The Deccan Volcanic Province (DVP), formed ∼65 Ma during India's northward drift and linked to the Réunion plume, reveals complex upper-mantle structures. This study uses P receiver function (RF) analysis from 76 broadband stations in Gujarat, Western India, to image upper-mantle discontinuities (d410 and d660) beneath the north-western DVP. RF depth migration was performed using 1-D and 3-D tomographic velocity models—GYPSUM, LLNL-G3Dv3, MEAN2, and a combined regional model (up to 300 km depth) incorporating LLNL-G3Dv3. The estimated mantle transition zone (MTZ) thickness varies from 233 to 248 km in Kachchh, Saurashtra, Cambay, South Gujarat, and the Arabian Sea, while in North Gujarat and the Narmada rift zones; it ranges from 251 to 255 km. The d410 discontinuity exhibits a uniform depression (410–430 km), whereas the d660 remains normal to slightly deepened (650–675 km). The eastern North Gujarat, Narmada zone, and parts of Kachchh exhibit a shallow 410 km and depressed 660 km discontinuity, indicating MTZ thickening. The Cambay thermal anomaly, bounded by these colder regions, likely reflects localized small-scale upwelling coupled with the downwelling of ancient subducted slab remnants. Additionally, 520 km discontinuity was detected, with amplitude peaks suggesting a low-velocity layer above d410. The Mean excess temperatures associated with d410 and d660depressions are ∼150 K and ∼ 323 K, respectively. MTZ structure, thermal anomalies, and mantle velocity heterogeneities collectively indicate plume–lithosphere interaction influenced by relic slab dynamics in the genesis of Deccan volcanism.
{"title":"Mantle transition zone dynamics beneath the Northwestern Deccan Volcanic Province, India: Implications for plume mediated upper mantle processes","authors":"Rema Vaishali , Madhusudhanarao Katlamudi , Ayoub Kaviani , Georg Rümpker","doi":"10.1016/j.tecto.2025.231000","DOIUrl":"10.1016/j.tecto.2025.231000","url":null,"abstract":"<div><div>The Deccan Volcanic Province (DVP), formed ∼65 Ma during India's northward drift and linked to the Réunion plume, reveals complex upper-mantle structures. This study uses P receiver function (RF) analysis from 76 broadband stations in Gujarat, Western India, to image upper-mantle discontinuities (d410 and d660) beneath the north-western DVP. RF depth migration was performed using 1-D and 3-D tomographic velocity models—GYPSUM, LLNL-G3Dv3, MEAN2, and a combined regional model (up to 300 km depth) incorporating LLNL-G3Dv3. The estimated mantle transition zone (MTZ) thickness varies from 233 to 248 km in Kachchh, Saurashtra, Cambay, South Gujarat, and the Arabian Sea, while in North Gujarat and the Narmada rift zones; it ranges from 251 to 255 km. The d410 discontinuity exhibits a uniform depression (410–430 km), whereas the d660 remains normal to slightly deepened (650–675 km). The eastern North Gujarat, Narmada zone, and parts of Kachchh exhibit a shallow 410 km and depressed 660 km discontinuity, indicating MTZ thickening. The Cambay thermal anomaly, bounded by these colder regions, likely reflects localized small-scale upwelling coupled with the downwelling of ancient subducted slab remnants. Additionally, 520 km discontinuity was detected, with amplitude peaks suggesting a low-velocity layer above d410. The Mean excess temperatures associated with d410 and d660depressions are ∼150 K and ∼ 323 K, respectively. MTZ structure, thermal anomalies, and mantle velocity heterogeneities collectively indicate plume–lithosphere interaction influenced by relic slab dynamics in the genesis of Deccan volcanism.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"918 ","pages":"Article 231000"},"PeriodicalIF":2.6,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145509780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-11-12DOI: 10.1016/j.tecto.2025.231001
Chongjin Zhao, Luolei Zhang, Huang Zuwei, Peng Yu
The Lower Yangtze region lies between the North China Craton and Cathaysia Block; yet, the offshore continuity of major sutures and the role of inherited basement faults remain debated. We integrate 3-D inversions of regional magnetic and gravity data for crustal framework imaging without reduction-to-the-pole. In particular, we perform magnetic inversion directly on the total magnetic intensity (TMI) under oblique field geometry, coupled with a sharp-boundary gravity inversion to the TMI-derived magnetic basement. Petrophysical ranges for densities and susceptibilities provide the sole priors, and edges are mapped with a tilt–hyperbolic–vertical–horizontal (THVH) operator. Misfits reach observational noise levels, and the recovered volumes resolve long- to intermediate-wavelength structures. Magnetization is concentrated beneath the East China Sea shelf and southern South Yellow Sea, while 10–20 km density slices delineate alternating uplift–depression couplets. Three surfaces (i.e., the Magnetic-basement top, Paleozoic-basement proxy depth, and Proterozoic residual-thickness proxy) define coherent gradients that, together with THVH ridges, map a consistent fault framework. We infer (i) an eastward offshore continuation of the Jiangshan–Shaoxing Fault that bends northeast and is truncated near the southwestern margin of Jeju Island; (ii) a lithosphere-scale Yangtze–North China boundary coincident with the Korea–West Fault; and (iii) four inherited NE–EW faults that segment the region into alternating uplifts and depressions. The architecture supports Late Cretaceous back-arc extension and selective reactivation of Precambrian discontinuities.
{"title":"Revealing deep-rooted pre-Paleozoic fault systems in the lower Yangtze region: Insights from 3D magnetic inversion and gravity inversion and integrated geophysical interpretation","authors":"Chongjin Zhao, Luolei Zhang, Huang Zuwei, Peng Yu","doi":"10.1016/j.tecto.2025.231001","DOIUrl":"10.1016/j.tecto.2025.231001","url":null,"abstract":"<div><div>The Lower Yangtze region lies between the North China Craton and Cathaysia Block; yet, the offshore continuity of major sutures and the role of inherited basement faults remain debated. We integrate 3-D inversions of regional magnetic and gravity data for crustal framework imaging without reduction-to-the-pole. In particular, we perform magnetic inversion directly on the total magnetic intensity (TMI) under oblique field geometry, coupled with a sharp-boundary gravity inversion to the TMI-derived magnetic basement. Petrophysical ranges for densities and susceptibilities provide the sole priors, and edges are mapped with a tilt–hyperbolic–vertical–horizontal (THVH) operator. Misfits reach observational noise levels, and the recovered volumes resolve long- to intermediate-wavelength structures. Magnetization is concentrated beneath the East China Sea shelf and southern South Yellow Sea, while 10–20 km density slices delineate alternating uplift–depression couplets. Three surfaces (i.e., the Magnetic-basement top, Paleozoic-basement proxy depth, and Proterozoic residual-thickness proxy) define coherent gradients that, together with THVH ridges, map a consistent fault framework. We infer (i) an eastward offshore continuation of the Jiangshan–Shaoxing Fault that bends northeast and is truncated near the southwestern margin of Jeju Island; (ii) a lithosphere-scale Yangtze–North China boundary coincident with the Korea–West Fault; and (iii) four inherited NE–EW faults that segment the region into alternating uplifts and depressions. The architecture supports Late Cretaceous back-arc extension and selective reactivation of Precambrian discontinuities.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"918 ","pages":"Article 231001"},"PeriodicalIF":2.6,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145515682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-11-12DOI: 10.1016/j.tecto.2025.231002
Cong Cao , Lingqiang Zhao , Yan Zhan , Yanfu Qi , Xiangyu Sun , Xiong Yang , Hongbin Lv , Qingliang Wang , Bowen Hou , Wenwen Qi
The Yitong Volcanic Area (YVA) in Jilin Province is a relatively rare “compression type” volcanic system worldwide. Its formation mechanism and eruption mode have unique features. The Yilan-Yitong Fault (YYF) runs through this volcanic rock belt and has demonstrated prominent segmented fracture characteristics since the Quaternary Period. The paleoseismic activity of the Yitong Fault Zone (YFZ) is different from that of other fault zones within this area. This study aimed to investigate the deep magma system in the YVA and its influence on the segmented activities of YYF. Magnetotelluric (MT) measurements were performed in the YVA. A total of 87 MT sites were arranged in the area. A high-resolution three-dimensional (3D) electrical structure model of the lithospheric scale from the crust to the upper mantle in the study area was established with the 3D inversion method. This model suggests that the shallow section of the upper crust of the YVA and the northwestern part of the Songliao Basin were mainly low-resistivity zones, which corresponded to the widely distributed sedimentary layers in this area. The middle and lower crust in the study area was primarily a complete high-resistivity body. A large-scale magmatic system began to appear at a depth of 25 km in the YVA. This magmatic system continued to extend downward, exceeding 70 km. The magma chamber in the YVA was in contact with the YYF in the lower crust. The YYF was the dominant material surging upward through the magma channel. Additionally, deep magmatic activities exerted a crucial influence on the seismic rupture segmentation characteristics along the YYF and the uplift mechanism of the Yitong Basin. The results of this study provide crucial geophysical constraints for depicting the fine depth structure of the YVA while enlightening the investigation of the rupture propagation mechanism within the volcanic terrain fault zone.
{"title":"3D magnetotelluric imaging of lithospheric magmatic systems in the Yitong Volcanic Area, Northeast China: Implications for fault-zone segmentation and seismic rupture dynamics along the Yilan-Yitong Fault","authors":"Cong Cao , Lingqiang Zhao , Yan Zhan , Yanfu Qi , Xiangyu Sun , Xiong Yang , Hongbin Lv , Qingliang Wang , Bowen Hou , Wenwen Qi","doi":"10.1016/j.tecto.2025.231002","DOIUrl":"10.1016/j.tecto.2025.231002","url":null,"abstract":"<div><div>The Yitong Volcanic Area (YVA) in Jilin Province is a relatively rare “compression type” volcanic system worldwide. Its formation mechanism and eruption mode have unique features. The Yilan-Yitong Fault (YYF) runs through this volcanic rock belt and has demonstrated prominent segmented fracture characteristics since the Quaternary Period. The paleoseismic activity of the Yitong Fault Zone (YFZ) is different from that of other fault zones within this area. This study aimed to investigate the deep magma system in the YVA and its influence on the segmented activities of YYF. Magnetotelluric (MT) measurements were performed in the YVA. A total of 87 MT sites were arranged in the area. A high-resolution three-dimensional (3D) electrical structure model of the lithospheric scale from the crust to the upper mantle in the study area was established with the 3D inversion method. This model suggests that the shallow section of the upper crust of the YVA and the northwestern part of the Songliao Basin were mainly low-resistivity zones, which corresponded to the widely distributed sedimentary layers in this area. The middle and lower crust in the study area was primarily a complete high-resistivity body. A large-scale magmatic system began to appear at a depth of 25 km in the YVA. This magmatic system continued to extend downward, exceeding 70 km. The magma chamber in the YVA was in contact with the YYF in the lower crust. The YYF was the dominant material surging upward through the magma channel. Additionally, deep magmatic activities exerted a crucial influence on the seismic rupture segmentation characteristics along the YYF and the uplift mechanism of the Yitong Basin. The results of this study provide crucial geophysical constraints for depicting the fine depth structure of the YVA while enlightening the investigation of the rupture propagation mechanism within the volcanic terrain fault zone.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"918 ","pages":"Article 231002"},"PeriodicalIF":2.6,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-11-12DOI: 10.1016/j.tecto.2025.230982
Sylvert Paul , Tony Monfret , Eric Calais , Françoise Courboulex , Bertrand Delouis , Anthony Lomax , Bernard M. de Lépinay , Steeve J. Symithe , Anne Deschamps , David Ambrois , Sadrac St Fleur , Dominique Boisson
On 14 August 2021, the Southern Peninsula of Haiti experienced a M7.2 earthquake, 15 years after the devastating M7.0 event that struck the capital city of Port-au-Prince on 12 January 2010. We use the data from a local temporary broadband seismic network, a national network of low-cost seismometers, and regional seismic networks, together with a probabilistic, global-search, non-linear location method (NLL-SSST-coherence), to obtain a catalog of 5341 precisely relocated events spanning 20 August 2021 to 6 February 2022, with local magnitudes ranging from 0.5 to 5.6. We compute focal mechanisms for a subset of 73 events through waveform inversion. The catalog can be split into aftershocks directly related to the Nippes earthquake rupture process, and two off-rupture clusters. A first one concerns the Anse-à-Veau–Miragoâne area and corresponds mostly to the aftershock sequence of two M 5.3 and 4.9 earthquakes that likely activated a segment of the offshore, south-dipping, Jérémie–Malpasse reverse fault system. A second sequence, offshore Jérémie and clustered close to the offshore trace of that same fault, started immediately after the Nippes mainshock and continued during the entire time interval of the present study. The swarm–like temporal distribution of this sequence, as well as evidence for directional propagation of the epicenters, indicate that it was likely driven by fluid migration. We interpret this seismicity as the result of oblique sub-crustal slip on a south-dipping fault which accounts for oblique convergence between the Gonâve and Caribbean plates in southern Hispaniola. Strain in the crust then partitions between reverse faulting on the Jérémie–Malpasse fault system, strike-slip on the Enriquillo fault, and hybrid faulting in between. Seismic hazard assessment for the region should therefore account for faults other than the Enriquillo fault as potential sources for future earthquakes.
{"title":"Precise relocation of the 14 August 2021 Mw 7.2 Nippes, Haiti, earthquake sequence using broadband and citizen-hosted short-period seismometers","authors":"Sylvert Paul , Tony Monfret , Eric Calais , Françoise Courboulex , Bertrand Delouis , Anthony Lomax , Bernard M. de Lépinay , Steeve J. Symithe , Anne Deschamps , David Ambrois , Sadrac St Fleur , Dominique Boisson","doi":"10.1016/j.tecto.2025.230982","DOIUrl":"10.1016/j.tecto.2025.230982","url":null,"abstract":"<div><div>On 14 August 2021, the Southern Peninsula of Haiti experienced a M<span><math><msub><mrow></mrow><mrow><mtext>w</mtext></mrow></msub></math></span>7.2 earthquake, 15 years after the devastating M<span><math><msub><mrow></mrow><mrow><mtext>w</mtext></mrow></msub></math></span>7.0 event that struck the capital city of Port-au-Prince on 12 January 2010. We use the data from a local temporary broadband seismic network, a national network of low-cost seismometers, and regional seismic networks, together with a probabilistic, global-search, non-linear location method (NLL-SSST-coherence), to obtain a catalog of 5341 precisely relocated events spanning 20 August 2021 to 6 February 2022, with local magnitudes ranging from 0.5 to 5.6. We compute focal mechanisms for a subset of 73 events through waveform inversion. The catalog can be split into aftershocks directly related to the Nippes earthquake rupture process, and two off-rupture clusters. A first one concerns the Anse-à-Veau–Miragoâne area and corresponds mostly to the aftershock sequence of two M<span><math><msub><mrow></mrow><mrow><mtext>w</mtext></mrow></msub></math></span> 5.3 and 4.9 earthquakes that likely activated a segment of the offshore, south-dipping, Jérémie–Malpasse reverse fault system. A second sequence, offshore Jérémie and clustered close to the offshore trace of that same fault, started immediately after the Nippes mainshock and continued during the entire time interval of the present study. The swarm–like temporal distribution of this sequence, as well as evidence for directional propagation of the epicenters, indicate that it was likely driven by fluid migration. We interpret this seismicity as the result of oblique sub-crustal slip on a south-dipping fault which accounts for oblique convergence between the Gonâve and Caribbean plates in southern Hispaniola. Strain in the crust then partitions between reverse faulting on the Jérémie–Malpasse fault system, strike-slip on the Enriquillo fault, and hybrid faulting in between. Seismic hazard assessment for the region should therefore account for faults other than the Enriquillo fault as potential sources for future earthquakes.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"918 ","pages":"Article 230982"},"PeriodicalIF":2.6,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Aceh Fault, a major strike-slip fault forming the northernmost segment of Great Sumatran Fault, exhibits recent faulting through prominent scarps along its 250-km length. Running northwest-southeast, it traverses northwestern Sumatra from Tripa to Banda Aceh, a city of over 268,000 residents that is more commonly associated with the 2004 tsunami, but also lies directly on this active fault zone. Understanding the earthquake rupture history, including pre-instrumental events, is essential to characterize long-term seismic patterns and to assess associated hazards. We investigated the fault using 8-m resolution DEM (DEMNAS) for the entire fault zone, 15-cm resolution lidar DEM for selected areas, field mapping, and paleoseismology. Two paleoseismic trenches excavated in the Geumpang area reveal evidence of at least three ground-rupturing earthquakes over the past ∼1000 years. Event timing was constrained by radiocarbon analysis of detrital charcoal, providing sufficient chronological control to identify two well-dated events and one older event with lower precision. These results confirm that the Aceh Fault is active, delineate its surface trace, and offer the first detailed record of prehistoric earthquakes along this fault. This information contributes to improved seismic hazard mapping and a clearer understanding of tectonic risk in the Banda Aceh region.
{"title":"Active fault map and paleoseismology results from the Aceh Fault in North Sumatra, Indonesia: Unravelling faulting dynamics along the Great Sumatran Fault system","authors":"Gayatri Indah Marliyani , Yann Klinger , Aulia Kurnia Hady , Agung Setianto , Wenqian Yao , Hurien Helmi , Telly Kurniawan , Retno Agung Prasetyo Kambali , Zulham Sugito , Abdi Jihad , Yosi Setiawan , Andi Azhar Rusdin , Jimmi Nugraha , Supriyanto Rohadi , Rahmat Triyono , Dwikorita Karnawati","doi":"10.1016/j.tecto.2025.230990","DOIUrl":"10.1016/j.tecto.2025.230990","url":null,"abstract":"<div><div>The Aceh Fault, a major strike-slip fault forming the northernmost segment of Great Sumatran Fault, exhibits recent faulting through prominent scarps along its 250-km length. Running northwest-southeast, it traverses northwestern Sumatra from Tripa to Banda Aceh, a city of over 268,000 residents that is more commonly associated with the 2004 tsunami, but also lies directly on this active fault zone. Understanding the earthquake rupture history, including pre-instrumental events, is essential to characterize long-term seismic patterns and to assess associated hazards. We investigated the fault using 8-m resolution DEM (DEMNAS) for the entire fault zone, 15-cm resolution lidar DEM for selected areas, field mapping, and paleoseismology. Two paleoseismic trenches excavated in the Geumpang area reveal evidence of at least three ground-rupturing earthquakes over the past ∼1000 years. Event timing was constrained by radiocarbon analysis of detrital charcoal, providing sufficient chronological control to identify two well-dated events and one older event with lower precision. These results confirm that the Aceh Fault is active, delineate its surface trace, and offer the first detailed record of prehistoric earthquakes along this fault. This information contributes to improved seismic hazard mapping and a clearer understanding of tectonic risk in the Banda Aceh region.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"918 ","pages":"Article 230990"},"PeriodicalIF":2.6,"publicationDate":"2025-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145473290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-11-07DOI: 10.1016/j.tecto.2025.230980
H. Tim Breitfeld , Marco W.A. van Hattum , Robert Hall , Stuart Burley , Juliane Hennig-Breitfeld , Max Franzel , Simon M. Suggate , Pieter Vermeesch , Max Webb
Most of Sabah in northern Borneo is covered with Paleogene to Lower Miocene deep marine turbidite sequences that were deposited along the southern side of the Proto-South China Sea (PSCS). They include the Sapulut and Trusmadi formations of central-south Sabah, the Labang and Kulapis formations of eastern Sabah, the Kudat Formation of NW Sabah and the Crocker Formation of western Sabah. Sandstone petrography, heavy mineral analysis and detrital zircon U-Pb geochronology reveals changing sources associated with the evolution of the PSCS. Volcanic lithic fragments in some Labang Formation samples and Middle Eocene zircons in a lower Crocker Formation sample, as well as unstable heavy minerals such as apatite and epidote indicate input from contemporaneous volcanism, likely derived from the PSCS subduction arc to the north. By contrast, abundant ultra-stable heavy minerals and Mesozoic zircons indicate multi-recycling from southern sources.
Changes in provenance are seen across key stratigraphies. The lower part of the Crocker Formation has similar provenance as the Rajang Group in Sarawak and is interpreted as a more distal equivalent. While the upper Crocker Formation has a similar provenance as the Nyalau Formation in Sarawak and is interpreted as its deeper marine continuation. Parts of the Labang and Kulapis formations suggest an extension of this depositional system into eastern Sabah. In the Early Miocene the Palawan microcontinental fragment collided with the Cagayan Arc, resulting in uplift of a forearc high and formation of mélanges in eastern Sabah. The uplifted forearc was most likely the provenance source for the Temburong Formation in western Sabah.
{"title":"Evolution of Paleogene to Early Miocene deep-water provenance sources in Sabah, northern Borneo reveals changing Proto-South China Sea paleogeography","authors":"H. Tim Breitfeld , Marco W.A. van Hattum , Robert Hall , Stuart Burley , Juliane Hennig-Breitfeld , Max Franzel , Simon M. Suggate , Pieter Vermeesch , Max Webb","doi":"10.1016/j.tecto.2025.230980","DOIUrl":"10.1016/j.tecto.2025.230980","url":null,"abstract":"<div><div>Most of Sabah in northern Borneo is covered with Paleogene to Lower Miocene deep marine turbidite sequences that were deposited along the southern side of the Proto-South China Sea (PSCS). They include the Sapulut and Trusmadi formations of central-south Sabah, the Labang and Kulapis formations of eastern Sabah, the Kudat Formation of NW Sabah and the Crocker Formation of western Sabah. Sandstone petrography, heavy mineral analysis and detrital zircon U-Pb geochronology reveals changing sources associated with the evolution of the PSCS. Volcanic lithic fragments in some Labang Formation samples and Middle Eocene zircons in a lower Crocker Formation sample, as well as unstable heavy minerals such as apatite and epidote indicate input from contemporaneous volcanism, likely derived from the PSCS subduction arc to the north. By contrast, abundant ultra-stable heavy minerals and Mesozoic zircons indicate multi-recycling from southern sources.</div><div>Changes in provenance are seen across key stratigraphies. The lower part of the Crocker Formation has similar provenance as the Rajang Group in Sarawak and is interpreted as a more distal equivalent. While the upper Crocker Formation has a similar provenance as the Nyalau Formation in Sarawak and is interpreted as its deeper marine continuation. Parts of the Labang and Kulapis formations suggest an extension of this depositional system into eastern Sabah. In the Early Miocene the Palawan microcontinental fragment collided with the Cagayan Arc, resulting in uplift of a forearc high and formation of mélanges in eastern Sabah. The uplifted forearc was most likely the provenance source for the Temburong Formation in western Sabah.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"918 ","pages":"Article 230980"},"PeriodicalIF":2.6,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145461751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-11-07DOI: 10.1016/j.tecto.2025.230999
Alvar Braathen , Elin Skurtveit
Current understanding of extensional faults, which are essential for subsurface CO2 storage, reveals that fault risk assessment and modeling are significantly hindered by uncertainty. This underscores the need for insights into the datasets and methodologies used for evaluating fault sealing and reactivation. Data on fault architecture from outcrops, combined with mechanical insights, indicate the presence of hydraulic anisotropy and varying strength relationships within faults that influence their potential for reactivation. We propose that large portions of faults may yield through minor slip events or creep, while sticky spots are responsible for larger fault slip events. Enhancing our detection and understanding of these sticky spots – primarily characterized by abrupt displacement gradients that require further investigation - could improve risk assessment, monitoring, and mitigation strategies related to fault reactivation and inform seismic activity in CO2 storage initiatives.
{"title":"Faults in CO2 storage: Anisotropy in flow and irregular displacement gradients informing reactivation","authors":"Alvar Braathen , Elin Skurtveit","doi":"10.1016/j.tecto.2025.230999","DOIUrl":"10.1016/j.tecto.2025.230999","url":null,"abstract":"<div><div>Current understanding of extensional faults, which are essential for subsurface CO2 storage, reveals that fault risk assessment and modeling are significantly hindered by uncertainty. This underscores the need for insights into the datasets and methodologies used for evaluating fault sealing and reactivation. Data on fault architecture from outcrops, combined with mechanical insights, indicate the presence of hydraulic anisotropy and varying strength relationships within faults that influence their potential for reactivation. We propose that large portions of faults may yield through minor slip events or creep, while sticky spots are responsible for larger fault slip events. Enhancing our detection and understanding of these sticky spots – primarily characterized by abrupt displacement gradients that require further investigation - could improve risk assessment, monitoring, and mitigation strategies related to fault reactivation and inform seismic activity in CO2 storage initiatives.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"918 ","pages":"Article 230999"},"PeriodicalIF":2.6,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145461759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-11-07DOI: 10.1016/j.tecto.2025.230987
Daian Chen , Shuangshuang Lan , Hongbiao Gu , Lixiao Wang
Earthquakes not only cause direct surface damage but also induce significant perturbations in subsurface aquifer systems. This study developed water level-barometric pressure/tide response models for three observation wells located in the Huaying Mountain Fault Zone, with the aim of quantitatively assessing the effects of the Wenchuan and Lushan earthquakes on both the structure and vulnerability of the aquifer. The results indicate that when there is a strong coherence between water level and barometric pressure/tide signals, the degree of model fitting is significantly improved, thereby enhancing the reliability of parameter inversion. Well B demonstrates greater suitability for the barometric model (BE = 0.907), while Wells A and C align more closely with tidal response characteristics. Overall, it was found that strong earthquakes lead to an increase in vertical leakage coefficients by 15 % to 50 %, whereas transmissivity decreases by 30 % to 50 %. Additionally, following these seismic events, the average fracture dip angle shifts by 15° to 25°, becoming more vertical; concurrently, there is a significant reduction in the aquifer vulnerability index (Cts) ranging from 20 % to 50 %. These findings suggest that earthquakes facilitate reorganization within fracture networks, enhance vertical permeability, and create new seepage channels while simultaneously diminishing pollution prevention capacity—thereby significantly elevating pollution risk. This study provides theoretical and technical support for the post-earthquake assessment of groundwater resources, as well as for the sustainable protection and targeted prevention of hydrogeological hazards.
{"title":"Quantitative estimation of earthquake effects on aquifer structure and vulnerability","authors":"Daian Chen , Shuangshuang Lan , Hongbiao Gu , Lixiao Wang","doi":"10.1016/j.tecto.2025.230987","DOIUrl":"10.1016/j.tecto.2025.230987","url":null,"abstract":"<div><div>Earthquakes not only cause direct surface damage but also induce significant perturbations in subsurface aquifer systems. This study developed water level-barometric pressure/tide response models for three observation wells located in the Huaying Mountain Fault Zone, with the aim of quantitatively assessing the effects of the Wenchuan and Lushan earthquakes on both the structure and vulnerability of the aquifer. The results indicate that when there is a strong coherence between water level and barometric pressure/tide signals, the degree of model fitting is significantly improved, thereby enhancing the reliability of parameter inversion. Well B demonstrates greater suitability for the barometric model (BE = 0.907), while Wells A and C align more closely with tidal response characteristics. Overall, it was found that strong earthquakes lead to an increase in vertical leakage coefficients by 15 % to 50 %, whereas transmissivity decreases by 30 % to 50 %. Additionally, following these seismic events, the average fracture dip angle shifts by 15° to 25°, becoming more vertical; concurrently, there is a significant reduction in the aquifer vulnerability index (Cts) ranging from 20 % to 50 %. These findings suggest that earthquakes facilitate reorganization within fracture networks, enhance vertical permeability, and create new seepage channels while simultaneously diminishing pollution prevention capacity—thereby significantly elevating pollution risk. This study provides theoretical and technical support for the post-earthquake assessment of groundwater resources, as well as for the sustainable protection and targeted prevention of hydrogeological hazards.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"919 ","pages":"Article 230987"},"PeriodicalIF":2.6,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145461763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Ghardimaou–North Constantine (GNC) fault zone in northeastern Algeria challenges conventional strike-slip fault behavior: despite its ∼400 km length and ∼ 2.4 mm/yr slip rate, it predominantly hosts moderate-magnitude earthquakes. The 2020 Mw5.3 El Kantour earthquake—the largest recorded event on this fault—provides critical insights into its mechanics. High-resolution aftershock relocations reveal a blind, steeply SSW-dipping fault (MSF1; N107–109°E) and secondary subparallel strands forming a distributed network that partitions strain and impedes large rupture propagation. Rupture growth is further constrained by a seismogenic thickness (∼14 km), coinciding with a regional lower-crustal low-velocity zone (LVZ) likely acting as decoupling layer and mid-crustal barrier. Stress inversions indicate mechanical weakness, with very low friction (μ ≈ 0.25) and high fault activation angles. The sequence exhibits dual seismic behaviors: (1) mainshock–aftershock patterns near the main fault at mid-crustal depths, and (2) swarm-like, shallow off-fault cluster (85 % of events) featuring severely misoriented fault at distance over 3 km from the mainshock. Spatiotemporal multiplet patterns—including a ∼ 0.8 km/day migration rate, rapid initial bursts up to 7 km/day, spatial distribution (∼6 km), and 42-day sporadic activity —support pore-pressure diffusion and aseismic slip activation. Post-seismic sand-laden spring discharges confirm transient pore-pressure perturbations. These observations reveal a multi-process coupling between coseismic stress transfer, pore-pressure diffusion, aseismic slip, and brittle failure, forming a self-regulating feedback system that distributes stress across a permeable fracture network and prevents runaway ruptures. Our findings underscore the need for integrative hydromechanical models accounting for fluid-driven weakening, aseismic slip, and crustal rheology to refine seismic hazard assessment in fluid-rich, mechanically weak fault systems.
阿尔及利亚东北部的Ghardimaou-North Constantine （GNC）断裂带挑战了传统的走滑断层行为：尽管其长度约400公里，滑动率约2.4毫米/年，但它主要发生中等震级地震。2020年发生的Mw5.3 El Kantour地震是该断层上有记录以来最大的地震，它为断层的机制提供了重要的见解。高分辨率的余震重定位揭示了一条盲目的、陡峭的ssw倾斜断层（MSF1; N107-109°E）和次级亚平行链，它们形成了一个分布式网络，分隔了应变，阻碍了大破裂的传播。断裂增长进一步受到发震厚度（~ 14 km）的限制，与区域下地壳低速带（LVZ）相吻合，可能起到解耦层和中地壳屏障的作用。应力反转表明机械弱点，摩擦力非常小（μ≈0.25），断层活化角很大。该序列表现出双重地震行为：(1)在地壳中部深处主断层附近的主震-余震模式；(2)在距离主震3公里以上的地方，以严重定向错误的断层为特征的群状浅层离断层群集（85%的事件）。时空多重模式——包括0.8公里/天的迁移速率、高达7公里/天的快速初始爆发、6公里的空间分布和42天的零星活动——支持孔隙压力扩散和地震滑动激活。地震后含砂弹簧泄放证实了瞬态孔隙压力扰动。这些观察结果揭示了同震应力传递、孔隙压力扩散、地震滑动和脆性破坏之间的多过程耦合，形成了一个自我调节的反馈系统，该系统将应力分布在渗透性裂缝网络中，并防止失控破裂。我们的研究结果强调，需要综合流体力学模型来考虑流体驱动的弱化、地震滑动和地壳流变，以完善富流体、机械弱断裂系统的地震危险性评估。
{"title":"Fluid-mediated and structural controls on small-to-moderate seismicity: Insights from the 2020 El Kantour Mw 5.3 sequence, Ghardimaou–North Constantine Fault Zone, NE Algeria","authors":"Hichem Bendjama , El-Mahdi Tikhamarine , Oualid Boulahia , Issam Abacha , Hamoud Beldjoudi","doi":"10.1016/j.tecto.2025.230988","DOIUrl":"10.1016/j.tecto.2025.230988","url":null,"abstract":"<div><div>The Ghardimaou–North Constantine (GNC) fault zone in northeastern Algeria challenges conventional strike-slip fault behavior: despite its ∼400 km length and ∼ 2.4 mm/yr slip rate, it predominantly hosts moderate-magnitude earthquakes. The 2020 Mw5.3 El Kantour earthquake—the largest recorded event on this fault—provides critical insights into its mechanics. High-resolution aftershock relocations reveal a blind, steeply SSW-dipping fault (MSF1; N107–109°E) and secondary subparallel strands forming a distributed network that partitions strain and impedes large rupture propagation. Rupture growth is further constrained by a seismogenic thickness (∼14 km), coinciding with a regional lower-crustal low-velocity zone (LVZ) likely acting as decoupling layer and mid-crustal barrier. Stress inversions indicate mechanical weakness, with very low friction (μ ≈ 0.25) and high fault activation angles. The sequence exhibits dual seismic behaviors: (1) mainshock–aftershock patterns near the main fault at mid-crustal depths, and (2) swarm-like, shallow off-fault cluster (85 % of events) featuring severely misoriented fault at distance over 3 km from the mainshock. Spatiotemporal multiplet patterns—including a ∼ 0.8 km/day migration rate, rapid initial bursts up to 7 km/day, spatial distribution (∼6 km), and 42-day sporadic activity —support pore-pressure diffusion and aseismic slip activation. Post-seismic sand-laden spring discharges confirm transient pore-pressure perturbations. These observations reveal a multi-process coupling between coseismic stress transfer, pore-pressure diffusion, aseismic slip, and brittle failure, forming a self-regulating feedback system that distributes stress across a permeable fracture network and prevents runaway ruptures. Our findings underscore the need for integrative hydromechanical models accounting for fluid-driven weakening, aseismic slip, and crustal rheology to refine seismic hazard assessment in fluid-rich, mechanically weak fault systems.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"918 ","pages":"Article 230988"},"PeriodicalIF":2.6,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145448032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2025-11-05DOI: 10.1016/j.tecto.2025.230989
Menglong Liao , Yuanzhi Cheng , Bo Han , Zhongxing Wang , Yinan Tian , Yanlong Kong
To reveal the seismogenic mechanism of the 2016 Aketao Mw6.6 earthquake and the formation mechanism of the Muji travertine cone group, this study deployed 56 magnetotelluric (MT) stations in the source region and surrounding the Muji Basin. Post-earthquake magnetotelluric data inversion results demonstrate that: (1) the earthquake hypocenter is located near the interface between low-resistivity body C1 and high-resistivity body R2, representing a finite rupture within high-resistivity body R2; (2) the deep-seated stable fluid system C8 influenced the occurrence of this earthquake, while the genesis and temporal evolution of low-resistivity body C1 remain uncertain; (3) a large-scale low-resistivity body C2 exists north of the Muji travertine cone group. Combined with regional structural analysis, we conclude that the seismogenic process of the 2016 Aketao earthquake was primarily controlled by the coupling between the regional tectonic stress field and local rock mass mechanical properties. The heterogeneity of both stress field and electrical structure along the Muji fault jointly controlled the complex rupture propagation process. Low-resistivity body C2 represents deep fluid presence, where the southwestern boundary fault of the Muji Basin provides migration pathways for deep fluids, thereby controlling the formation and distribution of the travertine cone group.
{"title":"Electrical structure of the Muji Basin and adjacent areas in the Pamir: Implications for the 2016 Aketao Mw 6.6 earthquake and the Muji travertine cone group","authors":"Menglong Liao , Yuanzhi Cheng , Bo Han , Zhongxing Wang , Yinan Tian , Yanlong Kong","doi":"10.1016/j.tecto.2025.230989","DOIUrl":"10.1016/j.tecto.2025.230989","url":null,"abstract":"<div><div>To reveal the seismogenic mechanism of the 2016 Aketao Mw6.6 earthquake and the formation mechanism of the Muji travertine cone group, this study deployed 56 magnetotelluric (MT) stations in the source region and surrounding the Muji Basin. Post-earthquake magnetotelluric data inversion results demonstrate that: (1) the earthquake hypocenter is located near the interface between low-resistivity body C1 and high-resistivity body R2, representing a finite rupture within high-resistivity body R2; (2) the deep-seated stable fluid system C8 influenced the occurrence of this earthquake, while the genesis and temporal evolution of low-resistivity body C1 remain uncertain; (3) a large-scale low-resistivity body C2 exists north of the Muji travertine cone group. Combined with regional structural analysis, we conclude that the seismogenic process of the 2016 Aketao earthquake was primarily controlled by the coupling between the regional tectonic stress field and local rock mass mechanical properties. The heterogeneity of both stress field and electrical structure along the Muji fault jointly controlled the complex rupture propagation process. Low-resistivity body C2 represents deep fluid presence, where the southwestern boundary fault of the Muji Basin provides migration pathways for deep fluids, thereby controlling the formation and distribution of the travertine cone group.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"918 ","pages":"Article 230989"},"PeriodicalIF":2.6,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145448033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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