Journal of Structural Geology最新文献

{"title":"Microstructural, compositional and textural inheritance in deformed mafic amphibolites","authors":"Laura Airaghi,&nbsp;Hugues Raimbourg,&nbsp;Jacques Précigout","doi":"10.1016/j.jsg.2026.105630","DOIUrl":"10.1016/j.jsg.2026.105630","url":null,"abstract":"<div><div>This study investigates the scales of compositional equilibria and the role of early hydration for the development of microstructures and mineral fabrics in mafic amphibolites, all deformed along a major tectonic plate boundary (Hokkaido, Japan). From fractured domains to mm-size shear bands and meter-size shear zones, element and cathodoluminescence mapping, as well as thermodynamic modelling show that both in plagioclase and in amphibole, strong compositional gradients were observed at the smallest (10–200 μm) scale, which in many instances were inherited from an early, static stage of fracturing, hydration and replacement of igneous minerals. Phase distribution and grain sizes in shear bands and shear zones were also inherited from this early metamorphic stage, giving rise to: (1) monomineralic amphibole layers derived from amphiboles replacing aggregates of Fe-Mg igneous minerals in metagabbros, (2) monomineralic plagioclase layers derived from plagioclase-rich domains of metagabbros that experienced limited early breakdown reactions and (3) intimately mixed and fine-grained amphibole-plagioclase layers developed only where symplectites after igneous minerals were previously formed. While crystallographic and shape preferred orientations of amphibole were acquired from early fracture-driven reactions, and then strengthened in shear bands/zones by dissolution-precipitation, nucleation and oriented growth, the ones of plagioclase, whose reaction was incomplete in fractured domains, continued to evolve with increasing viscous strain and reaction progress. Where plagioclase experienced early, partial breakdown, viscous strain was further accommodated by dissolution-precipitation and phase nucleation. In contrast, where igneous plagioclase was largely preserved, crystal plastic deformation accompanied dissolution-precipitation. Heterogeneous early hydration of mafic rocks led therefore to a patchwork of local reacted domains, where inherited microstructures gave rise to heterogeneous phase distribution, grain sizes, fabrics and preconditioned the rock for strain partitioning, and hence, strain localization at a scale of hundreds of microns. In particular, phase mixing was the product not of strain, but rather of an initial stage of chemical reactions.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"205 ","pages":"Article 105630"},"PeriodicalIF":2.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102615","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":"Variscan superposition on ordovician extensional fault-related folds in the Eastern Pyrenees","authors":"Pablo Granado ,&nbsp;Josep Maria Casas ,&nbsp;Marco de Matteis ,&nbsp;Òscar Gratacós","doi":"10.1016/j.jsg.2026.105629","DOIUrl":"10.1016/j.jsg.2026.105629","url":null,"abstract":"<div><div>Our study investigates pre-Variscan Ordovician tectonics in the La Molina area (Eastern Pyrenees, Spain) by means of geological mapping and structural analysis of mesostructural data. We revisit the structural interpretation of pre-Upper Ordovician folds, revealing two mutually orthogonal, cleavage-free fold systems (WNW–ESE and NNE–SSW striking) affecting the Late Cambrian to Early Ordovician Serdinya Formation. These folds are interpreted as fault-related folds formed above steeply-dipping extensional faults during Mid Ordovician rifting. The geometry and orientation of Variscan mesostructures are shown to be strongly influenced by these earlier Ordovician folds, explaining the wide dispersion of fold axes and cleavage-bedding intersection lineations only found below the Upper Ordovician unconformity. The Upper Ordovician unconformity seals and locally erodes the limbs of those pre-existing folds. The hectometric to kilometric scale cleavage-free Ordovician folds contrast with the finer smaller-scale Variscan syn-foliar folds, and thus explains the absence of fold interference patterns. This work highlight that collecting and analysing detailed mesostructural data in orogenic hinterlands remains essential for interpreting regional tectonics, and it advances our understanding of the early tectonic evolution of the northern Gondwana margin.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"204 ","pages":"Article 105629"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022945","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":"Pre-Neogene tectonics and early broken foreland basin stages in the Bermejo basin","authors":"Marcelo Gonzalez ,&nbsp;Federico Lince Klinger ,&nbsp;Cinthya Moreno ,&nbsp;Franco Clavel ,&nbsp;Federico Morales ,&nbsp;Cristian Ortiz ,&nbsp;Guido Gianni ,&nbsp;Miguel Ramos","doi":"10.1016/j.jsg.2025.105612","DOIUrl":"10.1016/j.jsg.2025.105612","url":null,"abstract":"<div><div>Broken foreland basins develop in response to far-field compressional stresses from active margins, resulting in deep-seated intraplate contractional structures that fragment the original foreland basin. This study investigates the tectono-sedimentary evolution of the Bermejo Basin, the first recognized broken foreland basin in South America, situated between the Eastern Precordillera and Western Pampean Ranges. Through the reprocessing of seismic data and gravity analyses, we identify three main tectono-sedimentary stages: Stage 1 (Pre-Neogene), Stage 2 (19-4 Ma), and Stage 3 (4–2.5 Ma to Present). Stage 1 generated structures that were buried and subsequently reactivated during Stage 2. This latter stage marked a significant reconfiguration of the basin with progressive northward propagation of compressional structures and a major shift in basin polarity around 6-5 Ma. These stages correspond to varying configurations of the Andean subduction zone, with strong foreland compression linked to flat subduction. However, the mild initial compression of a key structure active since 19-17 Ma, as evidenced by syntectonic strata, suggests that the foreland remained responsive to compressional forces transmitted from the plate margin during episodes of normal subduction. Our findings underscore the previously unrecognized role of inherited (or pre-Andean) compression in the evolution of the Bermejo Basin and provide evidence for a hybrid deformation style affecting the Eastern Precordillera, impacting the western margin of this basin. This study emphasizes the need for updated regional kinematic models that account for the interplay of ancient and more recent tectonic processes in the Bermejo Basin. Finally, our observations indicate that inherited compressional structures, such as the Carboniferous-Permian faults and the early Miocene Alto del Jumeal Range, have played a significant role in guiding subsequent deformation and sedimentation within the Bermejo basin.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"204 ","pages":"Article 105612"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885796","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":"Quantifying finite strain in the poly-deformed Lansdowne Klippe, Garhwal Himalaya, India: An appraisal of popular strain estimation techniques","authors":"Sayandeep Banerjee ,&nbsp;Sayan Maity ,&nbsp;Ashish Rawat ,&nbsp;Virendra Rana ,&nbsp;Yaspal Sundriyal ,&nbsp;Hari B. Srivastava","doi":"10.1016/j.jsg.2025.105585","DOIUrl":"10.1016/j.jsg.2025.105585","url":null,"abstract":"<div><div>Understanding finite strain in poly-deformed terranes remains a challenge due to multiple deformation phases, impacting accurate estimation. This study presents a comparative analysis of four distinct techniques (Rf/Φ, Fry's, Panozzo, and AMS-based strain estimation) to estimate the finite strain in the Lansdowne Klippe of the Garhwal Himalaya, India. In the estimation of strain, complexities might arise due to the inherent difficulties in assessing the original shape of strain indicators in areas with a history of multiple deformations. Such challenges significantly affect the precision of finite strain estimation, leading to inconsistencies in the obtained values. By analysing the quantitative and qualitative differences among the methodologies, this study reveals the discrepancies in determining 2-D finite strain and respective strain ellipses. The present attempt is the first rigorous multi-method comparison for quantifying strain within a poly-deformed klippe in the Himalayan orogen. In our comparative analysis, Rf/Φ and Fry methods yielded the highest finite strains (Rs ∼1.7–2.3), whereas the Panozzo method gave lower values (Rs ∼1.1–2.0). AMS-derived anisotropy (Pj ∼1.05–1.2) corresponds to only low finite strain. These systematic method-dependent differences underscore that strain magnitudes in a polyphase terrane are strongly influenced by the chosen technique. Our findings also highlight the inherent inconsistencies and limitations in estimating finite strain in regions with polyphase deformation.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"204 ","pages":"Article 105585"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771938","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":"Comparative studies of salt pillows in proximity to the Ringkøbing-Fyn High, Denmark","authors":"Cecilia E.B. Nielsen,&nbsp;Ole R. Clausen","doi":"10.1016/j.jsg.2025.105609","DOIUrl":"10.1016/j.jsg.2025.105609","url":null,"abstract":"<div><div>The salt structures in Denmark have become of increased interest for the current Carbon Capture and Storage (CCS) investigations, with most of the prospecting areas being in close relation to the structures. In this study we have investigated three salt pillows located on both sides of the Ringkøbing-Fyn High (RFH), Denmark, with focus on the timing and direction of salt movement. With the use of interpretation and restoration software, we have interpreted multiple 2D seismic lines and made a structural restoration of a defining line for each structure to determine the evolution of the salt movement. Our results show that the structures closest to the RFH have been created by Triassic gravitational gliding of the salt away from the high, while the salt further north most likely initiated by a combination of differential loading and local tectonics during the same period. Salt reactivation is more pronounced for the structures located north of the RFH, especially showing salt reactivation after the deposition of the late Cretaceous Chalk Group indicating a Cenozoic process only affecting the salt structures north of the high. However, the overall deformation of the three structures shows similar patterns, indicating that they all might represent structures located at the border zone of the Permian Zechstein salt basins, thus pushing the influence of the Sorgenfrei-Tornquist Zone in the Norwegian-Danish Basin much further west in the Norwegian-Danish basin than formerly understood.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"204 ","pages":"Article 105609"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771940","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":"Extrusion of high-grade metamorphic and anatectic rocks during inclined transpression in the central Brasília Orogen, Western Gondwana","authors":"Fernando Resende Honorato ,&nbsp;Marco Antônio Delinardo da Silva ,&nbsp;Ticiano José Saraiva dos Santos ,&nbsp;João Victor Oliveira Cunha ,&nbsp;Ewerton Benetti Poloni ,&nbsp;Pamela Pavanetto","doi":"10.1016/j.jsg.2026.105626","DOIUrl":"10.1016/j.jsg.2026.105626","url":null,"abstract":"<div><div>Ancient and modern orogens are related to transpressional tectonics due to the Earth's spherical surface, often recording synchronous deformation, metamorphism, and anatexis. In the western Gondwana supercontinent, such relations are found in the Brasília Orogen, which formed from the collision between the Paranapanema, São Francisco-Congo, and Amazonian paleoplates during the Neoproterozoic Brasiliano/Pan-African Cycle. This study aims to investigate the deformational, metamorphic, and anatectic processes active in the central Brasília Orogen through field-based geological mapping and structural analysis, petrography, and U-Pb geochronology in zircon. The data show that the internal zone of the central Brasília Orogen underwent crustal shortening in the northeast-southwest direction, synchronous with lateral escape tectonics toward the southeast, suggesting an inclined transpressional context involving strain partitioning and the extrusion of deep-to-middle crustal rocks. The structural evolution was coeval with upper amphibolite to granulite facies metamorphism and anatexis, suggesting spatial and temporal relationships between structural fabrics, metamorphic and anatectic products. In this scenario, structures acted as primary controls of melt migration and granite emplacement, just as melt weakened the crust and facilitated structure nucleation. The Tonian (<em>ca.</em> 0.88 and 0.80 Ga) mafic protolith of the migmatitic orthogneiss and its leucosomes together with the migmatitic paragneiss and syntectonic granites confined the feedback loop between active ductile deformation, metamorphism and anatexis to the Cryogenian and Ediacaran periods (<em>ca</em>. 0.65 to 0.62 Ga), broadly constraining the interval of expressive crustal flow in the Brasilia Orogen.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"204 ","pages":"Article 105626"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978550","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":"Ultracataclastic vein evolution within a granodiorite along the Naxos-Paros Detachment System","authors":"O. Rolfe ,&nbsp;R. Dubosq ,&nbsp;D.A. Schneider ,&nbsp;S. Zaefferer ,&nbsp;B. Grasemann","doi":"10.1016/j.jsg.2025.105613","DOIUrl":"10.1016/j.jsg.2025.105613","url":null,"abstract":"<div><div>Ultracataclastic and pseudotachylytic veins are interpreted as direct evidence of coseismic slip, reflecting the conditions and mechanisms associated with fault rupture. Although the Naxos granodiorite, Greece, is known for its pristine pseudotachylyte exposures, these features remain largely understudied in terms of their microstructural evolution and implications for upper and middle crustal seismicity. We examine a suite of well-preserved veins hosted in the deformed Miocene granodiorite, historically described as examples of melt-origin pseudotachylytes, but here are re-interpreted as dominantly ultracataclasites, produced from the comminution of host rock. The veins occur in the immediate footwall of the fluid-rich, low-angle Naxos-Paros Detachment System, active between c. 20-10 Ma, and possess a similar composition as the surrounding host rock of primarily albite (35%), quartz (25%), orthoclase (16%), and biotite (12%). Structural field observations from the highest strain zone reveal three distinct crosscutting vein sets. Electron backscatter diffraction mapping of host rock porphyroclasts of albite, orthoclase, and quartz crosscut by ultracataclastic veins demonstrates that cataclasis is the dominant deformation mechanism. Variations in microstructural maturity of vein fragments suggest episodic emplacement, with rupture exploiting pre-existing slip planes. Cuspate phase boundaries between orthoclase and albite, initially observed in optical and scanning electron microscopy, are confirmed by electron microprobe analyses as a result from dissolution-precipitation reactions. These features indicate deformation by dissolution-precipitation creep. The results suggest that fluid-mediated reactions localized at vein tips contributed to weakening, generating a mechanical-chemical feedback loop that promoted ultracataclastic vein propagation along the detachment.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"204 ","pages":"Article 105613"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022942","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":"Rift development at the Askja Fissure Swarm, Iceland","authors":"Fabio Luca Bonali ,&nbsp;Martina Pedicini ,&nbsp;Thomas R. Walter ,&nbsp;Alessandro Tibaldi","doi":"10.1016/j.jsg.2026.105623","DOIUrl":"10.1016/j.jsg.2026.105623","url":null,"abstract":"<div><div>Understanding how faulting and dyke intrusion interact to control rift development in volcanotectonic systems remains a key challenge, particularly in areas where multiple magma sources coexist. Here, we contribute to this topic by providing a high-resolution structural dataset for the Askja Fissure Swarm (AFS), one of the major rifts of the Northern Volcanic Zone of Iceland (NVZ), where central volcanoes and their associated dyke-fissure swarms act as magma plumbing systems and long-term eruption sources. We describe the Holocene structures of the AFS through the analysis of high-resolution remote sensing data and virtual field reconnaissance. We developed an inventory of 3749 individual structures, including dykes and fractures, mapped at a scale of 1:50,000, and systematically measured their strike, dip direction, length and kinematics. We recognized 395 eruptive fissures, 2301 extension dry fractures (fissures), and 1038 normal faults, of which 536 dip eastward and 502 westward. Along the main faults, we reconstructed the slip profiles, with the aim of evaluating the direction of along-axis fault and rift propagation. The overall dataset exhibits a predominant N–S to NNE–SSW strike, with an average strike of N17.5°E. Structure lengths vary from 10 m up to 13 km, with a mean of 445 m. Normal faults are generally longer than other structures, with a mean of 1042 m. With distance to the central volcanoes, we find the number of extension fractures and faults, their lengths and the slip profiles decrease. We interpret these characteristics as the effect of multiple dykes that laterally propagated outward from the magma chambers below Askja and Hrúthálsar central volcanoes. We also observed variation of fracture intensity and strike where the AFS intersects possibly hidden inherited transversal structures. Looking at the whole AFS, the tapering of fault slip profiles shows a dominant northward propagation of faults. This may indicate the superimposition of a regional northward propagation of the rift on the local effects of dykes and magma chambers, consistent with the northward spread of the NVZ.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"204 ","pages":"Article 105623"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978551","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":"Slab kinematics and strain localization in NE China: Polyphase deformation of the Hulin Complex during Late Mesozoic subduction","authors":"Wei Pi ,&nbsp;Han Zheng ,&nbsp;Jian Zhang ,&nbsp;Zhiyuan He ,&nbsp;Johan De Grave ,&nbsp;Ian P. Cawood ,&nbsp;Yong Liang ,&nbsp;Heng Peng ,&nbsp;Guochun Zhao","doi":"10.1016/j.jsg.2025.105614","DOIUrl":"10.1016/j.jsg.2025.105614","url":null,"abstract":"<div><div>Crustal shear zones in Northeast China preserve a critical record of Paleo-Pacific subduction, yet distinguishing the superimposed tectonic fabrics remains a challenge. We resolved this by reconstructing the structural and thermal history of the Hulin Complex, linking local deformation directly to specific slab dynamics. During the Late Jurassic to Early Cretaceous (D₁: ca. 160–130 Ma), a moderate oblique subduction angle (∼30–40°) drove NE–SW sinistral transpression. This phase produced distributed general shear (Flinn's <em>k</em> = 0.73–0.91; <em>W</em>_k = 0.64–0.67) under mid-crustal conditions (∼350–500 °C), accommodated by quartz rhomb &lt;<em>a</em>&gt; and prism &lt;<em>a</em>&gt; slip at differential stresses of 15–18 MPa. In the Cretaceous (D₂: ca. 130–85 Ma), accelerated SE-directed slab rollback stretched the lithosphere, triggering regional extension (Flinn's <em>k</em> = 0.85–1.01; <em>W</em>_k = 0.57–0.62). Strain localized into weak, mica-rich zones (&gt;15 vol%) as differential stresses dropped to 13–14 MPa and temperatures cooled to 300–400 °C. This extension facilitated synchronous magmatism. By the Late Cretaceous (D₃: ca. 85–68 Ma), a shift to W–NW subduction created a lower obliquity angle (∼20–30°). This renewed dextral transpression reactivated older structures in the mid-to-lower crust (≤300–400 °C) but at significantly higher stresses (21–34 MPa). Quartz fabrics shifted to basal &lt;<em>a</em>&gt; slip, reflecting strain repartitioning (Flinn's <em>k</em> = 0.63–0.76; <em>W</em>_k = 0.67–0.71). Our findings demonstrate that shear zone evolution is governed by specific subduction parameters: (1) shallower slab dips enhance coupling to localize strain; (2) rapid rollback weakens the lithosphere to drive extension; and (3) high convergence obliquity (angles &lt;30°) amplifies the simple shear component. Thus, the Hulin Complex acts as a sensitive rheological recorder, capturing the changing tempo and geometry of the subducting slab.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"204 ","pages":"Article 105614"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927350","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":"Rethinking the crustal architecture of the Neoproterozoic gneiss domes in the Nubian Shield: Constraints from the Meatiq dome, Egypt","authors":"Abdullah T. Mohammad ,&nbsp;Yahia El Kazzaz","doi":"10.1016/j.jsg.2026.105615","DOIUrl":"10.1016/j.jsg.2026.105615","url":null,"abstract":"<div><div>The Nubian Shield hosts amphibolite-grade, gneiss-cored domes surrounded by greenschist-grade island-arc and ophiolitic rocks. These domes record distinctly intense ductile deformation and higher metamorphism compared to adjacent rocks, yet their origin and geometry remain debated. Here we combine field observations, remote sensing, and structural–microstructural analyses to reassess the nature and architecture of these domes, focusing on the Meatiq dome in Central Eastern Desert of Egypt. Our results demonstrate that the dome represents a folded, thrust-related shear zone developed at mid-crustal levels within psammitic–pelitic metasediments overlain by ophiolitic and metavolcanic nappes. Microstructures record crystal-plastic deformation mechanisms at ∼670–450 °C with consistent top-to-NW shear indicators. Syn-kinematic emplacement of the Um Baanib and Abu Ziran granites occurred during NW-directed tectonic transport, with sub-magmatic microstructures recording the transition from magmatic to solid-state deformation. Both plutons display sheet-like geometries, controlled by lithological/rheological boundaries, and were later dissected by brittle thrust slices during doming. Although the Meatiq dome share some similarities with metamorphic core complexes, the absence of low-angle normal faults, rotational blocks, and migmatitic cores, combined with timing constraints, rules out core complex or diapiric origin. Instead, we argue that its domal geometry reflects thrust-related folding and multi-phase deformation associated with NW-directed tectonic transport during the East and West Gondwanaland collision (∼605–596 Ma), later modified by multiple Phanerozoic rifting phases. This evolutionary model highlights thrust-related tectonics as the primary driver of the Meatiq dome and prompts a reassessment of similar domes in the Nubian Shield. In addition, the results have broader implications for understanding gneiss-cored domes in orogenic belts worldwide and dynamic feedback between deformation and magmatism at mid-crustal shear zones.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"204 ","pages":"Article 105615"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927351","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}