Tectonophysics最新文献

{"title":"Lithospheric electrical structure of Zhenghe-Dapu fault in South China determined by multi-geophysical observations: Implications for geothermal mechanism","authors":"Song Han ,&nbsp;Liuyang Xu ,&nbsp;Xipeng Shan ,&nbsp;Xi Xu ,&nbsp;Xingtao Kuang ,&nbsp;Yanyun Sun ,&nbsp;Baodi Wang","doi":"10.1016/j.tecto.2025.230723","DOIUrl":"10.1016/j.tecto.2025.230723","url":null,"abstract":"<div><div>The Zhenghe-Dapu fault (ZDF), situated in the Cathaysia Block of South China, has played a major role in the tectono-magmatic and geothermal activities in the region since Mesozoic-Cenozoic. However, the regional topography restricts the availability of surface heat flow data, hindering lithospheric thermal structure studies. Therefore, we used a broadband and long-period magnetotelluric profile with 33 points across the Cathaysia Block and ZDF to obtain a 3-D electrical conductivity model. Tectonic zones, such as the Jiangshao fault and ZDF exhibit high-resistivity (&gt;1000 Ωm) blocks, interpreted as remnants of the cratonic lithosphere; low-conductivity areas (&lt;100 Ωm) indicate lithosphere modified by materials derived from the deep mantle. A high-conductivity body (&lt;10 Ωm) in the lower crust (~20–30 km) beneath the ZDF coincides with spatial position of low magnetic anomalies, high gravity, and low S-wave velocity. Moho depth (~34 km) is significantly greater than that in the adjacent areas (~28–32 km). Integrated geophysical observations suggest that the high-conductivity body may represent mantle-derived melt fluids ascending along faults, leading to the partial melting of lower crustal rocks. Mantle intrusion led to the thickening of the lower crust, that previously underwent regional thinning, ultimately resulting in the formation of a substantial amount of Mesozoic granite bodies, the radiogenic heat of which constitutes a major heat source. Since the Cenozoic, asthenospheric thermal material upwelling, magmatic underplating, and volcanic activity have provided heat to the upper crust. The radiogenic heat from the Mesozoic granites and Cenozoic magmatic-hydrothermal activities together contributed to the regional thermal anomaly, as supported by our resistivity model.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"906 ","pages":"Article 230723"},"PeriodicalIF":2.7,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143792672","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":"Active faulting in Samos Basin, Eastern Aegean Sea, Greece and paleogeographic implications","authors":"Dimitrios Papanikolaou ,&nbsp;Paraskevi Nomikou ,&nbsp;Danai Lampridou ,&nbsp;Jonas Preine ,&nbsp;Dimitris Litsas ,&nbsp;Yannis Tsaparas ,&nbsp;Ilias Koliopanos ,&nbsp;Maria Petroulia ,&nbsp;Christian Huebscher","doi":"10.1016/j.tecto.2025.230724","DOIUrl":"10.1016/j.tecto.2025.230724","url":null,"abstract":"<div><div>The geological analysis of the Samos Island region, particularly the Samos Basin, based on seismic profiling, has revealed a complex tectonic history marked by significant deformation and seismic activity. The Mw 7.0 earthquake in October 2020 is linked to the activation of the <em>E</em>-W marginal fault, resulting in the formation of a south-tilted half-graben. This was followed by aftershocks ranging from Mw 3.2 to 4.5, which correspond to the activation of smaller normal faults, mainly within the Vathy Hills. No significant deformation extends into the eastern margin of the Ikaria Basin, likely due to the different orientations and dips between the Samos Basin faults (<em>E</em>-W, dipping 40° N) and those in the Eastern Ikaria Basin (NE-SW, dipping 65° NW). The eastern Ikaria segment represents the primary seismic hazard for the Samos area, with a potential magnitude of 6.5. Low-angle normal faults of Tortonian age have been identified primarily in the eastern Vathy Hills and along the western segment of the <em>E</em>-W marginal fault of Samos, separating the basement from the overlying sediments. The basement is found beneath the Eastern Samos Basin and Vathy Hills but deepens to over 1600 m to the west. The overall deformation shows a significant westward increase, with displacements 4–5 times greater (700 m vs. 3300 m) over 50 km from Eastern Samos to Eastern Ikaria. Stratigraphic analysis indicates an eastward sea transgression during the Middle-Late Pleistocene over Messinian-Pliocene continental deposits. Canyons and landslides are observed along the southern margin of Samos. The paleogeographic evolution includes the uplift of the metamorphic basement during the Early Miocene, followed by the formation of continental sedimentary basins in the Middle-Late Miocene, marked by N-S marginal faults and volcanic activity. The Samos Island horst emerged due to <em>E</em>-W faulting, with the subsidence of the Samos Basin occurring during the Early-Middle Pleistocene.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"905 ","pages":"Article 230724"},"PeriodicalIF":2.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783585","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":"3-D seismic delineation of the North Anatolian Fault System shear zone in the Western Half of Marmara Basin, Türkiye","authors":"Ö. Yilmaz ,&nbsp;Z. Özer ,&nbsp;D.T. Beşevli ,&nbsp;J.E.L. Wu ,&nbsp;C. Özsoy ,&nbsp;S. Sevinç ,&nbsp;K.B. Bakioglu ,&nbsp;M.B. Ercengiz ,&nbsp;Ö.K. Şahin ,&nbsp;B. Dadak ,&nbsp;T. Hastürk ,&nbsp;Ö. Yapar ,&nbsp;H. Dalabasmaz ,&nbsp;N.Ö. Sipahioglu ,&nbsp;C. Demirci ,&nbsp;R.Ö. Temel ,&nbsp;M.F. Akalın ,&nbsp;M.S.B. Sadioglu","doi":"10.1016/j.tecto.2025.230726","DOIUrl":"10.1016/j.tecto.2025.230726","url":null,"abstract":"<div><div>We performed a 3-D AI-based structural interpretation of a seismic image volume derived from 3-D prestack time migration, and delineated fault geometries and the subsidiary Riedel shear fractures within the sedimentary overburden associated with the North Anatolian Fault System (NAFS) in the western half of Marmara Basin, Türkiye. We thus inferred existence of dextral strike-slip basement fault segments with extensional (releasing) and contractional (restraining) stepovers that gave rise to the formation of the geomorphic features --- the pull-apart Tekirdağ and Central Basins, and the Western High pop-up structure, respectively. The NAFS shear zone within the study area extends <em>E</em>-W and has a 20-km maximum N-S width. Previous investigations based on 3-D inversion of gravity data over the Sea of Marmara and the surrounding region, and long-range <em>E</em>-W seismic refraction profiling across the basin infer that the Moho depth is as shallow as 24 km in the western half of Marmara Basin --- nearly 6 km shallower than the average regional depth of 30 km. The Moho uplift forms a fairly narrow ridge (&lt;30 km) confined to the NAFS shear zone, coincident with the <em>E</em>-W principal strike direction of the NAFS. This implies that it may have been formed contemporaneously with the formation of the pull-apart basins which gave rise to crustal stretching within the stepovers, resulting in basin subsidence, crustal thinning, and Moho uplift. The segmentation in the NAFS and the <em>E</em>-W trending Moho ridge may have led to the formation of earthquake rupture barriers and weak zones in the brittle upper crust.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"905 ","pages":"Article 230726"},"PeriodicalIF":2.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783675","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":"Tectonic and magmatic segmentation interlinkage in the central main Ethiopian rift","authors":"Shimels Wendwesen ,&nbsp;Abera Alemu ,&nbsp;Wubamlak Nigussie ,&nbsp;Kevin Mickus ,&nbsp;Simeneh Wassihun ,&nbsp;Habtamu Wuletawu ,&nbsp;Yoseph Muhabaw","doi":"10.1016/j.tecto.2025.230725","DOIUrl":"10.1016/j.tecto.2025.230725","url":null,"abstract":"<div><div>The Main Ethiopian Rift (MER) presents a spectrum of rift sector evolution from embryonic continental rifting in the south to incipient oceanic spreading in the north. The central sector of the MER (CMER) remains relatively immature, characterized by strain accommodation through border faults, axial magmatic segments, and off-rift magmatic zones. However, understanding of the tectonic and magmatic segmentation within this sector is relatively incomplete. This study investigates the CMER at a crustal scale, utilizing gravity data to analyze the nature of tectonic segmentation (TS). While previous studies only considered the Aluto-Gedemsa magmatic segment (MS) within the CMER, our work maps three distinct MS for the first time: Tullu Moye-Gedemsa-MS, Aluto-MS, and Corbetti-Shalla-MS, based on subsurface imaging using gravity data. We find that the distribution of surface faults correlates with subsurface magmatic intrusion zones within the Tullu Moye-Gedemsa and Boseti-Kone MS, indicating a clear interlinkage between tectonic and magmatic segmentation and suggesting the TS stage of the region. In contrast, the absence of such association in the Corbetti-Shalla and Aluto-MS regions suggests that the southern section of the CMER may not be in a stage of TS.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"905 ","pages":"Article 230725"},"PeriodicalIF":2.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783587","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 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}