共查询到19条相似文献，搜索用时 171 毫秒
1.
隔槽式褶皱与隔档式褶皱构成侏罗山式褶皱。传统观点认为,侏罗山式褶皱是滑脱作用所形成,其典型实例是在刚性岩体(基底)之上有一层软弱岩层,在软弱层之上的岩层发生“台布式”滑动而形成隔档隔槽式褶皱。黔东南地区隔槽式褶皱实地调查发现：（1）隔槽式向斜核部的地层比两翼和背斜核部的地层厚;（2）沿隔槽式向斜核部发育多期次活动的纵向断层,断层走向与褶皱枢纽一致;（3）背斜产状平缓变形弱而向斜产状急变变形强,背斜与向斜相间出露构成典型的强弱应变域,复杂变形发生在向斜核部。在湘黔交界处的寒武系内发育了典型的露头尺度隔槽式褶皱。通过隔槽式褶皱的露头尺度解析与宏观变形分析,认为黔东南隔槽式褶皱的形成受多期活动的断层控制,早期沉积阶段的正断层,控制了隔槽式褶皱紧闭向斜的发育位置,构造反转之后,先期断层是应力集中区,正断层转为平移或逆冲断层,在隔槽式褶皱向斜核部发育复杂变形。其次,正断层对隔槽式褶皱发育与逆断层对断弯褶皱发育的控制不同,前者断层发育早,后者断层发育晚。 相似文献
2.
燕山板内造山带中部承德盆地复杂的中生代褶皱及逆冲断裂构造,曾被解释为土城子组沉积之后大型逆冲推覆构造(位移量大于40～45km)又经褶皱变形的结果。近年来,土城子组沉积相和物源区分析、中新元古界沉积古地理研究以及相关构造变形研究结果等,对这一变形大型逆冲构造模型提出了多方位质疑。但已有研究并未提出新的构造模型来解释这一复杂构造区域中生代构造变形样式和形成机制。文中通过对承德盆地区域主体构造——承德向斜、向斜两翼逆冲构造变形几何学与运动学特征、向斜转折端附近构造变形与断裂发育状况进行详细野外调查及对关键地质体同位素地质年代进行测试,发现承德向斜两翼逆冲断层为分别向向斜核部以外区域逆冲的独立逆冲断层,逆冲断层活动与承德向斜变形是在统一的收缩变形体制下准同时形成的。它们形成于土城子组之后、张家口组火山活动之前,即距今约139～136 Ma。据此提出了"承德逆冲构造"的背离向斜逆冲构造模型。这一模型合理地解释了燕山中部承德盆地区域中生代构造变形和相应的盆地充填特征,同时表明,燕山板内造山带并不存在碰撞造山带前陆褶皱逆冲带中常见的大型薄皮逆冲构造样式。这一研究结果展示了褶皱相关断裂构造模型在研究和揭示收缩构造变形区域大尺度褶皱与断裂构造相互关系及准确重建区域构造演化过程方面的重要意义。 相似文献
3.
华南地块雪峰山中生代板内造山带构造样式及其形成机制 总被引：4，自引：0，他引：4
华南大地构造核心问题之一是江南—雪峰山造山带的属性。在前人工作基础上,对横切雪峰山造山带的地质剖面进行了详细的区域地质、构造变形和部分重点区段地震反射剖面深部构造解释,划分出5个大地构造单元:(1)湘中复合逆冲构造带。该带位处雪峰山造山带东部,以龙山复合构造穹隆等为代表,是近EW向加里东造山带与NE向燕山造山带复合叠加的结果;其中燕山期构造样式总体为倾向SE逆冲断层控制的尖棱背斜构造。(2)雪峰山厚皮逆冲构造带。该带西以大庸逆冲断裂为界,带内板溪群浅变质褶皱基底大面积出露,总体发育指向NW的断层-褶皱组合。断坪-断坡式逆冲断层从板溪群内部薄弱层发育,向浅部产状明显变陡,并导致新元古界板溪群逆冲于古生界之上,控制了沅麻等中生代盆地的形成,沿断坡形成紧闭背斜和沿断坪形成宽缓向斜;表明其为典型的断层相关褶皱。断层褶皱组合与地表剥蚀共同作用,形成飞来峰和构造窗。(3)以梵净山构造穹隆为代表的梵净山—走马构造穹隆带。该带呈NE向长垣状,核部出露新元古界下部梵净山群。断坪-断坡式逆冲断层深切梵净山群,在断层上盘形成不对称箱状背斜。因此总体为典型的厚皮逆冲作用下的断层相关褶皱。(4)隔槽式逆冲构造带。此带主要发育一系列轴向NE的箱状背斜和尖棱向斜。箱状背斜核部为寒武系,向深部卷入震旦系—板溪群,形成基底卷入的断层-褶皱组合,其浅部形成叠瓦状逆冲断层-褶皱组合,从而构成主动双重逆冲构造。(5)华蓥山断裂与齐岳山断裂间的隔档式薄皮构造带。带内以发育尖棱背斜和箱状向斜为特征,是倾向SE断坪-断坡控制下的断展褶皱组合。上述5个构造单元变形区域卷入了上三叠统—下侏罗统,但为上白垩统角度不整合覆盖,表明变形时间为中生代中晚期,并且有从SE向NW渐次变新的趋势。将各构造单元及不同构造层次构造组合联系起来,建立起以断层相关褶皱为基本构造样式,从SE向NW,从深部向浅部发展的雪峰山中生代板内造山带的递进演化运动学新模式。 相似文献
4.
印度板块与欧亚大陆的汇聚作用和持续碰撞使中亚内陆沿天山、昆仑山、阿尔金山发生变形,山脉前沿发育褶皱冲断带。南天山库车褶皱冲断带中段库车河地区发育3～4排东西走向的逆冲(掩)断层和相关褶皱,逆冲(掩)断层由北向南扩展,断层和褶皱的形成时代自北向南逐渐变新,北部山前带的变形发生于前中新世,南部秋立塔克背斜带和亚肯背斜带的变形时代为上新世(5.2±0.2Ma)。通过构造几何学和运动学分析,作者提出了库车褶皱冲断带的构造变形方式和演化模型。 相似文献
5.
羌塘盆地由于受多期构造活动的影响形成多个构造层,不同构造层的变形特征存在明显差异。其中三叠纪构造层多形成一些紧闭倒转的小型背、向斜褶皱,侏罗纪构造层内多发育大型宽缓的背、向斜及复背斜、复向斜,而白垩纪—新近纪构造层多位于向斜核部和背斜翼部,形成宽缓的褶曲。褶皱变形以近东西向为主,从老到新不同构造层形成的褶皱由紧闭到宽缓,存在一定的继承性和递进叠加的特点。褶皱轴迹的空间展布及变形特点表明不同时期板块的拼合挤压是导致盆地变形的主要驱动力,基底断裂及基底凸凹变化对褶皱的展布和变形有一定程度的控制和影响。 相似文献
6.
秋里塔格构造带位于库车褶皱冲断前缘,其东段包括东秋里塔格背斜和库车塔吾背斜。野外调查和地震剖面解释表明:秋里塔格构造带东段盐下发育断层转折褶皱; 盐上东秋里塔格背斜为滑脱箱状背斜,库车塔吾背斜核部为南倾逆冲断层所破坏。演化剖面显示秋里塔格构造带东段在侏罗纪断陷期发育了正断裂,其后为平静期,直到库车晚期后逆冲断层和褶皱快速发育,背斜最终形成。膏盐岩及古构造对构造变形具有重要影响,一方面作为滑脱层,分割了盐下层与盐上层,导致二者形成不同的构造样式; 另一方面塑性流动充填于背斜核部。由于膏盐岩的厚度差异,东秋里塔格背斜盐上发育褶皱,而库车塔吾背斜核部被逆冲断层破坏,膏盐层厚度还影响了膏盐层上下构造高点的相对位置。盐下构造的发育受侏罗纪古构造控制,进而影响了盐上构造的发育。 相似文献
7.
深水褶皱冲断带的构造形态和特征会随着时间而变化进而影响深水油气勘探开发,而针对这个方面的研究在西北婆罗洲褶皱冲断带内相对薄弱.利用地震和地质相结合的方法,确定了逆冲相关褶皱的构造样式,探讨了其形成演化过程和主控因素,建立了研究区逆冲相关褶皱成藏模式.结果表明:研究区深水褶皱冲断带内发育隐伏型、顶部断裂型、滑塌型以及埋藏型4种逆冲相关褶皱构造样式,且平面上这4种逆冲相关褶皱自海向陆依次发育,其中隐伏型背斜褶皱幅度较低,海底无突出地形显示,主要发育于褶皱冲断带最前端;顶部断裂型背斜在海底有清晰的地形显示,以背斜顶部断裂发育为特征;滑塌型背斜顶部受正断层效应影响,翼部发育块体滑塌沉积;埋藏型背斜主要发育于现今陆架边缘附近,上覆厚层沉积层,在海底无突出地形表现.研究区所发育的4种逆冲相关褶皱构造是成因上有密切联系的统一整体,一个典型逆冲相关褶皱的形成大致经历滑脱、初始逆冲、强烈逆冲和埋藏4个阶段,依次发育隐伏型、顶部断裂型、滑塌型以及埋藏型4种背斜构造样式.同时,沿逆冲褶皱冲断带走向,受地形、沉积物供给、天然气水合物发育等因素控制,在同一挤压应力作用下,不同部位发育的逆冲相关褶皱样式存在差异性.在这种特殊的构造背景下,研究区发育独特的断裂控藏模式,极具勘探潜力. 相似文献
8.
斜向逆冲作用在自然界普遍存在,研究斜向逆冲断层相关褶皱的构造几何学特征,识别断层相关褶皱是否存在斜向逆冲有重要意义。文章采用Trishear 4.5、Gocad以及Trishear3D软件构建一系列不同滑移量的断层转折褶皱和断层传播褶皱的二维正演剖面,通过连接一系列不同排列方式的二维剖面建立了三种不同逆冲滑移方向的断层转折褶皱和断层传播褶皱的假三维模型,通过不同假三维模型的比较分析来探讨斜向逆冲断层相关褶皱的构造几何学特征。研究发现,斜向逆冲断层相关褶皱区别于正向逆冲断层相关褶皱的特征主要有两点：① 正向逆冲断层相关褶皱层面等高线图上的最高点与后翼等高线中点的连线以及水平切面上的核心点与后翼中点的连线方向均与断层走向垂直,而斜向逆冲断层相关褶皱的最高点以及核心点与后翼中点的连线方向均与断层走向斜交,并且最高点与后翼等高线中点的连线方向或者核心点与后翼中点的连线方向均与逆冲滑移方向一致;② 在褶皱平行断层走向纵剖面上,正向逆冲断层相关褶皱各个层面最高点的连线是直立的,而斜向逆冲断层相关褶皱各个层面最高点的连线发生倾斜。通过这两个特征可以判别褶皱是否存在斜向逆冲以及逆冲的方向。将模型分析结果运用到四川盆地西南部三维地震勘探资料所覆盖的邛西背斜和大兴西背斜的实例中。研究结果表明,两个背斜均存在右旋斜向逆冲,逆冲方向与各自断层走向的夹角均为70°左右,邛西背斜和大兴西背斜的逆冲方向分别是NE79°和NE77°左右,这与龙门山南段晚上新世以来的主应力方向以及反演的汶川地震最大主应力方向一致。 相似文献
9.
用地面露头、地震和CEMP(连续电磁剖面法)勘探资料揭示的库车坳陷-南天山盆山过渡带构造变形特征难以用经典的“A型俯冲”冲断褶皱楔变形模型来解释,因而文中提出一种“分层变形、垂向叠置”的“非俯冲”收缩构造解释模型。所谓分层变形是指受古近系膏盐岩层和侏罗系含煤地层等软弱岩层分隔,不同深度的岩层发育不同的收缩变形样式;所谓垂向叠置是指不同层次的强变形带在垂向上叠置,不存在区域性大位移的拆离断层。位于盐岩层之上的新生界以滑脱褶皱变形为主,而盐下层的中生界沉积层及盆地基底则以收缩断裂变形为主。浅部的滑脱褶皱表现出紧闭背斜和宽缓向斜组合,背斜具有不对称形态,其核部在古近系盐岩层或侏罗系含煤地层中滑脱,可在陡翼发育破冲断层或缓翼发育顺层滑脱逆冲断层。深层断裂变形以向山脉倾斜的高角度基底卷入逆冲断层为主干断层,断层上盘形成冲断隆起,次级断层相对较少,下盘则发育一系列同向倾斜的次级逆冲断层构成楔状叠瓦冲断构造。深层断层向上延伸在古近系盐岩层中尖灭,部分次级断层向下延伸并在侏罗系含煤地层中或盆地基底面滑脱,但是主干逆冲断层高角度切入基底,向上则对应于浅层背斜的核部。基底卷入的高角度主干逆冲断层可能利用了先存正断层发生反转位移,并成为控制局部构造变形的主要构造要素。天山上升引起的垂直剪切作用是导致库车坳陷-南天山盆山过渡带发育高角度逆冲断层或促成先存正断层的反转的可能原因。 相似文献
10.
东秋里塔格构造带是塔里木盆地库车坳陷的前缘构造带,整体表现为受新近系吉迪克组膏盐岩滑脱层控制的分层变形构造特征。盐上构造层主要发育断层相关褶皱,盐岩层以塑性流动变形为主,盐下构造层发育断层相关褶皱、冲起构造、逆冲断块等多种构造样式。依据盐下构造层变形特征,自西向东将东秋里塔格构造带划分为过渡构造段、叠瓦扇构造段、前端冲起构造段以及后端冲起构造段四段。过渡构造段内膏盐岩层发育层位由库姆格列木群转变为吉迪克组,盐下发育叠瓦扇构造;叠瓦扇构造段盐下发育典型的逆冲叠瓦构造样式;前端冲起构造段盐下发育断弯褶皱背斜,并在反冲断层的复合作用下发生冲起,主逆冲断层之下发育次级逆冲夹片;后端冲起构造段盐下发育断弯褶皱,并在背斜北翼发育一个独立的冲起构造。东秋里塔格构造带具备有利生储条件,构造分析表明过渡构造段、叠瓦扇构造段以及前端冲起构造段的盐下次级逆冲夹片具备勘探潜力,是有利的油气勘探区带。 相似文献
11.
Quaternary reactivation of flexural-slip folds by diapiric activity: example from the western Ebro Basin (Spain) 总被引：1，自引：0，他引：1
A. M. Casas I. Gil B. Leránoz H. Millán L. Simón 《International Journal of Earth Sciences》1994,83(4):853-867
In the western sector of the Ebro Basin two types of structures deform the Quaternary terraces and pediments developed by the Ebro River and its tributaries: (1) folds up to 10 km long in the lower levels of fluvial terraces and (2) normal listric faults that produce tilting and rollover anticlines of the Quaternary deposits. Both types of structures are linked to the geometrical and lithological features of the Tertiary beds that underlie the Quaternary deposits. Quaternary folds, whose axes are parallel to the strike of the Tertiary beds, are the result of reactivation of Tertiary large-scale (60 km long) folds due to diapirism of their gypsum cores, where the gypsum units reach a maximum thickness of 3 000 m. This reactivation produced flexural-slip in some beds on the limbs of the folds, bringing about the folding of the overlying Quaternary terraces. The mechanism of Quaternary folding involves layer-parallel shear in alternating Tertiary units and folding linked to detachments and reverse layer-parallel faults. Normal listric faults are widespread throughout the studied area. They are partly parallel to low dipping Tertiary beds and are the result of a NNE-SSW tectonic extension, compatible with minor structures and focal mechanisms of recent earthquakes. The relationship between the two kinds of Quaternary structures indicates that diapirism of the gypsum cores of the anticlines was activated by extensional tectonics. 相似文献
12.
Basement-involved structures associated with reverse, vertical and normal faults commonly involve non-parallel shear within a triangular deformation (trishear) zone located on the front limbs of the structures. Deformation within the trishear zone is characterized by shear gradients and an associated decrease in the dips of the beds in stratigraphically higher units. Geometric models suggest that the layer-parallel strain within the trishear zone depends on the type of fault (normal, reverse, or vertical), the dip and throw of the fault, the dip of the anticlinal or synclinal axial surfaces, and the distance of any unit above the initial tip of the trishear zone, located at the basement-sediment contact. At any given location, reverse faults typically show increasing layer parallel shortening, followed by decreasing layer parallel shortening and a transition to extension, with increasing throw. The transition from contraction to extension occurs at lower values of throw for stratigraphically lower units and also for faults with smaller dips. Vertical and normal faults exhibit increasing layer-parallel extension of all units with increasing throw, with larger extension for stratigraphically lower units. Experimental models suggest that the trishear zone can expand with increasing fault throw. The strain within the trishear zones is accommodated largely by secondary faults, which are rotated with progressive deformation. The strain variations in the experiments closely mimic those predicted by the geometric models for reverse, vertical, and normal faults. 相似文献
13.
《Journal of Structural Geology》2003,25(10):1659-1673
Detachment folds represent a major structural element in a number of fold belts. They are common in the Jura Mountains, the Zagros fold belt, the Central Appalachian fold belt, the Wyoming fold-belt, the Brooks Range, the Parry Islands fold belt, and parts of the SubAndean belt. These structures form in stratigraphic packages with high competency contrasts among units. The competent upper units exhibit parallel fold geometries, whereas the weak lower unit displays disharmonic folding and significant penetrative deformation. Two distinct geometric types, disharmonic detachment folds, and lift-off folds have been recognized. However, these structures commonly represent different stages in the progressive evolution of detachment folds. The structures first form by symmetric or asymmetric folding, with the fold wavelength controlled by the thickness of the dominant units. Volumetric constraints require sinking of units in the synclines, and movement of the ductile unit from the synclines to the anticlines. Continuing deformation results in increasing fold amplitudes and tighter geometries resulting from both limb segment rotation and hinge migration. Initially, limb rotation occurs primarily by flexural slip folding, but in the late stages of deformation, the rotation may involve significant internal deformation of units between locked hinges. The folds eventually assume tight isoclinal geometries resembling lift-off folds. Variations in the geometry of detachment fold geometry, such as fold asymmetry, significant faulting, and fold associated with multiple detachments, are related to variations in the mechanical stratigraphy and pre-existing structure. 相似文献
14.
P.F. Williams 《Journal of Structural Geology》1979,1(1):19-30
A group of folds in alternating pelites and cross-laminated siltstones is described. An interpretation of the finite strain state, in the competent silt layers, is proposed on the basis of an analysis of the angle between cross-lamination and the principal surface of accumulation. Strain magnitudes are greatest in the fold hinge where domains of layer parallel shortening and layer parallel extension are separated by a neutral surface. Strain magnitudes in the fold limbs are small and are largely related to the development of the asymmetry of the folds. In the incompetent pelitic layers, strain in the fold limbs has a large, layer parallel shear component. Deformation in the pelites is accompanied by, and presumably partially achieved by, migration of quartz from areas where there is a tendency for volume to decrease, to areas where it is tending to increase. This process involves local increases in volume of more than 50%.A kinematic model is proposed for development of the folds. It involves early development of small symmetrical folds followed by their modification to asymmetrical, parasitic structures on the limbs of later folds. In the late stages of folding, continued shortening perpendicular to the axial surface orientation is achieved by development of a conjugate crenulation cleavage. 相似文献
15.
The Variscan nappe stack of SE Sardinia originated as a result of several stages of nappe imbrication during the Lower Carboniferous phases of the Variscan orogeny. The crustal shortening caused regional SSW-and W-directed thrusting, greenschist facies metamorphism and open-to-isoclinal polyphase folding. The final stage of shortening produced large-scale antiforms and synforms.
Post-collisional deformation resulted in inversion of earlier thrusts as normal faults, development of low-angle normal faults, and refolding of earlier foliation and thrust planes by asymmetric folds with subhorizontal axial planes. Facing directions of these latest folds are directed horizontally outward from the hinge zones of main antiforms, suggesting that they cannot be regarded as parasitic folds of the latest thickening phase, but instead are the consequence of vertical shortening during gravitational collapse of dome-like km-scale antiforms, leading to denudation of antiformal culminations. 相似文献
Post-collisional deformation resulted in inversion of earlier thrusts as normal faults, development of low-angle normal faults, and refolding of earlier foliation and thrust planes by asymmetric folds with subhorizontal axial planes. Facing directions of these latest folds are directed horizontally outward from the hinge zones of main antiforms, suggesting that they cannot be regarded as parasitic folds of the latest thickening phase, but instead are the consequence of vertical shortening during gravitational collapse of dome-like km-scale antiforms, leading to denudation of antiformal culminations. 相似文献
16.
17.
Hand-specimen and outcrop scale examples of folds are analyzed here to identify the characteristic signatures of fold-accommodation faults. We describe and analyze the geometric and kinematic relationships between folds and their associated faults in detail including the structural position and spatial distribution of faults within a fold, the displacement distribution along the faults by applying separation–distance plots for the outcrop scale examples, and the change of cut-off angle when the fault cut across folded layers. A comparison between fold-accommodation faults and fault related folds based on their separation–distribution plots and the problem of time sequence between faulting and folding are discussed in order to distinguish fold-accommodation faults from the reverse faults geometrically and kinematically similar to them. The analysis results show that fold-accommodation faults originate and terminate within a fold and usually do not modify the geometry of the fold because of their limited displacement. The out-of-syncline thrust has a diagnostically negative slope (separation value decreasing away from the upper fault tip) in the separation–distance graph. The change of cut-off angle and the spatial distribution of faults display a close relationship with the axial surface of the fold. Our analyses show that fold-accommodation faults are kinematically consistent with the flexural slip of the fold. The interbedded strata with competence contrast facilitate formation of fold-accommodation faults. These characteristic signatures are concluded as a set of primary identification criteria for fold-accommodation faults. 相似文献
18.
Small regional folds, such as the Clover Hollow anticline of the Narrows thrust-sheet in southwest Virginia, U.S.A., are considered to be large buckle folds expressing lateral shortening above a subsurface décollement. Cleavage, mesoscopic and regional folds, and contraction faults have developed in these rocks under anchimetamorphic conditions, in a single, protracted deformation during thrust-sheet emplacement. The contraction faults dominate the structure at all scales. Three fault associations (isolated contraction faults, contraction faults in series and complex fault zones with intense folding) determine the pattern and intensity of local structures. Regional displacement transfer of strain along and across faults has produced local variations in structural style. Duplex-like systems of second-order faults terminate laterally into zones of intense folding and third-order faulting. Fold tightness, cleavage intensity, strain magnitude and total longitudinal strain (εT) are maximum in these regions. Contraction faults in this thrust-sheet have propagated along zones of high strain rate associated with mesoscopic folding and intense cleavage. Regional hinge migration, and greater structural complexity along the southeast limb of the Clover Hollow anticline, are considered to be due to emplacement of the adjacent thrust-sheet. 相似文献
19.
《Geodinamica Acta》1999,12(2):113-132
The Aguilón Subbasin (NE Spain) was originated daring the Late Jurassic-Early Cretaceous rifting due to the action of large normal faults, probably inherited from Late Variscan fracturing. WNW-ESE normal faults limit two major troughs filled by continental deposits (Valanginian to Early Barremian). NE-SW faults control the location of subsidiary depocenters within these troughs. These basins were weakly inverted during the Tertiary with folds and thrusts striking E-W to WNW-ESE involving the Mesozoic-Tertiary cover with a maximum estimated shortening of about 12 %. Tertiary compression did not produce the total inversion of the Mesozoic basin but extensional structures are responsible for the location of major Tertiary folds. Shortening of the cover during the Tertiary involved both reactivation of some normal faults and development of folds and thrusts nucleated on basement extensional steps. The inversion style depends mainly on the occurrence and geometry of normal faults limiting the basin. Steep normal faults were not reactivated but acted as buttresses to the cover translation. Around these faults, affecting both basement and cover, folds and thrusts were nucleated due to the stress rise in front of major faults. Within the cover, the buttressing against normal faults consists of folding and faulting implying little shortening without development of ceavage or other evidence of internal deformation. 相似文献