共查询到20条相似文献，搜索用时 31 毫秒
1.
It is shown that in two-dimensional and three-dimensional deformation accommodated by fracture, the symmetry of the fault patterns is an intrinsic attribute because it reflects the symmetry of either stress or strain tensors. The deformation accommodated by sliding along pre-existing planes, when there is kinematic interaction between that planes, forms multiple fault pattern and multiple slickenline sets during a single deformation event. These fault patterns have no restrictions with respect to symmetry, number of fault sets or fault orientation.
The kinematic analysis developed here shows that an interacting system is formed by two cross cutting faults and three slickenlines. One slickenline must be parallel to the intersection line between the planes. Also, it is demonstrated that the slickenlines generally do not correspond to the shear stress solution on the planes. Thus, the interaction between planes does not satisfy the assumption of parallelism between shear stress and slip vector. We conclude that the inversion methods to calculate paleostress tensors can lead to erroneous interpretations in structurally complex zones with many pre-existing planes of weakness.
We propose four possibilities to form multiple fault patterns: (1) two or more events of faulting obeying Coulomb's law with a change of orientation of the principal stresses in each event; (2) reactivation of non-interacting planes according to the Bott (1959) model; (3) one three-dimensional strain event that obeys the “Slip Model”; this mechanism will form an orthorhombic four-fault pattern and two slickenline sets in a single strain event; and (4) one or more events obeying the interacting block model proposed here, with or without rotation of the principal stresses. We propose the last origin as the most common in continental regions. 相似文献
2.
AbstractThe classical model of faulting predicts that slip planes occur in two conjugate sets. Theoretically, more sets can be contemporarily active if pre-existing structures are reactivated in a three-dimensional strain field. Four to six sets of faults have been active in the Holocene in the Zailiski Alatau mountain range, Kazakstan. Faults strike with the highest frequency ENE and ESE and show mostly left-lateral reverse and right-lateral reverse motions, respectively. These faults have a bimodal distribution of dips, forming four sets arranged in orthorhombic symmetry. Locally, NNW- to NNE- striking vertical faults have also been active in the Holocene and show right-lateral strike-slip and left-lateral strike-slip motions, respectively. All these fault sets accommodated the general three-dimensional deformation, given by N-S-directed horizontal shortening, vertical extension, and E-W-directed horizontal extension. Field evidence also shows that the reverse motions, even if with a minor strike-slip component, occurred on high-angle planes with inclination of 65°-85°. ENE- and ESE-striking faults reactivated older fracture zones, whereas the other sets are newly formed. Comparison of these field results with the structures obtained from published analogue models shows a strong similarity of fault geometry and kinematics. 相似文献
3.
Analysis of faulting in three-dimensional strain field 总被引：2，自引：0，他引：2
Ze'ev Reches 《Tectonophysics》1978,47(1-2)
Multiple faults, composed of three, four or more sets of faults, have been observed at a wide range of scales, from clay experiments to rift valleys. Multiple faults usually are explained by multiple phases of deformation. However, in several cases the multiple faults develop simultaneously; therefore, they cannot be explained by the common theories of faulting. Furthermore, these theories were derived for plane strain, whereas, multiple faults are associated with three-dimensional strain.An elementary analysis of faulting in three-dimensional strain field is presented here. The analysis considers the deformation of an idealized model due to slip along sets of faults; the model is subjected to strain boundary conditions. The analysis shows that (1) three or four sets of faults are necessary to accommodate three-dimensional strain, (2) there is a combination of four fault sets which minimize the dissipation of the deformation; the orientation of these faults depend on the strain state, and (3) if the resistance to slip along these four sets of faults is cohesive, then the stresses which cause slippage along them are equal or larger than the yielding stresses of a Tresca rigid-plastic with the same cohesion.The analysis presented here is too elementary to be directly applied to field observations; however, it indicates that multiple faults and rhomboid patterns of faults probably form when a body is strained three-dimensionally. 相似文献
4.
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. 相似文献
5.
U. Ring 《International Journal of Earth Sciences》1995,84(3):607-625
The results of a lithostratigraphic, tectonic and kinematic study of the Karoo deposits of northern Malawi are reported. The objective of the lithostratigraphic study is to correlate the deposits of the Karoo basins of northern Malawi with the well-known deposits of southern Tanzania, thus establishing a stratigraphic framework through which the timing of faulting can be constrained. The kinematic analysis of faulting constrains the opening direction for the Karoo graben in this area and provides basic data to discuss the Karoo graben development within the regional tectonic framework of south-eastern Africa. The studied adults are defined by moderately to steeply dipping cataclastic zones with a width of up to 15 m and are characterized by an array of slickensided fault surfaces with different orientations and slip directions. In this study, small faults (offset < 10 m) and meso-scale faults (offset > 10 m, but generally not exceeding 30–40 m) have been distinguished. Methods used to analyse the kinematic data include the ‘pressure tension’ (PT) method, which estimates the principal axes for the bulk brittle strain, and the internal rotation axis (IRA) method, which estimates the axis of bulk internal rotation and the overall sense of slip at the faults. A mass balance calculation reveals a volume increase of up to 16% during cataclastic deformation in the fault zones. The PT method shows an approximately east trending extension direction for faults that occur only in the latest Carboniferous (?) and Early Permian strata, whereas the fault kinematics from faults that cut middle Permian to Early Triassic rocks is characterized by a ESE to SE trending extension direction. The small faults yield essentially the same kinematic results as the meso-scale faults. In a transport-parallel cross-sectional view, the principal extension axes are at an acute angle of approximately 60° to the major fault planes. Given the moderate fault density, the relatively high angle between the orientation of the principal extension axis and the fault planes suggest only a moderate amount of horizontal extension across the Karoo graben of northern Malawi. Riedel structures in the fault zones formed within two conjugate sets of localized shear zones; slip on one set was top to the W/NW and, on the other, top to the E/SE. The two conjugate sets of Riedel structures have an acute angle about the regional shortening axes, implying that no pronounced rotation of the strain axes occurred. The internal rotation axes for the Riedel structures reveal a largely bimodal distribution and inferred weakly monoclinic to orthorhombic symmetry. Therefore the overall deformation during Karoo rifting in northern Malawi is interpreted to be close to a coaxial deformation with a limited amount of horizontal extension.[/p] 相似文献
6.
《Journal of Structural Geology》1987,9(3):353-363
Strike-slip faulting in the Builth Ordovician Inlier is demonstrated by large-scale maps of the Llanelwedd Quarries near Builth Wells, and by fault plane and slickenline data. In the main quarry steep NNW-striking strike-slip faults dominate the structure, together with significant strike-slip displacement on the W-dipping bedding surfaces and bedding-parallel faults. A zone of steep N-striking extensional dip-slip faults links two of the strike-slip strands and there is a weaker E-striking set of strike-slip faults. When the four fault sets are rotated so that the regional bedding is horizontal, three become vertical and one horizontal, probably their attitude during active life in late Ordovician to early Silurian time. They formed a linked fault system capable of accommodating three-dimensional bulk strain. The fault flats have the same kinematic role in a strike-slip system as lateral ramps or transfer faults in dip-slip systems.In the nearby Gelli Cadwgan quarry strike-slip faults are again dominant but strike E or ESE. This heterogeneity of fault pattern in the southern Builth Inlier resolves into more homogeneous domains with areas of 0.1 to 0.5 km2 separated by E to NE-striking dextral strike-slip faults: Domainal structure, an important general feature of strike-slip tectonics, may be present on a variety of scales. 相似文献
7.
《Journal of Structural Geology》1999,21(8-9):1065-1070
If faulting is treated as a stress-controlled phenomenon, the generation of a single fault set, or two sets in conjugate arrangement are inevitably predicted implying plane strain. Alternatively, considering faulting as a strain-controlled process, multiple-set patterns can be predicted. The analysis of multiple-set patterns requires identifying the type of fault pattern from four possibilities: Coulomb, isolated, orthorhombic and complex fault patterns.There are techniques that permit a unique solution of strain tensor for Coulomb and orthorhombic fault patterns. For isolated fault patterns, the principal paleostress directions could be used to approximate the principal strain directions. In this case, we need to assume a homogeneous stress field, independence between faults, and parallelism between shear stress and slip vector on the sliding plane.For complex fault patterns, it is not possible to uniquely determine the total strain tensor without knowledge of all the slip planes. Furthermore, inverting fault-slip data to determine the stress tensor is not correct because the assumptions of the inversion methods are not satisfied. Only a rough approximation is possible assuming that strain produced by major faults represents the total strain tensor. 相似文献
8.
Deformation studies require that geological bodies are kinematically moved along faults. Fault-parallel flow is one of a small number of kinematic restoration algorithms developed for this purpose. This scale-independent method describes how material nodes are displaced parallel to the fault plane, in the direction of fault movement. The one-dimensional strain of linear objects and two-dimensional strain of bodies within the hanging-wall during the restoration is shown for all cutoff angles and all angles of fault bends. A line moving over a fault bend is either shortened or extended depending on its initial orientation. However, the elongation of the line is significantly different under shortening and extension, with respect to the fault bend angle. The geometries of compressional fault systems, in which faults change angle by about 20 to 40°, generate low values of elongation. Modeling of extensional faults, which typically have steeper dips (60 to 80°) and therefore have tighter fault bends, causes high, unnatural values of elongation. The calculated strain ellipse ratios are directly proportional to the fault bend angle, corroborating the one-dimensional results. The fault-parallel flow method should be used primarily to kinematically restore and forward-model compressional faults, and other faults where the fault bend angles do not exceed 40°. 相似文献
9.
The spatial properties of events in the 1997 Colfiorito–Sellano seismic sequence (Northern Apennines, Italy) were investigated using coherence, a parameter derived from seismic moment tensors that quantifies the kinematic similarity between focal mechanisms. The 1997 Colfiorito–Sellano seismic sequence predominantly consists of normal faulting earthquakes, with a few strike-slip and reverse faulting episodes. This kinematic heterogeneity is possibly related to the contemporaneous activity of two different sets of faults: NW–SE normal faults and NNE–SSW sub-vertical faults, the latter inherited from the previous Miocene compressional phase. The study used two independently-derived data sets of the same seismic sequence characterized by a different number of events and by different precision of spatial localisation. Their statistical significances, assessed through a reshuffling procedure, reveal that data sets with at least some hundreds of events and good positional precision are required to obtain significant results through coherence analysis. Results from the better quality data set indicate that this seismic sequence is characterized by a rapid decrease in the kinematic similarity between earthquake pairs within 2 km of separation, particularly along directions sub-perpendicular to the normal fault strike. The decrease rate seems to be controlled by the geometric characteristics of the normal faults, given that the mean along-dip distance between fault segments is 2 km. In proximity to pre-existing tectonic lineaments the relative abundance of strike-slip and reverse faults tends to decrease the kinematic similarity between events but does not influence the coherence decrease rate. The presence of mixed focal mechanisms (normal, reverse and strike-slip) in a single seismic phase implies that mixed fault types are not restricted to polyphase tectonic histories: such heterogeneous kinematics during a single phase may be induced by the presence of inherited discontinuities. 相似文献
10.
多边断层在世界50多个沉积盆地中均有发现,它是指平面上走向多方位且相互交叉组合成多边形形态、具有层控特征的伸展断裂系统,主要发育在被动大陆边缘盆地和内克拉通盆地内的细粒沉积物中。这类断层为非构造成因断层,目前占主流地位的成因机制有密度反转、脱水收缩和重力载荷机制;与构造正断层相比,多边断层明显具有层控性、多边性和体积应变等方性等特点。共同的几何学特征有:延伸长度短,多为平直或铲式断层,倾角变化范围为30°～70°(平均为45°),走向随机,断层平面交叉组合呈多边形形态。多边断层对储层砂体形态以及流体、天然气水合物的运移和聚集具有重要的意义。文中综合了自多边断层提出以来的国内外研究资料,概括了多边断层发育的几何学特征和成因机制以及多边断层对流体运移的影响,希望能对中国以后的多边断层研究提供参考。 相似文献
11.
松辽盆地十屋—德惠地区断裂特征及其与油气的关系 总被引：3，自引：3，他引：0
摘 要 松辽盆地十屋—德惠地区断裂十分发育可分为基底主断裂、基底次级断裂和盖层
断裂。详细描述了断裂的类型及几何学特征探讨了断裂发育时期及其运动学特征分析了
断裂与油气的关系。 相似文献
12.
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。 相似文献
13.
Initiation and formation of folds and the Kazerun high-angle fault zone, in the Zagros fold-and-thrust belt, were related to the continuing SW–NE oriented contraction that probably initiated in the Late Cretaceous, and intensified, starting in Miocene, when the Arabian and Eurasian plates collided. The contraction that led to folding and thrusting of the Phanerozoic sequence in the belt has led to the strike–slip reactivation of basement faults that formed during the Precambrian. Two major systems of fractures have developed, under the same regional state of contraction, during the folding and strike–slip faulting processes. Folding led to the formation of a system of fold-related fractures that comprises four sets of fractures, which include an axial and a cross-axial set that trend parallel and perpendicular to the confining fold axial trace, respectively, and two oblique sets that trend at moderate angles to the axial trace. Slip along high-angle, strike–slip faults formed a system of fractures in the damage zone of the faults (e.g., Kazerun), and deformed folds that existed in the shear zone by rotating their axial plane. This fault-related fracture system is made of five sets of fractures, which include the two sets of Riedel shear fractures (R and R′), P- and Y-shear fractures, and an extensional set.
Remote sensing analysis of both fracture systems, in a GIS environment, reveals a related kinematic history for folding outside of the Kazerun shear zone and faulting and deformation (fracturing and rotation of folds) within the Kazerun fault zone. Rotation of the folds and formation of the five sets of the fault-related fractures in the Kazerun shear zone are consistent with a dextral motion along the fault. The mean trends of the shortening directions, independently calculated for the fold- and fault-related fracture systems, are remarkably close (N53 ± 4°E and N50 ± 5°E, respectively), and are perpendicular to the general NW–SE trend of the Zagros fold-and-thrust belt. Although segments of the Kazerun fault are variably oriented within a narrow range, the angular relationships between sets of fault-related fractures and these segments remain constant. 相似文献
14.
A system of left-lateral faults that separates the South American and Scotia plates, known as the Magallanes-Fagnano fault system, defines the modern tectonic setting of the southernmost Andes and is superimposed on the Late Cretaceous – Paleogene Patagonian fold-thrust belt. Fault kinematic data and crosscutting relationships from populations of thrust, strike-slip and normal faults from Peninsula Brunswick adjacent to the Magallanes-Fagnano fault system, presented herein, show kinematic and temporal relationships between thrust faults and sets of younger strike-slip and normal faults. Thrust fault kinematics are homogeneous in the study area and record subhorizontal northeast-directed shortening. Strike-slip faults record east—northeast-directed horizontal shortening, west—northwest-directed horizontal extension and form Riedel and P-shear geometries compatible with left-lateral slip on the main splay of the Magallanes-Fagnano fault system. Normal faults record north-south trending extension that is compatible with the strike-slip faults. The study area occurs in a releasing step-over between overlapping segments of the Magallanes-Fagnano fault system, which localized on antecedent sutures between basement terranes with differing geological origin. Results are consistent with regional tectonic models that suggest sinistral shearing and transtension in the southernmost Andes was contemporaneous with the onset of seafloor spreading in the Western Scotia Sea during the Early Miocene. 相似文献
15.
柴达木盆地内部发育有丰富的基底和浅层断裂，二者之间的成因机制目前还存在较大争议。文章基于高精度三维地
震反射数据和钻井资料，对柴达木盆地北缘南八仙背斜的深、浅断裂系统的几何形态和相互耦合关系进行了分析。南八仙
地区主要发育两条近EW走向的高角度基底断裂，分别为南倾的马仙断裂和北倾的仙南断裂，都是中生代晚期就开始发育
的老断裂，并在新生代重新活化。在新生界内部还发育NW走向和近EW走向两组浅层正断层体系，断距都很小。NW走向
正断层主要位于马仙断裂南侧（上盘），呈雁列式排列。近EW走向正断层范围较小，仅局限在南八仙背斜核部、仙南断裂
上部，由一系列近平行的正断层组成，在仙南断裂上部形成一个小型的地堑构造，切割了NW走向的正断层体系。分析认
为NW走向正断层与马仙断裂左旋走滑导致的尾端拉张有关，而近EW走向正断层体系与高角度仙南断裂逆冲活动导致的
浅层剪切拉张有关。综合前人研究成果认为柴达木盆地广泛存在的浅层断裂成因多变，深、浅断裂耦合关系十分复杂，先
存断裂在新生代构造活动中起到了一定的控制作用。 相似文献
16.
柴达木盆地内部发育有丰富的基底和浅层断裂,二者之间的成因机制目前还存在较大争议。文章基于高精度三维地
震反射数据和钻井资料,对柴达木盆地北缘南八仙背斜的深、浅断裂系统的几何形态和相互耦合关系进行了分析。南八仙
地区主要发育两条近EW走向的高角度基底断裂,分别为南倾的马仙断裂和北倾的仙南断裂,都是中生代晚期就开始发育
的老断裂,并在新生代重新活化。在新生界内部还发育NW走向和近EW走向两组浅层正断层体系,断距都很小。NW走向
正断层主要位于马仙断裂南侧（上盘）,呈雁列式排列。近EW走向正断层范围较小,仅局限在南八仙背斜核部、仙南断裂
上部,由一系列近平行的正断层组成,在仙南断裂上部形成一个小型的地堑构造,切割了NW走向的正断层体系。分析认
为NW走向正断层与马仙断裂左旋走滑导致的尾端拉张有关,而近EW走向正断层体系与高角度仙南断裂逆冲活动导致的
浅层剪切拉张有关。综合前人研究成果认为柴达木盆地广泛存在的浅层断裂成因多变,深、浅断裂耦合关系十分复杂,先
存断裂在新生代构造活动中起到了一定的控制作用。 相似文献
17.
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
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20.
《Journal of Structural Geology》1988,10(7):649-659
In a series of scale-experiments, we generated listric normal faults by extending models composed of colored sand layers deposited at regular time intervals throughout deformation during syntectonic sedimentation. Progressive bulk extension along a single set of faults caused domino-type tilting of fault blocks. Underlying tilted faults propagated upwards, with constant dips into newly sedimented layers. Hence fault profiles become progressively more listric. Tilting of the free surface resulted in asymmetrical depressions and in fan-shaped deposits.Stepwise or continuous geometric models of domino-tilting and synchronous sedimentation yield the same structural and stratigraphic features as observed in the sand models. The continuous geometric model shows that a critical parameter governing fault curvature is the ratio R between rates of bulk strain and sedimentation.Both types of models reveal that synchronous sedimentation and bulk extension are capable by themselves of generating listric normal faults. 相似文献