Journal of Structural Geology最新文献

{"title":"Multiscale fracture, physical and mechanical properties of stromboli volcano (Italy) edifice","authors":"T. Alcock ,&nbsp;S. Vinciguerra ,&nbsp;P.M. Benson ,&nbsp;D. Bullen","doi":"10.1016/j.jsg.2024.105155","DOIUrl":"10.1016/j.jsg.2024.105155","url":null,"abstract":"<div><p>The physical, mechanical and fracture properties at Stromboli volcano have been integrated at multiple scales to understand whether the interplay between a presumed NE/SW rift zone and the Sciara del Fuoco (SDF) depression has resulted in a zone of weakness able to promote fracturing prone to flank instability. Multiscale fracture quantification by imaging via FracPaQ toolbox both fractures and sample scale fractures has been integrated with rock physics and rock mechanics experiments on cm-scale samples belonging to the Paleostromboli, Vancori, Neostromboli, Pizzo and Present Deposit volcanic cycles that have been taken from within and outside the rift zone. The structural changes to the edifice have been quantitively assessed by mapping at different scale fracture properties such density and orientation within and outside the rift zone allowing to identify the potential damaged zones that could reduce the edifice strength.</p><p>Results indicate that basalt textures, microfracture density, porosity, chemical zoning and preferential alignments, despite lithologically dependent, can be related to the NE/SW zone of weakness at the regional scale and to collapsed volumes that have been subject to continuous intrusive activity. Numerical inversion models have been performed to cross correlate fracture density in the basalts at multiple scales.</p><p>A link between microfracture density and seismic velocities has been also established via numerical modelling, allowing to interpret in terms of degree of fracturing the results of seismic tomographies at the field scale, providing a novel method to image crack damage evolution within the inner structure of the volcano edifice.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S019181412400107X/pdfft?md5=c47e19e60392f90be0911ad102fccfe9&pid=1-s2.0-S019181412400107X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141053441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discrete element modeling of distal deformation propagation in thrust wedge and implications for early deformation on northern Tibetan and Iranian Plateaus","authors":"Chao Zhou ,&nbsp;Jiankun He ,&nbsp;Hao Su ,&nbsp;Weimin Wang ,&nbsp;Xinguo Wang ,&nbsp;Youjia Zhao ,&nbsp;Yong Jiang","doi":"10.1016/j.jsg.2024.105150","DOIUrl":"https://doi.org/10.1016/j.jsg.2024.105150","url":null,"abstract":"<div><p>Coulomb critical wedge theory predicts that thrust wedges would grow sequentially from the hinterland to the foreland, meaning that distal deformation occurs last. However, in the northern Tibetan and Iranian Plateaus, far away from the southern collision zones, widespread deformation occurs soon after collisions of Arabia and India with Eurasia. Additionally, despite the prevalence of weak lower crust and distal pre-existing faults or weak zones, their relationship to early distal deformation remains poorly understood. For this reason, we run systematic experiments of discrete element models involving basal décollement layer as well as distal pre-existing fault. Our model results reveal that (1) the presence of pre-existing faults is necessary for the occurrence of early distal deformation; (2) the early deformation of distal pre-existing fault is dependent on basal décollement strength and independent of model width; (3) strong basal décollement fails to activate the distal pre-existing faults, instead weak basal décollement can deform them at the early stage; (4) in the presence of weak basal décollement, a slower shortening rate not only facilitates greater shortening absorption by the distal pre-existing fault at the early stage but also results in a more pronounced deviation from sequentially-forward deformation propagation. These findings demonstrate that the preferential reactivation deformations of distal pre-existing faults are mechanically controlled by a weak basal décollement layer. Together with geological and geophysical observations, we suggest that the early deformations of northern Tibetan and Iranian Plateaus may be the result of the reactivation of pre-existing faults due to the existence of weak lower crust soon after collisions.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140918030","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":"Correction of linear fracture density and error analysis using underground borehole data","authors":"Dongsheng Cao ,&nbsp;Lianbo Zeng ,&nbsp;Enrique Gomez-Rivas ,&nbsp;Lei Gong ,&nbsp;Guoping Liu ,&nbsp;Guoqing Lu ,&nbsp;Paul D. Bons","doi":"10.1016/j.jsg.2024.105152","DOIUrl":"10.1016/j.jsg.2024.105152","url":null,"abstract":"<div><p>Fracture data acquired from drill core and borehole image logs require corrections for the bias due to fracture orientation, that are usually achieved by the Terzaghi correction technique. Previous studies often approximate the wellbore as a one-dimensional scanline, assuming that the length of the core axis within the sampling range is equal to the scanline length. This study refers to the commonly used workflow as the original Terzaghi correction method which is known to perform poorly when the angle (<em>θ</em>) between the core axis and the fracture is small. To address this issue, we propose an extension of the Terzaghi correction method that also considers the core diameter and is a function of both the fractures and the host layer dipping angle. The new method resolves the fracture density problem by selecting a new direction for the scanline perpendicular to the fracture and calculating the projection length of the sampling space in this direction. The fracture spatial arrangements and observed number of sampled fractures mainly affect the performance of this new approach. However, possible errors in the new correction method pertaining to the equidistant fracture density should decrease with increasing number of sampled fractures. It is found that an acceptable correction range exists for equidistant fracture density, though, when the corrected density is not within the acceptable correction range, the observed sampled fractures will not be equal to the true observed value. This means the corrected fracture density would be in an unacceptable range of errors. Moreover, the new method can provide results within the acceptable range when the angle between the fracture and the core axis is less than 20°. At the same time, this new method is free from other disadvantages in the original Terzaghi correction method, particularly, when the ratio of layers’ thickness to the core diameter is low. Therefore, the improved approach presented here is especially applicable to thin layers (no more than two times the core diameter) and conditions where the angle between the fracture and the core axis is less than 20°, which can contribute to fracture density characterization in the subsurface.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141041845","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 case of paleoseismic evidence of normal fault capable of triggering an M>8 earthquake − study on Sertengshan range-front fault, north margin of Hetao Basin, China","authors":"Haowen Ma ,&nbsp;Shaopeng Dong","doi":"10.1016/j.jsg.2024.105145","DOIUrl":"https://doi.org/10.1016/j.jsg.2024.105145","url":null,"abstract":"<div><p>The Sertengshan Range-front Fault (SRF) and Langshan Range-front Fault (LRF) constitute a normal fault system on the northern boundary of the Linhe Depression in its northwest, and an investigation of the LRF–SRF is significant for understanding the seismic activities of normal faults. We set four trenches at three study sites to reveal paleo-earthquakes in the western segment of the SRF (W-SRF) in this system, and established 5 surface rupture events along W-SRF since the Late Pleistocene. By integrating paleoseismic data from 27 trenches on multiple fault segments, we reconstructed the paleoseismic sequence for the LRF–SRF region since 15 ka, and identified 10 paleoseismic events with corresponding rupture segments and magnitudes. The slip rates at the three study sites decreased gradually from the west to east on the W-SRF, by comparing with previous studies, further evidencing that the tectonic activities of the two faults have gradually synchronized. Besides, based on the timing of the latest paleoseismic event (1.88−2.03 ka BP), earthquakes of &gt; M 8 surface ruptures of &gt;200 km can occur in the northwestern Ordos Block and its seismic behavior revealed the seismogenic possibility of normal faults triggering an M &gt; 8 earthquake.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140910250","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":"Deformation, evolution and controls of halokinetic megaflaps driven by vertically-stacked and laterally-shifting depocenters","authors":"O. Ferrer ,&nbsp;E. Roca ,&nbsp;M.G. Rowan ,&nbsp;J.A. Muñoz ,&nbsp;K.A. Giles ,&nbsp;O. Gratacós","doi":"10.1016/j.jsg.2024.105149","DOIUrl":"https://doi.org/10.1016/j.jsg.2024.105149","url":null,"abstract":"<div><p>Megaflaps comprise steeply dipping to overturned panels of the oldest suprasalt strata flanking steep diapirs, and represent the roofs of early inflated salt. These large-scale structures result from salt-sediment interaction at minibasin scales and entail multiple kilometres of folding and vertical relief. They are divided into two end-member types (halokinetic and contractional) and form by some combination of limb rotation and kink-band migration. They can be difficult to image and interpret adjacent to flaring diapirs and beneath allochthonous salt due to steep bedding dips and suboptimal illumination.</p><p>Using physical models, we investigate halokinetic megaflaps driven by differential loading. Models with vertically-stacked vs. laterally-shifting loading above a prekinematic layer have been run to determine the main processes and mechanisms controlling the growth and kinematic evolution of megaflaps. Parameters such as the thickness of the prekinematic cover, the width of the proto-salt wall, the synkinematic sedimentation rate, and variations in the mechanical properties of the prekinematic cover have been tested to evaluate their role in megaflap generation. The experimental results demonstrate that in absence of tectonic forces, halokinetic megaflaps are generated by a combination of 1) an early increase of pressure-head gradient between two adjacent minibasins with different rates of sedimentation and subsidence, and 2) the disappearance of this gradient that occurs when welding occurs beneath the more quickly subsiding minibasin. The geometry, kinematic evolution, and degree of small-scale deformation of the megaflaps in our analogue models are consistent with both exposed (e.g., Paradox Basin) and seismically imaged halokinetic megaflaps (e.g., deepwater northern Gulf of Mexico).</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0191814124001019/pdfft?md5=9a82c7aa13c497a65edb7e9a85fbaa7a&pid=1-s2.0-S0191814124001019-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140902441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analogue modelling of a salt ridge growth in M'Rhila-Labaied-Trozza fault relay zone, central Tunisia","authors":"Rim Zidi ,&nbsp;Nedhir Sebai ,&nbsp;Bruno C. Vendeville ,&nbsp;Oriol Ferrer ,&nbsp;Ferid Dhahri ,&nbsp;Wael Boudegga ,&nbsp;Mohamed Dhaoui","doi":"10.1016/j.jsg.2024.105147","DOIUrl":"10.1016/j.jsg.2024.105147","url":null,"abstract":"<div><p>Tunisia, located in the Northern African margin, was subjected to Late Permian-Early Cretaceous N–S extension subsequent to Pangea breakup and leading to the Tethyan opening and widening. During the Mid- and Late Cretaceous, the NE–SW crustal extension that established the Pantelleria-Malta-Sirt grabens system underlining the eastern margin stretched also the Tunisian Atlassic domain, creating and/or reactivating many NW-SE extensional structures as much as the grabens in central Tunisia and leading to volcanism and halokinesis along several weak zones. Neogene compressional tectonics inverted the earlier extensional structures and impacted most of the halokinetic features established within the post-Triassic cover. The M'Rhila-Labaied-Trozza fault relay zone, located in the middle of central Tunisia, shows both extensional and compressional structures with Triassic extrusive features and seems to be a key feature for understanding the geodynamic development of the area. In this work, we combined field and geophysical data together with analogue models to decipher the structure and the kinematic evolution of the study area. The results showed that the studied structures are associated with reactive Mesozoic salt ridges established along an extensional fault relay zone that utilized NW-SE, E-W and NE-SW inherited fractures. These initially created extensional corridors allowing Triassic evaporite extrusion and accumulation, then influenced the deformation of the area in transpressional and local pure compressional regimes depending on the fractures and stress orientations during tectonic inversion. Analogue guided interpretation of the successive deformational stages of the study area from salt ridge growth to its tectonic inversion.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141044490","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":"Salt-pillow formation during inversion of evaporite-filled half graben – Insights from seismic data interpretation and integrated analogue-numerical modelling","authors":"P. Krzywiec ,&nbsp;M. Adamuszek ,&nbsp;L. Filbà ,&nbsp;M.G. Rowan ,&nbsp;O. Ferrer","doi":"10.1016/j.jsg.2024.105148","DOIUrl":"https://doi.org/10.1016/j.jsg.2024.105148","url":null,"abstract":"<div><p>The Mid-Polish Anticlinorium is a regional structure that formed during Late Cretaceous inversion of the Permian-Mesozoic Polish Basin. Within the anticlinorium, local salt pillows built of the Upper Permian (Zechstein) evaporites are often located above reverse faults that accommodated basement inversion. Seismic data from the Szubin area in central Poland were used to guide a combined analogue and numerical modelling study to test whether locally thicker evaporites deposited within a half-graben, could indeed give rise to a salt pillow formed above the half-graben's hanging wall during its inversion. The results of the two approaches are internally consistent and prove that such a genetic relationship is fully viable, with the most important variables being the size of the half-graben, the viscosity of the salt, and the presence of any erosion of the pillow structure. Thus, the existence of salt pillows along the major inversion zones of the Mid-Polish Anticlinorium could possibly be used as indicators for the location of syn-depositional half-grabens during deposition of the Zechstein evaporites. This in turn might suggest that even in the basin center, shallower areas might have existed above the footwalls of such half-graben during Zechstein deposition, characterized by smaller thicknesses and somewhat different facies arrangement. Similar concepts likely apply to other intracontinental salt basins that experienced rifting and then inversion.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0191814124001007/pdfft?md5=fa75228b5078d10323da1b9cace61637&pid=1-s2.0-S0191814124001007-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140902442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanoscale visualization of high-angle misorientations in quartz-rich rocks using SEM-EBSD and Atomic Force Microscopy","authors":"Soham Dey ,&nbsp;Sandro Chatterjee ,&nbsp;Sushree Ritu Ritanjali ,&nbsp;Ritabrata Dobe ,&nbsp;Rabibrata Mukherjee ,&nbsp;Sumantra Mandal ,&nbsp;Saibal Gupta","doi":"10.1016/j.jsg.2024.105146","DOIUrl":"https://doi.org/10.1016/j.jsg.2024.105146","url":null,"abstract":"<div><p>High-angle misorientations can significantly influence material properties. In this study, optical microscopy, Scanning Electron Microscope-Electron Backscatter Diffraction (SEM-EBSD), and Atomic Force Microscopy (AFM) have been used to investigate high-angle misorientations in quartz-bearing crustal rocks. Thin sections of high-grade quartzofeldspathic rocks were subjected to chemical mechanical polishing (CMP) with colloidal silica. In quartz, high-angle misorientations like random high angle grain boundaries (RHAGBs) and Dauphiné twin boundaries (DTBs) could be discriminated using EBSD techniques but not optical microscopy. In nanoscale AFM images, indented channels are observed along RHAGBs but not DTBs; these result from material removal during CMP, indicating lower compactness of RHAGBs compared to DTBs. Along any RHAGB, EBSD reveals different misorientations across segments between consecutive RHAGB-DTB intersections. Grains adjacent to these RHAGB segments have angles between their c-axes varying from 61-66° with parallel {<span><math><mrow><mrow><mn>10</mn><mover><mn>1</mn><mo>‾</mo></mover><mn>2</mn></mrow><mo>}</mo></mrow></math></span> planes, and 81–84° with parallel {<span><math><mrow><mn>11</mn><mover><mn>2</mn><mo>‾</mo></mover><mn>2</mn></mrow></math></span>} planes, respectively. These symmetries represent the Japan and Sardinian twin laws of quartz, indicating that the RHAGB segments become low-energy twin boundaries, thereby reducing the overall surface energy of the aggregate. Finally, these results suggest that apart from surface topography quantification and high-resolution nanoscale imaging, AFM in conjunction with SEM-EBSD can be used for precisely locating sites for TEM study.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140825122","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":"Salt-related gravity-driven processes in the Levant Basin, Eastern Mediterranean: Insights from physical modeling","authors":"Th. Anagnostoudi ,&nbsp;B.C. Vendeville ,&nbsp;V. Gaullier ,&nbsp;O. Ferrer ,&nbsp;U. Schattner ,&nbsp;M. Lazar","doi":"10.1016/j.jsg.2024.105134","DOIUrl":"https://doi.org/10.1016/j.jsg.2024.105134","url":null,"abstract":"<div><p>The characterization of salt tectonics and its gravity-driven deformation processes are the key to a better understanding of the structural evolution of salt-bearing rifted margins. Unlike most salt basins that have experienced long-lasting deformation, the Messinian evaporites in the Levant Basin have been moderately deformed, offering the opportunity to study the early stage of salt tectonic deformation. Despite the availability of seismic reflection, borehole and bathymetrical data, some uncertainties still exist about the mechanisms responsible for the deformation and structural features observed in the deep-water Levant Basin. Our study includes physical experiments based on published seismic and structural interpretations conducted in the Levant Basin. Our physical experiments take into consideration the main driving parameters that controlled the development of the deep-water Levant Basin, testing the interplay and impact of gravity gliding and spreading from the Levant Margin, gravity spreading from the Nile Deep Sea Fan, and the influence of the passive buttress of the Eratosthenes Seamount. Deformation was imposed by depositing successive sand lobes and/or by tilting the experimental table. The physical models included a thick viscous silicone layer, analogue of the Messinian evaporitic sequence, overlain by a granular overburden, simulating the brittle clastic post-Messinian succession. Results show that the prominent gravity-driven force affecting the deformation pattern of the deep-water Levant Basin is the gravity spreading from the Nile Deep Sea Fan, whereas gravity spreading and gliding from the Levant Margin affect only the proximal to the margin areas. Additionally, the buttressing effect of the Eratosthenes Seamount and the location of the salt basin pinch-out played an important role in the final deformation pattern of this region of the Eastern Mediterranean.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140818249","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":"In-situ rock shattering and strain localization along a seismogenic fault in dolostones (Monte Marine fault, Italian Central Apennines)","authors":"S. Cortinovis ,&nbsp;M. Fondriest ,&nbsp;F. Balsamo ,&nbsp;A. Lucca ,&nbsp;F. La Valle ,&nbsp;M. Pizzati ,&nbsp;F. Storti ,&nbsp;G. Di Toro","doi":"10.1016/j.jsg.2024.105144","DOIUrl":"https://doi.org/10.1016/j.jsg.2024.105144","url":null,"abstract":"<div><p><em>In-situ</em> shattered rocks are often associated with seismogenic fault zones, but their mechanism of formation is still matter of debate, partly because of the limited number of field studies. Here we describe the characteristics of <em>in-situ</em> shattered rocks distribution along the NW-SE-striking seismogenic Monte Marine Fault (MMF) in the Italian Central Apennines. In the studied area, the MMF cuts through Mesozoic carbonates, is exhumed from &lt;3 km depth and consists of two &gt;5 km-long major hard-linked segments with normal kinematics. The linkage between the two fault segments occurs along a ∼2 km-long step-over zone with E-W trending faults and oblique-slip kinematics. To the northwest, fault-related shear deformation is localized in a ∼5 m-thick cataclastic fault core and off-fault deformation is dominated by <em>in-situ</em> shattered rocks up to ∼40 m-thick. Instead, in the step-over zone to the southeast, the <em>in-situ</em> shattered rocks are up to ∼500 m thick, particularly where MMF crosscuts older low-angle thrust faults.</p><p>We integrated detailed field structural surveys with microstructural and grain size distribution analyses of the fault rocks to assess the mechanism of (1) formation of <em>in-situ</em> shattered rocks and, (2) progressive localization of shear deformation along the MMF. The obtained results, after the viability of several formation mechanisms (mechanical models) have been reviewed, support the hypothesis that the formation of <em>in-situ</em> shattered rocks was associated with the propagation of (multiple) seismic ruptures (mainshocks and aftershock sequences) within a mechanically heterogeneous fault zone. Heterogeneity is due to the occurrence of preexisting damage related to previous earthquakes, but also inherited from the older low-angle thrust faults. Therefore, we suggest that the origin of these shattered rocks is more compatible with seismic related processes than only with quasi-static fault growth models. On the other hand, the cataclastic fault core derived from the progressive accommodation of shear deformation within the <em>in-situ</em> shattered rock volumes during several seismic cycles. We conclude that the large volumes of <em>in-situ</em> shattered rocks are the result of seismic-related dissipative processes in a geometrically and mechanically heterogeneous fault zone. In this scenario, large volumes of <em>in-situ</em> shattered rocks are compliant low velocity zones which can influence the propagation of earthquake ruptures.</p></div>","PeriodicalId":50035,"journal":{"name":"Journal of Structural Geology","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0191814124000968/pdfft?md5=d934e7ba51bcb3bd274e9c5268194e37&pid=1-s2.0-S0191814124000968-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140825071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}