向伸展,以及此后的坳陷沉降,才形成了苏德尔特构造带特殊的构造样式。贝中断陷的东侧边界断层是整个贝尔凹陷在大磨拐河组早期伸展的主干边界断层,并且断层面具有坡坪式特征。苏德尔特构造带是发育于第一阶断坪上部的"滚动背斜",是重力和边界断层几何形态共同控制的结果,形成机制属于重力影响下的横弯褶皱作用,而非侧向挤压引起的纵弯褶皱作用。     

Kinematics of fault-bend folding

The concept of bed-duplication folding, a process of folding by stacking of duplicate beds above a thrust ramp, was introduced by John L. Rich in 1934, and such folding has been studied mechanically and geometrically during the last few years.

This paper introduces two kinematical models to bridge between geometrical and mechanical analyses, so results of the two methods of determining the deformations and geometry of bed-duplication folding can be compared. One kinematical model is required for early stages and the other for late stages of bed-duplication folding, but each involves a simple, domainal, velocity distribution. It is remarkable that such simple kinematical models can produce complex geometrical models. The kinematical models clearly produce the type of bed-duplication fold developed by graphical construction and termed “fault-bend fold”. The kinematical models provide new insights into the essence of the type.

The velocity distributions assumed in the kinematical models are similar to those predicted by a first-order, mechanical model for thrust ramps with low slopes (less than about 20 degrees) and zero drag. The fold forms computed from the two sets of models are also similar, so geometrical construction roughly reproduces a simple, low-amplitude bed-duplication fold.

The approximation is poorer for steeper thrust ramps. The upper limit of the kinematical fold. and geometrical construction is 30 degrees and, at that ramp angle, the dip of the distal limb of the fold is twice the dip of the thrust ramp. Results of the mechanical analysis of relatively steep ramps, carried to second-order accuracy, indicate that the 30-degree limit of the ramp angle is an artifact of the geometrical analysis and that the block being thrusted is subjected to general simple shearing. The simple shear is absent in the kinematical models and the geometrical construction. Nevertheless, both the kinematical and mechanical models predict asymmetry of fold limbs.     

断层相关褶皱的几何学模型及其应用

在前陆盆地逆冲带中发育两种主要的断层相关褶皱构造样式：断层转折褶皱和断层传播褶皱。利用断层相关褶皱的下伏断层和上覆褶皱之间的角度参数存在的函数关系,可以对自然构造横剖面的构造解释进行检验。由于在时间地震剖面下的构造图形由于产生变形而与实际的自然构造有一定的偏差,这会影响几何学模型检验的有效性,因此在应用的过程中需要进行校正。通过地震速度谱将时问地震剖面转化为深度地震剖面,然后利用几何学关系对断层相关褶皱的构造剖面进行了检验。     

Structural analysis of the Lombard thrust sheet and adjacent areas in the Helena salient,southwest Montana,USA

The Helena salient is a prominent craton–convex curve in the Cordillera thrust belt of Montana, USA. The Lombard thrust sheet is the primary sheet in the salient. Structural analysis of fold trends, cleavage attitudes, and movement on minor faults is used to better understand both the geometry of the Lombard thrust and the kinematic development of the salient.Early W–E to WNW–ENE shortening directions in the Lombard sheet are indicated by fold trends in the center of the thrust sheet. The same narrow range of shortening directions is inferred from kinematic analysis of movement on minor faults and the orientations of unrotated cleavage planes along the southern lateral ramp boundary of the salient. As the salient developed, the amount and direction of shortening were locally modified as listric detachment faults rotated some tight folds to the NW, and as right-lateral simple shear, caused by lock-up and folding of the Jefferson Canyon fault above the lateral ramp, rotated other folds northeastward. Where the lateral ramp and frontal-oblique ramp intersect, folds were rotated back to the NW. Our interpretation of dominant W–E to WNW–ESE shortening in the Lombard sheet, later altered by local rotations, supports a model of salient formation by primary parallel transport modified by interactions with a lateral ramp.     

Three‐dimensional Evolutionary Models of the Qiongxi Structures,Southwestern Sichuan Basin,China: Evidence from Seismic Interpretation and Geomorphology

Fold terminations are key features in the study of compressional fault-related folds. Such terminations could be due to loss of displacement on the thrust fault or/and forming a lateral or oblique ramp. Thus, high-quality seismic data would help unambiguously define which mechanism should be responsible for the termination of a given fault-related fold. The Qiongxi and Qiongxinan structures in the Sichuan Basin, China are examples of natural fault-propagation folds that possess a northern termination and a structural saddle between them. The folds/fault geometry and along-strike displacement variations are constrained by the industry 3-D seismic volume. We interpret that the plunge of the fold near the northern termination and the structural saddle are due to the loss of displacement along strike. The fault geometry associated with the northern termination changes from a flat-ramp at the crest of the Qiongxinan structure, where displacement is the greatest, to simply a ramp near the northern tip of the Qiongxi structure, without forming a lateral or oblique ramp. In this study, we also use the drainage pattern, embryonic structure preserved in the crest of the Qiongxinan structure and the assumption that displacement along a fault is proportional to the duration of thrusting to propose a model for the lateral propagation of the Qiongxinan and Qiongxi structures. Specifically, we suggest that the structure first initiated as an isolated fault ramp within brittle units. With increased shortening, the fault grows to link with lower detachments in weaker shale units to create a hybridized fault-propagation fold. Our model suggests a possible explanation for the lateral propagation history of the Qiongxinan and Qiongxi structures, and also provides an alternative approach to confirming the activity of the previous Pingluoba structure in the southwestern Sichuan Basin in the late Cenozoic.     

Folding of a detachment and fault – Modified detachment folding along a lateral ramp,southwestern Montana,USA

The inversion of the Middle Proterozoic Belt sedimentary basin during Late Cretaceous thrusting in Montana produced a large eastwardly-convex salient, the southern boundary of which is a 200 km-long oblique to lateral ramp subtended by a detachment between the Belt rocks and Archean basement. A 10 km-long lateral ramp segment exposes the upper levels of the detachment where hanging wall Belt rocks have moved out over the Paleozoic and Mesozoic section. The hanging wall structure consists of a train of high amplitude, faulted, asymmetrical detachment folds. Initial west-east shortening produced layer parallel shortening fabrics and dominantly strike slip faulting followed by symmetrical detachment folding. “Lock-up” of movement on the detachment surface produced regional simple shear and caused the detachment folds to become asymmetrical and faulted. Folding of the detachment surface after lock-up modified the easternmost detachment folds further into a southeast-verging, overturned fold pair with a ramp-related fault along the base of the stretched mutual limb.     

Three-dimensional Evolutionary Models of the Qiongxi Structures, Southwestern Sichuan Basin, China: Evidence from Seismic Interpretation and Geomorphology

Fold terminations are key features in the study of compressional fault-related folds. Such terminations could be due to loss of displacement on the thrust fault or/and forming a lateral or oblique ramp. Thus, high-quality seismic data would help unambiguously define which mechanism should be responsible for the termination of a given fault-related fold. The Qiongxi and Qiongxinan structures in the Sichuan Basin, China are examples of natural fault-propagation folds that possess a northern termination and a structural saddle between them. The folds/fault geometry and along-strike displacement variations are constrained by the industry 3-D seismic volume. We interpret that the plunge of the fold near the northern termination and the structural saddle are due to the loss of displacement along strike. The fault geometry associated with the northern termination changes from a flat-ramp at the crest of the Qiongxinan structure, where displacement is the greatest, to simply a ramp near the northern tip of the Qiongxi structure, without forming a lateral or oblique ramp. In this study, we also use the drainage pattern, embryonic structure preserved in the crest of the Qiongxinan structure and the assumption that displacement along a fault is proportional to the duration of thrusting to propose a model for the lateral propagation of the Qiongxinan and Qiongxi structures. Specifically, we suggest that the structure first initiated as an isolated fault ramp within brittle units. With increased shortening, the fault grows to link with lower detachments in weaker shale units to create a hybridized fault-propagation fold. Our model suggests a possible explanation for the lateral propagation history of the Qiongxinan and Qiongxi structures, and also provides an alternative approach to confirming the activity of the previous Pingluoba structure in the southwestern Sichuan Basin in the late Cenozoic.     

伸展盆地的转换斜坡:控制储层发育与烃类运聚的重要构造单元

转换斜坡是指两条倾向相同并在走向上叠覆的正断层之间的强烈旋转地带.此定义自20世纪50年代提出以来,尤其是在20世纪90年代后得到了深入的研究.转换斜坡是伸展盆地中传递带的一种类型,对储层沉积和烃类运聚具有重要意义.基于正断层的生长机制形成的转换斜坡具有显著的位移和演化特征,虽成因相似但规模悬殊.由于转换斜坡部位较小的...     

Self-Similar Fold Evolution Under Prescribed End-Shortening

The evolution of single-layer folds under prescribed end-shortening conditions displays folds of varying wavelength. We investigate a simple model of this kind and characterize the long-term behaviour of fold profiles. In particular we determine the evolution of the axial load and the variation of the wavelength, and we show that fold profiles are highly self-similar.     

江南造山带北部早中生代岳阳—赤壁断褶带构造特征及变形机制研究

早中生代(晚印支-早燕山期)岳阳-赤壁断褶带位于江南造山带与中扬子前陆盆地交界地带.作者对该构造带进行了地表地质调查,以此为基础探讨了构造剖面结构及构造变形动力机制.岳阳-赤壁断褶带自南而北可分为岳阳-临湘基底滑脱-逆冲带,桃花泉-肖家湾盖层滑脱褶皱带,以及赤壁-嘉鱼前陆盆地断-褶-盆构造带.岳阳-临湘基底滑脱-逆冲带自南而北依次有郭镇向斜、官山背斜、临湘倒转向斜和聂市背斜,组成隔槽式褶皱组合.褶皱轴面多向南倾,褶皱变形面为南华系盖层与冷家溪群褶皱基底间的角度不整合面和顺界面的滑脱断裂面.桃花泉-肖家湾盖层滑脱褶皱带主要发育轴面南倾倒转褶皱,褶皱波长较小,卷入地层为南华系-志留系以及上石炭统-中三叠统沉积盖层.赤壁-嘉鱼前陆盆地断-褶-盆构造带以南倾蒲圻断裂(江南断裂)为南部边界,发育T3-J2前陆盆地沉积,带内褶皱与断裂卷入地层包括沉积盖层以及T3-J2地层:南部断裂与褶皱轴面南倾.北部轴面近直立.自南西至北东,研究区内构造线走向由EW向渐变为NEE-NE向.上述构造分带及变形特征反映出自南向北的运动指向,表明岳阳-赤壁断褶带具前陆冲断带构造性质.从断裂相关褶皱理论出发,以地表构造特征为依据,厘定了岳阳-赤壁地质剖面结构并进行了变形动力机制分析,认识如下:①自南而北、自下而上的多个滑脱层及其间的南倾逆断裂或断坡(主要为江南断裂)组成近似台阶状的逆冲断裂系统,从总体上控制了构造块体的滑移、逆冲以及相应的构造格架或变形分区.②郭镇向斜为基底滑脱褶皱,官山背斜具滑脱褶皱和断裂传播褶皱双重成因,聂市背斜为断裂转折褶皱;临湘向斜为受两侧背斜控制的被动向斜,由于弯滑褶皱作用在其两翼沿不整合界面形成滑脱断裂.③岳阳-临湘基底滑脱-逆冲带隔槽式褶皱的形成主要受控于褶皱基底的滑脱和基底整体的水平压缩,其形成机制类似于肿缩式褶皱.最后讨论认为湘东北-鄂东南地区不存在大规模、长距离的逆冲推覆构造.     

Kinematic evolution of thrust-related structures in the Umbro-Romagnan parautochthon (northern Apennines, Italy)

In the internal part of the Umbro-Marchean-Romagnan Apennines, the foredeep clastic wedge constituting the Neogene part of the sedimentary cover is completely detached from the underlying Mesozoic–Palaeogene succession. The resulting (Umbro-Romagnan) parautochthon consists of tectonostratigraphic units with a general geometry of broad synclinal blocks separated by narrow faulted anticlines.
Thrust-related structures observed in the field require thrust ramp propagation to have occurred within already folded rocks; therefore, they cannot be restored using simple fault-bend fold or fault-propagation folding models. Evidence for a passive fold origin in the studied rocks suggests that an early detachment folding episode preceded ramp propagation. The latter was facilitated by the enhanced thickness of incompetent material in the cores of detachment anticlines, which became the preferential sites where thrust ramps cut up-section. Depending on the trajectory of such thrust ramps, different types of fault-related structures could develop. Hanging-wall anticlines which give way to monoclinal structures higher up in the section are associated with listric thrust ramps, whereas hanging wall monoclines approximately parallel to the underlying fault surface are associated with straight-trajectory ramps.
This kinematic evolution, which occurred partly during syn-depositional compression, also accounts for the observed lithofacies distribution. The latter reflects an early differentiation of the foredeep trough into sub-basins that are progressively younger towards the foreland. The detachment anticlines that originally bounded such sub-basins were the site of later thrust propagation, leading to a tectonic juxtaposition of different tectonostratigraphic units consisting of broad NW-SE elongate synclinal blocks.