Pub Date : 2025-08-19DOI: 10.1016/j.jsg.2025.105533
F. Porta, L.R. Berio, C. Cavozzi, F. Balsamo
Prediction of sub-seismic fault properties is a key factor to mitigate the uncertainties in reservoir modeling. The present study focuses on the geometry and origin of the NE-trending sub-seismic faults in Monte Capanne pluton (Elba Island, Italy), characterized by transtensive kinematics and developed in an interacting sector between two regional-scale faults. A detailed analysis of the fracture network (digitized fractures >10,000) was conducted along and across the NE-trending faults using Digital Outcrop Model (DOM). This dataset was further integrated with field mapping at a 1:200 scale of four representative sectors. Overall, our multiscale mapping identifies three different fault-related fracture sets: (i) NE-SW-trending fractures, (ii) E-W-trending fractures, and (iii) NNW-SSE-trending fractures. Statistical analysis of fracture orientation and length in DOM reveals a heterogeneous spatial distribution of deformation in the outcrop, showing an increase in fracture density and intensity (P10 and P21), and connectivity (connections per branch CB) towards the northeastern region of the outcrop, where NE-trending faults are closely spaced. A comparison between DOM-based and DOM-integrated datasets reveals that the former tends to underestimate small-scale fractures due to pixel-resolution limit (truncation effect), leading to an underestimation of across-fault damage zone width and internal fracture density and intensity. However, the proportion of connected nodes (X, Y) and connectivity (CB) from the DOM-based dataset is consistent with topological parameters from the DOM-integrated dataset. This study highlights the necessity of a multiscale approach for fracture network characterization in sub-seismic faults, combining DOM with field mapping to develop reliable templates for reservoir analysis.
亚地震断层性质预测是降低储层建模不确定性的关键因素。本文研究了意大利厄尔巴岛Monte Capanne岩体北东向次地震断裂的几何形态和成因，该次地震断裂具有横向运动学特征，发育于两条区域尺度断裂之间的相互作用板块。利用数字露头模型（DOM）对北东向断裂进行了详细的裂缝网络（数字化裂缝>； 10000条）分析。该数据集进一步与四个代表性部门的1:200比例尺的实地测绘相结合。总的来说，我们的多尺度映射确定了三种不同的断层相关裂缝组：(i) ne - sw走向裂缝，（ii） e - w走向裂缝，（iii） nnw - se走向裂缝。DOM中裂缝方向和长度的统计分析表明，露头变形的空间分布不均匀，裂缝密度和强度（P10和P21）增加，连通性（每分支CB的连接）向露头东北地区靠拢，ne向断裂密集分布。基于dom的数据集与集成dom的数据集的对比表明，由于像素分辨率的限制（截断效应），前者往往低估了小尺度裂缝，从而低估了断层间损伤带宽度、内部裂缝密度和强度。然而，基于dom的数据集的连接节点（X， Y）和连通性（CB）的比例与dom集成数据集的拓扑参数一致。该研究强调了亚地震断层裂缝网络表征的多尺度方法的必要性，将DOM与现场测绘相结合，为储层分析开发可靠的模板。
{"title":"Multiscale characterization of fracture network in sub-seismic faults (Monte Capanne Pluton, Elba Island, Italy)","authors":"F. Porta, L.R. Berio, C. Cavozzi, F. Balsamo","doi":"10.1016/j.jsg.2025.105533","DOIUrl":"10.1016/j.jsg.2025.105533","url":null,"abstract":"<div><div>Prediction of sub-seismic fault properties is a key factor to mitigate the uncertainties in reservoir modeling. The present study focuses on the geometry and origin of the NE-trending sub-seismic faults in Monte Capanne pluton (Elba Island, Italy), characterized by transtensive kinematics and developed in an interacting sector between two regional-scale faults. A detailed analysis of the fracture network (digitized fractures >10,000) was conducted along and across the NE-trending faults using Digital Outcrop Model (DOM). This dataset was further integrated with field mapping at a 1:200 scale of four representative sectors. Overall, our multiscale mapping identifies three different fault-related fracture sets: (i) NE-SW-trending fractures, (ii) E-W-trending fractures, and (iii) NNW-SSE-trending fractures. Statistical analysis of fracture orientation and length in DOM reveals a heterogeneous spatial distribution of deformation in the outcrop, showing an increase in fracture density and intensity (P<sub>10</sub> and P<sub>21</sub>), and connectivity (connections per branch C<sub>B</sub>) towards the northeastern region of the outcrop, where NE-trending faults are closely spaced. A comparison between DOM-based and DOM-integrated datasets reveals that the former tends to underestimate small-scale fractures due to pixel-resolution limit (truncation effect), leading to an underestimation of across-fault damage zone width and internal fracture density and intensity. However, the proportion of connected nodes (X, Y) and connectivity (C<sub>B</sub>) from the DOM-based dataset is consistent with topological parameters from the DOM-integrated dataset. This study highlights the necessity of a multiscale approach for fracture network characterization in sub-seismic faults, combining DOM with field mapping to develop reliable templates for reservoir analysis.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"201 ","pages":"Article 105533"},"PeriodicalIF":2.9,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144934255","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 : 2025-08-18DOI: 10.1016/j.jsg.2025.105538
R. Bauer , M. Corsini , C. Matonti , D. Bosch , O. Bruguier , B. Issautier
The Nice arc architecture, located at the southern tip of the Western Alps, is very singular, with a strong and narrow curvature. This particular shape could be the result of inherited structures that guide subsequent deformations during compressional events, as has been demonstrated in other parts of the belt. To achieve this objective, we adopted a multidisciplinary approach to characterize the geometry, kinematics, and timing of deformations associated with the various tectonic episodes that structured the arc. A special focus on the Cretaceous formations has revealed that the Cenomanian deposits show significant thickness variations and strong disturbances associated with fault activity. At this time, the formation of narrow, elongated basins was controlled by a system of NNE-SSW trending left-lateral strike-slip faults associated with NW-SE trending normal strike-slip faults and normal faults, dated at 81 ± 13 Ma on calcite recrystallised on the fault planes. During the Cenozoic, two phases of shortening reactivated the faults bounding these basins. An Oligocene phase corresponds to a NE-SW compression, expressed by NW-SE trending folds and thrust and reactivation of first phase faults, dated at 28.7 ± 6.1 Ma, 28.8 ± 8.4 Ma and 27.3 ± 6.3 Ma. The Mio-Pliocene phase is characterised by N-S compression with E-W folds that interfere with the Oligocene folds and reactivate the earlier faults. A Lower Miocene age of 18.2 ± 1.1 Ma and a Pliocene age of 3.16 ± 0.47 Ma pinpoint the timing of these last deformation phases.
{"title":"The role of cretaceous tectonics in the present-day architecture of the nice arc (Western Subalpine foreland, France)","authors":"R. Bauer , M. Corsini , C. Matonti , D. Bosch , O. Bruguier , B. Issautier","doi":"10.1016/j.jsg.2025.105538","DOIUrl":"10.1016/j.jsg.2025.105538","url":null,"abstract":"<div><div>The Nice arc architecture, located at the southern tip of the Western Alps, is very singular, with a strong and narrow curvature. This particular shape could be the result of inherited structures that guide subsequent deformations during compressional events, as has been demonstrated in other parts of the belt. To achieve this objective, we adopted a multidisciplinary approach to characterize the geometry, kinematics, and timing of deformations associated with the various tectonic episodes that structured the arc. A special focus on the Cretaceous formations has revealed that the Cenomanian deposits show significant thickness variations and strong disturbances associated with fault activity. At this time, the formation of narrow, elongated basins was controlled by a system of NNE-SSW trending left-lateral strike-slip faults associated with NW-SE trending normal strike-slip faults and normal faults, dated at 81 ± 13 Ma on calcite recrystallised on the fault planes. During the Cenozoic, two phases of shortening reactivated the faults bounding these basins. An Oligocene phase corresponds to a NE-SW compression, expressed by NW-SE trending folds and thrust and reactivation of first phase faults, dated at 28.7 ± 6.1 Ma, 28.8 ± 8.4 Ma and 27.3 ± 6.3 Ma. The Mio-Pliocene phase is characterised by N-S compression with E-W folds that interfere with the Oligocene folds and reactivate the earlier faults. A Lower Miocene age of 18.2 ± 1.1 Ma and a Pliocene age of 3.16 ± 0.47 Ma pinpoint the timing of these last deformation phases.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105538"},"PeriodicalIF":2.9,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867380","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 : 2025-08-15DOI: 10.1016/j.jsg.2025.105537
Carlos Fernández , Manuel Díaz Azpiroz , Jorge Alonso-Henar
In this work, a triclinic transpression and transtension model is presented in which the coaxial part of the flow is general, including both constriction and flattening as well as pure shear. The results show that, for both transtension and transpression, the different combinations of the variables that control the model allow obtaining finite strain ellipsoids in all fields of the deformation diagram, including prolate and oblate ellipsoids. It is mainly the ζ angle between the simple-shearing direction and the extrusion (transpression) or sinking (transtension) direction, together with the value of the vorticity, and the characteristics of the coaxial part of the flow, which controls the shape of the finite strain ellipsoid in each case. The orientations of the principal axes (X, Y, Z) of the finite strain ellipsoids show a wide variation, also dependent on ζ. The model has been applied to natural examples, improving the knowledge of their kinematic evolution and tectonic interpretation.
{"title":"General transpression and transtension","authors":"Carlos Fernández , Manuel Díaz Azpiroz , Jorge Alonso-Henar","doi":"10.1016/j.jsg.2025.105537","DOIUrl":"10.1016/j.jsg.2025.105537","url":null,"abstract":"<div><div>In this work, a triclinic transpression and transtension model is presented in which the coaxial part of the flow is general, including both constriction and flattening as well as pure shear. The results show that, for both transtension and transpression, the different combinations of the variables that control the model allow obtaining finite strain ellipsoids in all fields of the deformation diagram, including prolate and oblate ellipsoids. It is mainly the <em>ζ</em> angle between the simple-shearing direction and the extrusion (transpression) or sinking (transtension) direction, together with the value of the vorticity, and the characteristics of the coaxial part of the flow, which controls the shape of the finite strain ellipsoid in each case. The orientations of the principal axes (<em>X</em>, <em>Y</em>, <em>Z</em>) of the finite strain ellipsoids show a wide variation, also dependent on <em>ζ</em>. The model has been applied to natural examples, improving the knowledge of their kinematic evolution and tectonic interpretation.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105537"},"PeriodicalIF":2.9,"publicationDate":"2025-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867379","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}
N‒S crustal shortening in the Tian Shan shows an obvious eastward decrease, which results in an eastward decrease in the width and uplift height of the topography. However, the highest peak in the Tian Shan region appears in its middle part (the Wensu area) instead of at the expected western end. At present, the kinematic information and N‒S crustal shortening rate of the Wensu foreland thrust system remain poorly constrained, which has led to controversy regarding the deformation characteristics and mechanism of geomorphic growth in this area. In this study, we focused on the kinematics and shortening rate of the Wensu fault-bend fold (WFBF), the frontal structural belt of the Wensu foreland thrust system. On the basis of interpretations of detailed high-resolution remote sensing images, field investigations, surveying of displaced terraces with an unmanned drone, the dating of late Quaternary sediments via OSL and trench excavation, we determined a relatively low N‒S crustal shortening rate of 1.31 ± 0.23 mm/yr over the past 24,000–40,000 years for the WFBF. We suggest that a listric thick-skinned fault geometry at depth results in more vertical uplift components, which is the key factor of significant topographic uplift amplitude in this region.
{"title":"Late Quaternary crustal shortening rate of the Wensu fault-bend fold in the southern Tian Shan, NW China","authors":"Kezhi Zang , Chuanyong Wu , Zhan Gao , Xuezhu Wang , Haiyang Yuan , Jinshuo Zhang , Sihua Yuan , Xiaohui Yu , Yunxiao Ma","doi":"10.1016/j.jsg.2025.105536","DOIUrl":"10.1016/j.jsg.2025.105536","url":null,"abstract":"<div><div>N‒S crustal shortening in the Tian Shan shows an obvious eastward decrease, which results in an eastward decrease in the width and uplift height of the topography. However, the highest peak in the Tian Shan region appears in its middle part (the Wensu area) instead of at the expected western end. At present, the kinematic information and N‒S crustal shortening rate of the Wensu foreland thrust system remain poorly constrained, which has led to controversy regarding the deformation characteristics and mechanism of geomorphic growth in this area. In this study, we focused on the kinematics and shortening rate of the Wensu fault-bend fold (WFBF), the frontal structural belt of the Wensu foreland thrust system. On the basis of interpretations of detailed high-resolution remote sensing images, field investigations, surveying of displaced terraces with an unmanned drone, the dating of late Quaternary sediments via OSL and trench excavation, we determined a relatively low N‒S crustal shortening rate of 1.31 ± 0.23 mm/yr over the past 24,000–40,000 years for the WFBF. We suggest that a listric thick-skinned fault geometry at depth results in more vertical uplift components, which is the key factor of significant topographic uplift amplitude in this region.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105536"},"PeriodicalIF":2.9,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144840641","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 : 2025-08-12DOI: 10.1016/j.jsg.2025.105534
Yehua Shan , Jian Zheng
It is a challenge to obtain the meaningful solution of deviatoric stress tensors from polyphase calcite twin data measured in multi-deformed rocks. Our paper advances current approaches that simultaneously determine stresses from polyphase twin data. Key refinements include the selection of the dimensionless stress space, the estimation of the dimensionless critical resolved shear stress (), the definition of the stress criterion including , and the exclusion or inclusion of incompatible untwinned planes (IU). The improved simultaneous-determination method (ISDM) is applied to three series of two–three-phase IU-free synthetic datasets generated under imposed stresses. Stress results demonstrate that the ISDM is accurate in principal stress direction, stress ratio, and , although the ISDM including IU is a little more accurate than the ISDM excluding IU. For two-phase equally-sized synthetic datasets, the ISDM excluding IU is generally more accurate than existing similar methods. Applying both the ISDM and an existing similar method to a natural dataset reveals that the ISDM excluding IU yields the most reasonable stress solution.
{"title":"Simultaneous determination of deviatoric stress tensors from polyphase calcite twin data: improvement and application","authors":"Yehua Shan , Jian Zheng","doi":"10.1016/j.jsg.2025.105534","DOIUrl":"10.1016/j.jsg.2025.105534","url":null,"abstract":"<div><div>It is a challenge to obtain the meaningful solution of deviatoric stress tensors from polyphase calcite twin data measured in multi-deformed rocks. Our paper advances current approaches that simultaneously determine stresses from polyphase twin data. Key refinements include the selection of the dimensionless stress space, the estimation of the dimensionless critical resolved shear stress (<span><math><mrow><msub><mover><mi>τ</mi><mo>‾</mo></mover><mi>c</mi></msub></mrow></math></span>), the definition of the stress criterion including <span><math><mrow><msub><mover><mi>τ</mi><mo>‾</mo></mover><mi>c</mi></msub></mrow></math></span>, and the exclusion or inclusion of incompatible untwinned planes (IU). The improved simultaneous-determination method (ISDM) is applied to three series of two–three-phase IU-free synthetic datasets generated under imposed stresses. Stress results demonstrate that the ISDM is accurate in principal stress direction, stress ratio, and <span><math><mrow><msub><mover><mi>τ</mi><mo>‾</mo></mover><mi>c</mi></msub></mrow></math></span>, although the ISDM including IU is a little more accurate than the ISDM excluding IU. For two-phase equally-sized synthetic datasets, the ISDM excluding IU is generally more accurate than existing similar methods. Applying both the ISDM and an existing similar method to a natural dataset reveals that the ISDM excluding IU yields the most reasonable stress solution.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105534"},"PeriodicalIF":2.9,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852671","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 : 2025-08-12DOI: 10.1016/j.jsg.2025.105532
Beihang Zhang , Jin Zhang , Heng Zhao , Jie Hui , Yaqi Yang , Yiping Zhang , Alimu Adina , Hai Jiang
The late Mesozoic intracontinental deformation in South China preserves rich insights into continental evolution, with close link to subduction and collision processes along the eastern margin of the Eurasian Plate. The Lower Yangtze Region, located in the northeastern part of South China, underwent complex intracontinental deformation during the late Mesozoic, making it a key area for understanding the tectonic evolution of East Asia. Through detailed field investigation of representative outcrops and structural analysis of fault-slip data from the regional faults, this study reconstructs the late Mesozoic deformation sequence and paleo-stress fields in the Lower Yangtze Region. Our new data, combined with published results, suggest that the Lower Yangtze Region experienced a three-stage tectonic evolution from the Late Jurassic to early Late Cretaceous, characterized by alternating contractional and extensional tectonic events. The first stage, contractional deformation from the Late Jurassic to early Early Cretaceous, was controlled by NW-SE contractional stress, generating sinistral strike-slip motion along the Tan-Lu Fault, the dextral strike-slip motion along the Chuhe Fault and Yangtze River Fault, and top-to-west thrusting of the Maoshan Fault. This contractional deformation is interpreted as being related to the westward low-angle subduction of the Paleo-Pacific Plate beneath the Eurasian Plate. The second stage is NW-SE extension during the Early Cretaceous, associated with a series of high-angle normal faults, which is correlated with the rollback of the Paleo-Pacific Plate. The third stage is another episode of contractional deformation that resulted in a tectonic inversion controlled by nearly N-S contraction during late Early Cretaceous to early Late Cretaceous. This contraction led to the sinistral strike-slip motion of the regional faults and was associated with a set of conjugate strike-slip faults. The oblique collision between the Okhotomorsk Block and the Eurasian Plate serves as the geodynamic driver for this contraction event. Comparative structural analysis reveals distinct deformation patterns between the Lower Yangtze Region and other areas of South China during the Late Jurassic to early Early Cretaceous. Under the same NW-SE contraction, the Lower Yangtze Region exhibited predominant strike-slip motion along the major faults, whereas other areas of South China developed NNE-SSW-striking thrust-and-fold deformation. This disparity is possibly caused by the unique tectonic position and pre-existing basement faults of the Lower Yangtze Region. Due to the obstruction of the rigid craton (i.e., the North China Craton), the crustal materials underwent lateral extrusion towards the northeast along the pre-existing faults, accommodating the continuous contraction that occurred during the Late Jurassic to early Early Cretaceous.
{"title":"Intracontinental deformation and paleo-stress fields of the lower yangtze region during the late Mesozoic: implications for the tectonic evolution of South China","authors":"Beihang Zhang , Jin Zhang , Heng Zhao , Jie Hui , Yaqi Yang , Yiping Zhang , Alimu Adina , Hai Jiang","doi":"10.1016/j.jsg.2025.105532","DOIUrl":"10.1016/j.jsg.2025.105532","url":null,"abstract":"<div><div>The late Mesozoic intracontinental deformation in South China preserves rich insights into continental evolution, with close link to subduction and collision processes along the eastern margin of the Eurasian Plate. The Lower Yangtze Region, located in the northeastern part of South China, underwent complex intracontinental deformation during the late Mesozoic, making it a key area for understanding the tectonic evolution of East Asia. Through detailed field investigation of representative outcrops and structural analysis of fault-slip data from the regional faults, this study reconstructs the late Mesozoic deformation sequence and paleo-stress fields in the Lower Yangtze Region. Our new data, combined with published results, suggest that the Lower Yangtze Region experienced a three-stage tectonic evolution from the Late Jurassic to early Late Cretaceous, characterized by alternating contractional and extensional tectonic events. The first stage, contractional deformation from the Late Jurassic to early Early Cretaceous, was controlled by NW-SE contractional stress, generating sinistral strike-slip motion along the Tan-Lu Fault, the dextral strike-slip motion along the Chuhe Fault and Yangtze River Fault, and top-to-west thrusting of the Maoshan Fault. This contractional deformation is interpreted as being related to the westward low-angle subduction of the Paleo-Pacific Plate beneath the Eurasian Plate. The second stage is NW-SE extension during the Early Cretaceous, associated with a series of high-angle normal faults, which is correlated with the rollback of the Paleo-Pacific Plate. The third stage is another episode of contractional deformation that resulted in a tectonic inversion controlled by nearly N-S contraction during late Early Cretaceous to early Late Cretaceous. This contraction led to the sinistral strike-slip motion of the regional faults and was associated with a set of conjugate strike-slip faults. The oblique collision between the Okhotomorsk Block and the Eurasian Plate serves as the geodynamic driver for this contraction event. Comparative structural analysis reveals distinct deformation patterns between the Lower Yangtze Region and other areas of South China during the Late Jurassic to early Early Cretaceous. Under the same NW-SE contraction, the Lower Yangtze Region exhibited predominant strike-slip motion along the major faults, whereas other areas of South China developed NNE-SSW-striking thrust-and-fold deformation. This disparity is possibly caused by the unique tectonic position and pre-existing basement faults of the Lower Yangtze Region. Due to the obstruction of the rigid craton (i.e., the North China Craton), the crustal materials underwent lateral extrusion towards the northeast along the pre-existing faults, accommodating the continuous contraction that occurred during the Late Jurassic to early Early Cretaceous.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105532"},"PeriodicalIF":2.9,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144840643","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 : 2025-08-05DOI: 10.1016/j.jsg.2025.105518
Giusy Lavecchia , Francesco Brozzetti , Simone Bello , Rita de Nardis
High-resolution microearthquake data provide a powerful window into active fault architecture from depth to surface in slowly deforming regions with sparse instrumental seismicity. We integrate microseismic clusters from enhanced catalogs with detailed structural mapping to reconstruct the 3D geometry of seismogenic extensional faults in the Latium-Abruzzi sector of central Italy. Investigated earthquake clusters align geometrically and kinematically with known and newly mapped normal faults showing evidence of Late Quaternary activity. The 3D model depicts a set of SW-to-SSW-dipping, non-planar faults with an average dip of ∼55° (Sora, San Donato Val di Comino, Villavallelonga, and Pescasseroli). Their cut-off depths deepen NNE-ward, from ∼7 to ∼14 km, suggesting an underlying basal discontinuity dipping∼30–35°. Microseismic patches at the roots of these faults are mostly elongated along dip rather than along strike. This unusual geometry suggests a stress release pattern governed by iso-oriented anisotropic roughness and corrugations on the basal discontinuity, which may focus upward fluid migration and trigger earthquakes along hangingwall splays. Stress inversion reveals a persistent NE–SW tensional stress field consistent across geological and instrumental timescales. An empirical magnitude-area relationship, accounting for both epistemic uncertainty in scaling laws and areal variability of fault surfaces, yields maximum magnitudes between 6.0 and 6.5, consistent with the regional seismotectonic framework. These findings provide new constraints on fault connectivity, stress distribution, and fluid-fault interactions, and help identifying potentially seismogenic sources that may remain unrecognized when geological and seismic data are considered separately.
高分辨率微地震数据提供了一个强大的窗口，从深度到地表，在缓慢变形的地区，稀疏的仪器地震活动。我们将来自增强目录的微地震集群与详细的结构测绘相结合，重建了意大利中部Latium-Abruzzi地区发震伸展断层的三维几何形状。所调查的地震群在几何上和运动学上与已知的和新测绘的正断层对齐，显示出晚第四纪活动的证据。三维模型描绘了一组sw - ssw倾斜的非平面断层，平均倾角为~ 55°（Sora, San Donato Val di Comino， Villavallelonga和Pescasseroli）。它们的截止深度向北北东方向加深，从~ 7到~ 14 km，表明下伏的基底不连续倾斜~ 30-35°。这些断层根部的微震斑块大多沿倾角而不是沿走向拉长。这种不寻常的几何形状表明应力释放模式是由等向各向异性粗糙度和基底不连续上的波纹控制的，这可能集中了向上的流体迁移并引发沿上壁面的地震。应力反演揭示了一个持续的NE-SW张性应力场，与地质和仪器时间尺度一致。考虑到标度定律的认知不确定性和断层表面的面积变异性，经验震级-面积关系得出的最大震级在6.0 - 6.5之间，与区域地震构造格局一致。这些发现为断层连通性、应力分布和流体-断层相互作用提供了新的约束条件，并有助于识别在单独考虑地质和地震数据时可能无法识别的潜在发震源。
{"title":"Mapping fault architecture from depth to surface: integrating microseismicity and structural geology in low-strain Apennine regions","authors":"Giusy Lavecchia , Francesco Brozzetti , Simone Bello , Rita de Nardis","doi":"10.1016/j.jsg.2025.105518","DOIUrl":"10.1016/j.jsg.2025.105518","url":null,"abstract":"<div><div>High-resolution microearthquake data provide a powerful window into active fault architecture from depth to surface in slowly deforming regions with sparse instrumental seismicity. We integrate microseismic clusters from enhanced catalogs with detailed structural mapping to reconstruct the 3D geometry of seismogenic extensional faults in the Latium-Abruzzi sector of central Italy. Investigated earthquake clusters align geometrically and kinematically with known and newly mapped normal faults showing evidence of Late Quaternary activity. The 3D model depicts a set of SW-to-SSW-dipping, non-planar faults with an average dip of ∼55° (Sora, San Donato Val di Comino, Villavallelonga, and Pescasseroli). Their cut-off depths deepen NNE-ward, from ∼7 to ∼14 km, suggesting an underlying basal discontinuity dipping∼30–35°. Microseismic patches at the roots of these faults are mostly elongated along dip rather than along strike. This unusual geometry suggests a stress release pattern governed by iso-oriented anisotropic roughness and corrugations on the basal discontinuity, which may focus upward fluid migration and trigger earthquakes along hangingwall splays. Stress inversion reveals a persistent NE–SW tensional stress field consistent across geological and instrumental timescales. An empirical magnitude-area relationship, accounting for both epistemic uncertainty in scaling laws and areal variability of fault surfaces, yields maximum magnitudes between 6.0 and 6.5, consistent with the regional seismotectonic framework. These findings provide new constraints on fault connectivity, stress distribution, and fluid-fault interactions, and help identifying potentially seismogenic sources that may remain unrecognized when geological and seismic data are considered separately.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105518"},"PeriodicalIF":2.9,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144828062","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 : 2025-08-05DOI: 10.1016/j.jsg.2025.105520
C. Manniello , V. La Bruna , E. Michie , R.E.B. Araùjo , F.H.R. Bezerra , D. Faulkner , M. Allen , X.M. Morais , G. Prosser , F. Agosta
Focusing on the Mesozoic and Eocene carbonate samples from the Viggiano Mt. and Raparo Mt., Southern Apennines of Italy, we examine the role of solution surfaces on the present-day porosity and permeability. Carbonate lithofacies include mudstones, packstones, grainstones, and rudstones and gas-porosimetry measurements show effective porosity up to 5 %. The value is mainly due to the secondary porosity localized along microfractures and within the rough bed-parallel and rough bed-oblique solution surfaces, contrary to what was found in the smooth bed-parallel ones, showing that roughness can control pore localization. NMR (Nuclear Magnetic Resonance) results indicate that the former group of solution surfaces include vugs characterized by subspherical to tubular shapes (pore throat r < 3 μm), and low aspect ratios (r < 2), forming pores with low sensitivity to compression. The microfractures form capillary porosity (r ≈ 1 μm) and are characterized by high aspect ratios (r > 2), typical of pores with high sensitivity to compression. Permeability measurements at room pressure reveal that samples with visible microfractures are characterized by values up 2 order magnitude greater than of those with only visible solution surfaces, showing that the pore connectivity is controlled by opening-mode, sub-mm scale microfractures. At confining pressures greater than 25 MPa, both fracture- and stylolite dominated samples show similar values of permeability, indicating that at depths larger than ca. 1 km, the rough stylolite localize effective porosity that may enhance the along-solution surface fluid flow in carbonates.
{"title":"Pore space properties and permeability of solution surfaces in Mesozoic shallow-water carbonates, southern Apennines, Italy","authors":"C. Manniello , V. La Bruna , E. Michie , R.E.B. Araùjo , F.H.R. Bezerra , D. Faulkner , M. Allen , X.M. Morais , G. Prosser , F. Agosta","doi":"10.1016/j.jsg.2025.105520","DOIUrl":"10.1016/j.jsg.2025.105520","url":null,"abstract":"<div><div>Focusing on the Mesozoic and Eocene carbonate samples from the Viggiano Mt. and Raparo Mt., Southern Apennines of Italy, we examine the role of solution surfaces on the present-day porosity and permeability. Carbonate lithofacies include mudstones, packstones, grainstones, and rudstones and gas-porosimetry measurements show effective porosity up to 5 %. The value is mainly due to the secondary porosity localized along microfractures and within the rough bed-parallel and rough bed-oblique solution surfaces, contrary to what was found in the smooth bed-parallel ones, showing that roughness can control pore localization. NMR (Nuclear Magnetic Resonance) results indicate that the former group of solution surfaces include vugs characterized by subspherical to tubular shapes (pore throat r < 3 μm), and low aspect ratios (r < 2), forming pores with low sensitivity to compression. The microfractures form capillary porosity (r ≈ 1 μm) and are characterized by high aspect ratios (r > 2), typical of pores with high sensitivity to compression. Permeability measurements at room pressure reveal that samples with visible microfractures are characterized by values up 2 order magnitude greater than of those with only visible solution surfaces, showing that the pore connectivity is controlled by opening-mode, sub-mm scale microfractures. At confining pressures greater than 25 MPa, both fracture- and stylolite dominated samples show similar values of permeability, indicating that at depths larger than ca. 1 km, the rough stylolite localize effective porosity that may enhance the along-solution surface fluid flow in carbonates.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105520"},"PeriodicalIF":2.9,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-07-31DOI: 10.1016/j.jsg.2025.105517
Hugo W. van Schrojenstein Lantman , Patricia A. Carvalho , David Wallis , Luca Menegon
Pseudotachylytes in the metamorphosed anorthosites of the Lofoten archipelago, Norway, preserve a record of seismic rupture in dry lower crust at temperatures and pressures of 650–750 °C and 0.8 GPa. Transient gigapascal-level stresses are suggested from microstructural evidence, however such high stresses have not been quantified. In this contribution, we combine microstructural analysis with the mapping of heterogeneity in residual stress in diopside from a lower-crustal pseudotachylyte from Nusfjord (Lofoten) using high-angular resolution electron backscatter diffraction (HR-EBSD). We aim to elucidate the deformation processes that led to this residual stress and to its spatial heterogeneity in the diopside grains.
The diopside contains micro-to nanoscale deformation twins within 3 mm of the fault and in clasts in the pseudotachylyte. Within clasts, the diopside lattice strongly undulates, indicating crystal plasticity at high driving stress. Residual stress heterogeneity ranges between ∼200 MPa and ∼800 MPa for in-plane normal stress, with greater values occurring closer to and in the pseudotachylyte. This trend is not apparent for the in-plane shear stress, which has residual stress heterogeneity between ∼150 and ∼250 MPa, not correlating with distance to the fault. The greatest residual stresses are present in a clast that exhibits lattice distortion resulting from dislocation glide. Mechanical twins, lattice undulations, and the distribution patterns of residual stress are truncated by coseismic fractures, suggesting that the microstructures and residual stress are the result of stress build-up prior to slip.
Given the extreme spatial localization of the residual stress heterogeneity, we conclude that it results from deformation occurring during earthquake rupture propagation. Despite high temperatures during frictional heating, thermal pressure did not contribute significantly to the residual stress. The behaviour of diopside as a stress recorder is influenced by mechanical twins: stress build-up in diopside may have partially dissipated by the formation of twins, and twins also appear to affect the residual stress, in particular shear stress.
{"title":"Residual stress in diopside: insight into localized transient high stress in seismogenic faults in the lower crust, Lofoten, Norway","authors":"Hugo W. van Schrojenstein Lantman , Patricia A. Carvalho , David Wallis , Luca Menegon","doi":"10.1016/j.jsg.2025.105517","DOIUrl":"10.1016/j.jsg.2025.105517","url":null,"abstract":"<div><div>Pseudotachylytes in the metamorphosed anorthosites of the Lofoten archipelago, Norway, preserve a record of seismic rupture in dry lower crust at temperatures and pressures of 650–750 °C and 0.8 GPa. Transient gigapascal-level stresses are suggested from microstructural evidence, however such high stresses have not been quantified. In this contribution, we combine microstructural analysis with the mapping of heterogeneity in residual stress in diopside from a lower-crustal pseudotachylyte from Nusfjord (Lofoten) using high-angular resolution electron backscatter diffraction (HR-EBSD). We aim to elucidate the deformation processes that led to this residual stress and to its spatial heterogeneity in the diopside grains.</div><div>The diopside contains micro-to nanoscale deformation twins within 3 mm of the fault and in clasts in the pseudotachylyte. Within clasts, the diopside lattice strongly undulates, indicating crystal plasticity at high driving stress. Residual stress heterogeneity ranges between ∼200 MPa and ∼800 MPa for in-plane normal stress, with greater values occurring closer to and in the pseudotachylyte. This trend is not apparent for the in-plane shear stress, which has residual stress heterogeneity between ∼150 and ∼250 MPa, not correlating with distance to the fault. The greatest residual stresses are present in a clast that exhibits lattice distortion resulting from dislocation glide. Mechanical twins, lattice undulations, and the distribution patterns of residual stress are truncated by coseismic fractures, suggesting that the microstructures and residual stress are the result of stress build-up prior to slip.</div><div>Given the extreme spatial localization of the residual stress heterogeneity, we conclude that it results from deformation occurring during earthquake rupture propagation. Despite high temperatures during frictional heating, thermal pressure did not contribute significantly to the residual stress. The behaviour of diopside as a stress recorder is influenced by mechanical twins: stress build-up in diopside may have partially dissipated by the formation of twins, and twins also appear to affect the residual stress, in particular shear stress.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105517"},"PeriodicalIF":2.9,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Neoarchean era marks a pivotal period in Earth's tectonic evolution and continental crust formation. In this context, crustal architecture and structural patterns serve as key indicators for reconstructing Neoarchean geodynamic processes. The Western Shandong Province (WSP) granite-greenstone belt, located in the North China Craton (NCC), preserves well-exposed Neoarchean rock assemblages and provides valuable insights into the Neoarchean tectonics. In this study, we conducted systematic geological mapping and detailed structural analysis, integrated with LA-ICP-MS zircon U-Pb geochronology, in the Qixingtai region of the WSP. Three stages of compressional deformation (D1 to D3) were identified. The earliest deformation D1, predating ∼2663 Ma, is characterized by NW-SE-trending, sub-vertically penetrative S1 foliation in early Neoarchean supracrustal rocks and TTG rocks, indicating an initial NE-SW compressional regime. This was followed by a regional extension during 2.60-2.55 Ga and deposition of the Shancaoyu Formation during 2.55-2.52 Ga. The subsequent deformation D2 (∼2520-2514 Ma) progressively overprinted earlier structures and generated NW-SE-trending upright isoclinal folds in late Neoarchean supracrustal and TTG rocks, indicating a consistent and prolonged compressive stress field. The last deformation D3, occurring around ∼2500 Ma, resulted in the development of ductile shear zones of variable scales along the major lithological boundaries and generated regional L-S tectonites with near-vertical foliation and horizontal lineation. Our results suggest that the WSP experienced a long-lasting NE–SW compressive stress field throughout the Neoarchean but lacks diagnostic features of typical subduction or collisional belts. Combined with previous studies, we propose a tectonic model for the tectonic evolution of the Qixingtai area. This area initially developed from an oceanic plateau in the early Neoarchean, experienced regional extension in the middle Neoarchean, and ultimately underwent extensive magmatism and horizontal shortening during the late Neoarchean.
{"title":"Multi-phase deformation in the Qixingtai region of Western Shandong Province: insights into the Neoarchean tectonic evolution of the eastern North China Craton","authors":"Shuhui Zhang , Jian Zhang , Guochun Zhao , Qihang Wu , Chen Zhao , Xiaoguang Liu , Changqing Yin , Jiahui Qian , Mingtao He","doi":"10.1016/j.jsg.2025.105516","DOIUrl":"10.1016/j.jsg.2025.105516","url":null,"abstract":"<div><div>The Neoarchean era marks a pivotal period in Earth's tectonic evolution and continental crust formation. In this context, crustal architecture and structural patterns serve as key indicators for reconstructing Neoarchean geodynamic processes. The Western Shandong Province (WSP) granite-greenstone belt, located in the North China Craton (NCC), preserves well-exposed Neoarchean rock assemblages and provides valuable insights into the Neoarchean tectonics. In this study, we conducted systematic geological mapping and detailed structural analysis, integrated with LA-ICP-MS zircon U-Pb geochronology, in the Qixingtai region of the WSP. Three stages of compressional deformation (D1 to D3) were identified. The earliest deformation D1, predating ∼2663 Ma, is characterized by NW-SE-trending, sub-vertically penetrative S1 foliation in early Neoarchean supracrustal rocks and TTG rocks, indicating an initial NE-SW compressional regime. This was followed by a regional extension during 2.60-2.55 Ga and deposition of the Shancaoyu Formation during 2.55-2.52 Ga. The subsequent deformation D2 (∼2520-2514 Ma) progressively overprinted earlier structures and generated NW-SE-trending upright isoclinal folds in late Neoarchean supracrustal and TTG rocks, indicating a consistent and prolonged compressive stress field. The last deformation D3, occurring around ∼2500 Ma, resulted in the development of ductile shear zones of variable scales along the major lithological boundaries and generated regional L-S tectonites with near-vertical foliation and horizontal lineation. Our results suggest that the WSP experienced a long-lasting NE–SW compressive stress field throughout the Neoarchean but lacks diagnostic features of typical subduction or collisional belts. Combined with previous studies, we propose a tectonic model for the tectonic evolution of the Qixingtai area. This area initially developed from an oceanic plateau in the early Neoarchean, experienced regional extension in the middle Neoarchean, and ultimately underwent extensive magmatism and horizontal shortening during the late Neoarchean.</div></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":"200 ","pages":"Article 105516"},"PeriodicalIF":2.9,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144750594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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