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How variations in intraplate stresses affect slip and dilation tendencies of faults: The onshore United Kingdom example 板内应力的变化如何影响断层的滑动和扩张趋势:以英国陆上为例
IF 2.9 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2025-11-05 DOI: 10.1016/j.jsg.2025.105571
T.G. Blenkinsop
Stresses in plate interiors vary in magnitude and orientations on various scales, implying that shear and normal stresses on faults may vary regionally. The effects of intraplate regional stress variations are analysed using a recent compilation of in-situ stress to calculate slip and dilation tendencies of United Kingdom onshore faults. The tendencies are normalised to maximum possible values. Stress in UK can be characterised by a strike slip stress field with variable orientations of maximum horizontal stress, SH. Throughout southern UK, SH is orientated NW, giving rise to very low slip and dilation tendencies on NE striking Caledonian faults. North and E to ESE striking faults have very high slip tendencies, and intermediate dilation tendencies. At a major boundary in stress orientation (the Highland Boundary Fault in Scotland), SH changes abruptly to a northerly trend. Steeply dipping Caledonian faults in northern UK such as the Great Glen Fault have very high slip tendencies and intermediate dilation tendencies. Faults with low dips (e.g. the Moine Thrust) have intermediate slip and dilation tendencies. The dramatic change in slip tendencies on steeply dipping Caledonian faults from southern to northern UK illustrates some of the profound consequences of regional scale stress variations. These conclusions are robust to reasonable uncertainties, but the coarse results of this study indicate that more detailed knowledge of stress and fault geometry is necessary for applications such as pump-storage schemes, nuclear power plants, radioactive waste disposal, mining, and carbon sequestration, as well as for seismic hazard analysis.
在不同的尺度上,板块内部的应力大小和方向不同,这意味着断层上的剪应力和正应力可能存在区域差异。利用最近的地应力汇编来计算英国陆上断层的滑动和扩张趋势,分析了板内区域应力变化的影响。趋势被归一化到最大可能的值。英国的应力特征是走滑应力场,其最大水平应力方向为SH。在整个英国南部,SH方向为NW,在东北走向的加里东断裂上产生了非常低的滑动和扩张趋势。北、东、东向走向断裂具有很高的滑动倾向和中等扩张倾向。在应力方向上的主要边界(苏格兰高地边界断层),SH突变为北向。英国北部大格伦断层等急倾加里东断裂具有非常高的滑动倾向和中等扩张倾向。低倾角断层(如摩因逆冲断层)具有中等滑动和扩张倾向。从英国南部到北部急倾的加里东断裂上滑动趋势的巨大变化说明了区域尺度应力变化的一些深刻后果。这些结论在合理的不确定性下是稳健的,但本研究的粗略结果表明,对于诸如抽水蓄能方案、核电站、放射性废物处理、采矿、碳封存以及地震危害分析等应用,更详细的应力和断层几何知识是必要的。
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引用次数: 0
Multiscale subsurface structural study – insights from the polish part of the Southern Permian Basin 多尺度地下构造研究——来自南二叠纪盆地波兰部分的启示
IF 2.9 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2025-11-04 DOI: 10.1016/j.jsg.2025.105568
Weronika Mikołajewska , Anita Torabi , Edyta Puskarczyk
We present a multiscale interpretation of faults and their damage zones in the subsurface, consisting of subseismic faults and deformation bands (DB), in the Upper Rotliegend deposits, in the Polish part of the Southern Permian Basin, using a multiscale approach, integrating seismic and well data. Full-bandwidth and high-frequency seismic data, utilising spectral decomposition, were used to interpret the main and minor (small) faults, respectively. Seismic attributes and deep convolutional neural network (DNN) fault volumes were used to improve the interpretation and fault geometric characterization. Faults were visualised and mapped by both DNN and ant tracking analyses, while DNN indicates higher fault probability and continuity. The study area displays two fault trends: a dominant NW–SE trend, initially formed during the basin extension, and a secondary NE–SW trend, formed during the basin inversion, which is more clearly visible in high-frequency component. Well data, resistivity image logs supported by gamma ray logs and well cores, allowed us to identify and map DBs and their connection with fault damage zones. The number of DB increases with faults' proximity, throw and in dune and interdune sandstones.
Investigation of the basin geomorphology and the depositional environments provided insights into the multistage tectonic evolution, which has influenced fault displacement and damage zone geometry and extent. Despite the uncertainties in the data, a positive correlation between fault length and throw (fault scaling law) is evident, which can be further used to strengthen our prediction of fault geometric attributes.
本文采用多尺度方法,综合地震和井数据,对南二叠纪盆地波兰部分的上Rotliegend矿床的断层及其地下破坏带进行了多尺度解释,包括次地震断层和变形带(DB)。利用频谱分解技术,利用全带宽和高频地震数据分别解释了主要断层和次要断层。利用地震属性和深度卷积神经网络(DNN)断层体积来改进解释和断层几何特征。通过深度神经网络和蚂蚁跟踪分析对故障进行可视化和映射,而深度神经网络具有更高的故障概率和连续性。研究区主要表现为两大断裂走向:一是在盆地伸展初期形成的北西-东南断裂为主,二是在盆地反转期间形成的北东-西南断裂次向,在高频分量上更为明显。井数据、由伽马测井和井芯支持的电阻率成像测井,使我们能够识别和绘制db及其与断层破坏带的联系。断层与沙丘和沙丘间砂岩的距离越近、距离越远,DB的数量越高。通过对盆地地貌和沉积环境的研究,揭示了盆地的多阶段构造演化过程,这些构造演化过程影响了断裂位移和损伤带的几何形状和范围。尽管数据存在不确定性,但断层长度与断层落差(断层标度律)之间存在明显的正相关关系,这可以进一步加强我们对断层几何属性的预测。
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引用次数: 0
Comparative analysis of manual and digital approaches for extracting geological hiatuses. A case study from China 人工与数字地质断层提取方法的对比分析。一个来自中国的案例研究
IF 2.9 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2025-10-29 DOI: 10.1016/j.jsg.2025.105565
Berta Vilacís , Sara Carena , Jorge N. Hayek , Gabriel Robl , Hans-Peter Bunge , Jincheng Ma
Dynamic topography is a crucial geodynamic observable that emerges as a consequence of flow in the mantle. Buoyancies associated with mantle convection induce vertical deflections at the Earth’s surface. Negative surface deflections create depositional environments and allow sedimentation to occur, while positive surface deflections create erosional/non-depositional environments, that induce gaps (hiatuses) in the geological record. The temporal and spatial extent of these gaps can be mapped using geological maps and regional studies, thus providing a means of tracking mantle processes through geological time. Here, we compare a manual and digital extraction of hiatus distributions in China. We utilise a manually compiled dataset of un/conformable contacts from a previous publication and compare it to a digital contact extraction using the recently published digital geological map of China. The digital approach is limited to surface data, whereas the manual approach allows the utilisation of subsurface information. We find that the digital approach is substantially faster than the manual extraction. Our results indicate that the optimal methodology combines digital processing with refinement of manual subsurface information. Furthermore, we observe that mapping the absence and presence of a geological series shows very similar results when processed using either approach. The current limitation to a wider application of this approach is the limited availability of digital geological maps. A standardised digital database of geological maps enhanced with subsurface information (i.e., covered geological maps) is necessary to promote the use of geological data within the wider Earth science community, and would increase the opportunities for interdisciplinary collaboration.
动态地形是一个重要的地球动力学观测结果,它是地幔流动的结果。与地幔对流有关的浮力在地球表面引起垂直偏转。负的表面偏转创造了沉积环境,使沉积得以发生,而正的表面偏转创造了侵蚀/非沉积环境,在地质记录中形成了间隙(断裂)。这些裂缝的时间和空间范围可以通过地质图和区域研究来绘制,从而提供了一种通过地质时间跟踪地幔过程的方法。在这里,我们比较了手工和数字提取在中国的间隙分布。我们利用以前出版物中手工编制的不符合接触数据集,并将其与使用最近出版的中国数字地质图的数字接触提取进行比较。数字方法仅限于地面数据,而手动方法可以利用地下信息。我们发现数字方法比人工提取要快得多。我们的结果表明,最优的方法是将数字处理与人工地下信息的细化相结合。此外,我们观察到,当使用任何一种方法处理时,绘制地质序列的缺失和存在显示非常相似的结果。目前这种方法广泛应用的限制是数字地质图的有限可用性。为了促进在更广泛的地球科学界内使用地质数据,有必要建立一个利用地下资料(即覆盖的地质图)加强的标准化地质图数字数据库,并将增加跨学科合作的机会。
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引用次数: 0
Effects of pre-existing fractures on dike propagation: new insights from field data and numerical modelling 已有裂缝对岩脉扩展的影响:来自现场数据和数值模拟的新见解
IF 2.9 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2025-10-22 DOI: 10.1016/j.jsg.2025.105563
A. Luppino , F.L. Bonali , A. Gudmundsson , A. Tibaldi
To better understand the conditions and mechanisms under which dikes interact with pre-existing vertical fractures, we analyzed the fracture swarm and volcanic vents developed during the 1947 eruption (North-East Rift, Etna), and reconstructed the pre-1947 fracture field by historical aerial photos. Then we developed Finite Element Method numerical models, varying the number, spacing, width and vertical and lateral distance of pre-existing fractures with respect to a dike, as well as the dike overpressure. Although in general the 1947 dike followed the path of a previous dike, at a more detailed scale the 1947 vents are shifted up to 11 m laterally with respect to the nearest pre-existing fracture. In areas where few fractures were already present, a significant number of new fractures developed during the 1947 event, whereas if several fractures pre-existed, a few new ones formed. In the case of a pre-existent single fracture, numerical models suggest two scenarios: nucleation of a new fracture bending toward the pre-existing one, possibly followed by dike deflection, or the vertical propagation of the dike. The latter is facilitated by close pre-existing fractures, because dike/fracture interaction enhances tensile stress above the dike tip. This stress increase is sensitive to horizontal fracture spacing, dike/fracture depth difference, and dike overpressure. Stress concentration towards the dike tip and fracture base means a lower probability of new fractures formation at the surface if pre-existing fractures are already widespread. A dike located nearby, or in the middle, of already existing fractures, receives a stress “booster” enhancing its probability of further propagation.
为了更好地了解岩脉与已有垂直裂缝相互作用的条件和机制,我们分析了1947年埃特纳东北裂谷喷发期间发育的裂缝群和火山口,并通过历史航空照片重建了1947年前的裂缝场。然后,我们开发了有限元数值模型,改变了岩脉的数量、间距、宽度、裂缝的垂直和横向距离,以及岩脉超压。虽然1947年的岩脉总体上沿袭了先前岩脉的路径,但在更详细的尺度上,1947年的喷口相对于最近的先前裂缝横向移动了11米。在裂缝很少的地区,在1947年的事件中出现了大量的新裂缝,而如果之前存在一些裂缝,则会形成一些新的裂缝。在先前存在的单一裂缝的情况下,数值模型显示了两种情况:新裂缝向先前存在的裂缝弯曲成核,可能随后发生岩脉偏转,或者岩脉垂直扩展。由于岩脉/裂缝之间的相互作用增强了岩脉尖端上方的拉应力,从而促进了致密裂缝的形成。这种应力增加对水平裂缝间距、岩脉/裂缝深度差和岩脉超压敏感。应力集中在岩脉尖端和裂缝底部,如果现有裂缝已经广泛分布,则地表形成新裂缝的可能性较低。位于已经存在的裂缝附近或中间的堤防会受到应力“增强”,从而提高其进一步扩展的可能性。
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引用次数: 0
What do flexural normal faults tell us about fold-and-thrust belts and foredeep flexures? Cantabrian zone (Ibero-Armorican Orocline core) examples 弯曲的正断层告诉我们关于褶皱冲断带和前深弯曲的什么信息?坎塔布连带(伊比利亚-阿莫里亚奥罗斜核)的例子
IF 2.9 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2025-10-21 DOI: 10.1016/j.jsg.2025.105564
Mayte Bulnes , Hodei Uzkeda , Josep Poblet , Iván García Zuazua
This work describes how flexural normal faults related to a flexure produced in the foredeep of a fold-and-thrust belt develop, how they can be recognized, especially when they formed in early or intermediate stages of development of the fold-and-thrust belt, what information provide about the fold-and-thrust belt and the foredeep flexure, and different procedures to obtain it. The application of these methodologies to a natural example is shown through the detailed analysis of normal faults preceding the folds and thrusts in the western part of the Cantabrian Zone, the foreland fold-and-thrust belt of the Variscan Orogen in the northwest portion of the Iberian Peninsula. These faults are interpreted as flexural normal faults formed during the fold-and-thrust belt development. The strike of the longitudinal flexural normal faults illustrates the orientation of the old fold-and-thrust belt front, resulting in an arcuate distribution consistent with the geometry of the Ibero-Armorican or Asturian Arc. The low fracturing intensity due to the longitudinal faults indicates that the flexure curvature and the flexure inclined-limb dip were very gentle, and that the flexure interlimb angle was very high. This may suggest that the fold-and-thrust belt weight was low at that time. The timing of these flexural normal faults indicate that the thrusts propagated following a forward-breaking or “piggy-back” sequence, as deduced by other authors employing different methods. Finally, the transverse flexural normal faults are interpreted as a result of large oblique/lateral thrust ramps in some thrust sheets located in the southern part of the Cantabrian Zone.
本文描述了与褶皱冲断带前深产生的弯曲有关的弯曲正断层是如何发育的,如何识别它们,特别是当它们形成于褶皱冲断带发育的早期或中期阶段时,提供了关于褶皱冲断带和前深弯曲的哪些信息,以及不同的获取方法。通过对伊比利亚半岛西北部瓦里斯坎造山带前陆褶皱冲断带坎塔布连带西部褶皱冲断前正断层的详细分析,说明了这些方法在一个自然实例中的应用。这些断裂被解释为褶皱冲断带发育过程中形成的弯曲正断层。纵向弯曲正断层的走向说明了旧褶皱冲断带前缘的走向,形成了与伊比利亚-阿莫里亚弧或阿斯图里亚弧的几何形状一致的弧形分布。纵向断裂造成的压裂强度较低,表明挠曲曲率和挠曲斜翼倾角非常平缓,挠曲斜翼间角非常大。这可能说明当时的褶皱冲断带重量较低。这些弯曲的正断层的时间表明逆冲是在向前断裂或“背驮式”序列下传播的,这是其他作者用不同方法推断出来的。最后,将横向弯曲正断层解释为位于坎塔布连带南部的一些逆冲片上的大型斜/侧向逆冲斜坡的结果。
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引用次数: 0
A catalogue of extensional and contractional structures generated along gravity-driven detachments 沿重力驱动分离体产生的伸展和收缩构造目录
IF 2.9 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2025-10-21 DOI: 10.1016/j.jsg.2025.105561
G.I. Alsop , S. Marco , R. Weinberger , T. Levi
<div><div>Although detachments form an integral component of gravity-driven downslope movement, their largely bed-parallel nature can make them difficult to identify in both seismic and outcrop studies. Sediments above bed-parallel detachments (BPDs) associated with intra-stratal deformation are carried passively downslope and therefore represent a form of mass transport deposit (MTD). Using outcrop examples of MTDs created in late-Pleistocene lacustrine sediments around the Dead Sea, we present a catalogue of exceptional extensional and contractional structures generated along BPDs. Detachments may form individual structures that locally ramp to higher structural levels, creating extensional ramps in the upslope direction and contractional ramps further downslope. Alternatively, detachments may comprise multiple strands that kinematically interact with one another via ‘soft-linkage’, or are geometrically coupled via connecting faults to create a ‘hard-linkage’. Lower detachments involving multiple slip surfaces interact with one another to create localised extensional and contractional duplexes, whilst collectively forming the base of the slide sheet. Upper detachments may consist of several strands, or alternatively form ‘soft-linked detachments’ where deformation is distributed across units with no discrete slip surface. Thrusts above detachments frequently follow a ‘piggyback’ sequence with younger shallower thrusts displaying less overall shortening forming downslope of older steeper imbricates. This suggests that they are formed during downslope migration of the duplex rather than upslope propagation of compressive strain during ‘locking up’ of gravity-driven deformation. The fields of extensional and contractional strain may expand and change location during evolution of the slide, leading to normal faults and thrust faults locally overprinting one another. In addition, thrust and normal faults may operate coevally, or locally reactivate one another during positive and negative inversion of individual structures. Transfer of BPD displacement to different levels is achieved by local ramping across older normal and thrust faults, resulting in significant changes to the stratigraphic position of BPDs, together with notable variations in heave across fault zones. Movement on the BPDs is facilitated by high fluid pressures that create sediment injections along the slide planes, especially where normal faults intersect the lower detachment. Where multiple BPDs are formed along the lower detachment, sediment injections cut the upper detachment, suggesting that deformation and movement was longer-lived along the lowermost BPD in a system. Overall, the observation that all measured BPDs (N > 170) consistently display a top-towards the basin sense of displacement suggests that they were sequentially developed through the sediment pile during numerous slope failures, rather than forming synchronously in a single major event that could lead to loca
尽管分离体是重力驱动的下坡运动的一个组成部分,但它们在很大程度上与床层平行,这使得它们在地震和露头研究中都难以识别。与层内变形有关的平行层体(bpd)上的沉积物被被动地带下坡,因此代表了一种体块搬运沉积(MTD)。利用在死海周围晚更新世湖泊沉积物中形成的mtd的露头例子,我们提出了沿bpd产生的特殊伸展和收缩构造的目录。分离体可能形成单独的构造,局部向更高的构造层倾斜,在上坡方向形成伸展坡道,在下坡进一步形成收缩坡道。或者,分离可以由多个链组成,这些链通过“软链接”在运动学上相互作用,或者通过连接故障在几何上耦合以创建“硬链接”。涉及多个滑动表面的较低分离相互作用,形成局部拉伸和收缩的双重结构,同时共同形成滑动片的底部。上部分离可能由几股组成,或者形成“软连接分离”,其中变形分布在各个单元之间,没有离散的滑移面。离层上的逆冲断层通常遵循“背带”序列,较年轻的较浅逆冲断层总体缩短较少,形成较老的较陡峭的叠瓦层的下坡。这表明它们是在双相的下坡迁移过程中形成的,而不是在重力驱动变形“锁定”过程中压缩应变的上坡传播过程中形成的。伸展应变场和收缩应变场在滑块演化过程中会扩展和改变位置,导致正断层和逆冲断层局部重叠。此外,逆冲断层和正断层可能共同作用,或者在个别构造的正反转和负反转期间局部地相互激活。通过在老的正断层和逆冲断层上的局部斜坡,实现了BPD位移向不同水平的转移,导致BPD的地层位置发生了显著变化,同时断裂带上的隆起也发生了显著变化。高压流体沿着滑动面注入沉积物,促进了bpd上的运动,特别是在正常断层与下部分离相交的地方。当沿下部拆离形成多个BPD时,沉积物注入会切割上部拆离,这表明在一个体系中,沿下部BPD形成的变形和运动时间更长。总的来说,观察到所有测量的bpd (N > 170)一致显示出顶部向盆地方向的位移,这表明它们是在多次边坡破坏期间通过沉积物桩顺序发展的,而不是在单个主要事件中同步形成的,该事件可能导致相邻bpd在剪切意义上的局部明显逆转。
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引用次数: 0
Structural and geochronological studies of the Cona detachment and Cona Rift: Implications for the Miocene evolution of the Cona region Cona拆离和Cona裂谷的构造和年代学研究:对Cona地区中新世演化的启示
IF 2.9 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2025-10-20 DOI: 10.1016/j.jsg.2025.105562
Zhuo Tang , Hanwen Dong , Rongze Fei , Linghao Zhao , Li'e Gao , Yaying Wang , Lilong Yan , Lingsen Zeng
The upper-crustal extensional structures developed in the Himalayan orogen record deep dynamics, that have played significant roles in the Himalayan tectonic evolution. This study presents new detailed field investigations, microstructures, quartz [c] axis crystallographic preferred orientation (CPO) patterns, kinematic vorticity, deformation temperatures, zircon U-Pb, and mica 40Ar/39Ar geochronology data of the two sets of intersecting extensional structures in the Cona area of the eastern Himalayan orogen. The results suggest that the Cona Detachment (CD) is mainly in simple shear deformation and the ductile deformation temperature ranges from 280 °C to 517 °C. It was active between 19 and 16 Ma, and ceased at 15 Ma. However, the Cona Rift (CR) is mainly in pure shear deformation and its top-down-to-the-E ductile deformation is recorded at temperatures from 500 °C to 608 °C. It initiated at ∼16 Ma, and ceased activity before 10 Ma. During the transition from N-S to E-W extension, the change in dynamic mechanism led to coupled fluid injection and crustal heating. This study indicates that the N-S and E-W extensional structures in the Cona area exhibited overlapping deformation histories during 16–15 Ma.
喜马拉雅造山带发育的上地壳伸展构造记录了深部动力学,在喜马拉雅构造演化中起着重要作用。本文介绍了东喜马拉雅造山带Cona地区两套相交伸展构造的详细野外考察、微观构造、石英[c]轴结晶学优选取向(CPO)模式、运动涡度、变形温度、锆石U-Pb和云母40Ar/39Ar年代学资料。结果表明:Cona剥离主要以单纯剪切变形为主,韧性变形温度范围为280 ~ 517℃;它在19至16毫安之间活跃,并在15毫安时停止。然而,Cona裂谷(CR)主要是纯剪切变形,在500°C至608°C的温度范围内记录了其自顶向下的韧性变形。它开始于~ 16 Ma,并在10 Ma之前停止活动。在南北向向东西向伸展过渡过程中,动力学机制的变化导致流体注入与地壳加热耦合。研究表明,在16 ~ 15 Ma期间,Cona地区的南北向和东西向伸展构造表现出重叠的变形历史。
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引用次数: 0
Decoding microstructures of fault carbonate rocks with X-ray microtomography: A deep learning approach to fabric classification and analysis 用x射线微层析成像解码断层碳酸盐岩的微观结构:织物分类和分析的深度学习方法
IF 2.9 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2025-09-23 DOI: 10.1016/j.jsg.2025.105559
Marco Voltolini , Luca Smeraglia , Andrea Billi , Eugenio Carminati , Flavio Cognigni , Marco Rossi , Michele Zucali
Fault zones in carbonate rocks exhibit distinct microstructural fabrics that develop different microstructures with increasing deformation, going from the outer zone towards the fault core. These fabrics can be effectively characterized using X-ray micro-computed tomography (XRμCT), a powerful imaging technique that supports a wide range of analyses, from morphometric measurements (e.g., pore size distribution, fractures orientation) to digital rock physics (i.e., virtual experiments on 3D volumes). However, the need for an automated, user-independent tool to classify these microstructures is crucial for large-scale studies. Furthermore, a fully quantitative classification of fault rock fabrics provides valuable insights into the extent and nature of deformation within these rocks. In this study, we present a deep learning-based supervised neural network designed to automate the classification of fault rock microstructures. This system offers rapid, quantitative, and scalable analysis of XRμCT data, facilitating the identification and classification of fabrics of brittle fault limestone rocks with high precision. The network was trained and validated on purpose collected datasets representing specific fabrics, then it was successfully used on different limestone fault rocks collected from the same area or obtained from the literature. The results show that the software can reliably classify fault rock fabrics affected by brittle deformation into three primary categories, each representing a distinct stage of deformation: fractured limestone, breccia, and cataclasite. The network assigns identification probabilities to each image, which can then be visualized in a ternary diagram for intuitive comparison and interpretation. This classification system streamlines fabric analysis and provides a quantitative measure of the degree of deformation within the rock. This automated classification tool paves the way for advanced studies on the anisotropic properties of fault rocks, enabling high-throughput analysis and enhancing our understanding of fault zone mechanics.
碳酸盐岩断裂带具有明显的微结构组构,随着变形的增大,从外带向断核发育不同的微结构。这些结构可以使用x射线微计算机断层扫描(XRμCT)进行有效表征,这是一种强大的成像技术,支持从形态测量(例如,孔隙大小分布,裂缝方向)到数字岩石物理(例如,在3D体积上的虚拟实验)的广泛分析。然而,需要一种自动化的、独立于用户的工具来对这些微观结构进行分类,这对于大规模研究至关重要。此外,断层岩石组构的完全定量分类为了解这些岩石的变形程度和性质提供了有价值的见解。在这项研究中,我们提出了一种基于深度学习的监督神经网络,用于断层岩石微观结构的自动分类。该系统提供快速、定量、可扩展的XRμCT数据分析,有助于脆性断层灰岩组构的高精度识别和分类。该网络在代表特定结构的数据集上进行训练和验证,然后成功地用于从同一地区收集或从文献中获得的不同灰岩断层岩。结果表明,该软件可以可靠地将受脆性变形影响的断层岩组构分为三大类,每一类代表一个不同的变形阶段:破碎灰岩、角砾岩和碎裂岩。该网络为每个图像分配识别概率,然后可以在三元图中可视化,以便直观的比较和解释。这种分类系统简化了构造分析,并提供了岩石内部变形程度的定量测量。这种自动分类工具为断层岩石各向异性特性的深入研究铺平了道路,实现了高通量分析,增强了我们对断层带力学的理解。
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引用次数: 0
Boundary curvature as a first-order control on strain localization in arcuate shear zone: Insights from field observations, analogue and numerical modelling 边界曲率作为弓形剪切带应变局部化的一阶控制:来自现场观测、模拟和数值模拟的见解
IF 2.9 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2025-09-20 DOI: 10.1016/j.jsg.2025.105557
Nandini Choudhury , Suman Guha , Mark D. Lindsay , Atin Kumar Mitra
Curved shear zones are common in orogenic systems, yet the role of boundary curvature in governing strain localization remains underexplored. Using the Singhbhum Shear Zone (SSZ) in eastern India as a natural analogue, we develop an integrated approach combining analytical Couette flow theory, physical analogue modelling with Newtonian viscous Polydimethylsiloxane (PDMS), and finite element simulations. The results consistently reveal a non-monotonic velocity profile with a neutral radius where flow reverses direction, creating distinct zones of localized shear. Strain markers in the experiment deform most intensely near the inner arc and progressively less outward, mirroring field evidence from the SSZ, where high-strain mylonites and strong non-cylindrical folds transition into overprinting crenulations and open folds. This convergence between model predictions and field observations demonstrates that the boundary curvature alone, absent of mechanical or lithological heterogeneity can explain strain partitioning, flow reversal, and fold overprinting in a ductile regime. The study provides a transferable kinematic framework for interpreting curved tectonic interfaces and underscores the often-underestimated role of geometry in shaping deformation. (Words: 168)
弯曲剪切带在造山带中很常见,但边界曲率在控制应变局部化中的作用尚未得到充分探讨。利用印度东部的Singhbhum剪切带(SSZ)作为自然模拟,我们开发了一种综合方法,将分析库埃特流理论、牛顿粘性聚二甲基硅氧烷(PDMS)物理模拟建模和有限元模拟相结合。结果一致显示出一个非单调的速度剖面,具有中性半径,其中流动方向相反,形成明显的局部剪切区。实验中的应变标记在靠近内弧处变形最强烈,向外逐渐减弱,反映了来自SSZ的现场证据,在那里,高应变糜棱岩和强非圆柱形褶皱转变为套印纹纹和开放褶皱。模型预测和现场观测之间的这种收敛表明,在没有力学或岩性非均质性的情况下,仅边界曲率就可以解释韧性状态下的应变分配、流动逆转和褶皱叠加。该研究为解释弯曲的构造界面提供了一个可转移的运动学框架,并强调了几何在塑造变形中的作用往往被低估。(单词:168)
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引用次数: 0
Strain localization and rheological weakening along mid-crustal anisotropies as recorded in the Itapetim and Tendó shear zones (northeastern Brazil) 巴西东北部Itapetim和Tendó剪切带中地壳各向异性应变局部化和流变减弱
IF 2.9 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2025-09-16 DOI: 10.1016/j.jsg.2025.105558
Raylline Silva , Rhander Taufner , Gustavo Viegas , Claudia Trepmann , Lauro Montefalco , Carlos J. Archanjo , Tiago Lyra , Thais Silva
The Central Borborema Province (CBP) in NE Brazil hosts well-preserved mid-crustal shear zones that formed during the Pan-African orogeny in a strike-slip tectonic setting. These structures are key to investigate the strength-controlling processes in high-temperature continental shear zones, which are often obliterated from the geological record during late exhumation. We have analyzed mylonites and ultramylonites from the Itapetim and Tendó shear zones (ISZ and TSZ), two major NE-trending shear zones in the CBP, using a combination of field mapping, microfabric analysis and mineral chemistry. Both the ISZ and TSZ are primarily composed of granitic mylonites with discrete, thin ultramylonitic layers. In mylonites, K-feldspar porphyroclasts form a load-bearing framework that deforms through microfracturing, dislocation-glide-controlled deformation and grain boundary migration. Plastic strain is preferentially accommodated in discontinuous monomineralic quartz ribbons alternating with plagioclase-rich layers. The ultramylonitic layers are spatially and genetically associated with quartz veins and aplitic dykes, in which fluid-rock interactions induce strain softening. This process leads to the development of myrmekite-derived K-feldspar neoblasts and biotite-rich layers, further enhancing rheological weakening. The data gathered in this study suggest that strain is preferentially localized along lithological boundaries, resulting in the development of sinistral shear zones that conform to the overall tectonic setting of the central block of the Borborema Province. Our findings demonstrate strain compatibility between these NE-trending sinistral shear zones and the major E-W dextral lineaments that bound them, offering valuable insights into the mechanisms of rheological weakening in the post-collisional stage of continental orogens.
巴西东北部borborrema省中部(CBP)拥有保存完好的中地壳剪切带,该剪切带形成于泛非造山运动时期的走滑构造背景下。这些构造是研究高温大陆剪切带强度控制过程的关键,这些构造往往在后期的地质记录中被抹去。我们利用野外制图、微组构分析和矿物化学相结合的方法,分析了CBP中两个主要的北东向剪切带Itapetim和Tendó剪切带(ISZ和TSZ)中的糜棱岩和超长岩。ISZ和TSZ主要由花岗质糜棱岩组成,具有离散的薄超长岩层。在糜棱岩中,钾长石卟啉碎屑形成了一个承载框架,通过微压裂、位错-滑动控制变形和晶界迁移进行变形。塑性应变优先适应于不连续的单矿物石英带和富斜长石层交替发生。超长晶石层在空间和成因上与石英脉和胶结岩脉有关,其中流体-岩石相互作用导致应变软化。这一过程导致金绢石衍生的钾长石新母细胞和富黑云母层的发育,进一步增强了流变弱化作用。研究结果表明,应变沿岩性边界优先定位,形成了符合borborrema省中部地块整体构造背景的左旋剪切带。我们的发现证明了这些北东向左旋剪切带与束缚它们的主要东西向右旋构造之间的应变兼容性,为大陆造山带碰撞后阶段流变减弱的机制提供了有价值的见解。
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引用次数: 0
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Journal of Structural Geology
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