Journal of Structural Geology最新文献_第3页

Thrust ramps, detachments, and fault-related folding kinematics in the South-Central San Joaquin Fold-and-Thrust Belt, California 加州中南部圣华金褶皱冲断带的逆冲斜坡、分离和断层相关的褶皱运动学

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2025-11-29 DOI: 10.1016/j.jsg.2025.105603

Robert M. Welch , John H. Shaw

The 1982 (M 5.5) New Idria, 1983 (M 6.5) Coalinga, and 1985 (M 6.1) Kettleman Hills earthquakes demonstrated the activity of blind-thrust ramps in the San Joaquin Fold-and-Thrust Belt, California. However, the potential geometric continuity of these and other faults in the system, including thrust ramps that lie along the strike of the epicentral zones and the underlying basal detachments, remains poorly understood. Previously published cross-sections throughout the region are spatially restricted and have varied in their representation of thrust ramps and detachments. To overcome the limitations of previous studies, we present a new internally consistent regional 3D model of these structures, including fault segments along strike from the 1980s earthquake sequences (Kettleman Middle and South Domes, Lost Hills) and into the San Joaquin Basin. This model is based on an analysis of industry seismic data and coupled with horizon picks from the USGS and CalGEM Oil and Gas Well Data, as well as a relocated seismicity catalog and focal mechanism solutions. Our model reveals that along strike, the system changes from a structural wedge to a composite growth fault-bend fold. Where these structural style changes occur, we observe distinct variations in the eastern extent of deformation in the basin. Specifically, those segments characterized by fault-bend folding send slip into the basin on an upper detachment, which is manifest in both detachment folds and additional thrust ramps. At depth, these fault segments are linked to two major basal detachment levels that extend west beneath the Temblor Ranges.

1982年（5.5级）新伊德里亚地震、1983年（6.5级）Coalinga地震和1985年（6.1级）Kettleman Hills地震证明了加州圣华金褶皱冲断带的盲冲斜坡的活动。然而，这些断层和系统中其他断层的潜在几何连续性，包括沿震中带走向的逆冲坡道和下面的基底分离，仍然知之甚少。以前发表的整个区域的横截面在空间上受到限制，并且在它们对冲断坡道和支队的表现方面各不相同。为了克服以往研究的局限性，我们提出了这些构造的一个新的内部一致的区域三维模型，包括从20世纪80年代地震序列（Kettleman Middle and South Domes, Lost Hills）到圣华金盆地的断层段。该模型基于对行业地震数据的分析，结合USGS和CalGEM油气井数据的层位选择，以及重新定位的地震活动目录和震源机制解决方案。模型表明，沿走向，该体系由构造楔向复合生长断弯褶皱转变。在这些构造样式变化发生的地方，我们观察到盆地东部变形程度的明显变化。其中，以断弯褶皱为特征的断弯段通过上拆离向盆地内送滑，主要表现为拆离褶皱和附加逆冲斜坡。在深部，这些断层段与两个主要的基底拆离层相连，这两个基底拆离层向西延伸，位于地震山脉之下。

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引用次数: 0

FoldApp: A MATLAB application for area-depth-strain (ADS) analysis of detachment folds FoldApp：用于分离褶皱的面积-深度-应变（ADS）分析的MATLAB应用程序

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2025-11-29 DOI: 10.1016/j.jsg.2025.105604

Juan Contreras , Ismael Yarbuh , Luis Ángel Vega-Ramírez , Ronald M. Spelz

The Area-Depth-Strain (ADS) method is a mass-balance approach to quantify shortening, depth to detachment, and strain in both contractional and extensional systems We introduce FoldApp, a MATLAB-based, cross-platform app that automates ADS calculations to asses the deformation in detachment folds. The software is organized into three modules that guide users through the necessary steps required by the method: (i) import a seismic interpretation, (ii) set the location of pinning lines in adjacent synclines, (iii) compute the area above the syncline regionals, and (iv) find the best-fit to changes in folded area as a function of stratigraphic thickness. FoldApp also estimates uncertainties in strain and detachment depth, improves reproducibility as users can test the sensitivity of the seismic interpretation to noise, and integrates corrections for shortening caused by tectonic compaction and pure shear layer thickening. Although these effects are rarely considered in mass-balance restorations, they give rise to significant mismatches between the estimated and actual shortening. We tested FoldApp on a representative detachment fold from the Mexican Ridges Fold Belt, western Gulf of Mexico, obtaining robust estimates of tectonic transport, consistent with previously published manual calculations including compaction effects in the transport direction, with quantified uncertainties. FoldApp thus provides a reliable and accessible platform for structural geologists, bridging the gap between traditional interpretation workflows and quantitative analysis.

面积-深度-应变（ADS）方法是一种质量平衡方法，用于量化收缩和伸展系统中的缩短、离体深度和应变。我们介绍了FoldApp，这是一款基于matlab的跨平台应用程序，可自动计算ADS以评估离体褶皱中的变形。该软件分为三个模块，指导用户完成该方法所需的必要步骤：(i)导入地震解释，（ii）设置相邻向斜中固定线的位置，（iii）计算向斜区域上方的面积，以及（iv）找到最适合褶皱面积变化的地层厚度函数。FoldApp还可以估计应变和剥离深度的不确定性，提高再现性，因为用户可以测试地震解释对噪声的敏感性，并集成了构造压实和纯剪切层增厚造成的缩短的修正。虽然在质量平衡恢复中很少考虑这些影响，但它们会导致估计和实际缩短之间的严重不匹配。我们在墨西哥湾西部墨西哥脊褶皱带的一个代表性拆离褶皱上测试了FoldApp，获得了构造运输的可靠估计，与之前发表的人工计算一致，包括运输方向的压实作用，并具有量化的不确定性。因此，FoldApp为构造地质学家提供了一个可靠且可访问的平台，弥合了传统解释工作流程与定量分析之间的差距。

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引用次数: 0

Anisotropy of fracture nodes using wavelet analysis 小波分析裂缝节点的各向异性

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2025-11-28 DOI: 10.1016/j.jsg.2025.105602

Pradeep Gairola, Sandeep Bhatt

Fracture networks exert a strong influence on rock mechanics, fluid flow, and crustal deformation; however, conventional characterization methods often overlook the spatial anisotropy of fracture nodes. This study introduces a wavelet-based angular variance approach to quantify multiscale anisotropy in fracture network nodes (I, Y, X, X + Y-nodes, and barycenters) using both synthetic and natural datasets. Synthetic tests demonstrate that node populations are spatially random under isotropic conditions but develop distinct directional clustering (cross-shaped NE–SW and NW–SE patterns) under anisotropic configurations. Application to natural datasets reveals node-type–specific anisotropy consistent with structural fabric. In the Jabal Akhdar dataset, X- and X + Y-nodes exhibit strong, statistically significant elongation along ENE–WSW, I-nodes show weak lobation in the same direction, and barycenters remain isotropic. At Getaberget, barycenters, Y, X, and X + Y-nodes are significantly anisotropic, trending N–S to NNW and aligning with NE–SW and NW–SE fracture sets. These findings demonstrate that wavelet-based node analysis effectively captures subtle and multiscale anisotropy in fracture systems. The method provides a sensitive, directionally continuous, and scalable framework for quantifying fracture network organization, offering new insights for reservoir characterization, geothermal resource assessment, and fracture-controlled fluid migration in geological systems.

裂缝网络对岩石力学、流体流动和地壳变形有很强的影响；然而，传统的表征方法往往忽略了裂缝节点的空间各向异性。本研究引入了一种基于小波的角方差方法，使用合成和自然数据集来量化裂缝网络节点（I、Y、X、X + Y节点和质心）的多尺度各向异性。综合试验表明，各向异性条件下，节点种群在空间上是随机的，而在各向异性条件下，节点种群呈现出明显的方向性聚类（NE-SW和NW-SE十字形模式）。对自然数据集的应用揭示了与结构结构一致的节点类型特定的各向异性。在Jabal Akhdar数据集中，X-和X + y节点沿ENE-WSW呈现出明显的统计学意义上的延伸，i节点在同一方向上呈现出微弱的分形，质心保持各向同性。在Getaberget，质心、Y、X和X + Y节点具有明显的各向异性，从N-S走向NNW，与NE-SW和NW-SE裂缝组对齐。这些发现表明，基于小波的节点分析可以有效地捕获裂缝系统中细微的多尺度各向异性。该方法为量化裂缝网络组织提供了一个敏感、定向连续和可扩展的框架，为储层表征、地热资源评估和地质系统中裂缝控制的流体运移提供了新的见解。

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引用次数: 0

Detecting transition of stress and friction conditions by fault-slip analysis: Application to outcrop-scale faults in the Quaternary graben fill in the southwest Japan arc 断层滑动分析检测应力和摩擦条件的转变：在日本西南弧第四纪地堑充填体露头尺度断层中的应用

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2025-11-27 DOI: 10.1016/j.jsg.2025.105601

Katsushi Sato

Conventional stress tensor inversion techniques detect multiple stress conditions by minimizing misfit angles between observed fault-slip directions and calculated shear stress directions. Although this strategy is effectual for analyzing reactivated faults, frictionless faults, and faults overpressured with crustal fluids, it tends to fall into a low detectability of stress tensors because of the weak constraint. This study incorporated the fault instability (friction condition) into the objective function of stress tensor inversion for the purposes of improving the detectability and determining the friction coefficients on faults. The modified function was found to be useful to detect multiple stress and friction conditions from heterogeneous fault-slip data especially when they have concentrations of fault plane orientations. The method was applied to outcrop-scale faults cutting the Quaternary strata which filled the Beppu-Shimabara graben in the southwest Japan arc. As a result, a stress transition from ENE-WSW tension to NNE-SSW tension at ca. 1 Ma was found. The friction coefficient on faults has changed from 0.5 to 0.9, which implies a hardening of the strata through diagenesis.

传统的应力张量反演技术通过最小化观测到的断层滑动方向与计算得到的剪应力方向之间的失配角来检测多种应力条件。虽然该策略对重新激活的断层、无摩擦断层和有地壳流体的超压断层的分析是有效的，但由于约束较弱，它往往陷入应力张量的低可探测性。本研究将断层不稳定性（摩擦条件）纳入应力张量反演的目标函数，以提高断层的可检测性和确定断层上的摩擦系数。修正后的函数可用于从非均匀断层滑动数据中检测多种应力和摩擦条件，特别是当它们具有断层面方向集中时。该方法应用于日本西南弧别府-岛原地堑第四纪充填的露头尺度断裂。结果发现，在约1 Ma时，应力从ENE-WSW张力转变为NNE-SSW张力。断层摩擦系数从0.5变化到0.9，表明地层在成岩作用下发生了硬化。

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引用次数: 0

Temperature-dependent frictional properties of opal gouge and their implications for faulting in opaline chert at the Japan Trench subduction zone 日本海沟俯冲带蛋白岩断层的温度相关摩擦特性及其意义

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2025-11-22 DOI: 10.1016/j.jsg.2025.105589

Kyuichi Kanagawa, Tomoya Nakanishi , Junya Fujimori , Sayumi Sagano , Michiyo Sawai

Recent seismic and ocean-drilling data at the Japan Trench subduction zone suggest that the plate-boundary thrust is located within opaline chert in some places. Because seismogenic faulting along the plate-boundary thrust is known to be temperature-dependent, we investigated temperature-dependent frictional properties of opal gouge and their relevance to faulting in opaline chert at the Japan Trench subduction zone. For this purpose, we conducted triaxial friction experiments on opal gouge at a confining pressure of 150 MPa, a pore-water pressure of 50 MPa, temperatures (T) of 25–200 °C, and axial displacement rates changed stepwise among 0.1, 1 and 10 μm/s.

Opal gouge showed frictional strength increasing with increasing T, rate-weakening behavior at T ≥ 100 °C, and stick slips at T ≥ 150 °C. When fitted by the rate- and state-dependent friction constitutive law, friction parameter a decreases while friction parameter b significantly increases with increasing T ≥ 100 °C, so that (a – b) value resultantly decreases to negative at T ≥ 100 °C. Microstructures of the opal gouge after the experiments at T ≥ 100 °C suggest the operation of pressure solution during those experiments. Thermally activated pressure solution possibly promoted healing of gouge particles to significantly increase b value with increasing T ≥ 100 °C, thereby decreasing (a – b) value to negative at T ≥ 100 °C. Our experimental results also suggest that seismogenic faulting at the Japan Trench subduction zone possibly occurs at depths where T ≥ 100 °C, provided that the plate boundary thrust is located within opaline chert on the subducting Pacific plate.

最近在日本海沟俯冲带的地震和海洋钻探资料表明，板块边界冲断作用位于某些地方的蛋白岩中。由于已知沿板块边界逆冲的发震断裂与温度有关，我们研究了蛋白石泥的温度相关摩擦特性及其与日本海沟俯冲带蛋白石燧石断裂的相关性。为此，我们对蛋白石泥进行了围压150 MPa、孔隙水压力50 MPa、温度25 ~ 200℃条件下的三轴摩擦实验，轴向位移速率在0.1、1、10 μm/s之间逐步变化。蛋白石泥的摩擦强度随温度的增加而增加，在温度≥100℃时表现为速率弱化行为，在温度≥150℃时表现为粘滑。当采用速率和状态相关的摩擦本构律拟合时，随着温度≥100℃的升高，摩擦参数a减小，摩擦参数b显著增大，因此（a - b）值在温度≥100℃时减小为负值。温度≥100℃实验后，蛋白石泥的显微结构表明实验过程中进行了压力溶液处理。热激活压力溶液可能促进泥颗粒的愈合，随着温度≥100℃的升高，b值显著增加，而在温度≥100℃时，（a - b）值降至负值。我们的实验结果还表明，如果板块边界逆冲位于俯冲太平洋板块的蛋白石燧石内，则日本海沟俯冲带的发震断裂可能发生在T≥100°C的深度。

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引用次数: 0

Dehydroxylation and amorphization of wet serpentinite gouges during experimental seismic slip and implications for coseismic fluid drainage 实验地震滑动过程中湿蛇纹岩沟槽的去羟基化和非晶化及其同震流体排水意义

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2025-11-22 DOI: 10.1016/j.jsg.2025.105591

Li-Wei Kuo , Wei-Hsin Wu , Matthew S. Tarling , Steven A.F. Smith , Thi Trinh Nguyen , Wen-Jie Wu , Jialiang Si

Dehydroxylation and amorphization of serpentinite occur in natural fault zones and laboratory experiments due to frictional heating during high-velocity slip. Although these processes have been demonstrated under relatively dry experimental conditions, it is unclear whether they are triggered in the presence of water. To address this, we performed rotary-shear friction experiments on water-saturated serpentinite powders at a slip rate of 1 m/s and a normal stress of 10 MPa, in both fluid-drained and undrained conditions. In all experiments, the apparent friction coefficient (i.e., shear stress divided by normal stress) decreased from a peak value of ∼0.32–0.42 to a steady-state value of ∼0.09–0.29. Undrained experiments were associated with gouge compaction, and the temperature measured by a thermocouple in the slip zone reached ∼180 °C by the end of the experiments. Fluid-drained experiments were associated with both gouge compaction and dilation, and the maximum temperature reached ∼635 °C. Using a combination of scanning electron microscopy, focused ion beam transmission electron microscopy, and synchrotron X-ray diffraction analysis, we demonstrate that dehydroxylation and amorphization of serpentinite to form nanocrystalline olivine and enstatite only occurs in fluid-drained conditions. One-dimensional numerical modeling accounting for the main phase changes (water to vapor and serpentine to olivine) shows that the temperature increases rapidly in both the undrained and drained experiments. However, fluid drainage progressively reduces the efficiency of thermal pressurization, leading to increased shear heating and the onset of dehydroxylation and amorphization under fluid-drained conditions. Our results suggest that the distinctive nanocrystalline products of dehydroxylation and amorphization reactions in natural fault zones can only form if fluid drainage occurs away from the slip zone during coseismic slip.

蛇纹岩的脱羟基化和非晶化发生在自然断裂带和实验室实验中，主要是由于高速滑动过程中的摩擦加热。虽然这些过程已经在相对干燥的实验条件下被证明，但尚不清楚它们是否在存在水的情况下被触发。为了解决这个问题，我们在排水和不排水两种条件下，对饱和水蛇纹石粉末进行了旋转剪切摩擦实验，滑动速率为1 m/s，法向应力为10 MPa。在所有实验中，表观摩擦系数（即剪切应力除以法向应力）从峰值~ 0.32-0.42下降到稳态值~ 0.09-0.29。不排水的实验与泥泥压实有关，在实验结束时，在滑动区通过热电偶测量的温度达到了~ 180°C。流体排水实验与泥击实和膨胀相关，最高温度达到~ 635°C。通过扫描电子显微镜、聚焦离子束透射电子显微镜和同步加速器x射线衍射分析，我们证明了蛇纹石的去羟基化和非晶化形成纳米橄榄石和辉辉石只发生在流体干燥的条件下。考虑主要相变（水到蒸汽和蛇纹石到橄榄石）的一维数值模拟表明，在不排水和排水的实验中，温度都迅速升高。然而，流体排水会逐渐降低热压效率，导致剪切加热增加，并在流体排水条件下发生去羟基化和非晶化。我们的研究结果表明，只有在同震滑动时流体排水远离滑动带时，自然断裂带中才能形成独特的去羟基化和非晶化反应的纳米晶产物。

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引用次数: 0

Controlling factors of the strike-slip fault segmentation: insight from DEM modelling 走滑断层分割的控制因素：来自DEM模拟的洞察

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2025-11-21 DOI: 10.1016/j.jsg.2025.105586

Liqing Jiao , Yang Jiao , Yueqiao Zhang

Strike-slip shearing is widespread in the brittle crust and is typically expressed as segmented rupture zones with characteristic spacing. Yet, the key factors controlling this geometric pattern remain poorly understood. In this study, we use discrete element method (DEM) simulations to systematically explore the fundamental physical and tectonic controls on fault segment spacing in strike-slip systems. Our results show that spacing is influenced by both physical and tectonic factors. Physically, spacing increases with crustal thickness and strength, but decreases with density and gravitational acceleration. A near-linear relationship emerges between the ratio of spacing length to thickness and the ratio of strength to the combined effects of density, gravity, and thickness. Tectonically, spacing is reduced by increasing thrust components but enlarged by extensional components. Pre-existing weak zones strongly localize rupture, while surface topography modulates rupture propagation, with segments preferentially forming in lower-elevation areas. These results offer new insights into the mechanics of segmented strike-slip ruptures on Earth and other planetary bodies and provide a framework for better assessing natural hazard risks.

走滑剪切作用在脆性地壳中广泛存在，通常表现为具有特征间距的分段破裂带。然而，控制这种几何模式的关键因素仍然知之甚少。在这项研究中，我们采用离散元方法（DEM）模拟系统地探索了走滑系统中断层段间距的基本物理和构造控制。结果表明，储层间距受物理因素和构造因素的双重影响。物理上，间距随地壳厚度和强度增大而增大，随密度和重力加速度增大而减小。间距长度与厚度之比和强度与密度、重力和厚度的综合效应之比之间呈现出近似线性关系。构造上，逆冲成分的增加使断层间距减小，伸展成分的增加使断层间距增大。先前存在的脆弱区域强烈地局部化破裂，而表面地形调节破裂的传播，片段优先在低海拔地区形成。这些结果为了解地球和其他行星上的分段走滑断裂机制提供了新的见解，并为更好地评估自然灾害风险提供了框架。

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引用次数: 0

Water-induced shear localization and slip mode partitioning in montmorillonite gouge 蒙脱土泥水致剪切局部化及滑移模式分配

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2025-11-19 DOI: 10.1016/j.jsg.2025.105590

Sangwoo Woo , Raehee Han

Montmorillonite is a clay mineral that commonly occurs in shallow subduction zones and crustal faults and may exhibit a lower frictional strength than other clay minerals when wet. Water in the interlayers can modify the frictional strength of montmorillonite by forming thin water films that lubricate grain contacts and, by reducing effective normal stress under undrained compression where fluid cannot escape. However, little is known about how water affects the development of deformation structures within montmorillonite gouge and slip behavior. We conducted low-velocity shear experiments to explore such aspects using dry powders and wet pastes of Ca-montmorillonite and Na-montmorillonite. The dry powder experiments exhibited high frictional strength, high apparent shear stiffness (or the stiffness reflecting the combined effects of loading frame, forcing blocks, and gouge layers), and stable slip behavior with predominant foliated structures. In contrast, the wet paste experiments showed a lower frictional strength, lower apparent shear stiffness, and unstable stick-slip behavior, with the development of both foliated zones and shear localization zones. The stable slip in the dry powder was possible because the rheological stiffness, or the rate of fault weakening during slip, of the material with foliated zones was negative and thus lower than the apparent shear stiffness. In the wet paste, unstable stick-slip was possible because the shear localization zone had a rheological stiffness higher than the apparent shear stiffness, and stable slip is inferred to have occurred in the foliated zones. Our findings reveal that water in montmorillonite gouges not only significantly lowers the frictional strength but also promotes the formation of shear localization zones as well as foliated zones, eventually leading to the partitioning of slip into different structural zones of montmorillonite-bearing faults. While the velocity-strengthening behavior of a slip zone is generally interpreted as precluding unstable slip, our study provides evidence that this is not necessarily the case, as velocity-weakening and stick-slip events can still occur within slip localization zones, which are parts of the slip zone. This structure-related slip mode partitioning offers a new perspective on conventional fault stability assessments.

蒙脱石是一种粘土矿物，通常出现在浅层俯冲带和地壳断层中，在潮湿的情况下，蒙脱石的摩擦强度可能比其他粘土矿物低。中间层中的水可以通过形成润滑颗粒接触的薄水膜来改变蒙脱土的摩擦强度，并通过降低流体无法逃逸的不排水压缩下的有效法向应力。然而，关于水如何影响蒙脱石断层内变形结构的发育和滑动行为，人们知之甚少。我们利用ca -蒙脱土和na -蒙脱土的干粉和湿膏进行了低速剪切实验来探索这些方面。干粉试验表现出高摩擦强度、高表观剪切刚度（或反映荷载框架、强制块体和断层层综合作用的刚度）和稳定的滑移行为，主要是片理结构。湿膏体试验表现出较低的摩擦强度、较低的表观剪切刚度和不稳定的粘滑行为，同时发育片理区和剪切局部化区。干粉的稳定滑移是可能的，因为具有片理带的材料的流变刚度或滑移期间断层弱化的速率为负，因此低于表观剪切刚度。在湿膏体中，由于剪切局部化区流变刚度高于表观剪切刚度，可能出现不稳定粘滑，推测在片理区发生了稳定滑移。研究结果表明，蒙脱石断层中的水分不仅显著降低了蒙脱石断层的摩擦强度，而且促进了剪切局部化带和片理带的形成，最终导致滑动被划分为含蒙脱石断层的不同构造带。虽然滑移带的速度增强行为通常被解释为排除不稳定滑移，但我们的研究提供的证据表明，情况并非一定如此，因为速度减弱和粘滑事件仍然可能发生在滑移局部化区域内，这些区域是滑移带的一部分。这种与结构相关的滑动模式划分为传统的断层稳定性评估提供了新的视角。

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引用次数: 0

Coeval buckling-necking and tablet boudinage of oblique single layers in bulk flattening strain fields: Results from analogue modelling 体压扁应变场中倾斜单层的同时期屈曲颈缩和片状边界：模拟模型的结果

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2025-11-19 DOI: 10.1016/j.jsg.2025.105587

Chao Cheng , Janet Zulauf , Gernold Zulauf , Elke Hattingen

We applied a series of scaled analogue experiments to investigate how the initial orientation of a single competent layer influences the development of folds and boudins in a bulk flattening strain regime. The initial angle between the competent layer and the shortening axis (θ_Z(i)) was systematically adjusted in 11.25° increments from 0° to 90°. As θ_Z(i) increased, layer thickening decreased, and the resulting structures evolved from coeval folds and boudins to predominantly tablet boudins. Folding and boudinage may be active coevally if θ_Z(i) < 45°, with boudin necks oriented perpendicular to the fold axes. Three distinct stages of overprinting, including folding, necking and refolding, are characteristic for one and the same run. In contrast, when θ_Z(i) > 45°, tablet boudins became dominant. Incremental studies indicate that the tablet boudins evolve from previous pinch-and-swell structures by tensile fractures. A striking decrease in their size and aspect ratio with progressive strain reflects strain hardening, which is also common in natural rocks. The experimental structures closely resemble natural examples found in salt rocks and other settings of bulk flattening strain.

我们应用了一系列的比例模拟实验来研究单个能层的初始取向如何影响体扁平应变状态下褶皱和边界的发展。主管层与缩短轴之间的初始角度（θZ(i)）以11.25°的增量从0°到90°进行系统调整。随着θZ(i)的增加，层增厚减小，由此产生的结构从同时期的褶皱和结合演变为以片状结合为主。当θZ(i) <； 45°时，褶曲和褶曲可能同凹地活跃，褶曲颈垂直于褶轴方向。套印的三个不同阶段，包括折叠、缩口和再折叠，是同一次印刷的特点。相反，当θZ(i) >； 45°时，片剂成为主导。越来越多的研究表明，片剂结合体是由先前的挤压-膨胀结构通过拉伸断裂演变而来的。它们的尺寸和长径比随着应变的增加而显著减小，反映了应变硬化，这在天然岩石中也很常见。实验结构与在盐岩和其他体压扁应变环境中发现的自然例子非常相似。

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引用次数: 0

Spatial heterogeneity of burial-related fracture networks controls compartmentalized fluid flow in volcano-sedimentary sequences 埋藏相关裂缝网络的空间非均质性控制着火山-沉积层序的分区流体流动

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2025-11-17 DOI: 10.1016/j.jsg.2025.105588

Sodam Park , Chae-Eun Park , Namgwon Kim , Hyojong Lee , Seung-Ik Park

Fracture networks fundamentally control subsurface fluid flow in sedimentary basins, yet the characteristics and controls of burial-related fractures that developed prior to localized tectonic deformation remain poorly understood in sedimentary rocks with marked volcanic input. We investigate fracture network heterogeneity in a Cretaceous volcano-sedimentary sequence from Wi Island, South Korea, which displays negligible tectonic deformation. Through integrated sedimentary petrological analyses and geometrical/topological fracture characterization of outcrop exposures, we demonstrate distinct spatial variations in fracture intensity and permeability anisotropy across different stratigraphic positions. Fracture intensity correlates strongly with lithological parameters, reaching maximum values at lithological boundaries with high brittle mineral content, and showing elevated intensity in areas with high matrix content and cryptocrystalline texture compared to other stratigraphic levels. Calculated permeability characteristics reveal compartmentalized, anisotropic fluid flow patterns that vary with stratigraphic position. These bed-confined fracture networks predominantly provide lateral connectivity within individual layers while maintaining vertical sealing capacity across fine-grained layers, thereby preventing cross-layer fluid migration. This architecture of fracture networks provides critical insights for predicting initial permeability structure in volcano-sedimentary basins before tectonic modification.

裂缝网络从根本上控制了沉积盆地的地下流体流动，但在具有明显火山输入的沉积岩中，在局部构造变形之前发育的埋藏相关裂缝的特征和控制尚不清楚。我们研究了韩国Wi岛白垩系火山-沉积层序裂缝网络的非均质性，该层序显示可以忽略的构造变形。通过综合沉积岩石学分析和露头暴露的几何/拓扑裂缝表征，我们发现不同地层位置的裂缝强度和渗透率各向异性存在明显的空间差异。裂缝强度与岩性参数相关性强，在脆性矿物含量高的岩性边界处裂缝强度最大，在基质含量高、隐晶结构高的区域裂缝强度高于其他地层水平。计算出的渗透率特征揭示了不同地层位置的区隔、各向异性流体流动模式。这些床层封闭裂缝网络主要在单个层内提供横向连通性，同时在细粒层间保持垂直密封能力，从而防止流体跨层运移。这种裂缝网络结构为预测构造改造前火山-沉积盆地的初始渗透率结构提供了重要的见解。

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引用次数: 0