Journal of Structural Geology最新文献

{"title":"Primary ultra-high-grade Au mineralisation driven by sustained fracture dilation and fluid flow","authors":"Lauri T. Virnes ,&nbsp;Nicolas Thébaud ,&nbsp;Helen B. McFarlane ,&nbsp;Laura Petrella ,&nbsp;Denis Fougerouse ,&nbsp;Laure Martin","doi":"10.1016/j.jsg.2026.105662","DOIUrl":"10.1016/j.jsg.2026.105662","url":null,"abstract":"<div><div>Ultra-high-grade Au (UHG Au) is a texturally distinct vein-hosted Au mineralisation style in epithermal and orogenic Au deposits. The localised hyper-enrichment of Au appears to defy the Au transport capacity of typical ore-forming fluids; thus, the genesis of UHG Au remains debated. In this contribution, the genesis of UHG Au was investigated at the Beta-Hunt Au mine (Kambalda, Western Australia). The Beta-Hunt deposit hosts ∼2640 Ma, structurally controlled orogenic Au mineralisation with two distinct Au mineralisation styles: (1) low-moderate grade Au, occurring as isolated fine grains hosted within a hydrothermally altered shear foliation and (2) coarse-grained UHG Au hosted solely by albite-quartz-carbonate extension veins overprinting the foliation. We employed a multi-disciplinary methodology, conducting characterisation of vein morphology, microtextural analysis, μ-XRF mapping and 3D synchrotron X-ray tomography. Our observations show that UHG Au and associated gangue minerals precipitated within a sustained fluid-filled open space formed by progressively dilating, low aspect-ratio (length/width) fractures during a single or few opening-infill cycles. The low aspect-ratio geometry of UHG Au-hosting veins implies that viscoelastic wall rock deformation contributed to the dilation of the veins, establishing a stable mineral growth environment. Our observations deviate from the expectations of the current orogenic Au system framework, which involves quasi-instantaneous fracturing and growth of veins, via rapid infilling during fluctuating pressure and chemical conditions. We explain our observations through a viscoelastic fracture growth model, which couples the generation of mineral growth space with sustained fluid flow for steady nutrient supply, extending the scope of current models for the genesis of UHG Au.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"206 ","pages":"Article 105662"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleozoic polyphase strain and rheological evolution of the Shangdan shear zone, Qinling Orogen, central China","authors":"Linlin Zeng ,&nbsp;Han Zheng ,&nbsp;Ian P. Cawood ,&nbsp;Dexian Zhang ,&nbsp;Shibo Han ,&nbsp;Peixuan Kang ,&nbsp;Guochun Zhao","doi":"10.1016/j.jsg.2026.105641","DOIUrl":"10.1016/j.jsg.2026.105641","url":null,"abstract":"<div><div>The Shangdan Shear Zone (SSZ) preserves a continuous record of deformation localization across the Paleozoic subduction-collision cycle of the Qinling Orogen. This study integrates field-based finite strain, kinematic vorticity (<em>W</em>_k), and crystallographic preferred orientation analyses alongside quartz rheometry and zircon U–Pb geochronology to quantify the thermomechanical evolution of the orogenic crust. Deformation manifests initially as diffuse, lower-crustal flow (&gt;650 °C) during oceanic-continental subduction (D₁, ca. 540–500 Ma), where high-temperature conditions and anatexis suppressed strain concentration. During this phase, regional compression was accommodated by pure-shear-dominated flattening (<em>W</em>_k = 0.24–0.41). The transition to continental collision (D₂, ca. 432–395 Ma) triggered mid-crustal strain localization facilitated by fluid-assisted weakening. Syn-deformational fluid influx amplified strain rates to 10^−12.58–10^−15.46 s⁻¹—approximately two orders of magnitude higher than in subsequent stages—under differential stresses of 33.95–45.12 MPa, facilitating sinistral transpression (<em>W</em>_k = 0.27–0.48). During post-collisional deep subduction (D₃, ca. 357–330 Ma), strain localization intensified within narrowing felsic bands as the system exhumed and cooled to 300–400 °C. This stage is marked by a kinematic reversal to dextral simple shear (<em>W</em>_k = 0.53–0.74) under differential stresses of 24.82–44.68 MPa and pronounced mineral-scale strain partitioning, yielding a vorticity difference of ≈0.15–0.20 between quartz and feldspar. These results identify a succession of strain localization mechanisms within the orogenic cycle, transitioning from thermal anatexis during subduction to fluid-assisted weakening during collision and mineral-scale rheological partitioning during deep subduction. The findings demonstrate that syn-deformational fluid influx is the key driver of intense strain localization. Furthermore, mineral-scale partitioning ensures that plate interfaces remain active and accommodate kinematic reorganization even as the system cools and exhumes. This quantitative framework identifies the SSZ as a dynamic determinant of lithospheric strength that enables the crust to sustain localized deformation across diverse crustal levels throughout the orogenic lifecycle.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"206 ","pages":"Article 105641"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Loop-Component Index (LCI): A bounded topological metric for quantifying transition from component to loop-dominated fracture networks","authors":"Sivaji Lahiri","doi":"10.1016/j.jsg.2026.105658","DOIUrl":"10.1016/j.jsg.2026.105658","url":null,"abstract":"<div><div>Topological characterization of fracture networks is essential for understanding their structural organization and large-scale hydraulic behavior. In this study, I introduce the Loop–Component Index (LCI), a bounded and scale-independent metric derived from the Euler number (E = β₀ − β₁), where β₀ represents the number of disconnected components and, β₁ denotes the number of enclosed loops. Disconnected components are isolated fracture clusters/fracture-traces with no topological connection to other clusters within the mapped domain, whereas loops are closed polygonal regions formed by intersecting fracture segments. The raw Euler number, however, strongly depends on map size—particularly given the limited availability of large, well-exposed outcrops across different locations—making direct comparison between datasets unreliable. Moreover, ‘E’ can theoretically range from −∞ to +∞ and therefore, unbounded in characteristics. This absence of fixed limits complicates its use in comparative or statistical analyses, especially when compared with other fracture-network descriptors that are typically normalized per unit area or length.</div><div>To overcome these limitations, ‘E’ is first normalized by map area and then transformed using a hyperbolic tangent function (tanh f(x)), yielding LCI values constrained between 0 and 1. In this framework, LCI → 0 indicates component-dominated networks with limited interconnection, whereas LCI → 1 reflects loop-dominated systems characterized by abundant interconnections. An intermediate value of LCI = 0.5 marks the critical topological transition (E = 0), where components and loops are balanced.</div><div>Analyses of synthetic fracture networks show that LCI effectively captures topology transitions driven by fracture density, trace length, and intersection angle. Percolation consistently occurs at LCI &gt;0.5, and the positive correlation between LCI and equivalent permeability (k_eq) underscores its effectiveness as a bounded, scale-independent descriptor of fracture-network structural evolution.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"206 ","pages":"Article 105658"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estimating anisotropy of fracture patterns using gray level Co-occurrence matrix (GLCM) approach: Implication on understanding permeability anisotropy","authors":"Raghubeer Rai ,&nbsp;Sivaji Lahiri ,&nbsp;Ayoti Banerjee ,&nbsp;Somnath Santra ,&nbsp;Sachin Kumar ,&nbsp;Manish A. Mamtani","doi":"10.1016/j.jsg.2026.105661","DOIUrl":"10.1016/j.jsg.2026.105661","url":null,"abstract":"<div><div>Fractures are the main pathways for fluid flow in reservoir rocks with low matrix permeability. Natural fractures are typically anisotropic, causing fluid flow to vary by direction. Accurate characterization of this anisotropy is essential for predicting reservoir behaviour and performance. This study applies a second-order statistical method—Gray-Level Co-occurrence Matrix (GLCM) analysis—to quantify fracture network anisotropy. Grayscale fracture images were examined in horizontal (0° East) and vertical (90° North) directions, and textural anisotropies were computed for key GLCM features: Contrast, Dissimilarity, Homogeneity, Energy, and Entropy. Permeability anisotropy was further estimated through numerical simulations, and its correlation with GLCM-based textural anisotropy was evaluated for both natural and synthetic fracture patterns.</div><div>Results show that GLCM-based textural anisotropy captures not only pixel-level directional intensity variations but also is sensitive to the variation in underlying fracture geometrical attributes—orientation, density, aperture variation, and length distribution—that control directional flow. Across all datasets, permeability anisotropy correlated positively with Homogeneity and Energy anisotropies, and negatively with Contrast, Dissimilarity, and Entropy anisotropies. Among these, Entropy-anisotropy consistently emerged as the strongest predictor of permeability anisotropy. Applying this method to natural fracture networks, including fault damage zones, confirmed that GLCM-based textural anisotropy can non-invasively reveal fracture network anisotropy governing directional permeability. This approach has potential applications in reservoir characterization, hydrogeological modelling, and geothermal resource assessment.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"206 ","pages":"Article 105661"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Folding of a single layer in an effectively anisotropic host: the role of viscosity stratification and confinement on growth rates and fold patterns","authors":"Marta Adamuszek ,&nbsp;Weronika Wiesławska ,&nbsp;Jerzy Gamdzyk ,&nbsp;Marcin Dabrowski","doi":"10.1016/j.jsg.2026.105635","DOIUrl":"10.1016/j.jsg.2026.105635","url":null,"abstract":"<div><div>We investigate how multilayer stack geometry and viscosity stratification influences fold shapes, focusing on the case of a competent layer embedded within a layered host subject to 60% layer-parallel shortening. First, we compare the growth rate spectra calculated with an upscaled anisotropic model and a fully discrete multilayer model. We derive a novel analytical expression for growth rates of a single layer embedded in a confined anisotropic medium. The growth rates computed for the layered host case inherently split depending on whether the low- or high viscosity host layer is in contact with the main layer. For fine host layering, their average converges to the growth rates calculated for the equivalent anisotropic host. Further, using a series of two-dimensional finite element numerical simulations, we vary the internal structure of host layering and analyse the resulting fold patterns. To isolate the influence of geometric configuration, we adjust host layer viscosities to maintain a fixed effective host anisotropy factor across the simulations. To quantify fold shapes in deforming multilayer sequences, we propose a new method that is based on reconstructing an average fold shape for each folded layer. Using the fold classification diagram of Srivastava and Lisle (2004), we obtain a robust characterization of the simulated fold geometries and analyse shape variations within each model and across studied multilayer configurations. Our results demonstrate that even for the same effective anisotropy factor, variations in host layer thicknesses produce a wide spectrum of fold shapes, emphasising the important role of host layer geometry in controlling fold development.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"206 ","pages":"Article 105635"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geometry and kinematics of superimposed detachment folds: A case study of the Longdongping Anticline in the southeastern Sichuan Basin, China","authors":"Chiyue Liu ,&nbsp;Dengfa He ,&nbsp;Weikang Zhang ,&nbsp;Guo Lu ,&nbsp;Jia Ma ,&nbsp;Shiqi Deng ,&nbsp;Hanyu Huang","doi":"10.1016/j.jsg.2026.105657","DOIUrl":"10.1016/j.jsg.2026.105657","url":null,"abstract":"<div><div>Quantitative analysis of the kinematics of superimposed detachment folds remains challenging in fold-thrust belts with multiple detachments. This study investigates the geometry and kinematics of a superimposed detachment fold—Longdongping anticline, Southeastern Sichuan Basin, China. 3D seismic reflection and borehole data image a detachment fold comprising an asymmetric Cambrian evaporite-cored box fold superimposed by fault-propagation fold geometry, overlain by a gentle Ordovician-Jurassic detachment anticline. Both structural culminations show no significant migration. Balanced cross sections quantify lithology-controlled differential shortening across structural layers, documenting negligible values in the basal layer, 0.66 km in the lower layer, a peak of 1.23 km in the middle layer, and 0.83 km in the upper layer. Thermochronology, restoration, and kinematic modeling reveal that the Longdongping Anticline experienced progressive multi-stage deformation since the Late Cretaceous, involving early detachment folding and subsequent fault-controlled modification under continuous regional compression. 2D kinematic modeling which can be explained by an open-system model demonstrates a composite deformation mechanism, where the basal Cambrian evaporites deform mainly by pure shear and the overlying competent strata by flexure, with fault slip accommodating strain differences. This deformation reflects vertical deformation decoupling and shortening partitioned among multiple detachment horizons. Comparable superimposed deformation patterns in the eastern Sichuan and Dabashan fold–thrust belts suggest that their deformation mechanisms are analogous to those governing the Longdongping Anticline. The results provide new insights into the kinematic evolution of multilayer detachment folds and fault superimposition in foreland fold–thrust systems.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"206 ","pages":"Article 105657"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interplay of small-scale exhumed faults with crustal-scale shear zones and associated paleostress condition in Neoarchean Granite","authors":"Gourav Das,&nbsp;Tridib Kumar Mondal","doi":"10.1016/j.jsg.2026.105660","DOIUrl":"10.1016/j.jsg.2026.105660","url":null,"abstract":"<div><div>We investigate the brittle tectonic history of the Neoarchean Closepet Granite (2.56–2.51 Ga), in the Eastern Dharwar Craton, India, using paleostress analysis of small-scale fault-slip data. The analysis reveals a strike-slip stress regime driven by a regional NE-SW to E–W maximum horizontal far-field compressive stress. The study area is subdivided into three zones: Zone 1, Zone 2, and Zone 3 based on changes in the pluton boundary orientation. All three zones are characterised by both dextral and sinistral strike-slip to oblique-slip faults. These fault patterns are consistent with a large-scale Riedel shear system, which developed due to regional-scale shearing along the pluton boundary. The faults developed in Zones 1 and 2 are the consequence of sinistral shearing along the NW-SE-oriented shear zone and the pluton boundary, respectively. In contrast, the faults in Zone 3 are the result of dextral shearing along the N-S-oriented pluton boundary. We interpret that these variations in the sense of shear within the shear zones resulted from the angular relationship between E-W far-field compression and both the orientation of the pluton boundary and the internal tectonic fabric of the pluton. We conclude that regional-scale shearing along the pluton boundary, active during and after its emplacement, controlled the localization of strain and produced the intra-pluton fault pattern.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"206 ","pages":"Article 105660"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Factors controlling the impact of deformation bands on the petrophysical properties of the Upper Rotliegend sandstones (Southern Permian Basin, Poland)","authors":"Weronika Mikołajewska ,&nbsp;Barbara Rybak-Ostrowska ,&nbsp;Edyta Puskarczyk","doi":"10.1016/j.jsg.2026.105659","DOIUrl":"10.1016/j.jsg.2026.105659","url":null,"abstract":"<div><div>The Upper Rotliegend aeolian and fluvial sandstones in the Southern Permian Basin of western Poland reveal an abundance of deformation bands. Well core and thin section analyses supplemented with field-emission electron microscope analysis, as well as porosity and permeability measurements were performed on 100 samples from 12 wells. This enabled the integration of the distribution and composition of the host sandstones with types of deformation bands, along with changes of band petrophysical properties across depths ranging from 1500 m to 4900 m. The main factors controlling the petrophysical properties of sandstones and deformation bands include: sandstone composition, texture and sorting, degree of cementation (quartz, clay minerals, anhydrite, carbonates) during diagenesis, and burial depth. The permeability of deformation bands decreased up to 3 orders of magnitude in relation to the host sandstones. The permeability contrast between the sandstones and the deformation bands is the highest at shallow depths, and decreases with the depth and the degree of cementation and compaction of the host sandstones. The degree of permeability reduction in the analysed samples is consistent with the data reported in other areas of the Southern Permian Basin, although the analysed data show slightly lower porosity and permeability compared to analogous regions in the western part of the basin. Therefore, this analysis provides data representative of the Polish part of the basin and may contribute to more accurate flow modelling, as deformation bands can act as baffles to fluid flow and thus influence the structure and quality of the Upper Rotliegend reservoir.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"206 ","pages":"Article 105659"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural control of gold mineralization in the Jiaodong Peninsula, Eastern China","authors":"Zhonghua Tian ,&nbsp;Zhengjiang Ding ,&nbsp;Doug MacKenzie ,&nbsp;Guoming Chen ,&nbsp;Qibin Zhang ,&nbsp;Fulai Liu ,&nbsp;Wenjiao Xiao","doi":"10.1016/j.jsg.2026.105654","DOIUrl":"10.1016/j.jsg.2026.105654","url":null,"abstract":"<div><div>The Jiaodong Peninsula, located along the western margin of the Paleo-Pacific Plate, hosts one of the world's largest gold provinces with over 5500 tonnes of proven gold resources. Despite its economic significance, the mechanisms of mineralization and the nature of ore-controlling structures remain debated. This study is primarily based on structural analysis, field observations, core drilling, and Electron Backscatter Diffraction (EBSD), supplemented by regional geochronological data, to investigate the tectonic evolution of ore-controlling structures during the Jurassic-Cretaceous West Pacific subduction. Numerous thrust and strike-slip faults have been identified, all overprinted by later detachment faults. A tectonic transition from NW–SE compression to NW–SE extension is identified at ∼135 Ma. The main gold mineralization event occurred at ∼120 Ma, postdating this transition. Two contemporaneous end-member types of mineralization are recognized: disseminated-type deposits in low-angle detachment faults (∼two-thirds of resources) and quartz vein-type mineralization in steeply dipping fractures (∼one-third), formed in structural sites with distinct geometric characteristics. We integrate the fault-valve and the more recently developed mode-switching models to explain the spatial zonation between the two mineralization styles, attributing their formation to periodic changes in ore-forming fluid behavior controlled by fluctuations in effective stress, fluid pressure, and permeability. Our findings highlight the critical role of tectonic transition and structural evolution in controlling the large-scale enrichment of gold deposits in the Jiaodong region and, through the first application of the mode-switching model to this area, provide a novel unified genetic framework for these giant ore deposits.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"206 ","pages":"Article 105654"},"PeriodicalIF":2.9,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147387627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fault reactivation and tectonic conditions for unconformity-related uranium deposit: A paleostress approach (Athabasca Basin, Canada)","authors":"Manon Bulliard ,&nbsp;Roger Soliva ,&nbsp;Gaétan Milesi ,&nbsp;Olivier Gerbeaud ,&nbsp;Alexandre Laramas ,&nbsp;Julien Mercadier","doi":"10.1016/j.jsg.2026.105631","DOIUrl":"10.1016/j.jsg.2026.105631","url":null,"abstract":"<div><div>High-grade unconformity-related uranium (URU) deposits in the Athabasca Basin are spatially associated with graphitic-rich shear zones rooted in the basement and their propagation as brittle faulting and damage zones in the overlying sandstone. Investigating the tectonic phases associated with URU formation is particularly challenging due to its large polyphased history. This study is based on geological observations from 19 exploration drill cores in the Waterfound project (NE Athabasca Basin) and combines structural characterization with paleostress joint-inversions. Three main tectonic regimes were identified: (1) a pre-Athabasca Basin deposition NNE–SSW shortening affecting only the basement, (2) a syn-lithification NW–SE extension, and (3) a post-Athabasca NW–SE shortening. This polyphased tectonic history led to an increase in both the density and variety of fractures in the basin above a low-friction ENE–WSW graphitic shear zone in the basement. The extensional phase (2) developed with low horizontal differential stress, low fluid pressure and potentially relates to post-orogenic collapse or burial stress conditions only. The latest shortening stage (3), associated with uranium mineralization, locally reactivated a pre-existing fracture network in the sandstone and developed above an inherited ENE–WSW-trending graphitic shear zone in the basement. It requires tectonic stresses and fluid pressures estimated at 45–65 MPa to explain the observed structures. These results highlight the interplay between the mechanical strength of inherited structures, stress states, and fluid pressure in governing uranium-bearing fluid flow and provide new insights for Athabasca URU deposits exploration.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"205 ","pages":"Article 105631"},"PeriodicalIF":2.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}