Journal of Structural Geology最新文献

{"title":"40Ar/39Ar dating of poly-orogenic rocks: an example from the Cap de Creus peninsula (Eastern Pyrenees, Spain)","authors":"Patrick Monié ,&nbsp;Émilien Oliot ,&nbsp;Gaétan Milesi ,&nbsp;Maël Allard ,&nbsp;Agathe Faucher","doi":"10.1016/j.jsg.2025.105489","DOIUrl":"10.1016/j.jsg.2025.105489","url":null,"abstract":"<div><div>A new ⁴⁰Ar/³⁹Ar study has been conducted on variably deformed rocks from the Cap de Creus massif in the Eastern Pyrenees with a focus on NW-SE crosscutting low-grade shear zones. Outside the shear zones, in the unsheared low pressure - high temperature Variscan metamorphic rocks (P∼3,5 kbar, T∼635 °C), mica porphyroblasts yield partially reset ⁴⁰Ar/³⁹Ar ages of 240 Ma to 150 Ma. In shear zones (P∼5-5,3 kbar, T∼435–505 °C) from the Northern Shear Belt, synkinematic fine-grained muscovite provides a crystallization age of 44-42 Ma while inherited clastic muscovite has ages between 175 and 100 Ma depending on grain size. In the Southern Shear Belt, magmatic biotite from granodioritic protomylonites preserves small amount of inherited argon while synkinematic newly crystallized metamorphic micas from mylonites and ultramylonites have crystallization ages between 44 and 38 Ma. Therefore, this step-heating and <em>in situ</em> laser probe ⁴⁰Ar/³⁹Ar study of micas from unsheared Variscan rocks and mylonitic to ultramylonitic rocks show a conspicuous relationship between the deformation gradient, the amount of syntectonic (re)crystallization, the change in mineral composition, the resetting of Variscan mica chronometers and the record of Eocene crystallization ages by newly formed synkinematic micas. It is suggested that low-grade shear zones in the poly-orogenic Cap de Creus massif were active during the main period of Eocene convergence of the Iberian and European plates and emplacement of the south-verging crustal nappes. We propose that such NW-SE mylonitic structures developed as R′-Riedel faults within a huge system of NE-SW trending crustal faults and that they may represent onshore precursors of offshore transfer faults related to the early opening of the Gulf of Lion.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105489"},"PeriodicalIF":2.6,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144501216","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":"Simulation and modelling of an argon age spectrum from biotite in the Yilgarn Craton immediately adjacent to the Albany–Fraser Orogen, Western Australia","authors":"Gordon Lister ,&nbsp;Marnie Forster ,&nbsp;Laura Morrissey ,&nbsp;Raphael Quentin de Gromard ,&nbsp;David Kelsey","doi":"10.1016/j.jsg.2025.105487","DOIUrl":"10.1016/j.jsg.2025.105487","url":null,"abstract":"<div><div>Here we further show how modelling based on argon geochronology can be used to develop constraints as to the nature of the temperature–time path followed by an individual sample in the natural environment, by demonstrating how to estimate palaeodepth, and its variation through time. The method is of general application to the interpretation of any biotite age spectrum with a well-developed age plateau, as long as there is relatively minor loss of radiogenic argon evident in the initial steps, and as long as those initial steps are not masked by the release of excess argon. Accurate simulation relies on how well the morphology of the measured age spectrum has been delineated, especially in the initial heating steps. The requisite detail depends on precise control of temperature variation during step-heating, and on the aliquot having sufficient mass to allow many steps. Here we numerically model the morphology of a single age spectrum produced by step-heating an aliquot of biotite grains separated from a single sample from the Kalgoorlie Terrane, in the Yilgarn Craton, Western Australia. The sample location is less than 15 km from the inferred location of the fault that separates the Archean Yilgarn Craton from the Albany-Fraser Orogen (AFO). Potentially therefore the age spectrum should reflect thermal disturbance related to the juxtaposition of the AFO against the Yilgarn Craton during the Mesoproterozoic. The absence of significant effects implies that the high-grade portions of the AFO had cooled prior to their juxtaposition, and/or that the sample from the Yilgarn Craton was already at such shallow crustal levels that it was little affected by any thrusting orthogonal to the margin during juxtaposition.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105487"},"PeriodicalIF":2.6,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144517530","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":"Porosity and pore and throat size distributions in carbonate-rich salt caprock of halite diapirs: effect of deformation and geochemical processes","authors":"P. Závada ,&nbsp;M. Staněk ,&nbsp;M. Machek ,&nbsp;S. Adineh ,&nbsp;Y. Géraud ,&nbsp;J. Bruthans ,&nbsp;S. Heuss-Aßbichler ,&nbsp;M. Zare","doi":"10.1016/j.jsg.2025.105483","DOIUrl":"10.1016/j.jsg.2025.105483","url":null,"abstract":"<div><div>Microscopic porosity of salt caprock on two salt diapirs, Karmostaj and Siah Taq in southern Iran, was studied on a range of samples that represent the major lithological types of salt caprock in the area: the gypsum matrix-supported and clast-supported dissolution breccia, the dolomite and limestone stringers of the Hormuz Formation and gypsum mylonites. Mercury intrusion porosimetry alongside the microstructural analysis with digital image analysis of resin-saturated thin-sections was employed and revealed a large variation in porosity of 2–35 % and in the median throat size of 0.1–50 μm. The highest porosity values are associated with vuggy dolomites and limestones interspersed by a dense network of gypsum veins and gypsum matrix-supported breccia with low degree of deformation. In contrast, low porosity is linked with strongly deformed gypsum matrix-supported breccias and dark micritic carbonate stringers that were not interspersed with the gypsum. Large variation in porosity and pore throat size and pore shape is attributed to 1) metasomatization of carbonate to gypsum due to reaction of H₂SO₄ with carbonate after oxidation of H₂S or elemental sulfur in caprock and subsequent dissolution of gypsum in metasomatized carbonates creating the abundant vuggy porosity and 2) deformation of the caprock that was responsible for recrystallization and mechanical closure of pores in the frontal, downslope margins of both reactivated diapirs. While the deformed and gypsum-rich parts of the diapir caprocks (∼30–60 % of caprock on the diapirs) are associated with estimated permeabilities of ∼10⁻¹⁶ - 10⁻¹⁵ m², caprocks in central parts of reactivated diapirs with less deformed caprock (undeformed gypsum- and clast-supported breccia) display higher permeabilities ranging between ∼10⁻¹⁵ m² and 10⁻¹³ m².</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105483"},"PeriodicalIF":2.6,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144534750","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":"Active crustal extension accommodated through frictional faulting and magma intrusions in the Cuitzeo Lake basin, central México","authors":"Martha Gabriela Gómez-Vasconcelos ,&nbsp;Jorge Alejandro Ávila-Olivera ,&nbsp;Denis-Ramón Avellán","doi":"10.1016/j.jsg.2025.105486","DOIUrl":"10.1016/j.jsg.2025.105486","url":null,"abstract":"<div><div>This study comprehensively analyzes for the first time the present-day deformation of the Cuitzeo Lake basin in central México, its implications for crustal extension rates, and its accommodation through normal and oblique faulting and magma intrusions. We used a 2.2 mm/yr velocity from a permanent geodetic survey (2008–2023, TLALOCNet) to evaluate the crustal extension in the Cuitzeo Lake basin. We estimated an extension from normal frictional faulting and magmatic processes by comparing the geodetic data with geological data since 8 Ma, derived from regional fault slip rates, magma volumes, and dike intrusions. Our results reveal that the deformation here is dominantly accommodated by normal frictional faulting processes (up to 55 %) and partly by magmatic processes (41 %), of which 11 % is associated with volcanic eruptions and 89 % with arrested magmatic intrusions. These results confirm that the Cuitzeo Lake basin is relatively mature, where frequent interactions occur between faults and the magmatic system.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105486"},"PeriodicalIF":2.6,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307739","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":"A novel multi-scale approach to fault network analysis and visualization: test case Franconian Platform (SE Germany)","authors":"Johannes D. Wiest ,&nbsp;Saskia Köhler ,&nbsp;Daniel Koehn ,&nbsp;Harald Stollhofen ,&nbsp;Kathrin Dengler ,&nbsp;Hamed Fazlikhani","doi":"10.1016/j.jsg.2025.105481","DOIUrl":"10.1016/j.jsg.2025.105481","url":null,"abstract":"<div><div>Faults are essential to reconstruct geologic histories and their presence (or absence) in the subsurface plays a significant role for many societal issues, such as geothermal energy, carbon, hydrogen and hydrocarbon storage or nuclear waste deposition. In the area of the Permo-Mesozoic Franconian Platform (Northern Bavaria, SE Germany) the existence and properties of faults in the subsurface are poorly known due to limited exposure and lack of geophysical data coverage.</div><div>To address this issue, we have constructed a new fault network based on stratigraphic offsets identified in a network of 18 cross sections. In this contribution, we present our workflow which allows the effective construction of an internally consistent cross-section network covering a study area of &gt;30,000km², while representing the geology in high detail. Data input is provided by &gt; 3500 (mostly shallow) wells and &gt;250 high-resolution geological maps, complemented by geophysical surveys and field data. We demonstrate how fault segments and their attributes (e.g., fault type, dip direction, offset, certainty of the interpretation, etc.) can be inferred from the profiles, resulting iteratively in consistent profile and fault networks.</div><div>While we highlight the non-uniqueness of the interpretation and its restriction to vertical offsets, we demonstrate advantages of the fault network, inferred through this pseudo-3D approach, compared to previously available datasets. We discuss the role of newly identified fault populations for Cretaceous inversion tectonics and Cenozoic rifting. Through the incorporation of basic measures of uncertainty and scale-dependency in the resulting fault model, quantification of the fault network can be achieved. This enables the comparison with independent datasets and different model realizations.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105481"},"PeriodicalIF":2.6,"publicationDate":"2025-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263482","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":"Exploring spatial heterogeneity and topological properties of fracture Networks: A statistical characterization","authors":"Sivaji Lahiri ,&nbsp;Ayoti Banerjee ,&nbsp;Ankur Roy ,&nbsp;Madhav Jha ,&nbsp;Sufi Md Gulzar ,&nbsp;Alessio Lucca","doi":"10.1016/j.jsg.2025.105482","DOIUrl":"10.1016/j.jsg.2025.105482","url":null,"abstract":"<div><div>Analyzing fracture patterns and estimating their topological and spatial properties are essential for the predictive stochastic modelling of fractured rocks. In this study, we examined 83 natural fracture patterns compiled from existing literatures, covering diverse geological settings. To investigate spatial clustering in two dimensions (2D), we employed a multiscale spatial statistical parameter ‘Lacunarity’ which quantifies textural heterogeneity. Unlike previous studies that focused solely on the clustering of two-dimensional fracture arrays, our analysis also considers the spatial clustering of topological nodes—specifically, intersection and end-tip points within fracture networks.</div><div>Our findings indicate that the spatial distribution of nodes within a fracture network follows a non-random pattern. As fracture arrays become more clustered, the clustering of nodes also intensifies. With an increase in clustering of fracture arrays, the mean branch length weakly reduces owing to the proliferation of smaller branches within the network. Moreover, we noted that the clustering of fracture array has little correlation with the topological connectivity of the fracture networks. This is because topological connectivity only considers the abundance of different types of nodes within a pattern, without considering their spatial distribution. Finally, leveraging the estimated topological and spatial properties of the analyzed fracture patterns, we have proposed a statistical model, which would be useful to modellers and engineers involved in research on the circulation of any sub-surface fluid.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105482"},"PeriodicalIF":2.6,"publicationDate":"2025-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263430","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":"Partitioning of strain rates and stresses between a thin shear zone and its walls under transpression or transtension","authors":"Pierre-Yves F. Robin ,&nbsp;Alexander R. Cruden","doi":"10.1016/j.jsg.2025.105484","DOIUrl":"10.1016/j.jsg.2025.105484","url":null,"abstract":"<div><div>Within a mid-crustal domain deforming in transpression or transtension, thin zones may exhibit higher strain than their immediately adjacent walls. The lower transpressive strain of the host may sometimes not be recognized and these thin bands might thus be interpreted as simple shear zones. However, their kinematic indicators should reflect the transpressional or transtensional strain imposed by the less deformed host. In order to explore the contrasting strain between such a zone and its walls, we analyse a simple model of a narrow low-viscosity oblique transcurrent shear zone held coherently within a broader, higher-viscosity host rock. The model uses strain rate as a proxy for strain.</div><div>We evaluate the contrasts in strain rate intensities and in shape parameters between such a shear zone and its walls as functions of viscosity contrast and of convergence angles. We find important differences between transpressional or transtensional shear zones and the more familiar simple shear zones.</div><div>Strain fabrics observed in some crustal scale shear zones and their walls, such as the Archean Larder Lake-Cadillac Deformation Zone (LCDZ) in Ontario and Québec, Canada, which combine transcurrent shear sense indicators and steeply plunging lineations, can indeed be explained by transpression.</div><div>We also examine the contrast in stresses between the shear zone and its walls. We find that, in transpression, buoyant fluids that might be generated in the deep crust, near the base of a deformation zone such as the LCDZ, should in fact move through the wall rock rather than within that high-deformation zone. This has implications for the location of mineral deposits traditionally associated with such deformation zones.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105484"},"PeriodicalIF":2.6,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263483","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":"Pliocene-Quaternary activity of the Dalmatian unit basal thrust – a potential seismogenic source in the Dubrovnik epicentral area (Croatia)","authors":"Marin Sečanj ,&nbsp;Bruno Tomljenović ,&nbsp;Marijan Herak ,&nbsp;Iva Dasović ,&nbsp;Helena Latečki ,&nbsp;Josip Stipčević","doi":"10.1016/j.jsg.2025.105485","DOIUrl":"10.1016/j.jsg.2025.105485","url":null,"abstract":"<div><div>This study focused on the identification of seismically active structures in the southeastern part of the External Dinarides around the city of Dubrovnik. The wider region is characterized by a relatively high seismicity rate, with intermittent occurrences of strong events, indicating ongoing tectonic activity. Historical, instrumental, and paleoseismological records indicate that this area has been affected by at least a dozen strong earthquakes over the last 3000 years. Among these, the most significant was the Great Dubrovnik earthquake from 1667 (<em>M</em>_L = 6.9), which devastated the region. To identify potential seismogenic sources and active faults in the Dubrovnik offshore area, 106 offshore 2D seismic lines and three deep exploration wells were analysed. Identified offshore faults were mapped, and a regional balanced seismotectonic cross-section was constructed by correlating the hypocentral distribution of recorded seismicity and onshore geological and structural data with offshore 2D seismic lines and well logs. Our results suggest that the main seismogenic source offshore of Dubrovnik is related to the NE-dipping frontal thrust and fault splays of the Dalmatian tectonic unit in the External Dinarides. The ongoing propagation of this fault system is documented by syn-tectonic deposition and folded Plio-Quaternary sediments that can be traced for 40 km along the strike. Based on kinematic modelling, the average slip rate estimated for the active frontal thrust and its splays is 1.13 mm/yr, while average shortening is 0.9 mm/yr from the Late Miocene to recent times. These findings are thus suggestive of repeated seismogenic events, such as the one in 1667, to accommodate shortening in the area.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105485"},"PeriodicalIF":2.6,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144280832","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":"Mid-crustal strain localisation triggered by localised fluid influx and activation of dissolution–precipitation creep","authors":"Manon Carpenter,&nbsp;Sandra Piazolo,&nbsp;Tim Craig,&nbsp;Tim J. Wright","doi":"10.1016/j.jsg.2025.105461","DOIUrl":"10.1016/j.jsg.2025.105461","url":null,"abstract":"<div><div>Understanding mid-crustal deformation is vital for determining the spatial and temporal distribution of strain localisation, with implications for upper-crust deformation including seismic hazard. Here, we conduct fieldwork and microstructural and minerochemical analyses on the amphibolite-facies, 100-m-wide Upper Badcall shear zone in northwest Scotland, which deforms initially anhydrous quartzofeldspathic gneiss and a mafic dyke. We show that with increasing strain, m-scale strain distribution and mineral chemistry become increasingly homogeneous, while hydrous phases and syntectonic quartz veins become more abundant. With increasing strain there is an overall increase in grain size, grain boundary alignment and shape preferred orientation in amphibole, plagioclase and quartz. Only amphibole and large grained quartz exhibit crystallographic preferred orientation in strained areas. Subtle microstructures that may be overlooked elsewhere, particularly in felsic gneiss, indicate dominant activity of dissolution–precipitation creep and equivalent rheological weakening in both mafic and felsic rocks. We propose that brittle fractures, now preserved as syntectonic quartz veins, allowed localised fluid-infiltration in previously anhydrous crust. This triggered local retrogressive reactions and introduced sufficient grain boundary fluid for deformation to favour dissolution–precipitation creep over dislocation creep. Our study suggests that dissolution–precipitation creep may be more dominant in mid- to lower-crustal localised zones of deformation than previously thought.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105461"},"PeriodicalIF":2.6,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307738","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":"Integration of deformed objects into a composite object analogous to the strain ellipse: a novel graphic method of Rf/ϕ strain analysis","authors":"Yehua Shan","doi":"10.1016/j.jsg.2025.105470","DOIUrl":"10.1016/j.jsg.2025.105470","url":null,"abstract":"<div><div>The composite object of post-strain elliptical objects is defined as having a radial length that is the square root of the normalized sum of the squared radial lengths of the objects. It proves analogous to the strain ellipse and makes <em>R</em>_<em>f</em><em>/ϕ</em> strain analysis simple. The finite strain is estimated from the overall shape of the composite object. The discrepancy between the composite object and the estimated strain ellipse is used to appraise the assumption of the uniformly distributed major axes of pre-strain objects. Two strain methods, direct calculation and numerical estimation, are developed to determine the strain from the composite object. Synthetic and natural datasets are used to validate the methods.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"199 ","pages":"Article 105470"},"PeriodicalIF":2.6,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144255196","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}