Tectonophysics最新文献

{"title":"Seismic structure of African slab beneath Antalya bay southern Turkey","authors":"Irina Medved ,&nbsp;Gulten Polat","doi":"10.1016/j.tecto.2025.230720","DOIUrl":"10.1016/j.tecto.2025.230720","url":null,"abstract":"<div><div>In this passive seismic tomography study, we examined the seismic structure of the African slab beneath the Antalya coast, extending from the Isparta Angle to the island of Cyprus, using regional data. The southern part of Turkey, adjacent to the Mediterranean Sea, has a highly complex structure due to a wide range of tectonic and geodynamic processes, contributing to the high seismic activity of the region. We collected a 14-year data catalog from AFAD (T. C. Ministry of Interior Disaster and Emergency Management Department Earthquake Department Directorate). The resulting dataset contained the arrival times of 66,805 P-waves and 46,197 S-waves from 6158 events, which were used to produce high-resolution seismic tomography models down to 120 km depth. The results revealed a low-velocity anomaly beneath the Paphos fault at a depth of approximately 70 km, which may indicate a rupture between the Cyprus and Antalya slabs. Moreover, the Antalya slab seems to become thinner at this depth. The structure of the continental crust of the Anatolian Plate under the Central Taurus Mountains is characterized by two anomalies: an upper high-velocity and a lower low-velocity one. This indicates the heating of the lower crust from the ascending asthenospheric flow penetrated through the gap between the Antalya and Cyprus slabs. The research findings made it possible not only to clarify the structure of the African slab beneath the Antalya coast, but also to detect local heterogeneities not investigated previously.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"905 ","pages":"Article 230720"},"PeriodicalIF":2.7,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783677","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}

{"title":"Mapping structural geometry and tectonics of the continental margin of Vietnam and adjacent areas using an enhanced horizontal gradient of gravity data","authors":"Korimilli Naga Durga Prasad ,&nbsp;Dat Viet Nguyen ,&nbsp;Minh Le-Huy ,&nbsp;Tran Van Kha ,&nbsp;Thanh Duc Do ,&nbsp;Luan Thanh Pham ,&nbsp;Haseeb Rehman","doi":"10.1016/j.tecto.2025.230719","DOIUrl":"10.1016/j.tecto.2025.230719","url":null,"abstract":"<div><div>The exploration of hidden structures beneath complex tectonic regions using potential field edge detection techniques poses a significant challenge. Traditional edge enhancement methods encounter inherent limitations, such as generating low-resolution outcomes or heavily depending on source depth. To overcome these challenges, we introduced an innovative edge detector called the Enhanced Horizontal Gradient (EHG). Through thorough testing on synthetic models (both 2D and 3D), we evaluated its performance against other conventional edge enhancement techniques. Our results demonstrate that the proposed detector effectively generates clear signals along source boundaries, minimizes the introduction of false edges, and operates independently of source depth. Applying the EHG method to Bouguer gravity anomalies, in conjunction with prominent tectonic faults, suture zones, mantle Bouguer anomalies, and Moho structure, provides substantial insights into comprehending the gravity characteristics of the continental margin of Vietnam and adjacent areas. Key findings from our research encompass the identification of discontinuities in the Red River Fault Zone, the absence of the Tam Ky-Phuoc Son (TK-PS) fault, the mapping of the extension of the magmatic zone in the oceanic region toward the northeast part of the Phu Khanh Basin, and a noticeable shift in gravity trends from NNE-SSW in the northeastern region of the East Vietnam Sea (EVS) to NNW-SSE direction. Moreover, the Moho depth obtained from gravity inversion, ranging from 7 to 54 km in the study area, closely corresponds with the intricate tectonics, offering conclusive evidence of a mechanism involving the flow of crustal magmatic material and associated uplift. In conclusion, our study suggests that interactions among tectonic plates likely play a role in shaping complex tectonic settings and the underlying uplift mechanism, ultimately influencing changes in bathymetry and seafloor structure.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"905 ","pages":"Article 230719"},"PeriodicalIF":2.7,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783586","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}

{"title":"Dyke emplacement and its interaction with fracture systems and regional stress fields: Combination of a field study and geochronology in Cserhát Hills, Hungary","authors":"Dorina Juhász ,&nbsp;Chiara Lanzi ,&nbsp;Zsolt Benkó ,&nbsp;Freysteinn Sigmundsson ,&nbsp;Barbara Beke ,&nbsp;Françoise Bergerat ,&nbsp;László Fodor","doi":"10.1016/j.tecto.2025.230722","DOIUrl":"10.1016/j.tecto.2025.230722","url":null,"abstract":"<div><div>Widespread andesitic volcanism with several eruption centres occurred during the Middle Miocene in the Cserhát Hills, central – northern Hungary. In this time, an extensive dyke system developed in the area, where some dykes have exposed maximum length of 23 km, and maximum width of 25 m. This dyke system shows a change in its strike from E–W to NNW–SSE. Here we integrate new and previous field observations to derive structural maps and study dykes and fractures in the Cserhát Hills. K/Ar geochronology is used to understand the temporal evolution of regional fault patterns before, during and after the formation of the dykes and also to gain insights into the interaction between the dyke emplacement and the regional stress field. Fault-slip data were collected at 27 different sites along the dykes and were combined with reinterpreted datasets from 16 sites located at a distance from dykes. The field observations, integrated with the geochronological data sets suggests that dykes with different orientations were emplaced in two different eruptive cycles around 15.4 and 14.7 Ma. The deformation history of the Pannonian Basin involved a clockwise change in regional minimal stress axis, probably as a result of regional vertical–axis counter-clockwise block rotation. Our field observations suggest strike-slip stress regime may occur near propagating dyke tips, and the direction of minimal stress axis may have locally rotated counter-clockwise where dykes changed their strikes and emplaced along pre-existing fractures, mostly normal faults.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"906 ","pages":"Article 230722"},"PeriodicalIF":2.7,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Complex seismogenic fault system for the 2022 Ms6.0 Maerkang (China) earthquake sequence resolved with reliable seismic source parameters","authors":"Lihua Mo ,&nbsp;Minhan Sheng ,&nbsp;Risheng Chu ,&nbsp;Jun Xie ,&nbsp;Sidao Ni","doi":"10.1016/j.tecto.2025.230718","DOIUrl":"10.1016/j.tecto.2025.230718","url":null,"abstract":"<div><div>The Bayan Har block in central Tibetan Plateau is characterized by low historical seismicity and has rarely experienced M6+ earthquakes. However, on June 10, 2022, at 01:28 AM (UTC + 8), an <span><math><msub><mi>M</mi><mi>s</mi></msub></math></span>6.0 earthquake struck Maerkang in Sichuan Province, China, within the Bayan Har block. Four foreshocks and eight aftershocks with magnitudes greater than 3 occurred during the week of the mainshock with the largest foreshock reaching <span><math><msub><mi>M</mi><mi>s</mi></msub></math></span>5.8. Previous studies have suggested two probable seismogenic faults. One proposes that the earthquake sequence occurred on the V-shaped Songgang secondary fault, while the other suggests an unmapped fault located east of the V-shaped fault is the causative fault. Additionally, there are inconsistencies in the focal depth and rupture direction in these studies. To better identify the seismogenic faults of the Maerkang earthquakes, we first estimated the focal mechanisms and centroid depths of all M<span><math><mo>≥</mo></math></span>2.9 events during one week of the mainshock occurence, using both regional and teleseismic waveform data. We then refined the mainshock epicenter by by incorporating 3D velocity models to account for their influence on the earthquake location. Other events were relocated relative to the mainshock using the surface wave differential times. Finally, we analyzed the rupture directivity of the mainshock and the <span><math><msub><mi>M</mi><mi>s</mi></msub></math></span>5.8 foreshock via the empirical Green's function (EGF) method. The results suggest that the mainshock likely ruptured along an unmapped fault to the east of the V-shaped Songgang secondary fault, while the <span><math><msub><mi>M</mi><mi>s</mi></msub></math></span>5.8 foreshock occurred on the Songgang fault itself, suggesting complex fault system for the earthquake sequence.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"904 ","pages":"Article 230718"},"PeriodicalIF":2.7,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747890","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}

{"title":"Seismotectonic characteristics of the 1976 MS 7.8 Tangshan earthquake sequence revealed by high-resolution tomography","authors":"Chenghao Jiang ,&nbsp;Zhiwei Li ,&nbsp;Feng Bao ,&nbsp;Jian Zhang ,&nbsp;Tianyao Hao ,&nbsp;Yufeng Deng ,&nbsp;Ya Xu ,&nbsp;Song Huang","doi":"10.1016/j.tecto.2025.230721","DOIUrl":"10.1016/j.tecto.2025.230721","url":null,"abstract":"<div><div>The fine shallow velocity model of the Tangshan Fault Zone (TSFZ) is of paramount importance in understanding the intricate geological structure and seismogenesis in this area. In this study, a dense seismic array consisting of 110 short-period seismometers was deployed in the TSFZ for ∼2 months. With this dataset, a 3-D shallow structure model deep to 4 km with the highest resolution up to now are obtained by using an ambient noise tomography, which can provide clear seismotectonic characteristics of the 1976 <em>M</em>_<em>S</em> 7.8 Tangshan earthquake sequence in the upper crust. The results show that the <span><math><msub><mi>V</mi><mi>S</mi></msub></math></span> model is influenced by sedimentary strata and characterized by a conspicuous high-velocity anomaly in the northern region and a contrasting low-velocity anomaly in the southern region of the TSFZ. The velocity structure correlates well with the geological structure, and a significant velocity contrast can be observed at depths greater than 1 km on both sides of the TSFZ. By combining previous research findings with our novel discoveries, we suggest that the distribution of low-velocity sediments in the TSFZ is not only consistent with the shallow fault system but also related to local transtensional effects. Earthquakes in the middle and upper crust are primarily concentrated near the high-resistivity and high-velocity body in the northeastern part of the Tangshan Fault. Under the influence of right-lateral strike-slip motion, this high-resistivity and high-velocity body will rupture when the accumulated stress reaches a critical threshold.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"907 ","pages":"Article 230721"},"PeriodicalIF":2.7,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143838291","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}

{"title":"Delineation of crustal structure and composition in the Northwest Himalaya and adjoining Indo-Gangetic Plain","authors":"Amlanjyoti Das ,&nbsp;Devajit Hazarika ,&nbsp;Pritom Neog ,&nbsp;Naresh Kumar ,&nbsp;Dilip Kumar Yadav","doi":"10.1016/j.tecto.2025.230717","DOIUrl":"10.1016/j.tecto.2025.230717","url":null,"abstract":"<div><div>We utilize the H-<em>k</em> stacking technique on <em>P</em>-wave receiver functions from 38 seismic stations to estimate the crustal thickness and Vp/Vs ratio in the NW Himalaya and the adjoining Indo-Gangetic Plain (IGP). We observe varying crustal thickness from ∼29 km in the IGP to ∼50–60 km in the Higher Himalayan Crystalline Zone. An abrupt crustal thickening of ∼47–54 km observed near Jwalamukhi Thrust is due to significant crustal shortening along the fault. Inferred higher Vp/Vs values of 1.78–1.84 in the IGP may result from the underplating of mafic materials in the Precambrian. The presence of thick sediments towards the Himalayan Frontal Thrust, further, contributes to the extremely high Vp/Vs of 1.89–2.02. The intermediate Vp/Vs of ∼1.74 in the Sub Himalayan Zone indicates the reworking of the mafic crust by delamination of the lower crust or the greater influence of the overlying Himalayan wedge, comprised of felsic to intermediate rock composition. Higher Vp/Vs values in the Kishtwar (1.81–1.93) and Kashmir Valley (1.80–1.93) are possibly due to the presence of volcanic rocks and the effect of the mid-crustal low-velocity layer. Integration of our results with previous studies reveals a heterogenous crustal structure characterized by both arc-normal and arc-parallel variations which may have resulted from varying convergence rates and the influence of subsurface extension of active transverse ridges beneath the Himalaya. The varying Vp/Vs values may result from diverse crustal rock compositions and partial melt/fluid zones. These partial melts alter the mechanical properties of rocks leading to brittle failure and thus promoting seismicity.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"904 ","pages":"Article 230717"},"PeriodicalIF":2.7,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143761235","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}

{"title":"Geodynamics of the Makran subduction zone inferred from relocated seismicity","authors":"Abdolreza Ghods ,&nbsp;Eric Bergman ,&nbsp;Maryam Akbarzadeh Aghdam ,&nbsp;Matin Khaledzadeh ,&nbsp;Mohammad Enayat","doi":"10.1016/j.tecto.2025.230716","DOIUrl":"10.1016/j.tecto.2025.230716","url":null,"abstract":"<div><div>The Makran Subduction Zone is unusual, with an EN<em>E</em>-WSW trending volcanic arc that is nonparallel to its ∼E-W trending accretionary prism. The discrepancy has been attributed to an eastward reduction of the subduction angle. To assess this theory, we relocated 146 moderate to large earthquakes in the region during the period 1968 to 2022. We found that in eastern Makran, the region with intermediate-depth earthquakes has a constant width of ∼180 km, with a trend sub-parallel with the trend of the volcanic arc. The fault planes of most of the normal-faulting intermediate-depth earthquakes are also parallel to the trend of the volcanic arc. These observations suggest an EN<em>E</em>-WSW trending subducting plate hinge and a constant subduction angle in eastern Makran. The ∼<em>E</em>-W trend of the intermediate-depth earthquakes in western Makran indicates an ∼E-W trending subducting plate hinge. We relate the different orientation of the plate hinges in eastern and western Makran to the different shape of the overriding plates. The cumulative Wadati-Benioff zone for eastern Makran shows a subduction angle of ∼15^o in the depth range of ∼45–80 km, increasing to ∼45^o at depths greater than 80 km. The significant component of strike-slip faulting of the intermediate-depth events in western Makran implies that the subducting plate in western and eastern Makran experience different stress regimes. Alignment of a considerable number of intermediate-depth earthquakes along narrow ENE-WSW lineaments implies a pre-existing weakness in the subducting plate.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"905 ","pages":"Article 230716"},"PeriodicalIF":2.7,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783676","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}

{"title":"Seismic evidence of subduction during assembly of the North China Craton from multimodal dispersion inversion","authors":"Yanyan Zhang ,&nbsp;Xiaofei Chen ,&nbsp;Juqing Chen ,&nbsp;Gongheng Zhang ,&nbsp;Zhengbo Li ,&nbsp;Lei Pan ,&nbsp;Jiannan Wang ,&nbsp;Zhifeng Ding ,&nbsp;Xingchen Wang ,&nbsp;Songyong Yuan","doi":"10.1016/j.tecto.2025.230715","DOIUrl":"10.1016/j.tecto.2025.230715","url":null,"abstract":"<div><div>The Precambrain basement of the North China Craton (NCC) was formed through the merger of micro-continental blocks, the amalgamation mode of which has remained debated. To provide further insights and better understand the underground structures, we construct a more detailed shear wave velocity model of crust and uppermost mantle in the central and western NCC using multimodal ambient noise tomography. The multimodal Rayleigh wave dispersion curves are obtained through the Frequency-Bessel transform, utilizing seismic records from 548 stations in the ChinArray-Himalaya project. Subsequently, we employ the quasi-Newton method to invert the shear wave velocity model to a depth of 60 km. The results reveal a southward low-velocity subduction-like feature in the upper-middle crust south of the Solonker Suture Zone to the Inner Mongolia Suture Zone. This feature likely represents the subduction remnants associated with the southward subducted Paleo-Asian Ocean slab. Additionally, the model highlights a westward intra-crustal low-velocity downthrust body beneath the Trans-North China Orogen, potentially indicating relics of subduction from the Paleoproterozoic amalgamation of the NCC. Moreover, we observe a widely distributed low-velocity layer within the lower crust of the Ordos Block, which may indicate a felsic-dominated lower crust, likely formed during the prolonged tectonic stability following the ancient subduction-collision processes of the NCC.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"904 ","pages":"Article 230715"},"PeriodicalIF":2.7,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725295","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}

{"title":"Analysis of seismic reflection data from the Northern Hispaniola margin: Implications for the recent evolution of the Northern Caribbean Plate boundary","authors":"A. Oliveira de Sá ,&nbsp;S. Leroy ,&nbsp;E. d'Acremont ,&nbsp;S. Lafuerza ,&nbsp;J.L. Granja-Bruña ,&nbsp;R. Momplaisir ,&nbsp;D. Boisson ,&nbsp;L. Watremez ,&nbsp;B. Moreno ,&nbsp;J. Corbeau","doi":"10.1016/j.tecto.2025.230714","DOIUrl":"10.1016/j.tecto.2025.230714","url":null,"abstract":"<div><div>The northern margin of Hispaniola features an accretionary prism with morphological structures shaped by tectonic, hydrodynamic and sedimentary processes in oblique convergence between North American and Caribbean plates. The HAITISIS data in the northern Caribbean plate boundary elucidate the relationships between fault-driven tectonic activity, seafloor morphology, and effects of transpressional deformation. We evidence an <em>E</em>-W-trending spatial variation in deformation accommodation and sedimentary records along the accretionary prism. The distinct morpho-structural character of the seafloor and sedimentation patterns originated during the Upper Miocene-Pliocene tectonic reorganization of the northern Caribbean Plate boundary, which is associated with the onset of the oblique collision of the Caribbean and North American Plates carrying Hispaniola to the transpressive plate boundary opposite the Bahamas Carbonate Platform. An accretionary prism is formed, and segments of the eastern strand of the Septentrional-Oriente Fault Zone (SOFZ) are activated, resulting in lateral sediment source displacements, influencing sedimentary infill and deformation patterns.</div><div>A mass transport deposit (MTD) in the Eastern domain caused differential compaction and remobilization of recent seismic units and has affected the seafloor morphology. The MTD is absent in the Western domain, and canyons are found in the Eastern domain.</div><div>The early Miocene SOFZ onset and evolution is not a continuous eastward propagation. Lateral displacements of canyons provide a chronology for strike-slip and thrust faults before the SOFZ initiation and the formation of the current fault segments. The variations in fault density, cumulative displacement along strike-slip faults, morphology of Northern Hispaniola insular slope (including width and tectonic style), and tilting of basin surfaces suggest the underthrusting of the North American plate beneath the Caribbean plate has ceased at the transition between the Eastern and Western domains. This may be attributed to westward rheological transition of North American plate's crust (from oceanic to continental) at the level of the Bahamas platform.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"904 ","pages":"Article 230714"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"The Lyngen Magmatic Complex ophiolite: preservation of pre- and syn-collisional structures and implications for the nappe thrusting sequence in the Northern Norwegian Caledonides","authors":"Marina Galindos-Alfarache ,&nbsp;Holger Stünitz ,&nbsp;Mathieu Soret ,&nbsp;Guillaume Bonnet ,&nbsp;Benoît Dubacq ,&nbsp;Morgan Ganerød","doi":"10.1016/j.tecto.2025.230706","DOIUrl":"10.1016/j.tecto.2025.230706","url":null,"abstract":"<div><div>The Lyngen Magmatic Complex (Northern Norway) marks a major discontinuity in the metamorphic gradient of the North Norwegian Caledonides nappe sequence. The Lyngen Magmatic Complex preserves pre- and <em>syn</em>-collisional structures and parageneses of the Caledonian orogeny. This study differentiates the two deformation events and offers a tectono-metamorphic model for the region, using a combination of field-based data, geochemical analysis, radiochronometric dating, and thermodynamic modelling. It is demonstrated that the precollisional event (D1) developed in a dextral strike-slip transpressional regime, generating N<img>S-trending subvertical shear zones with subhorizontal shear displacement and steeply inclined isoclinal folding. The D1 metamorphic fabrics developed at 486 ± 9 Ma on a retrograde temperature-path, from amphibolite (680<img>800 °C, 0.5<img>0.9 GPa) to greenschist facies (300<img>450 °C, 0.3<img>0.75 GPa) conditions. The subsequent <em>syn</em>-collisional event (D2) produced a subhorizontal foliation, top-to-SE-directed thrust deformation at the base of the Lyngen Magmatic Complex. D2 rock fabrics represent typical nappe stacking structures during the Scandian collisional stage (∼430 Ma). The vertical D1 structures are overprinted by D2 fabrics in the thrust contact region only. Mineral assemblages crystallizing during D2 indicate a transition from lower amphibolite to greenschist conditions. Thermobarometry suggests significant re-heating after D1, with D2 maximum conditions ∼650 °C and 1.1 GPa at the base of the Lyngen Magmatic Complex and ∼558<img>610 °C and 0.8<img>1.3 GPa for the underlying graphite-bearing metasediments. Argon dating and the temperature difference between the Lyngen Magmatic Complex and the underlying units testify to out-of-sequence thrusting at 426 ± 7.5 Ma at the base of the Lyngen Magmatic Complex. The present results constrain the localization of the oceanic units of the North Norwegian Caledonides outboard and to the North of their present position. Consequently, stacking of uppermost units (likely of Laurentian origin) on top of the Lyngen Magmatic Complex occurred before their final emplacement onto the Reisa Nappe Complex (probably mostly Baltica-derived).</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"904 ","pages":"Article 230706"},"PeriodicalIF":2.7,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143679982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}