共查询到20条相似文献，搜索用时 15 毫秒
1.
Paul Wilson Rob L. Gawthorpe David Hodgetts Franklin Rarity Ian R. Sharp 《Journal of Structural Geology》2009,31(8):759-775
The geometry and architecture of a well exposed syn-rift normal fault array in the Suez rift is examined. At pre-rift level, the Nukhul fault consists of a single zone of intense deformation up to 10 m wide, with a significant monocline in the hanging wall and much more limited folding in the footwall. At syn-rift level, the fault zone is characterised by a single discrete fault zone less than 2 m wide, with damage zone faults up to approximately 200 m into the hanging wall, and with no significant monocline developed. The evolution of the fault from a buried structure with associated fault-propagation folding, to a surface-breaking structure with associated surface faulting, has led to enhanced bedding-parallel slip at lower levels that is absent at higher levels. Strain is enhanced at breached relay ramps and bends inherited from pre-existing structures that were reactivated during rifting. Damage zone faults observed within the pre-rift show ramp-flat geometries associated with contrast in competency of the layers cut and commonly contain zones of scaly shale or clay smear. Damage zone faults within the syn-rift are commonly very straight, and may be discrete fault planes with no visible fault rock at the scale of observation, or contain relatively thin and simple zones of scaly shale or gouge. The geometric and architectural evolution of the fault array is interpreted to be the result of (i) the evolution from distributed trishear deformation during upward propagation of buried fault tips to surface faulting after faults breach the surface; (ii) differences in deformation response between lithified pre-rift units that display high competence contrasts during deformation, and unlithified syn-rift units that display low competence contrasts during deformation, and; (iii) the history of segmentation, growth and linkage of the faults that make up the fault array. This has important implications for fluid flow in fault zones. 相似文献
2.
To investigate the physical processes operating in active fault zones, we conduct analogue laboratory experiments where we track the morphological and mechanical evolution of an interface during slip. Our laboratory friction experiments consist of a halite (NaCl) slider held under constant normal load that is dragged across a coarse sandpaper substrate. This set-up is a surrogate for a fault surface, where brittle and plastic deformation mechanisms operate simultaneously during sliding. Surface morphology evolution, frictional resistance and infra-red emission are recorded with cumulative slip. After experiments, we characterize the roughness developed on slid surfaces, to nanometer resolution, using white light interferometry. We directly observe the formation of deformation features, such as slip parallel linear striations, as well as deformation products or gouge. The striations are often associated with marginal ridges of positive relief suggesting sideways transport of gouge products in the plane of the slip surface in a snow-plough-like fashion. Deeper striations are commonly bounded by triangular brittle fractures that fragment the salt surface and efficiently generate a breccia or gouge. Experiments with an abundance of gouge at the sliding interface have reduced shear resistance compared to bare surfaces and we show that friction is reduced with cumulative slip as gouge accumulates from initially bare surfaces. The relative importance of these deformation mechanisms may influence gouge production rate, fault surface roughness evolution, as well as mechanical behavior. Finally, our experimental results are linked to Nature by comparing the experimental surfaces to an actual fault surface, whose striated morphology has been characterized to centimeter resolution using a laser scanner. It is observed that both the stress field and the energy dissipation are heterogeneous at all scales during the maturation of the interface with cumulative slip. Importantly, we show that the formation of striations on fault planes by mechanical abrasion involves transport of gouge products in the fault plane not only along the slip direction, but also perpendicular to it. 相似文献
3.
Normal faults on Malta were studied to analyse fault propagation and evolution in different carbonate facies. Deformation of carbonate facies is controlled by strength, particle size and pore structure. Different deformation styles influence the damage characteristics surrounding faults, and therefore the fault zone architecture. The carbonates were divided into grain- and micrite-dominated carbonate lithofacies. Stronger grain-dominated carbonates show localised deformation, whereas weaker micrite-dominated carbonates show distributed deformation. The weaker micrite-dominated carbonates overlie stronger grain-dominated carbonates, creating a mechanical stratigraphy. A different architecture of damage, the ‘Fracture Splay Zone’ (FSZ), is produced within micrite-dominated carbonates due to this mechanical stratigraphy. Strain accumulates at the point of juxtaposition between the stronger grain-dominated carbonates in the footwall block and the weaker micrite-dominated carbonates in the hanging wall block. New slip surfaces nucleate and grow from these points, developing an asymmetric fault damage zone segment. The development of more slip surfaces within a single fault zone forms a zone of intense deformation, bound between two slip surfaces within the micrite-dominated carbonate lithofacies (i.e., the FSZ). Rather than localisation onto a single slip surface, allowing formation of a continuous fault core, the deformation will be dispersed along several slip surfaces. The dispersed deformation can create a highly permeable zone, rather than a baffle/seal, in the micrite-dominated carbonate lithofacies. The formation of a Fracture Splay Zone will therefore affect the sealing potential of the fault zone. The FSZ, by contrast, is not observed in the majority of the grain-dominated carbonates. 相似文献
4.
Ramil Ahmadov Atilla Aydin Mohammad Karimi-Fard Louis J. Durlofsky 《Hydrogeology Journal》2007,15(7):1239-1250
The effect of open and filled slip surfaces on the upscaled permeability of two fault zones with 6 and 14 m strike-slip in an eolian Aztec Sandstone, Nevada, USA is evaluated. Each fault zone is composed of several fault components: a fault core, bounded by filled through-going slip surfaces referred to as slip bands, and a surrounding damage zone that contains joints and deformation bands. Slip band geometry, composition, and petrophysical properties are characterized. Measurements and modeling show that slip band permeabilities can vary over 12 orders of magnitude depending on the degree of fill within the slip bands. The slip bands along with other fault zone components are represented in finite volume numerical calculations and the impact of various slip-band representations on upscaled fault zone permeability is tested. The results show 2 orders of magnitude variation in upscaled fault zone permeability in the fault-normal direction and a factor of 2 variation in the fault-parallel direction. The numerical results presented here are compared to the earlier numerical results in which structured Cartesian grids were used for the numerical simulations, and are in qualitative agreement with earlier calculations but use about a factor of 250–400 fewer numerical cells. 相似文献
5.
Fault zone geometry of a mature active normal fault: A potential high permeability channel (Pirgaki fault, Corinth rift, Greece) 总被引：2，自引：1，他引：2
We present results from petrophysical analysis of a normal fault zone with the aim of defining the flow pathways and their behavior during seismic and interseismic periods. Data are obtained on porosity geometry, strain structure and mineralogy of different domains of a normal fault zone in the Corinth rift. Data point out a close relationship between mineralogy of the clayey minerals, porosity network and strain structures and allow definition of a macroscopic anisotropy of the flow parameters with a strong control by microscopic ultracataclasite structures. The Pirgaki fault zone, developed within pelagic limestone, has a sharp asymmetric porosity profile, with a high porosity volume in the fault core and in the damage zone of the hanging wall. From porosity volumes and threshold measurements, a matrix permeability variation of 6 orders of magnitude could be expected between the protolith and the fault core. Modifications of this pathway during seismic and interseismic phases are depicted. Healing of cracks formed during seismic slip events occurred in the fault core zone and the porous network in the damage zone is sealed in a second step. The lens geometry of the fault core zone is associated with dissolution surfaces and open conduits where dissolved matter could move out of the fault core zone. These elementary processes are developed in particular along Riedel's structures and depend on the orientation of the strain surfaces relative to the local stress and depend also on the roughness of each surface type. P-surfaces are smooth and control shearing process. R-surfaces are rough and present two wavelengths of roughness. The long one controls localization of dissolution surfaces and conduits; the short one is characteristic of dissolution surfaces. The dissolved matter can precipitate in the open structures of the hanging wall damage zone, decreasing the connectivity of the macroscopic conduit developed within this part of the fault zone. 相似文献
6.
Field-based structural analysis of an exhumed, 10-km-long strike-slip fault zone elucidates processes of growth, linkage, and termination along moderately sized strike-slip fault zones in granitic rocks. The Gemini fault zone is a 9.3-km-long, left-lateral fault system that was active at depths of 8–11 km within the transpressive Late-Cretaceous Sierran magmatic arc. The fault zone cuts four granitic plutons and is composed of three steeply dipping northeast- and southwest-striking noncoplanar segments that nucleated and grew along preexisting cooling joints. The fault core is bounded by subparallel fault planes that separate highly fractured epidote-, chlorite-, and quartz-breccias from undeformed protolith. The slip profile along the Gemini fault zone shows that the fault zone consists of three 2–3-km-long segments separated by two ‘zones’ of local slip minima. Slip is highest (131 m) on the western third of the fault zone and tapers to zero at the eastern termination. Slip vectors plunge shallowly west-southwest and show significant variability along strike and across segment boundaries. Four types of microstructures reflect compositional changes in protolith along strike and show that deformation was concentrated on narrow slip surfaces at, or below, greenschist facies conditions. Taken together, we interpret the fault zone to be a segmented, linked fault zone in which geometrical complexities of the faults and compositional variations of protolith and fault rock resulted in nonuniform slip orientations, complex fault-segment interactions, and asymmetric slip-distance profiles. 相似文献
7.
四川汶川5.12大地震同震滑动断层泥的发现及意义 总被引：4，自引：0，他引：4
2008年汶川8.0级地震沿龙门山断裂带内的映秀—北川断裂和灌县—安县断裂产生了近300 km的同震地表破裂带。震后地质科学考察发现地表变形以逆冲为主,并伴有右旋走滑。地震地表破裂带大多沿古生代碳质泥岩、页岩和三叠系煤系地层内的滑动面出露地表,这些软弱地层为地震破裂带冲到地表提供了超低摩擦滑动带。我们发现在同震垂直和水平位错达6m左右的地表破裂带,地震的同震滑动发生在厚度约0.5~2cm 的狭窄滑动带内,以发育新鲜的灰色断层泥为特征,这些断层泥是地震断层快速滑动过程中岩石—流体相互作用的结果。 相似文献
8.
Structurally controlled, syn-rift, clastic depocentres are of economic interest as hydrocarbon reservoirs; understanding the structure of their bounding faults is of great relevance, e.g. in the assessment of fault-controlled hydrocarbon retention potential. Here we investigate the structure of the Dombjerg Fault Zone (Wollaston Forland, NE Greenland), a syn-rift border fault that juxtaposes syn-rift deep-water hanging-wall clastics against a footwall of crystalline basement. A series of discrete fault strands characterize the central fault zone, where discrete slip surfaces, fault rock assemblages and extreme fracturing are common. A chemical alteration zone (CAZ) of fault-related calcite cementation envelops the fault and places strong controls on the style of deformation, particularly in the hanging-wall. The hanging-wall damage zone includes faults, joints, veins and, outside the CAZ, disaggregation deformation bands. Footwall deformation includes faults, joints and veins. Our observations suggest that the CAZ formed during early-stage fault slip and imparted a mechanical control on later fault-related deformation. This study thus gives new insights to the structure of an exposed basin-bounding fault and highlights a spatiotemporal interplay between fault damage and chemical alteration, the latter of which is often underreported in fault studies. To better elucidate the structure, evolution and flow properties of faults (outcrop or subsurface), both fault damage and fault-related chemical alteration must be considered. 相似文献
9.
G. Molli G. Cortecci L. Vaselli G. Ottria A. Cortopassi E. Dinelli M. Mussi M. Barbieri 《Journal of Structural Geology》2010,32(9):1334-1348
We studied the geometry, intensity of deformation and fluid–rock interaction of a high angle normal fault within Carrara marble in the Alpi Apuane NW Tuscany, Italy. The fault is comprised of a core bounded by two major, non-parallel slip surfaces. The fault core, marked by crush breccia and cataclasites, asymmetrically grades to the host protolith through a damage zone, which is well developed only in the footwall block. On the contrary, the transition from the fault core to the hangingwall protolith is sharply defined by the upper main slip surface. Faulting was associated with fluid–rock interaction, as evidenced by kinematically related veins observable in the damage zone and fluid channelling within the fault core, where an orange–brownish cataclasite matrix can be observed. A chemical and isotopic study of veins and different structural elements of the fault zone (protolith, damage zone and fault core), including a mathematical model, was performed to document type, role, and activity of fluid–rock interactions during deformation. The results of our studies suggested that deformation pattern was mainly controlled by processes associated with a linking-damage zone at a fault tip, development of a fault core, localization and channelling of fluids within the fault zone. Syn-kinematic microstructural modification of calcite microfabric possibly played a role in confining fluid percolation. 相似文献
10.
This paper reports the first example of fault mirrors developed in an unusual protolith, consisting of tourmaline crystals with interstitial goethite. The deformation mechanisms active in the fault zone have been investigated from the outcrop to the nanoscale, aiming to identify possible traces of frictional heating at seismic slip rate, as observed for other fault mirrors in different protoliths. The investigation revealed the superposition of two main deformational stages. The first was dominated by brittle processes and produced a cataclastic/ultracataclastic principal slip zone, a few mm thick; the second was associated with seismic slip and produced a sharp discontinuity (the principal slip surface) within the cataclastic/ultracataclastic zone. The mirror-like coating, a few microns thick, occurs on the principal slip surface, and is characterized by 1) absence of interstitial goethite; 2) occurrence of truncated tourmaline crystals; 3) highly variable grain size, from 200 μm to 200 nm; 4) tourmaline close packing with interlobate grain boundaries, and 5) tourmaline random crystallographic orientation.Micro and nanostructural investigations indicate the occurrence of thermally-activated processes, involving both interstitial goethite and tourmaline. In particular, close to the principal slip surface, goethite is completely decomposed, and produced an amorphous porous material, with local topotactic recrystallization of hematite. Tourmaline clasts are typically characterized by strongly lobate boundaries, indicative of reaction and partial decomposition at grain boundaries. TEM observations revealed the occurrence of tourmaline nanograins, a few tens of nm in size, characterized by rounded shape and fading amorphous boundaries, that cannot be obtained by brittle processes. Lastly, the peculiar interlobate microstructure of the mirror surface is interpreted as the result of grain boundary recrystallization processes taking place by deformation at high-T conditions. Our results show that tourmaline fault mirrors recorded localized high-T processes triggered by frictional heating and can be therefore considered as reliable traces of ancient earthquakes. 相似文献
11.
Fault zone structure and lithology affect permeability of Triassic Muschelkalk limestone-marl-alternations in Southwest Germany, a region characterized by a complex tectonic history. Field studies of eight fault zones provide insights into fracture system parameters (orientation, density, aperture, connectivity, vertical extension) within fault zone units (fault core, damage zone). Results show decreasing fracture lengths with distances to the fault cores in well-developed damage zones. Fracture connectivity at fracture tips is enhanced in proximity to the slip surfaces, particularly caused by shorter fractures. Different mechanical properties of limestone and marl layers obviously affect fracture propagation and thus fracture system connectivity and permeability. Fracture apertures are largest parallel and subparallel to fault zones and prominent regional structures (e.g., Upper Rhine Graben) leading to enhanced fracture-induced permeabilities. Mineralized fractures and mineralizations in fault cores indicate past fluid flow. Permeability is increased by the development of hydraulically active pathways across several beds (non-stratabound fractures) to a higher degree than by the formation of fractures interconnected at fracture tips. We conclude that there is an increase of interconnected fractures and fracture densities in proximity to the fault cores. This is particularly clear in more homogenous rocks. The results help to better understand permeability in Muschelkalk rocks. 相似文献
12.
The distribution of deformation bands in damage zones of extensional faults in porous sandstones has been analyzed using 106 outcrop scanlines along which the position and frequency of deformation bands have been recorded. The analysis reveals a non-linear relationship between damage zone width and fault throw, a logarithmic decrease in deformation band frequency away from the fault core, as well as a fractal spatial distribution associated with clustering of the deformation bands. Furthermore, damage zones appear wider in the hanging wall than in the footwall, although the deformation band density is similar on both sides. Statistical trends derived from the database imply that fault growth in porous sandstones can be considered as a scale invariant process. From an initial process zone, the damage zone grows by a constant balance between the development of new deformation bands in the existing damage zone and the creation of new bands outside. Moreover, as the width of the damage zone increases throughout the active lifetime of a fault, the distribution of the deformation bands in the damage zone remains self-similar. Hence band distribution and damage zone width for seismically mapped faults can be predicted from the relationships found in this paper. 相似文献
13.
Faults in carbonates are well known sources of upper crustal seismicity throughout the world. In the outer sector of the Northern Apennines, ancient carbonate-bearing thrusts are exposed at the surface and represent analogues of structures generating seismicity at depth. We describe the geometry, internal structure and deformation mechanisms of three large-displacement thrusts from the km scale to the microscale. Fault architecture and deformation mechanisms are all influenced by the lithology of faulted rocks. Where thrusts cut across bedded or marly limestones, fault zones are thick (tens of metres) and display foliated rocks (S-CC′ tectonites and/or YPR cataclasites) characterized by intense pressure-solution deformation. In massive limestones, faulting occurs in localized, narrow zones that exhibit abundant brittle deformation. A general model for a heterogeneous, carbonate-bearing thrust is proposed and discussed. Fault structure, affected by stratigraphic heterogeneity and inherited structures, influences the location of geometrical asperities and fault strain rates. The presence of clay minerals and the strain rate experienced by fault rocks modulate the shifting from cataclasis-dominated towards pressure-solution-dominated deformation. Resulting structural heterogeneity of these faults may mirror their mechanical and seismic behaviour: we suggest that seismic asperities are located at the boundaries of massive limestones in narrow zones of localized slip whereas weak shear zones constitute slowly slipping portions of the fault, reflecting other types of “aseismic” behaviour. 相似文献
14.
《Geodinamica Acta》2013,26(6):427-453
This paper aims to illustrate and discuss mechanism(s) responsible for the growth and evolution of large-scale corrugated normal faults in southwest Turkey. We report spectacular exposures of normal fault surfaces as parts of the Manisa Fault - a ?50-km-long northeast-ward arched active fault that defines the northwestern edge of the Manisa graben, which is subsidiary to the Gediz Graben. The fault is a single through-going corrugated fault system with distinct along-strike bends. It follows NW direction for 15 km in the south, then bends into an approximately E-W direction in the northwest. The fault trace occurs at the base of topographic scarps and separates the Quaternary limestone scree and alluvium from the highly strained, massive bed-rock carbonates. The fault is exposed on continuous pristine slip surfaces, up to 60 m high. The observed surfaces are polished and ornamented by well-preserved various brittle structural features, such as slip-parallel striations, gutters and tool tracks, and numerous closely spaced extension fractures with straight or crescentic traces. The rocks both in the footwall and hanging-wall of the fault possess a well-developed fault rock stratigraphy made up, from structurally lowest to the top, of massive undeformed recrystallized limestone, a zone of cemented breccia sheets, corrugated polished slip planes, and first brecciated, then unbrecciated scree. The observed slip surfaces of the Manisa Fault contain two sets of striations that suggest an early phase of sinistral strike-slip and a subsequent normal-slip movements. The first phase is attributed to: (i) approximately E-W-directed compression that commenced during either (?) Early-Middle Pliocene time or (ii) the current extensional tectonics and consequent modern graben formation in southwest Turkey that initiated during the Plio-Quaternary. During this period, the Manisa Fault was reactivated and it became a major segment. Stress inversion of fault slip data suggests that southwest Turkey has been experiencing multidirectional crustal extension, with components of approximately N-S, E-W, NE-SW and NW-SE extension. Following the reactivation, the inherited fault segments were connected to each other through interaction, linkage and amalgamation of previously discontinuous and overlapping smaller stepping adjacent faults. Linkage was via the formation of new connecting (breaching) fault(s) or by curved propagation of fault-tips. The result is a single through-going corrugated fault trace with distinct along-strike bends. The final geometry of the Manisa Fault is thus the combined result of reactivation and continuing interaction between previously discontinuous segmented fault traces. 相似文献
15.
断裂的形成演化过程对油气的运聚成藏具有重要的影响。本文系统分析了呼和湖凹陷断裂特征、断裂演化及其与油气成藏的关系。研究表明,呼和湖凹陷以T_(22)和T_(04)反射层为界,划分为3套构造层,分别为下部伸展断陷构造层、中部断坳构造层,上部坳陷构造层,其中上部构造层中断裂不发育。纵向上主要发育了两套断裂系统,下部断裂系统展布方向主要是北东东向、北东向和北北东向。上部断裂系统展布方向主要为北北东向和北北西向。发育4种类型的断裂,分别为早期伸展断裂,中期走滑断裂,早期伸展中期走滑断裂和早期伸展中期走滑晚期反转断裂。断裂的主要形成时期为南屯组末期、伊敏组末期和青元岗组末期。断裂的形成和演化影响烃源岩的分布和热演化程度,形成多种类型的圈闭,为油气垂向运移提供良好的运移通道。其中在主力生油洼槽及其周边的几个控陷断层附近有利于油气富集。 相似文献
16.
In many extensional provinces, large normal faults dip in the same direction forming fault domains. Features variously named transfer faults, transfer zones, and accommodation zones (hereafter non-genetically referred to as fault-domain boundaries) separate adjacent fault domains. Experimental modeling of distributed extension provides insights on the origin, geometry, and evolution of these fault domains and fault-domain boundaries. In our scaled models, a homogeneous layer of wet clay or dry sand overlies a latex sheet that is stretched orthogonally or obliquely between two rigid sheets. Fault domains and fault-domain boundaries develop in all models in both map view and cross-section. The number, size, and arrangement of fault domains as well as the number and orientation of fault-domain boundaries are variable, even for models with identical boundary conditions. The fault-domain boundaries in our models differ profoundly from those in many published conceptual models of transfer/accommodation zones. In our models, fault-domain boundaries are broad zones of deformation (not discrete strike-slip or oblique-slip faults), their orientations are not systematically related to the extension direction, and they can form spontaneously without any prescribed pre-existing zones of weakness. We propose that fault domains develop because early-formed faults perturb the stress field, causing new nearby faults to dip in the same direction (self-organized growth). As extension continues, faults from adjacent fault domains propagate toward each another. Because opposite-dipping faults interfere with one another in the zone of overlap, the faults stop propagating. In this case, the geometry of the domain boundaries depends on the spatial arrangement of the earliest formed faults, a result of the random distribution of the largest flaws at which the faults nucleate. 相似文献
17.
18.
This paper describes the structural, petrophysical and hydromechanical properties relationships between a small fault zone and the porous layered carbonate series which host it. In a gallery located at 250-m depth, the deformation of a 22-m thick section of layered carbonates-, affected by a strike slip-fault have been characterized by means of structural (Q-value), acoustic velocities (Vp), porosity and uniaxial compressive strength (σc) measurements conducted in situ at the meter scale, and on laboratory samples at the infra-centimeter scale. A clear influence of the layers initial properties on fault architecture and properties evolution is underlined. In the porous layers with a low σc, there is an important accommodation of the deformation by micro-mechanisms resulting in a progressive decrease in the porosity toward the fault core. In the low-porosity layers with a high σc, deformations are accommodated toward the fault core by: an increase in the fracture porosity, in the micro-cracks porosity, and by displacements along pre-existing fractures resulting from a joint roughness decrease. The fault zone appears as relatively stiff and low permeable zones intercalated with low stiffness and high fracture permeability zones that extend one to tens of meters from the fault following the initial properties contrasts and geometry of the sedimentary layers. 相似文献
19.
白龙江流域坪定-化马断裂带滑坡特征及其形成演化 总被引：1，自引：0，他引：1
沿坪定-化马断裂带发育数个大型或巨型滑坡。这些断裂带滑坡特点明显,成因类似,各滑坡一般发育多个次级滑坡体,滑坡岩土体由次生黄土、断裂带强风化带、断裂破碎带组成,具双层或三层结构。滑坡总体顺断裂走向下滑,历史上曾多次活动。近年来变形监测资料表明,断裂带滑坡目前处于匀速蠕变阶段,表现为蠕滑→拉裂（塑流拉裂）→次级滑坡体启动下滑的特征。它是在断裂活动、地震、降雨、人类工程活动等内外动力耦合作用下形成的,坪定-化马断裂的长期活动为滑坡形成提供了前提条件,断裂带的岩土体性质是滑坡长期活动的物质基础,而降雨、地震、坡脚开挖等是滑坡体失稳下滑的主要诱发因素。因而,有必要进一步研究断裂带滑坡在内外动力耦合作用下的成灾机理,为滑坡灾害防治预警提供科学依据。 相似文献
20.
We report for the first time the occurrence of polygonal faults in sandstone, which is compelling given that layer-bound polygonal fault systems have been observed so far only in fine-grained sediments such as clay and chalk. The polygonal faults are shear deformation bands that developed under shallow burial conditions via strain hardening in dm-wide zones. The edges of the polygons are 1–5 m long. The shear deformation bands are organized as conjugate faults along each edge of the polygon and form characteristic horst-like structures. The individual deformation bands have slip magnitudes ranging from a few mm to 1.5 cm; the cumulative average slip magnitude in a zone is up to 10 cm. The deformation bands heaves, in aggregate form, accommodate a small isotropic horizontal extension (strain <0.005). The individual shear deformation bands show abutting T-junctions, veering, curving, and merging where they mechanically interact. Crosscutting relationships are rare. The interactions of the deformation bands are similar to those of mode I opening fractures. The documented fault networks have important implications for evaluating the geometry of km-scale polygonal fault systems in the subsurface, top seal integrity, as well as constraining paleo-tectonic stress regimes. 相似文献