Journal of Structural Geology最新文献

{"title":"Pore space properties and permeability of solution surfaces in Mesozoic shallow-water carbonates, southern Apennines, Italy","authors":"C. Manniello ,&nbsp;V. La Bruna ,&nbsp;E. Michie ,&nbsp;R.E.B. Araùjo ,&nbsp;F.H.R. Bezerra ,&nbsp;D. Faulkner ,&nbsp;M. Allen ,&nbsp;X.M. Morais ,&nbsp;G. Prosser ,&nbsp;F. Agosta","doi":"10.1016/j.jsg.2025.105520","DOIUrl":"10.1016/j.jsg.2025.105520","url":null,"abstract":"<div><div>Focusing on the Mesozoic and Eocene carbonate samples from the Viggiano Mt. and Raparo Mt., Southern Apennines of Italy, we examine the role of solution surfaces on the present-day porosity and permeability. Carbonate lithofacies include mudstones, packstones, grainstones, and rudstones and gas-porosimetry measurements show effective porosity up to 5 %. The value is mainly due to the secondary porosity localized along microfractures and within the rough bed-parallel and rough bed-oblique solution surfaces, contrary to what was found in the smooth bed-parallel ones, showing that roughness can control pore localization. NMR (Nuclear Magnetic Resonance) results indicate that the former group of solution surfaces include vugs characterized by subspherical to tubular shapes (pore throat r &lt; 3 μm), and low aspect ratios (r &lt; 2), forming pores with low sensitivity to compression. The microfractures form capillary porosity (r ≈ 1 μm) and are characterized by high aspect ratios (r &gt; 2), typical of pores with high sensitivity to compression. Permeability measurements at room pressure reveal that samples with visible microfractures are characterized by values up 2 order magnitude greater than of those with only visible solution surfaces, showing that the pore connectivity is controlled by opening-mode, sub-mm scale microfractures. At confining pressures greater than 25 MPa, both fracture- and stylolite dominated samples show similar values of permeability, indicating that at depths larger than ca. 1 km, the rough stylolite localize effective porosity that may enhance the along-solution surface fluid flow in carbonates.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105520"},"PeriodicalIF":2.9,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810158","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":"Residual stress in diopside: insight into localized transient high stress in seismogenic faults in the lower crust, Lofoten, Norway","authors":"Hugo W. van Schrojenstein Lantman ,&nbsp;Patricia A. Carvalho ,&nbsp;David Wallis ,&nbsp;Luca Menegon","doi":"10.1016/j.jsg.2025.105517","DOIUrl":"10.1016/j.jsg.2025.105517","url":null,"abstract":"<div><div>Pseudotachylytes in the metamorphosed anorthosites of the Lofoten archipelago, Norway, preserve a record of seismic rupture in dry lower crust at temperatures and pressures of 650–750 °C and 0.8 GPa. Transient gigapascal-level stresses are suggested from microstructural evidence, however such high stresses have not been quantified. In this contribution, we combine microstructural analysis with the mapping of heterogeneity in residual stress in diopside from a lower-crustal pseudotachylyte from Nusfjord (Lofoten) using high-angular resolution electron backscatter diffraction (HR-EBSD). We aim to elucidate the deformation processes that led to this residual stress and to its spatial heterogeneity in the diopside grains.</div><div>The diopside contains micro-to nanoscale deformation twins within 3 mm of the fault and in clasts in the pseudotachylyte. Within clasts, the diopside lattice strongly undulates, indicating crystal plasticity at high driving stress. Residual stress heterogeneity ranges between ∼200 MPa and ∼800 MPa for in-plane normal stress, with greater values occurring closer to and in the pseudotachylyte. This trend is not apparent for the in-plane shear stress, which has residual stress heterogeneity between ∼150 and ∼250 MPa, not correlating with distance to the fault. The greatest residual stresses are present in a clast that exhibits lattice distortion resulting from dislocation glide. Mechanical twins, lattice undulations, and the distribution patterns of residual stress are truncated by coseismic fractures, suggesting that the microstructures and residual stress are the result of stress build-up prior to slip.</div><div>Given the extreme spatial localization of the residual stress heterogeneity, we conclude that it results from deformation occurring during earthquake rupture propagation. Despite high temperatures during frictional heating, thermal pressure did not contribute significantly to the residual stress. The behaviour of diopside as a stress recorder is influenced by mechanical twins: stress build-up in diopside may have partially dissipated by the formation of twins, and twins also appear to affect the residual stress, in particular shear stress.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105517"},"PeriodicalIF":2.9,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810157","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":"Multi-phase deformation in the Qixingtai region of Western Shandong Province: insights into the Neoarchean tectonic evolution of the eastern North China Craton","authors":"Shuhui Zhang ,&nbsp;Jian Zhang ,&nbsp;Guochun Zhao ,&nbsp;Qihang Wu ,&nbsp;Chen Zhao ,&nbsp;Xiaoguang Liu ,&nbsp;Changqing Yin ,&nbsp;Jiahui Qian ,&nbsp;Mingtao He","doi":"10.1016/j.jsg.2025.105516","DOIUrl":"10.1016/j.jsg.2025.105516","url":null,"abstract":"<div><div>The Neoarchean era marks a pivotal period in Earth's tectonic evolution and continental crust formation. In this context, crustal architecture and structural patterns serve as key indicators for reconstructing Neoarchean geodynamic processes. The Western Shandong Province (WSP) granite-greenstone belt, located in the North China Craton (NCC), preserves well-exposed Neoarchean rock assemblages and provides valuable insights into the Neoarchean tectonics. In this study, we conducted systematic geological mapping and detailed structural analysis, integrated with LA-ICP-MS zircon U-Pb geochronology, in the Qixingtai region of the WSP. Three stages of compressional deformation (D1 to D3) were identified. The earliest deformation D1, predating ∼2663 Ma, is characterized by NW-SE-trending, sub-vertically penetrative S1 foliation in early Neoarchean supracrustal rocks and TTG rocks, indicating an initial NE-SW compressional regime. This was followed by a regional extension during 2.60-2.55 Ga and deposition of the Shancaoyu Formation during 2.55-2.52 Ga. The subsequent deformation D2 (∼2520-2514 Ma) progressively overprinted earlier structures and generated NW-SE-trending upright isoclinal folds in late Neoarchean supracrustal and TTG rocks, indicating a consistent and prolonged compressive stress field. The last deformation D3, occurring around ∼2500 Ma, resulted in the development of ductile shear zones of variable scales along the major lithological boundaries and generated regional L-S tectonites with near-vertical foliation and horizontal lineation. Our results suggest that the WSP experienced a long-lasting NE–SW compressive stress field throughout the Neoarchean but lacks diagnostic features of typical subduction or collisional belts. Combined with previous studies, we propose a tectonic model for the tectonic evolution of the Qixingtai area. This area initially developed from an oceanic plateau in the early Neoarchean, experienced regional extension in the middle Neoarchean, and ultimately underwent extensive magmatism and horizontal shortening during the late Neoarchean.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105516"},"PeriodicalIF":2.9,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144750594","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":"Thermo-mechanical intrusion-wall rock interaction and granite emplacement mechanisms of the Peninsula granite at the Sea Point contact, Cape Town, South Africa","authors":"Musa Mhlanga,&nbsp;Russell Bailie,&nbsp;Jürgen Reinhardt","doi":"10.1016/j.jsg.2025.105513","DOIUrl":"10.1016/j.jsg.2025.105513","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Sea Point contact, Cape Town, South Africa exposes the intrusive contact between the ∼540 Ma S-type Peninsula Granite and the ∼560–555 Ma metasedimentary rocks of the Malmesbury Group of the Pan-African Saldania Belt. The western Saldania Belt was subjected to low-grade greenschist facies metamorphism and deformation during the ∼560–540 Ma Saldanian orogeny. The Peninsula Granite intruded as a series of numerous granite sheets which made use of the pre-existing country rock anisotropy in order to propagate. These are the steeply dipping S&lt;sub&gt;0&lt;/sub&gt; bedding due to folding during the Saldanian orogeny, and a steeply dipping axial planar S&lt;sub&gt;2&lt;/sub&gt; foliation to the F&lt;sub&gt;2&lt;/sub&gt; folds developed during the dominant D&lt;sub&gt;2&lt;/sub&gt; deformation. Magma overpressure relative to tensile stresses in the country rock and regional NE-SW-orientated compressional stresses allowed intrusion of variably crystal-laden magma along the anisotropies. The granitic sheets are commonly concentrated in the hinge zones of F&lt;sub&gt;2&lt;/sub&gt; folds, where structural traps facilitated magma “trapping.” Filter pressing at the tail of the magma-filled hydrofracture caused closing during magma through-flow resulting in the entrapping of magmatic crystals, most notably K-feldspar megacrysts, in the wall rock as well as xenoliths dislodged during magma infiltration and stoping, and possibly magma flow. Magma stresses have brought about the alignment of K-feldspar megacrysts as well as the long axes of xenoliths parallel to the orientation of granite sheets and wall rock septa in the complex lit-par-lit zone and adjacent to the contact. A degree of assimilation (and possibly partial melting) is evident in the rounded shapes of xenoliths, but, more notably in mixed zones where there are gradational contacts not only between different granite types, reflecting multiple granite pulse intrusion, but also between the granites and wall rock, giving rise to hybrid granites. Xenoliths with remnant S&lt;sub&gt;0&lt;/sub&gt; and S&lt;sub&gt;2&lt;/sub&gt; were picked up and rotated during magma flow, with some embedded in the wall rock during filter pressing. The timing of granite intrusion relative to deformation is evident from examining contact-metamorphic cordierite porphyroblasts and their inclusions. The variation of inclusion patterns relative to the external foliation indicate that thermal metamorphism and, by implication, magma intrusion, occurred from early D&lt;sub&gt;2&lt;/sub&gt;- to late-D&lt;sub&gt;3&lt;/sub&gt; deformation with continued flattening of the schist matrix leading to an enveloping of the porphyroblasts by the S&lt;sub&gt;2&lt;/sub&gt; foliation. The intrusion thus was accompanied by progressive deformation and tightening of the F&lt;sub&gt;2&lt;/sub&gt; folding. Some granites, notably the coarse-grained megacrystic granite, crosscut other granite types and intruded late-to post-tectonic. Magma loading led to the development of a shallowly dipping, widely spaced S&lt;sub&gt;3&lt;/sub&gt; crenulation. Subsequent magma injections led t","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105513"},"PeriodicalIF":2.9,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144750592","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":"Strain localization in quartzo-feldspathic mylonites from Patos shear zone revealed by EBSD data","authors":"Matheus Alves da Silva ,&nbsp;Leonardo Lagoeiro ,&nbsp;Carolina Cavalcante ,&nbsp;Paola Ferreira Barbosa","doi":"10.1016/j.jsg.2025.105514","DOIUrl":"10.1016/j.jsg.2025.105514","url":null,"abstract":"<div><div>Understanding how strain is localized and concentrated in the mid-crust is critical to geological research. Investigating the microstructure and texture of quartzo-feldspathic mylonites is essential in this context. The Patos shear zone (PSZ), stretching ∼600 km long and responsible for the deformation of the paleoproterozoic basement in the Borborema Province under varying temperature conditions, is a significant shear zone for exploration. Combining techniques, including optical and scanning electron microscopy and Electron Backscatter Diffraction (EBSD) our research focused on quartzo-feldspathic mylonites to comprehend the solid-state processes responsible for strain localization within the Patos shear zone. As materials undergo uplift and deformation transition from a submagmatic to a solid-state flow, strain is concentrated within increasingly narrow zones. Our results demonstrated that after melt solidification, biotite-rich layers at temperatures exceeding 650 °C become weaker domains that accommodate strain through dislocation creep in feldspar, biotite and to a lesser extent in quartz, with the activation of prism-[c] slip system. During late reactivation, under upper greenschist/lower amphibolite facies, dislocation creep, strain-induced myrmekitization, solution-precipitation mechanisms are the dominant mechanisms for grain-size reduction in feldspar, with the resulting fine-grained matrix deforming via dislocation-accommodated and fluid-assisted grain boundary sliding (GBS). Quartz undergoes recrystallization as it transitions from grain boundary migration to subgrain rotation, with the activation of prism-&lt;a&gt; slip system. At temperatures below 450 °C, in the southern Patos shear zone, quartz ribbons experience bulging recrystallization with the activation of prism-&lt;a&gt; and rhomb&lt;a&gt; slip systems. Feldspar porphyroclasts undergo fracturing, myrmekitization and dissolution-precipitation creep. Rock rheology is controlled by fine-grained polyphase aggregates deforming via Dislocation-accommodated GBS. Finally, our study highlights the role of discontinuities during low-temperature deformation, such as the contact between rheologically contrasting layers and transgranular fractures, which serve as a precursor that led to shear zones nucleation in the northern block of the Patos shear zone.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105514"},"PeriodicalIF":2.9,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144723563","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":"Mineral heterogeneity dominates the tensile failure mode of Eastern Himalayan Gneiss","authors":"Shijie Liu ,&nbsp;Hengxing Lan ,&nbsp;C. Derek Martin ,&nbsp;Langping Li ,&nbsp;Han Bao","doi":"10.1016/j.jsg.2025.105515","DOIUrl":"10.1016/j.jsg.2025.105515","url":null,"abstract":"<div><div>As two fundamental fracture types in rock engineering, tension and shear fractures are commonly considered to operate under different stress conditions. However, abundant recent research shows that the microscale heterogeneity of rocks leads to the possibility of microscale tensile and shear fracturing under any stress state. In particular, localised stress concentrations and tensile fractures caused by mineral heterogeneity under compressive stress have been widely studied. However, the heterogeneity-induced processes involved in the shear fracture under direct tension conditions remain ambiguous. In this study, a micro-direct tensile test was used to comprehensively reveal the process and mechanism by which mineral heterogeneity leads to shear fracture in the gneiss of the eastern Himalayas under direct tension. Microscopic observation of the failure process under direct tension, normalised crack initiation and propagation stress, and transverse strain dilation caused by shear behaviour indicate that gneiss with an exceptional anisotropy angle may exhibit more pronounced shear sliding during progressive tensile failure processes. Micro shear sliding significantly increased the strength of the gneiss and changed its tensile strain, elastic modulus, and progressive failure process, which were determined using a direct tension test. Depending on the degree of frictional sliding, the tensile failure mode of gneiss can be divided into three modes: tensile, hybrid, and shear. Mineral heterogeneity influences the pattern of crack propagation through potential fracture planes, altering the crack propagation stress, significantly affecting the mobilisation of frictional strength, and resulting in a progressive transition between the three modes. The observation of shear sliding under direct tension caused by heterogeneity emphasises the importance of mineral-scale heterogeneity in evaluating the tensile strength of anisotropic rocks.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105515"},"PeriodicalIF":2.6,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696806","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":"Pressure-temperature-time deformation of an Ediacaran-Cambrian foreland fold-and-thrust belt: the Southern Espinhaço Front, Araçuaí Orogen","authors":"Henrique C. Joncew ,&nbsp;Ginaldo A.C. Campanha ,&nbsp;Melina C.B. Esteves ,&nbsp;Frederico M. Faleiros ,&nbsp;Leonardo E. Lagoeiro ,&nbsp;Klaus Wemmer ,&nbsp;Ruy A.C. Vasconcelos ,&nbsp;Bruno V. Ribeiro ,&nbsp;Mathias Hueck","doi":"10.1016/j.jsg.2025.105512","DOIUrl":"10.1016/j.jsg.2025.105512","url":null,"abstract":"<div><div>To reconstruct the tectonic evolution of a foreland fold-and-thrust belt, a multi-method approach was carried out involving field-based structural observations, strain quantification, analyses of quartz crystallographic textures, fluid inclusions and illite crystallinity (IC), and in situ muscovite Rb-Sr dating and K-Ar dating of fine fractions of white mica. The studied area encompasses the Southern Espinhaço Front in Serra do Cipó, Brazil, marking the boundary between the Foreland Domain (FLD) of the São Francisco Craton (west) and the Fold-and-Thrust Domain (FTD) of the Araçuaí-West Congo Orogen (east). In this area, the Mesoproterozoic Espinhaço Supergroup was thrust over the Ediacaran-Cambrian Bambuí Group during the Brasiliano-Pan-African orogeny. All structural features indicate west-verging tectonics, with oblate strain ellipsoids, suggesting flattening strain and volume loss. Quartz crystallographic textures indicate primarily rhomb &lt;a&gt; dislocation glide for the larger granulometric fractions (&gt;100 μm), with finer grains experiencing dissolution-precipitation creep. Primary, aqueous fluid inclusions hosted in syn-tectonic veins indicate local intra-basinal fluid circulation. Deformation conditions ranges were 300–410 °C and 1.7–6.0 kbar in the FLD, and 385–450 °C and 2.8–8.0 kbar in the FTD. Rb-Sr muscovite dating suggests a metamorphic peak at 549 ± 17 Ma. K-Ar ages for &lt;2 μm mica were 510–496 Ma in the FLD and 476–456 Ma in the FTD, and &lt;0.2 μm mica dated at 432.6 ± 7.5 Ma. These results indicate progressive crustal wedge thickening under a critical taper model, driving deformation and basal detachment propagation into the foreland accompanied by exhumation.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105512"},"PeriodicalIF":2.9,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144750593","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":"Seismogenesis in the brittle–plastic transition zone of the Yecheon shear zone, South Korea","authors":"Jae Hoon Kim ,&nbsp;Jin-Han Ree","doi":"10.1016/j.jsg.2025.105511","DOIUrl":"10.1016/j.jsg.2025.105511","url":null,"abstract":"<div><div>This study investigates seismogenesis in the brittle–plastic transition zone of the Yecheon Shear Zone, South Korea. The NE-to NNE-striking right-lateral shear zone cuts a Mesozoic granitoid pluton in an outcrop that was investigated in this study. We focus on light green layers within granite mylonitic rocks that preserve evidence of seismic slip events and subsequent plastic deformation. Field observations and microstructural analysis reveal a complex history of brittle and plastic deformations. The light green layers, formed by frictional melting during seismic events, contain injection structures, flow textures, and euhedral to subhedral microlites with inclusions. Elevated pore-fluid pressure might have played a crucial role in initiating seismic ruptures in the brittle–plastic transition zone, forming shear band ruptures or R shear planes and implosion breccia in the releasing stepovers in shear band ruptures. We propose a seismogenic model involving fluid pressure buildup, formation of shear band ruptures, rupture propagation into the <em>C</em> foliation, and the formation and subsequent alteration of pseudotachylytes. The fine-grained nature of the altered pseudotachylytes would have promoted strain localization during interseismic periods, leading to their transformation into ultramylonite. These findings improve our understanding of earthquake nucleation processes in the brittle–plastic transition zone and highlight the importance of fluids in inducing seismic events.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105511"},"PeriodicalIF":2.6,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144679911","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":"Fracture analysis of the lithium-bearing Cligga Head granite: Impacts on critical mineral mobilisation and fluid flow","authors":"Andrew J.M. Evans ,&nbsp;Natalie J.C. Farrell ,&nbsp;David A. Neave ,&nbsp;Margaret E. Hartley ,&nbsp;David Healy ,&nbsp;John P. Waters ,&nbsp;Tara R. McElhinney ,&nbsp;Joshua J. Shea ,&nbsp;Nico Bigaroni ,&nbsp;Simon A. Hunt","doi":"10.1016/j.jsg.2025.105510","DOIUrl":"10.1016/j.jsg.2025.105510","url":null,"abstract":"<div><div>Fracture systems within low-permeability crystalline granitic rocks are critical pathways for fluid flow within these bodies. Constraining the sequence of mineralisation in fracture sets is key to effectively determining the mineral potential and exploitability of rare and critical metals within granite bodies. This study presents the results of a field fracture analysis at the greisen-bearing, lithium-rich Cligga Head granite—a satellite granitic body of the Cornubian Batholith in southwest England. Field mapping of the well-exposed granite body, younging tables and scanning electron microscopy (SEM) are used to develop a temporal model for the evolution of fractures in the Cligga Head granite. Seven fracture sets with varying mineral infill were identified. These fractures exhibit a sequence of cross-cutting relationships that broadly correspond to regional lineament trends — associated with the Variscan Orogeny. As high-quality granite exposure in the region is limited, detailed fracture analysis of satellite granite bodies like Cligga Head provides valuable context for regional critical mineral exploration.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"201 ","pages":"Article 105510"},"PeriodicalIF":2.9,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145332741","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":"Analysis of middle to deep-depth strike-slip faults in the southern Ordos Basin, China: A case study of the Xunyi area","authors":"Yunwen Guan ,&nbsp;Qichao Wang ,&nbsp;Renhai Pu ,&nbsp;Sujie Yan ,&nbsp;Shuo Chen ,&nbsp;Siyu Su","doi":"10.1016/j.jsg.2025.105509","DOIUrl":"10.1016/j.jsg.2025.105509","url":null,"abstract":"<div><div>High-resolution 3D seismic reflection data and coherence attribute analysis reveal a complex network of small-scale strike-slip faults (0.2–20 km in length) within the Xunyi area of the southern Ordos Basin at burial depths of 0.4–3.5 km. These structures exhibit a multi-phase evolution history characterized by distinct deformation patterns across different stratigraphic intervals.</div><div>Structural analysis identifies four distinct tectonic episodes: (1) initial development of NE and NW-trending fault systems during the Caledonian movement (Cambrian-Ordovician), (2) limited reactivation during the Hercynian event (Carboniferous-Permian), (3) formation of NWW to E-W-trending sinistral strike-slip faults during the Indosinian event (Early-Middle Triassic), and (4) right-lateral transpressional reactivation during the Yanshanian event (Late Jurassic-Early Cretaceous).</div><div>Mohr space analysis reveals that the angular relationship between fault orientation and regional stress fields fundamentally controls three distinct patterns of structural inheritance: (1) The XY1 fault maintains continuous activity through all tectonic phases due to its optimal N72-86°E orientation relative to successive stress fields; (2) The XY2-4 faults exhibit early termination after the Caledonian period despite their basement-cutting nature, attributed to their unfavorable orientation under subsequent stress regimes; (3) The Mesozoic faults (W1-4) initiated independently during the Indosinian period with N64-86°E strikes, displaying 33–44° counterclockwise rotation from pre-existing Paleozoic structures.</div><div>Detailed fault growth analysis reveals an early stress interaction mechanism where approaching fault segments develop secondary faults and displacement patterns before geometric overlap occurs. This observation challenges the traditional four-stage fault linkage model that assumes significant interaction only after substantial fault overlap, suggesting more complex stress field interactions during early fault development.</div><div>This integrated study provides critical insights into intraplate deformation processes within cratonic basins, demonstrating how the orientation of pre-existing structures relative to evolving regional stress fields fundamentally controls fault reactivation patterns in multi-phase tectonic settings.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105509"},"PeriodicalIF":2.6,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144655257","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}