高邮凹陷南断阶调节带断层构造特征分析与数值模拟

在高邮凹陷南断阶北界上,始新世出现的总体北北东走向、左阶雁列状真②断层带内发育了许庄与方巷调节带。各反射层构造图显示,这两个调节带内部发育了连接与非连接两大类断层。其中连接断层可分为垂向连接、斜向连接与弧形连接3类,而非连接断层可分为同向平行断层、区域斜向正断层、斜向与横向断坡拉张断层、斜向与垂向连接-扩展断层、派生斜列断层、网状断层8类。本文通过有限差分法与有限单元法数值模拟,再现了调节带内各类断层的发育过程。结果表明,调节带内的断层一方面是区域应力直接作用的产物,另一方面是边界断层斜向拉张与扩展、断坡弯曲等影响的结果。故而,调节带内断层的发育受多种因素影响,常形成复杂的断层组合。     

伸展域构造变换带内部构造类型研究

分别从传递带和调节带两个方面论述了构造变换带内的构造类型，将传递带内的构造类型分为传递断层等四种类型，将调节带内的构造类型划分为背斜等四种类型。分析了传递带与调节带内各构造类型的发育条件、几何形态特征以及它们之间的相互关系。研究认为，传递带和调节带内的构造类型主要取决于其发育位置处的构造背景及边界控制条件。     

Sand-box modelling of basement-controlled transfer zones in extensional domains

The interaction modalities of transfer zones connecting rift segments may be influenced by several factors. Amongst these, the location and architecture of transfer zones in narrow rifts has been repeatedly associated with the presence of inherited basement anisotropies. Sand-box models were made to investigate how the orientation, geometry and kinematics of transfer zones depend upon pre-existing basement anisotropies. Analogue models reproduced offset rift segments linked by transfer zones bordered by arcuate normal faults. Strike-slip faults are present inside the transfer zone, provided that angle α (between the extension direction and the axis of the transfer zone) is less than 50°. Narrower transfer zones, striking oblique to the extension direction, occur for angle φ (between the direction perpendicular to the extension direction and the direction of the basement anisotropy) less than 90°; wider transfer zones, subparallel to the extensional direction, occur for φ > 90°. Increasing the overstep induces narrower transfer zones striking subparallel to the extension direction. Similar geometrical and kinematical patterns have been found at transfer zones in narrow rifts. The comparison between experimental and natural data shows how the geometry, kinematics and orientation of natural transfer zones depends upon the trend of inherited anisotropies: transfer zones along inherited basement structures set at lower angles to the extension direction, and display lower aspect ratios, than transfer zones where inherited anisotropies are absent.     

Centrifuge modelling of the influence of crustal fabrics on the development of transfer zones: insights into the mechanics of continental rifting architecture

Centrifuge analogue experiments are used to model the reactivation of pre-existing crustal fabrics during extension. The models reproduced a weakness zone in the lower crust whose geometry was varied in order to investigate its role in controlling the architecture of rift segments and related transfer zones. The typical rift system geometry was characterised by two offset rift segments connected by a major transfer zone in which boundary faults were oblique to the extension vector and displayed a significant transcurrent component of movement. The transfer zone was also characterised by cross-basin faults with both trend and strike-slip component of movement opposite to that displayed by the master faults. Typically, different structural patterns were obtained by changing the offset angle φ between the rift segments, supporting that the structural pattern at transfer zones is strongly influenced by the orientation of pre-existing discontinuities with respect to the stretching vector. In the models, the aspect ratio (ratio of length vs. width) of the transfer zone shows a positive correlation with the offset angle (i.e., the more the inherited fabric is parallel to the extension direction, the longer and narrower the transfer zones). In case of staircase offset of the rift segments (φ=90°), the structural pattern was characterised by two isolated rift depressions linked by a narrow transfer zone in which border faults with alternating polarity overlapped. Prominent rise of the ductile lower crust was also observed at the transfer zone. Many of these geometrical features display striking similarities with natural rift systems. The results of the current experiments provide useful insights into the mechanics of continental rift architecture, supporting that rift propagation, width and along-axis segmentation may be strongly controlled by the reactivation of pre-existing pervasive crustal fabrics.     

冀中坳陷深县凹陷主伸展期的构造调节带及其对沉积环境的控制作用

深县凹陷沙河街组发育的构造调节带控制着沉积体系的迁移路径和平面展布。根据断层的组合特点与断距变化,可将构造调节带分同向、对向、背向及单线4大类。同向和单线调节带主要发育在北部何庄-兵曹-崔家庄一带,规模小,数量多; 对向调节带发育在榆科地区和赵家庄地区,规模较大,分布稀疏。背向调节带极不发育。伸展作用的不均一性以及地层力学性质差异是形成调节带的主要因素。单线调节带控制小规模的沉积体穿过断层进入汇水盆地,如衡水断层下降盘中的水下扇; 同向调节带控制何庄-西魏村、田家庄、东阳乡等辫状河三角洲的入湖路径和展布特征; 对向调节带控制深湖的形成,如赵家庄一带的深湖; 而背向调节带造成的正地形起到了阻隔物源作用。     

Antithetic fault linkages in a deep water fold and thrust belt

Deep water fold and thrust belts consist of both forethrusts and backthrusts that can link along strike to form continuous folds in the overburden. The interaction of faults of opposing dip are termed ‘antithetic thrust fault linkages’ and share the common feature of a switch in vergence of overlying hangingwall anticlines. Using three-dimensional seismic data, on the toe-of-slope of the Niger Delta, linkages are classified into three distinct structural styles. This preliminary classification is based on the vertical extent of faulting within a transfer zones relative to the branch line of the antithetic faults. The stratigraphic level of the lateral tip of the fault, the shape of lateral tip region of a fault plane and the stratal deformation within the transfer zones is also distinctive in each type of fault linkage. A Type 1 linkage comprises faults that overlap exclusively above the level of the branch line. A ‘pop-up’ structure forms within the transfer zone with sediments below remaining planar. The lower tip lines of faults climb stratigraphically towards the linkage zone creating asymmetric, upward-tapering lateral tip regions. In Type 2 linkages fault overlap occurs lower than the level of the branch line such that lateral fault tips are located within the footwall of the counterpart fault. Faulting is thus limited to the deeper section within the transfer zone and creates unfaulted, symmetric, bell-shaped folds in the overburden. Upper tip lines of faults lose elevation within the transfer zone creating asymmetric, downwards-tapering lateral tip regions. In Type 3 linkages both faults continue above and below the branch line within the transfer zone resulting in cross-cutting fault relationships. Horizon continuity across the folds, through the transfer zones, varies significantly with depth and with the type of fault intersection.     

渤海湾地区构造变换带及油气意义

利用地震剖面解释结果和构造编图成果,分析了渤海湾地区构造变换带的特征及其油气地质意义。渤海湾地区主要发育区域横向调节带和局部变换带两类构造变换带。区域横向调节带由北西向大型走滑断裂带充当,这些断裂带同时也是强地震活动带,将渤海海域地区分为北、中、南3段。局部变换带主要发育在相互作用的分段正断层的叠置区内。根据分段正断层的倾向及其组合特征,可将局部变换带分为转换斜坡型、斜向背斜型和地垒型3类。渤海湾地区构造变换带具有重要的油气地质意义,主要表现为控制构造圈闭的形成、有利于优质储集层的发育及控制油气运移过程等。     

Seismic reflection and refraction studies for investigating fault zones along the Geotraverse Rhenoherzynikum

In 1973 detailed seismic crustal studies were performed across the prominent fault zone between the Hercynian fold systems of the Rhenish Slate Mountains (western part of Rhenoherzynikum) and the Saar-Nahe trough. Reflection data show a zone of strongly dipping reflectors, separated from another area with nearly horizontal layering. Data from refraction stations confirm the picture of a fault zone cutting two old crustal blocks down to the Moho. A similar but smaller survey was performed in 1975 across the western Rhine graben fault near Landau. This fault is tensionsal and could not be observed with the same certainty and up to the same depth range as the former one. Apparently, its dip near the surface is smaller than anticipated and may even assume still smaller values at intermediate crustal depths. Moreover, high temperatures in this area tend to limit the maximum depth of the fault zone, in accordance with the concept of a direct relationship between the depths of seismicity along faults and the temperature—viscosity regime. The area between the two reflection surveys was studied by refraction observations, making use of the shots of the reflection work. In general, the reflection investigations are well able to reveal the geometry and the maximum depth of fault zones and show many structural details, while the supplementing refraction work determines the overall velocity depth relation and may follow important horizons.     

Seismic and field evidence for selective inversion of Cretaceous normal faults, Salta rift, northwest Argentina

Northwestern Argentina was the site of the continental Salta rift in Cretaceous to Paleogene time. The Salta rift had a complex geometry with several subbasins of different trends and subsidence patterns surrounding a central high. Fault trends in the rift were extremely variable. There is evidence of normal and/or transfer faults trending N, NE, E and SE. It is not clear if all these faults were active at the same time, indicating a poorly defined extension direction, or if they formed in different, non-coaxial extension phases. In either case, their trends were very likely influenced by preexisting fault systems. Beginning in early Eocene time, the rift basins were superseded by Andean foreland basins and later became caught in the Andean thrust deformation propagating eastward, resulting in the inversion of rift faults. Due to their different orientations, not all faults were equally prone to reactivation as thrusts. N to NNE trending faults were apparently most strongly inverted, probably often to a degree where the traces of their normal fault origin have become obliterated. We present seismic evidence of moderately inverted N trending faults in the Tres Cruces basin and field examples of preserved E trending normal faults. However, reactivation sometimes also affects faults trending approximately parallel to the main Neogene shortening direction, indicating short-term deviations from the general pattern of Neogene thrust deformation. These pulses of orogen-parallel contraction may be linked to the intermittent activity of oblique transfer zones.     

中国东部NWW向活动断裂带构造特征:以张家口-蓬莱断裂带为例

中国东部新构造期活动强烈,前人对该时期NE向构造已有很多研究,但NWW向构造研究程度较低.本文以张家口-蓬莱断裂带为例,从几何学、运动学、动力学及地震活动性四个方面对中国东部的NWW向活动断裂带进行了分析.结果表明,中国东部的NWW向活动断裂带具有左行走滑的运动性质,并控制了第四纪盆地左阶雁列的展布样式;NWW向活动断裂带是孕震断裂,诱发了多次地震活动.在动力学上,这些断裂带是扳缘的不同段落变形在板内不同块体间响应调节的产物,且在周边板块的联合作用下,华北和华南南部NWW向断裂可能印度-欧亚板块碰撞的影响占主导,而东北和华南东部NWW向断裂可能太平洋板块俯冲的影响占主导.     

调节带和转换带及其在伸展区的分段作用

调节带和转换事是一种重要的构造现象,近年已逐渐爱到重视。由于大多数正断层体系都终止于调节带或转换带,使其成为产生区域公段的主因。转换带是平行于拉张方向具走滑和斜滑断层作用的不连续带;调节带是多个断层叠覆终止的区带。对不同伸民区和被动力缘调节带和转换带几何形态和运动特征的总结认为,调节带和转换带中的变形方式不依赖于伸民规模。调节带和转换带不但控制地形起伏和沉积环境,而且对烃类及地下水的聚集亦有重要影     

黄骅坳陷中区新生代断裂系统及其成因分析

断裂是黄骅坳陷新生代主要构造变形类型,对该区油气成藏有重要影响。本文将黄骅坳陷中区的断裂划分为6个系统,并综合分析了它们之间的关系。每一断裂系统至少有一条主干基底断层,发育在该断层上、下盘的次级断层以不同形式与主干基底断层组合在一起,其剖面上的构造样式和平面上的构造组合显示了该断裂系统在新生代的运动学特征。在系统分析黄骅坳陷中区新生代断裂系统的断层组合、构造样式、主干断层位移方式及生长史的基础上,结合区域构造背景、伸展边界条件及断层间的相互作用,探讨了该区断裂系统的形成机制。分析结果表明:区域构造背景下存在的伸展边界控制了整个黄骅坳陷中区新生代断裂系统总的构造格局,系统中主要断层走向与伸展边界近于平行。这进一步证实了区内右旋走滑作用与伸展作用的相互耦合,致使断层沿走滑构造带出现转向或中断。各断裂系统之间及系统内部断层间的运动学关系表明黄骅坳陷古近纪受两个构造动力控制,一是地幔热作用引起岩石圈北西—南东向引张作用,二是北北东向深断裂带的右旋剪切作用。     

Mechanical stratigraphy as a factor controlling the development of a sandbox transfer zone: a three-dimensional analysis

In thrust belts, fold–fault terminations are common features of the structural architecture and can pose complicated problems to unravel, in particular when two or more terminations are in close proximity. Such terminations usually reflect pre-existing attributes. Amongst the many factors, lateral variations in the mechanical stratigraphy can control along-strike geometry and kinematics of fault-related folds.A displacement transfer zone was produced in a compressional sandbox model by means of two adjacent, mechanically different stratigraphic domains. The experiment allowed two discrete chains to develop in the different domains, so that a complex structural setting occurred in the connecting area. Periclinal folds, oblique thrust fronts and oblique ramps developed in the resulting transfer zone. The interaction between periclines in the transfer zone produced lateral culminations in the folded structures. The analysis of displacement across the structural domains revealed that a significant loss of slip along the faults occurred in the relay zone. In this area, imbricate faulting was partially replaced by layer-parallel shortening. A linear relationship appears to exist between the bed length of the thrust sheet and the related fault slip.     

蒙古国塔木察格盆地塔南凹陷早白垩世构造古地貌控砂机制*

构造活动是源-汇系统中形成古地貌和砂分散体系的重要影响因素。塔木察格盆地塔南凹陷在早白垩世是一个典型的断陷湖盆,经历了多期幕式断陷活动,但同沉积构造活动及其配置所产生的古地貌对层序结构特征、沉积体系及砂体分布的控制作用仍不明确。文中以地震、测井、岩心资料为基础,以层序地层学理论和古地貌控砂理论为指导,建立了塔南凹陷下白垩统层序地层格架;结合断层活动性分析,阐明了不同类型古地貌对沉积体系和砂体分布的控制作用和规律。构造演化和沉积充填的综合研究表明: 受控盆主断裂的幕式断陷活动及同沉积断裂的差异断陷活动影响,塔南凹陷发育横向凸起和走向斜坡2种类型的构造调节带,这些构造调节带是水系入盆的通道,控制着盆地的主体物源方向、沉积体系类型与分布特征;根据断层的几何形态及发育部位,共识别出4种类型构造坡折带,分别是陡坡断崖型坡折带、陡坡断阶型坡折带、缓坡反向断阶型坡折带和盆内坡折带,它们各自控制了不同类型沉积体系的形成与分布;沉积物入盆后,沉积物分散体系和砂体的分布特征受同沉积断裂的组合样式控制,研究区共发育梳状断裂系、叉状断裂系和平行断裂系3种同沉积断裂平面组合;与构造调节带相对应的断裂坡折带低部位是大型储层砂体,特别是低位扇三角洲或盆底扇砂体发育的有利部位,是寻找砂岩油气藏的有利区带。研究成果对于深化断陷湖盆源-汇系统理论、指导断陷湖盆砂体分布预测具有重要的理论意义和实际价值。     

The geometrical evolution of normal fault systems

The purpose of this paper is to examine the kinematic behaviour of normal fault systems and see what general conditions govern their geometrical evolution. We pay particular attention to seismological and surface data from regions of present day active normal faulting, as the instantaneous three-dimensional geometry at the time of fault movement is better known in active regions than in areas where the faults are now static.Most normal faults are concave upward, or listric. This shape can be produced by geometric constraints, either because the faults reactivate curved thrusts, or because they must be curved to accommodate rotations. Another effect which will produce curved faults is the variation of rheology with depth: brittle failure at shallow depths produces less fault rotation than does distributed creep in the lower part of the crust. An important geometric feature of normal faulting is the uplift of the footwall. The amount of such uplift is related not only to the elastic properties of the lithosphere, but also to the throw and dip of the fault. A striking feature of active normal faults is that they occur in groups in which all the faults dip in the same direction. This behaviour arises because the faults cannot intersect: if they do, one must cease to be active. The rotation which such fault systems produce reduces the dip of the faults until a new steeply dipping fault is formed. Once a new fault cuts pre-existing faults the earlier faults become locked, and a new set of faults must propagate rapidly across the whole region involved. Many of these geometric constraints also apply to thrust faulting.     

Kinematic History and Changes in the Tectonic StressRegime during the Cenozoic along the Qinling andSouthern Tanlu Fault Zones

Since the mid-late Eocene, North China has been subjected to extensional stress, resulting in the formation and development of basins. The dynamic origin of this crustal extension has long been an issue of debate. This paper presents the results of kinematic analyses of faults obtained from two seperated areas in North China. In the Weihe graben situated on the southernmost margin of the Ordos block, analyses of fault kinematics were coupled with an analysis of the basin's subsidence history. Three successive extensional tectonic phases accompaning the basin's formation and development have been distinguished. The Palaeogene extension was oriented in a WNW-ESE direction; the Neogene extension in a NE-SW direction and the Pliocene-Quaternary extension in a NW-SE direction. Such changes have also been recorded by fault kinematics along the southern Tanlu fault zone. This has been demonstrated by three successive sets of fault striations indicating normal dip slip resulting from NW-SE extension, then left-     

Vector analysis of fault bends and intersecting faults

An analogy is drawn between intersecting faults or shear zones and triple junctions of lithospheric plates. Vector analysis shows that fault intersections are always unstable for rigid fault blocks but can be stabilized by the presence of zones of kinking or volume change within the fault blocks.The method allows rapid assessment of the likely location and orientation of wall-rock strains for any fault geometry and should be used to test kinematic models erected to account for field data.     

川滇西部上新世以来构造地貌:断裂控制的盆地发育及对于远程陆内构造过程的约束

青藏高原隆升、周边地貌形成是新生代时期印度-欧亚板块碰撞后的重要响应。在滇西北地区发育了一系列由晚新生代(上新世以来)活动断裂所控制的盆地,例如宾川盆地、洱海盆地、鹤庆盆地、弥渡盆地等。宾川盆地是近南北向程海左行走滑断裂在走滑剪切作用下产生的北西向正断层和北东向走滑断层共同作用而形成的一个较大的拉分盆地。洱海盆地是由两组陡立的共轭张剪性(Transtensional)断层组限定的,为一伸展断陷盆地,总体上反映了近E-W向的区域伸展。滇西北地区发育的其它晚新生代盆地,如弥渡盆地、鹤庆盆地、剑川盆地等,也为区域走滑断裂及其分支断裂所控制,并且这些分支断裂在区域上为一组NE-SW和NW-SE向的共轭正断裂,反映了该区域近E-W向的伸展。将藏东南三江地区发育的活动断裂按照其走向分为三组:(1)NW-SE走向的断裂,如红河断裂、无量山-营盘山断裂等;(2)近N-S向断裂系,以程海断裂、小江断裂等为代表;(3)NE-SW走向的断裂,如丽江-剑川断裂、鹤庆-洱源断裂和南定河断裂等。这些断裂的震源机制解表明地震断裂活动性或者是走滑性质或者是伸展属性,它们的组合型式也揭示出藏东南三江地区在上新世以来表现为近E-W向的伸展。区域上,在藏东北部地区发育的断层构造组合普遍反映了以近E-W向挤压为主导的应力场。推测这一现象为上新世以来藏东地区上地壳围绕喜马拉雅东构造结做顺时针旋转所致,区域上受印度-欧亚会聚过程中印度板块顺时针旋转诱发的差异性应力场制约。     

Accretion of oceanic crust under conditions of oblique spreading

The accretion of oceanic crust under conditions of oblique spreading is considered. It is shown that deviation of the normal to the strike of mid-ocean ridge from the extension direction results in the formation of echeloned basins and ranges in the rift valley, which are separated by normal and strike-slip faults oriented at an angle to the axis of the mid-ocean ridge. The orientation of spreading ranges is determined by initial breakup and divergence of plates, whereas the within-rift structural elements are local and shallow-seated; they are formed only in the tectonically mobile rift zone. As a rule, the mid-ocean ridges with oblique spreading are not displaced along transform fracture zones, and stresses are relaxed in accommodation zones without rupture of continuity of within-rift structural elements. The structural elements related to oblique spreading can be formed in both rift and megafault zones. At the initial breakup and divergence of continental or oceanic plates with increased crust thickness, the appearance of an extension component along with shear in megafault zones gives rise to the formation of embryonic accretionary structural elements. As opening and extension increase, oblique spreading zones are formed. Various destructive and accretionary structural elements (nearly parallel extension troughs; basin and range systems oriented obliquely relative to the strike of the fault zone and the extension axis; rhomb-shaped extension basins, etc.) can coexist in different segments of the fault zone and replace one another over time. The Andrew Bain Megafault Zone in the South Atlantic started to develop as a strike-slip fault zone that separated the African and Antarctic plates. Under extension in the oceanic domain, this zone was transformed into a system of strike-slip faults divided by accretionary structures. It is suggested that the De Geer Megafault Zone in the North Atlantic, which separated Greenland and Eurasia at the initial stage of extension that followed strike-slip offset, evolved in the same way.     

张扭性盆地隐性断裂带识别、演化及控藏作用——以苏北盆地金湖凹陷为例

隐性断裂带是由区域或局部应力场或基底断裂活动影响下, 在凹陷沉积盖层中产生的断裂趋势带。重磁、三维地震资料处理解释成果证实苏北盆地金湖凹陷存在北东、北西两组基底断裂。部分北东向的基底断裂活动强烈, 控制了凹陷形成和演化; 北西向和部分北东向的基底断裂活动性较弱, 沉积盖层中形成了隐性断裂带。它们表现为成带分布的雁列式小断层、断断续续沿固定方向分布的小断层、一系列沉积扇体或油气圈闭成带成串分布等线状构造。随机测线的剖面上表现为地震同相轴没有明显错断或呈现杂乱反射。除上述两组隐性断裂带, 区域右行应力场在凹陷内部产生的东西方向的挤压应力分量也形成了断续状、串状的南北向隐性断裂带。研究表明, 隐性断裂带由"隐性"逐渐向"显性"过渡。经历了早期弱雁列式隐性期、早中期强雁列式隐性期、中期断续状隐-显期、中后期串状显-隐期4个隐性阶段, 最终演化为"显性"张扭性走滑断裂。沉积盖层中形成的这些隐性断裂带控制了储集砂体分布、改善了储层物性、使隐性圈闭成带成串分布, 是油气聚集成藏的有利区带。