Pub Date : 2025-04-21DOI: 10.1016/j.jsg.2025.105442
Wenxiong Yang , Gang Rao , Pengcheng Tang , Chao Zhu , Renfu Wang
The theory of thrust-related folding has significantly enhanced our comprehension of the kinematic evolution of folds, especially those associated with fault ramps. Despite extensive research into the deformation mechanisms of the fore-limb in the hanging wall folds, the factors influencing back-limb deformation remain relatively underexplored. This study employs a series of discrete-element simulations to investigate the evolution of ramp-related folding, particularly focusing on the factors governing the development of back-thrusts. Comparative analyses reveal diverse deformation styles within the hanging wall of a ramp fold. Notably, when the upper layer exhibits significantly greater strength relative to the lower layer, and an intermediate décollement exists between them, decoupled deformation occurs, characterized by back-thrusting predominantly in the lower layer. This phenomenon is analogous to the deep thrust belts beneath the Shizigou anticline in the western Qaidam Basin, northern Tibetan Plateau, where multiple hydrocarbon-bearing layers have been identified. The findings offer significant insights into the mechanisms of thrust-related folding, thereby improving efficient hydrocarbon exploration in relevant regions. Furthermore, unlike the commonly reported nucleation of a fault ramp from the basal décollement or at an intermediate level, our observations indicate initiation from the shallow section. The detailed mechanism underlying such differential deformation warrant further investigation.
{"title":"Discrete-element numerical simulations of thrust-related folding: Insights into back-limb deformation","authors":"Wenxiong Yang , Gang Rao , Pengcheng Tang , Chao Zhu , Renfu Wang","doi":"10.1016/j.jsg.2025.105442","DOIUrl":"10.1016/j.jsg.2025.105442","url":null,"abstract":"<div><div>The theory of thrust-related folding has significantly enhanced our comprehension of the kinematic evolution of folds, especially those associated with fault ramps. Despite extensive research into the deformation mechanisms of the fore-limb in the hanging wall folds, the factors influencing back-limb deformation remain relatively underexplored. This study employs a series of discrete-element simulations to investigate the evolution of ramp-related folding, particularly focusing on the factors governing the development of back-thrusts. Comparative analyses reveal diverse deformation styles within the hanging wall of a ramp fold. Notably, when the upper layer exhibits significantly greater strength relative to the lower layer, and an intermediate décollement exists between them, decoupled deformation occurs, characterized by back-thrusting predominantly in the lower layer. This phenomenon is analogous to the deep thrust belts beneath the Shizigou anticline in the western Qaidam Basin, northern Tibetan Plateau, where multiple hydrocarbon-bearing layers have been identified. The findings offer significant insights into the mechanisms of thrust-related folding, thereby improving efficient hydrocarbon exploration in relevant regions. Furthermore, unlike the commonly reported nucleation of a fault ramp from the basal décollement or at an intermediate level, our observations indicate initiation from the shallow section. The detailed mechanism underlying such differential deformation warrant further investigation.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"197 ","pages":"Article 105442"},"PeriodicalIF":2.6,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143877275","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}
Pub Date : 2025-04-17DOI: 10.1016/j.jsg.2025.105438
P.A. Kukla , J.L. Urai , S. Back , F. Sachse
The Central European Basin System contains the Permian Zechstein salt giant, which includes a large number and variety of subsurface salt structures formed by salt tectonics in Mesozoic and Cenozoic times. Early descriptions of salt-body geometries originate mostly from salt-mining activities of the early 20th century in Germany and Poland. Inventories found in the mines are primarily documented as line drawings and from descriptions of miners and mine geologists. With the advancement of geophysical acquisition of the past decades, in particular active multidimensional seismic-reflection surveying combined with borehole geophysics and numerical and analogue modelling techniques, the description and interpretation of the external form of salt bodies and internal salt stratigraphy and geometry has made a major step forward. This study highlights the value of integrating detailed high-resolution salt-system knowledge from legacy field and mining data with modern 2D and 3D seismic-reflection data and observations from modelling for improved geological subsurface interpretations in salt terrains. Such integration will play an important role in the increased utilization of subsurface salt structures in the context of energy-transition strategies and the sustainable storage of renewable energy materials and waste.
{"title":"External and internal salt geometries – a mining and geoscience review","authors":"P.A. Kukla , J.L. Urai , S. Back , F. Sachse","doi":"10.1016/j.jsg.2025.105438","DOIUrl":"10.1016/j.jsg.2025.105438","url":null,"abstract":"<div><div>The Central European Basin System contains the Permian Zechstein salt giant, which includes a large number and variety of subsurface salt structures formed by salt tectonics in Mesozoic and Cenozoic times. Early descriptions of salt-body geometries originate mostly from salt-mining activities of the early 20th century in Germany and Poland. Inventories found in the mines are primarily documented as line drawings and from descriptions of miners and mine geologists. With the advancement of geophysical acquisition of the past decades, in particular active multidimensional seismic-reflection surveying combined with borehole geophysics and numerical and analogue modelling techniques, the description and interpretation of the external form of salt bodies and internal salt stratigraphy and geometry has made a major step forward. This study highlights the value of integrating detailed high-resolution salt-system knowledge from legacy field and mining data with modern 2D and 3D seismic-reflection data and observations from modelling for improved geological subsurface interpretations in salt terrains. Such integration will play an important role in the increased utilization of subsurface salt structures in the context of energy-transition strategies and the sustainable storage of renewable energy materials and waste.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"197 ","pages":"Article 105438"},"PeriodicalIF":2.6,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873569","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}
Pub Date : 2025-04-17DOI: 10.1016/j.jsg.2025.105437
Erhui Ren , Xiuli Yan , Tao Yang , Tsafrir Levi , Ram Weinberger , Shmuel Marco , Lishun Luo , Guodong Wang
Fluid infiltration within fault zones is intimately linked to the physical and chemical attributes of fault rocks, thereby playing a critical role in deformation and evolution of faults. Magnetic properties of fault rocks have proven to be an emerging source of information on faulting processes. To document evidence of fluid infiltration within the Red River Fault (RRF), detailed rock magnetic measurements in combination with mineralogical, and geochemical analyses are conducted on fault rocks collected from the Matouzhai outcrop along the range-front fault of the southern segment of the RRF. The results reveal that the ferrimagnetic fraction in the fault rocks is dominated by magnetite, with a small amount of hematite present in (proto-)cataclasites and fault gouges. Magnetic grain size and concentration decrease significantly from host rocks (mylonitized gneiss), via (proto-)cataclasites to fault gouges. Fault gouges are enriched in volatiles (CO2, LOI, H2O+), rare earth elements (REEs), and calcite, but are depleted in high-field strength (HFS) elements and exhibit negative δEu and δCe anomalies. These results indicate pervasive infiltration of the fault zone by CO2-rich oxidizing hydrothermal fluids, leading to the depletion of magnetite and oxidation of magnetite to hematite, with dissolution of silicates and precipitation of abundant calcite (high pH). Magnetic parameters, particularly the high-field magnetic susceptibility, show significant correlations with HFS elements and REEs. These observations suggest that the rock magnetic properties of fault rocks are highly sensitive to fluid infiltration, and could serve as indicators of fluid conditions and fluid-rock interactions within fault zones.
{"title":"Fluid infiltration in the southern segment of the Red River Fault, China: Insights from rock magnetic, mineralogical, and geochemical analyses of fault rocks","authors":"Erhui Ren , Xiuli Yan , Tao Yang , Tsafrir Levi , Ram Weinberger , Shmuel Marco , Lishun Luo , Guodong Wang","doi":"10.1016/j.jsg.2025.105437","DOIUrl":"10.1016/j.jsg.2025.105437","url":null,"abstract":"<div><div>Fluid infiltration within fault zones is intimately linked to the physical and chemical attributes of fault rocks, thereby playing a critical role in deformation and evolution of faults. Magnetic properties of fault rocks have proven to be an emerging source of information on faulting processes. To document evidence of fluid infiltration within the Red River Fault (RRF), detailed rock magnetic measurements in combination with mineralogical, and geochemical analyses are conducted on fault rocks collected from the Matouzhai outcrop along the range-front fault of the southern segment of the RRF. The results reveal that the ferrimagnetic fraction in the fault rocks is dominated by magnetite, with a small amount of hematite present in (proto-)cataclasites and fault gouges. Magnetic grain size and concentration decrease significantly from host rocks (mylonitized gneiss), via (proto-)cataclasites to fault gouges. Fault gouges are enriched in volatiles (CO<sub>2</sub>, LOI, H<sub>2</sub>O<sup>+</sup>), rare earth elements (REEs), and calcite, but are depleted in high-field strength (HFS) elements and exhibit negative δEu and δCe anomalies. These results indicate pervasive infiltration of the fault zone by CO<sub>2</sub>-rich oxidizing hydrothermal fluids, leading to the depletion of magnetite and oxidation of magnetite to hematite, with dissolution of silicates and precipitation of abundant calcite (high pH). Magnetic parameters, particularly the high-field magnetic susceptibility, show significant correlations with HFS elements and REEs. These observations suggest that the rock magnetic properties of fault rocks are highly sensitive to fluid infiltration, and could serve as indicators of fluid conditions and fluid-rock interactions within fault zones.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"197 ","pages":"Article 105437"},"PeriodicalIF":2.6,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873570","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}
Pub Date : 2025-04-14DOI: 10.1016/j.jsg.2025.105429
Kristoff Svensson , Bart van Oosterhout , Jürgen Hesser , Christopher J. Spiers , Ben Laurich
Compacted granular salt backfill is widely regarded as the most favorable geotechnical barrier for sealing a radioactive waste repository within a rock salt formation. However, the reduction of salt backfill porosity and permeability during compaction by slowly converging cavity walls is still a matter of on-going research, both in laboratory and underground experiments, as well as in computational forecasting. Here, we present an in-depth microstructural analysis of a dense, formerly deployed salt backfill material, recovered from the decommissioned salt mine Sigmundshall, Bokeloh, Germany. The backfill compacted over 40 years, resulting in as little as 1 % porosity (+4/-1 %). Some differences are inevitable compared to a potential future backfill emplaced in a radioactive repository, notably in grain size, moisture content and backfill height (178 m vs. ∼ 5 m). However, this valuable “natural laboratory” sampling opportunity has allowed microstructural evidence to be sought for the deformation mechanisms that control salt backfill compaction under in-situ deployment conditions and on timescales that cannot be achieved in laboratory tests. For the present example of grain sizes in the range of 50 μm to 3 mm, our results show that more or less complete densification of granular salt is feasible in a timeframe of decades (<40 y). Pressure solution is likely the main deformation mechanism along with limited cataclasis, which presumably occurred only in the early stages during/after emplacement. This conclusion is evident from tight, indenting, truncating and interpenetrating grain boundaries, as well as from the fact that almost all grains appear to be substructure-free, despite limited signs of recrystallization. The absence of intra-crystalline deformation indicators excludes dislocation creep as a compaction-contributing mechanism, which, on the other hand, is known to occur in many laboratory-based compaction tests. We outline the impact of this difference on the long-term in-situ compaction under repository conditions.
Note: The Sigmundshall mine is not considered as a future repository for radioactive waste.
{"title":"Microstructural evolution of compacted granular salt: insights from 40-year-old backfill at a former potash mine (Sigmundshall, northern Germany)","authors":"Kristoff Svensson , Bart van Oosterhout , Jürgen Hesser , Christopher J. Spiers , Ben Laurich","doi":"10.1016/j.jsg.2025.105429","DOIUrl":"10.1016/j.jsg.2025.105429","url":null,"abstract":"<div><div>Compacted granular salt backfill is widely regarded as the most favorable geotechnical barrier for sealing a radioactive waste repository within a rock salt formation. However, the reduction of salt backfill porosity and permeability during compaction by slowly converging cavity walls is still a matter of on-going research, both in laboratory and underground experiments, as well as in computational forecasting. Here, we present an in-depth microstructural analysis of a dense, formerly deployed salt backfill material, recovered from the decommissioned salt mine Sigmundshall, Bokeloh, Germany. The backfill compacted over 40 years, resulting in as little as 1 % porosity (+4/-1 %). Some differences are inevitable compared to a potential future backfill emplaced in a radioactive repository, notably in grain size, moisture content and backfill height (178 m vs. ∼ 5 m). However, this valuable “natural laboratory” sampling opportunity has allowed microstructural evidence to be sought for the deformation mechanisms that control salt backfill compaction under in-situ deployment conditions and on timescales that cannot be achieved in laboratory tests. For the present example of grain sizes in the range of 50 μm to 3 mm, our results show that more or less complete densification of granular salt is feasible in a timeframe of decades (<40 y). Pressure solution is likely the main deformation mechanism along with limited cataclasis, which presumably occurred only in the early stages during/after emplacement. This conclusion is evident from tight, indenting, truncating and interpenetrating grain boundaries, as well as from the fact that almost all grains appear to be substructure-free, despite limited signs of recrystallization. The absence of intra-crystalline deformation indicators excludes dislocation creep as a compaction-contributing mechanism, which, on the other hand, is known to occur in many laboratory-based compaction tests. We outline the impact of this difference on the long-term in-situ compaction under repository conditions.</div><div>Note: The Sigmundshall mine is not considered as a future repository for radioactive waste.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"197 ","pages":"Article 105429"},"PeriodicalIF":2.6,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143877277","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}
Pub Date : 2025-04-11DOI: 10.1016/j.jsg.2025.105428
Martin D. Clark , Elizaveta Kovaleva , Matthew S. Huber , Stephanus Riekert , Francois D. Fourie
Large meteorite impact events produce significant amounts of crustal melt, which can be emplaced as dikes below the crater floor over protracted time periods following the cratering process. Their emplacement is theorized to be controlled by stresses associated with the presence and opening of crustal-scale fractures, hydrostatic pressures associated with the overlying melt sheet, and lithostatic stresses of the impacted crust. At least two compositionally distinct phases of impact melt are present within the impact melt dikes at the Sudbury and Vredefort Impact Structures, underpinning the debated concept of a prolonged and multi-phase emplacement process.
In this study, cooling fractures within the Lesutoskraal impact melt dike at Vredefort are investigated as a possible pathway to facilitate multi-phase emplacement. Through a combination of high-resolution (0.612 mm/pixel) drone orthophotography and numerical simulation of stress induced during cooling of impact melt shows that (1) the dominant fracture orientation within the impact melt dike is parallel to dike margins, related to a perpendicular and tensional cooling stress, and (2) the magnitude of the tensional cooling stress could reach up to −75 MPa, sufficient to overcome the lithostatic stresses at the observed depth of dike emplacement. Depending on simulation parameters such as the initial temperature of the impact melt, cooling fractures in the impact melt are shown to form within 150 days after their emplacement representing a possible mechanism for emplacement of later phases of impact melt into the centre of earlier impact melt phase.
{"title":"Cooling induced fracturing in impact melt dikes derived from drone photogrammetry and Python simulation: Example from the Lesutoskraal Granophyre Dike in South Africa","authors":"Martin D. Clark , Elizaveta Kovaleva , Matthew S. Huber , Stephanus Riekert , Francois D. Fourie","doi":"10.1016/j.jsg.2025.105428","DOIUrl":"10.1016/j.jsg.2025.105428","url":null,"abstract":"<div><div>Large meteorite impact events produce significant amounts of crustal melt, which can be emplaced as dikes below the crater floor over protracted time periods following the cratering process. Their emplacement is theorized to be controlled by stresses associated with the presence and opening of crustal-scale fractures, hydrostatic pressures associated with the overlying melt sheet, and lithostatic stresses of the impacted crust. At least two compositionally distinct phases of impact melt are present within the impact melt dikes at the Sudbury and Vredefort Impact Structures, underpinning the debated concept of a prolonged and multi-phase emplacement process.</div><div>In this study, cooling fractures within the Lesutoskraal impact melt dike at Vredefort are investigated as a possible pathway to facilitate multi-phase emplacement. Through a combination of high-resolution (0.612 mm/pixel) drone orthophotography and numerical simulation of stress induced during cooling of impact melt shows that (1) the dominant fracture orientation within the impact melt dike is parallel to dike margins, related to a perpendicular and tensional cooling stress, and (2) the magnitude of the tensional cooling stress could reach up to −75 MPa, sufficient to overcome the lithostatic stresses at the observed depth of dike emplacement. Depending on simulation parameters such as the initial temperature of the impact melt, cooling fractures in the impact melt are shown to form within 150 days after their emplacement representing a possible mechanism for emplacement of later phases of impact melt into the centre of earlier impact melt phase.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"197 ","pages":"Article 105428"},"PeriodicalIF":2.6,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826309","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}
Pub Date : 2025-04-05DOI: 10.1016/j.jsg.2025.105419
Qǐháng Wú , Shoufa Lin , Thomas Gemmell , Sandra L. Kamo , Jian Zhang , Lijun Wang
{"title":"Corrigendum to “Structural evolution of the southern Swayze greenstone belt, Superior Craton: Implications for the Neoarchean crustal dynamics” [J. Struct. Geol. (2025) 105373]","authors":"Qǐháng Wú , Shoufa Lin , Thomas Gemmell , Sandra L. Kamo , Jian Zhang , Lijun Wang","doi":"10.1016/j.jsg.2025.105419","DOIUrl":"10.1016/j.jsg.2025.105419","url":null,"abstract":"","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"196 ","pages":"Article 105419"},"PeriodicalIF":2.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143838103","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}
Pub Date : 2025-04-03DOI: 10.1016/j.jsg.2025.105421
Nina Zamani , Sara Satolli , Michael Murphy , Francois Demory , Bruno Pace , Jérôme Gattacceca , Ján Kaňuk , Michaela Nováková , Raphael Gottardi , Eric C. Ferré
The Mw 7.0 Avezzano earthquake in the Abbruzzo region of Italy claimed ∼33,000 lives on January 13, 1915 making it one of the worst disasters in modern Italian history. The main rupture occurred along the Venere Fault, characterized by a polished, locally shiny, or powdery fault mirror showing extensive downdip striations, slickensides, and local reddish iron-oxide/hydroxide stains. The layer immediately below the mirror is a carbonate ultracataclasite that locally grades into an unconsolidated carbonate gouge.
This type of carbonate fault mirror typically forms through two distinct synkinematic processes: i) intense frictional heating causing decarbonation, or ii) progressive grain-size reduction during slip at seismic velocities. In either case, friction drops substantially after initial displacement. The first process also results in intense fault pressurization followed by subsequent drastic drop in normal stress. Despite recent advances, the switch from high-friction/low slip velocity to low-friction/high slip velocity conditions in carbonate is still not fully understood.
The Venere Fault, characterized by proven friction at seismic slip velocity, provides an ideal setting to investigate the nature and extent of dynamic weakening processes in carbonate faults. We use the high temperature sensitivity of iron oxide/hydroxide assemblages, and their magnetic remanence, to estimate frictional heat. Evidence for seismic slip in iron oxides and temperature uniformity along the fault surface have been tested through demagnetization experiments and 1D heat conduction modeling. Our data shows that the fault mirror underwent frictional heating during the 0.8 m slip event, but that this displacement was insufficient to reach pervasive decarbonation. We constrain the peak coseismic temperature along the fault plane to <400 °C through demagnetization experiments and 1D heat conduction modeling. Our results emphasize that coseismic deformation along natural faults is complex and therefore requires complementary field observations at multiple scales in order to encompass a broad range of faulting processes.
{"title":"Record of seismic slip in carbonates: Insights from the Venere Fault during the 1915 Avezzano earthquake (Mw 7.0), Central Italy","authors":"Nina Zamani , Sara Satolli , Michael Murphy , Francois Demory , Bruno Pace , Jérôme Gattacceca , Ján Kaňuk , Michaela Nováková , Raphael Gottardi , Eric C. Ferré","doi":"10.1016/j.jsg.2025.105421","DOIUrl":"10.1016/j.jsg.2025.105421","url":null,"abstract":"<div><div>The Mw 7.0 Avezzano earthquake in the Abbruzzo region of Italy claimed ∼33,000 lives on January 13, 1915 making it one of the worst disasters in modern Italian history. The main rupture occurred along the Venere Fault, characterized by a polished, locally shiny, or powdery fault mirror showing extensive downdip striations, slickensides, and local reddish iron-oxide/hydroxide stains. The layer immediately below the mirror is a carbonate ultracataclasite that locally grades into an unconsolidated carbonate gouge.</div><div>This type of carbonate fault mirror typically forms through two distinct synkinematic processes: i) intense frictional heating causing decarbonation, or ii) progressive grain-size reduction during slip at seismic velocities. In either case, friction drops substantially after initial displacement. The first process also results in intense fault pressurization followed by subsequent drastic drop in normal stress. Despite recent advances, the switch from high-friction/low slip velocity to low-friction/high slip velocity conditions in carbonate is still not fully understood.</div><div>The Venere Fault, characterized by proven friction at seismic slip velocity, provides an ideal setting to investigate the nature and extent of dynamic weakening processes in carbonate faults. We use the high temperature sensitivity of iron oxide/hydroxide assemblages, and their magnetic remanence, to estimate frictional heat. Evidence for seismic slip in iron oxides and temperature uniformity along the fault surface have been tested through demagnetization experiments and 1D heat conduction modeling. Our data shows that the fault mirror underwent frictional heating during the 0.8 m slip event, but that this displacement was insufficient to reach pervasive decarbonation. We constrain the peak coseismic temperature along the fault plane to <400 °C through demagnetization experiments and 1D heat conduction modeling. Our results emphasize that coseismic deformation along natural faults is complex and therefore requires complementary field observations at multiple scales in order to encompass a broad range of faulting processes.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"197 ","pages":"Article 105421"},"PeriodicalIF":2.6,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143843330","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}
Pub Date : 2025-04-02DOI: 10.1016/j.jsg.2025.105426
Guoqing Lu , Lianbo Zeng , Guoping Liu , Jian Su , José Luis Drummond Alves , Junfeng Zhao , Mehdi Ostadhassan
Current fault detection methods mainly take advantage of a convolutional neural network, simplified U-Net, for seismic image semantic segmentation, which is a computer vision task aimed at generating a dense pixel-wise segmentation map of an image, where each pixel is assigned to a specific class or object. However, these methods face challenges such as unclear segmentation boundaries and limited receptive fields, which hinder the model's capability to detect all features of the fault. To address these issues, this paper proposes a method based on the integration of Graph Neural Network (GNN) and U-Net, referred to as GNU-Net, which incorporates fault graph structures and graph computation modules into U-Net. This approach aims to expand the receptive field, clarify segmentation boundaries, and optimize fault segmentation and continuity analysis through a joint loss function. The method consists of five modules: graph construction, data augmentation, fault segmentation, fault continuity analysis, and joint training. The graph construction module grids the fault labels with a grid edge length of 8 voxels, sets vertices at the locations where the fault intersects the grid, and selects representatives from the voxels labeled as faults within each grid as vertices. The dilation function is applied to expand the fault voxels in the labels and construct a velocity field, in which the geodesic distance between vertices is computed to establish connections between vertices. Data augmentation of the 3D seismic data and fault labels is achieved by rotating the images. A custom rotation matrix is applied to transform the vertex feature coordinates of the graph structure, significantly increasing the size and diversity of the training dataset. The fault segmentation module employs a simplified U-Net with square convolution kernels, and the segmentation loss includes both Dice and binary cross-entropy losses. The fault continuity analysis module leverages a graph neural network with irregular convolution kernels to capture macroscopic fault features and enhance fault continuity, employing a connection loss based on binary cross-entropy. Compared to the original U-Net, the modified GNU-Net achieves a fault detection accuracy of 97.39 % on the testing set, an improvement of 3.96 % over the original U-Net.
{"title":"Fault detection based on U-Net and GNN integration","authors":"Guoqing Lu , Lianbo Zeng , Guoping Liu , Jian Su , José Luis Drummond Alves , Junfeng Zhao , Mehdi Ostadhassan","doi":"10.1016/j.jsg.2025.105426","DOIUrl":"10.1016/j.jsg.2025.105426","url":null,"abstract":"<div><div>Current fault detection methods mainly take advantage of a convolutional neural network, simplified U-Net, for seismic image semantic segmentation, which is a computer vision task aimed at generating a dense pixel-wise segmentation map of an image, where each pixel is assigned to a specific class or object. However, these methods face challenges such as unclear segmentation boundaries and limited receptive fields, which hinder the model's capability to detect all features of the fault. To address these issues, this paper proposes a method based on the integration of Graph Neural Network (GNN) and U-Net, referred to as GNU-Net, which incorporates fault graph structures and graph computation modules into U-Net. This approach aims to expand the receptive field, clarify segmentation boundaries, and optimize fault segmentation and continuity analysis through a joint loss function. The method consists of five modules: graph construction, data augmentation, fault segmentation, fault continuity analysis, and joint training. The graph construction module grids the fault labels with a grid edge length of 8 voxels, sets vertices at the locations where the fault intersects the grid, and selects representatives from the voxels labeled as faults within each grid as vertices. The dilation function is applied to expand the fault voxels in the labels and construct a velocity field, in which the geodesic distance between vertices is computed to establish connections between vertices. Data augmentation of the 3D seismic data and fault labels is achieved by rotating the images. A custom rotation matrix is applied to transform the vertex feature coordinates of the graph structure, significantly increasing the size and diversity of the training dataset. The fault segmentation module employs a simplified U-Net with square convolution kernels, and the segmentation loss includes both Dice and binary cross-entropy losses. The fault continuity analysis module leverages a graph neural network with irregular convolution kernels to capture macroscopic fault features and enhance fault continuity, employing a connection loss based on binary cross-entropy. Compared to the original U-Net, the modified GNU-Net achieves a fault detection accuracy of 97.39 % on the testing set, an improvement of 3.96 % over the original U-Net.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"197 ","pages":"Article 105426"},"PeriodicalIF":2.6,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143777224","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}
Pub Date : 2025-03-28DOI: 10.1016/j.jsg.2025.105423
Medina-Cascales I. , Carrazana A. , Gomez-Rivas E. , Martin-Rojas I. , García-Tortosa F.J. , Bons P.D. , Alfaro P.
Veins provide insights into the strain conditions under which they formed, the timing and sequence of fracturing, and the nature of the fluids from which their cement precipitated. Intense fracturing within fault zones promotes vein formation, but there are still open questions about the extent of fault control on vein formation, the type of veins and their development. This study analyses the influence of an active strike-slip fault —the Galera Fault, Southern Spain— on the formation, distribution, and evolution of gypsum vein networks hosted in Pliocene and Pleistocene rocks. Field mapping and structural analysis reveal veins are concentrated within the fault damage zone, with their spatial distribution being controlled by fault geometry, kinematics, and the lateral continuity of host lithologies. Structural analysis at 18 sites indicates that vein orientation correlates with tectonic structures. Veins near faults exhibit organized, consistent strikes, while those farther away show more variable orientations. Vein strike is highly sensitive to the local strain defined by the geometry, kinematics, and interactions of faults and subsidiary structures. Additionally, vein length tends to increase near faults. Vein intensity and density are controlled by vein length and orientation, and the thickness of vein-hosting beds. Moreover, veins formed shortly after sediment deposition under minimal lithostatic load, likely driven by fault-related strain. This early formation is supported by microstructures such as cone-in-cone and the rotation of early veins due to tectonic tilting. In conclusion, this research highlights the strong tectonic influence on vein formation, evolution, distribution, and attributes.
{"title":"FAULT-CONTROLLED GYPSUM VEIN NETWORKS: INSIGHTS FROM THE ACTIVE GALERA FAULT, SOUTHERN SPAIN","authors":"Medina-Cascales I. , Carrazana A. , Gomez-Rivas E. , Martin-Rojas I. , García-Tortosa F.J. , Bons P.D. , Alfaro P.","doi":"10.1016/j.jsg.2025.105423","DOIUrl":"10.1016/j.jsg.2025.105423","url":null,"abstract":"<div><div>Veins provide insights into the strain conditions under which they formed, the timing and sequence of fracturing, and the nature of the fluids from which their cement precipitated. Intense fracturing within fault zones promotes vein formation, but there are still open questions about the extent of fault control on vein formation, the type of veins and their development. This study analyses the influence of an active strike-slip fault —the Galera Fault, Southern Spain— on the formation, distribution, and evolution of gypsum vein networks hosted in Pliocene and Pleistocene rocks. Field mapping and structural analysis reveal veins are concentrated within the fault damage zone, with their spatial distribution being controlled by fault geometry, kinematics, and the lateral continuity of host lithologies. Structural analysis at 18 sites indicates that vein orientation correlates with tectonic structures. Veins near faults exhibit organized, consistent strikes, while those farther away show more variable orientations. Vein strike is highly sensitive to the local strain defined by the geometry, kinematics, and interactions of faults and subsidiary structures. Additionally, vein length tends to increase near faults. Vein intensity and density are controlled by vein length and orientation, and the thickness of vein-hosting beds. Moreover, veins formed shortly after sediment deposition under minimal lithostatic load, likely driven by fault-related strain. This early formation is supported by microstructures such as cone-in-cone and the rotation of early veins due to tectonic tilting. In conclusion, this research highlights the strong tectonic influence on vein formation, evolution, distribution, and attributes.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"197 ","pages":"Article 105423"},"PeriodicalIF":2.6,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792773","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}
Pub Date : 2025-03-28DOI: 10.1016/j.jsg.2025.105425
Qianqian Li , Sanzhong Li , Wei Gong , Lei Xing , Hongwei Liu , Chong Xu , Xiaodian Jiang
The Ontong Java Plateau (OJP), as the largest oceanic plateau in the world, has drawn much attention because of its subduction along the West Melanesian Trench and the North Solomon Trench. Based on the first observed multichannel seismic (MCS) and multibeam data across the northwestern margin of the OJP, we show that the forearc region along the West Melanesian Trench is dominated by a series of normal faults which show this trench as an erosive subduction zone. Under the control of the seaward-tilting normal faults, the forearc region presents the topographic characteristics of gradually descending toward the trench and can be divided into the upper slope, middle slope and lower slope. However, some areas of the forearc region may be affected by underplating duplex deformation at the upper/lower plate interface, which leads to the formation of the outer-arc high and modification of the early tectono–stratigraphic structure, along with a series of arcward-tilting normal faults. We suggest that the forearc region between New Ireland Island and the West Melanesian Trench generally exhibits a strong extension, which is in sharp contrast to the thrust-imbricate collage of the forearc region east of the Solomon Islands. The extension indicates that the buoyant OJP is not subducted beneath the New Ireland Island along the West Melanesian Trench but may be collocated only with the overriding island arc system, as evidenced by no relative motion between the Pacific Plate and the New Ireland Island Arc and few earthquakes in the inactive trench.
{"title":"Subduction of the Ontong Java Plateau: Insights from seismic reflection imaging of the forearc along the West Melanesian Trench","authors":"Qianqian Li , Sanzhong Li , Wei Gong , Lei Xing , Hongwei Liu , Chong Xu , Xiaodian Jiang","doi":"10.1016/j.jsg.2025.105425","DOIUrl":"10.1016/j.jsg.2025.105425","url":null,"abstract":"<div><div>The Ontong Java Plateau (OJP), as the largest oceanic plateau in the world, has drawn much attention because of its subduction along the West Melanesian Trench and the North Solomon Trench. Based on the first observed multichannel seismic (MCS) and multibeam data across the northwestern margin of the OJP, we show that the forearc region along the West Melanesian Trench is dominated by a series of normal faults which show this trench as an erosive subduction zone. Under the control of the seaward-tilting normal faults, the forearc region presents the topographic characteristics of gradually descending toward the trench and can be divided into the upper slope, middle slope and lower slope. However, some areas of the forearc region may be affected by underplating duplex deformation at the upper/lower plate interface, which leads to the formation of the outer-arc high and modification of the early tectono–stratigraphic structure, along with a series of arcward-tilting normal faults. We suggest that the forearc region between New Ireland Island and the West Melanesian Trench generally exhibits a strong extension, which is in sharp contrast to the thrust-imbricate collage of the forearc region east of the Solomon Islands. The extension indicates that the buoyant OJP is not subducted beneath the New Ireland Island along the West Melanesian Trench but may be collocated only with the overriding island arc system, as evidenced by no relative motion between the Pacific Plate and the New Ireland Island Arc and few earthquakes in the inactive trench.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"196 ","pages":"Article 105425"},"PeriodicalIF":2.6,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734667","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}
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