Tectonophysics最新文献

{"title":"Seismic lithospheric model across Ukrainian Shield from the Carpathians to the Dnieper-Donets Basin and its tectonic interpretation","authors":"V. Starostenko ,&nbsp;T. Janik ,&nbsp;A. Murovskaya ,&nbsp;W. Czuba ,&nbsp;P. Środa ,&nbsp;T. Yegorova ,&nbsp;P. Aleksandrowski ,&nbsp;O. Verpakhovska ,&nbsp;K. Kolomiyets ,&nbsp;D. Lysynchuk ,&nbsp;T. Amashukeli ,&nbsp;T. Burakhovych ,&nbsp;D. Wójcik ,&nbsp;V. Omelchenko ,&nbsp;O. Legostaeva ,&nbsp;D. Gryn ,&nbsp;S. Chulkov","doi":"10.1016/j.tecto.2024.230540","DOIUrl":"10.1016/j.tecto.2024.230540","url":null,"abstract":"<div><div>The SW-NE directed wide-angle reflection-refraction (WARR) SHIELD’21 profile crosses entire width of Ukraine. It targeted the structure of the crust and uppermost mantle in the southwestern part of the East European Craton (EEC), between Carpathians and Voronezh Massif, across Ukrainian Shield and Dnieper-Donets Basin. The ∼660 km-long profile is an extension of the RomUkrSeis profile in Romania and Ukraine. SHIELD’21 experiment, using TEXAN and DATA-CUBE short-period seismic stations, provided high-quality seismic sections from 10 shot points. This allowed construction of a ray-tracing P-wave velocity model, supplemented by V_p/V_s ratio, for the upper part of the lithosphere in the Sarmatia segment of the EEC and constraining geodynamic processes that led to the formation of the Ukrainian Shield and its margins since Archean times.</div><div>The velocity distribution in the crystalline crust indicates a rather uniform structure, with velocity changing from 6.0 km/s near the surface to 6.8 km/s at the Moho. The entire section shows the lack of a high-velocity lower crust (V_p &gt; 6.8 km/s), presumably resulting from delamination of the primitive mafic lower crust during early evolution of a juvenile continental crust. The seismic boundaries in the upper crust reflect a Paleoproterozoic extensional detachment system below the SW flank of Dnieper-Donets rift basin, initiated in the Devonian. At larger depths, a wide dome of the lower crust with velocities of 6.5–6.8 km/s in the SW-central segment of the profile, probably represents an enormous Palaeoproterozoic(?) granitoid batholith. In the southwesternmost part of the profile, the crystalline crust shows exclusively low velocities. The prominent Moho is undulating and varies in depth between 32 and 50 km. It is underlain by high-velocity bodies (V_p: 8.36–8.40 km/s), against the background of 8.16–8.25 km/s in the mantle. The velocity model corresponds with the anomalies of potential fields and zones of high electric conductivity.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"892 ","pages":"Article 230540"},"PeriodicalIF":2.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552852","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":"Present-day incipient fault coalescence at a relay zone (Jiloca extensional basin, Spain): Evidence from instrumental seismicity","authors":"Alba Peiro ,&nbsp;Lucía Lozano ,&nbsp;Luis E. Arlegui ,&nbsp;Juan V. Cantavella ,&nbsp;Sandra Ruiz-Barajas ,&nbsp;José L. Simón","doi":"10.1016/j.tecto.2024.230541","DOIUrl":"10.1016/j.tecto.2024.230541","url":null,"abstract":"<div><div>The relay zones between NW-SE to NNW-SSE striking faults of the Jiloca graben (Iberian Chain) mostly show distributed along-strike fault and fracture patterns. The latter are chiefly controlled by the Late Pliocene-Quaternary regional stress field, and secondarily respond to local controls from inherited structures. Such fracture patterns contrast with the classical models of transverse connecting faults controlled by relay kinematics. North of the Concud fault trace, at the relay zone with the Sierra Palomera fault, an unusually high seismic activity has been noticed since 2014, with magnitudes up to M = 3.5. Upgrading of the National Seismic Network allowed obtaining such new detailed records, while the installation of a new seismometer by the IGN within the study area has improved the reliability of focal depth data since 2017. A high-precision absolute relocation of seismicity from 01/01/2000 to 30/05/2022 has been carried out. The results show that (i) the epicentres are significantly clustered along a nearly N-S trending band, and (ii) the focal depths range from 0 to 14 km, in good agreement with the thickness of the brittle crust. This 3D spatial distribution of seismicity is interpreted as a consequence of activation of either a single fault or a fault zone, nearly vertical and N-S striking. Such structural setting is consistent with the surficial fracture patterns observed at both map and outcrop scale: NNW-SSE and NNE-SSW oriented faults and fractures, orthogonal to the ENE-WSW to ESE-WNW regional σ₃ trajectories, together with NW-SE trending ones controlled by inherited contractive faults. The present-day seismic activity suggests that along-strike, incipient fault propagation at the relay zone between the Concud and Sierra Palomera faults is currently operating under the control of the remote stress field.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"893 ","pages":"Article 230541"},"PeriodicalIF":2.7,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578717","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":"Upper mantle shear velocity structure of the Cathaysia Block and surrounding areas: New insight into deep geodynamics","authors":"Yao Xu ,&nbsp;Qingtian Lü ,&nbsp;Dapeng Zhao ,&nbsp;Jiayong Yan ,&nbsp;Danian Shi ,&nbsp;Yongqian Zhang ,&nbsp;Shuai Ruan ,&nbsp;Zhiwu Xu ,&nbsp;Changxin Chen ,&nbsp;Wenwen Zhang ,&nbsp;Xu Wang","doi":"10.1016/j.tecto.2024.230542","DOIUrl":"10.1016/j.tecto.2024.230542","url":null,"abstract":"<div><div>The Cathaysia Block (CAB) and its surrounding areas experienced intensive magmatism and mineralization in the Yanshanian period (ca. 200–90 Ma), but their mechanism and deep geodynamics are still debated. In addition, the origin and structures of the Hainan mantle plume are still unclear. To resolve these issues and investigate the large-scale lithospheric thinning and extension in the eastern South China Block, we determine a detailed 3-D S-wave velocity (Vs) model down to 700 km depth by collecting 24,190 S-wave teleseismic data recorded at 164 permanent stations and 125 portable stations deployed in the CAB and surrounding areas. Our results show that high-Vs anomalies exist separately in the study volume. Two high-Vs anomalies appear in the shallow upper mantle and the mantle transition zone, which may reflect the present thin lithosphere and the stagnant Paleo-Pacific slab, respectively. Two other high-Vs anomalies exist in the upper mantle, which may reflect the detached lithosphere and subducting slabs. In contrast, low-Vs anomalies appear widely beneath the CAB, which reflect a tilting magmatic conduit beneath the Wuyishan metallogenic belt (WYMB) and magmatic chambers beneath the Nanling metallogenic belt (NLMB). In addition, our results show that the Hainan plume has a double-layered appearance. Combining our tomographic results with previous multidisciplinary findings, we consider that (1) the subduction and rollback of the Paleo-Pacific Plate may have played different roles in the Yanshanian mineralization of the WYMB and the NLMB; (2) the double-layered appearance of the Hainan plume may be formed due to the influence of plume self-evolution dynamics and pre-existing deep structures; and (3) lithospheric delamination triggered by gravity instability may have occurred beneath the Xuefengshan Mountain in the late Mesozoic.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"892 ","pages":"Article 230542"},"PeriodicalIF":2.7,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552767","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":"Tectonomagmatic evolution of Pune – Nasik Deccan Dykes: Insights from structure and dimension scaling","authors":"Ragini Kumari,&nbsp;Jyotirmoy Mallik,&nbsp;Garima Shukla","doi":"10.1016/j.tecto.2024.230539","DOIUrl":"10.1016/j.tecto.2024.230539","url":null,"abstract":"<div><div>The Deccan Continental Flood Basalt of the Indian Peninsula is characterized by extensive basaltic eruptions ornamented with three spectacular distinct dyke swarms: the Pune – Nasik, Narmada – Tapi, and Western Coastal dyke swarms. Our study area is the Pune – Nasik dyke swarm, which has ∼465 mappable dykes. These dykes exhibit different orientations with a predominant trend of N101° and vary in length from less than 1 km to ∼64 km. These dykes are massively jointed and occasionally contain vesicles filled with secondary minerals like quartz and calcite. The host rock is weathered basalt of various older Deccan flows. In this study, we have calculated magmatic overpressures and magma chamber depths using the aspect ratios (length/thickness) of the dykes. The average estimated source depth is ∼13 km, based on an average Young's modulus for the host rock basalt (E_avg, 7.5 GPa). Additionally, we compared the inferred magma source depths of the Pune – Nasik, and Narmada-Tapi dyke swarms which include the Nandurbar – Dhule, and Pachmarhi dykes of the Deccan Flood Basalt Province. Our findings indicate that the magma chamber source depth is greater in the Pune – Nasik dyke swarm compared with other dyke swarms. The variation in strike distribution of the Pune-Nasik dyke swarm may be attributed to several factors, including a larger magma chamber, local stress fields generated by shallow magma chamber, or the superimposition of tectonic stress fields (N-S and <em>E</em>-W extension) during the emplacement of dykes. This contrasts with the commonly held belief that the dykes are solely connected to a central edifice of the Reunion hotspot.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"891 ","pages":"Article 230539"},"PeriodicalIF":2.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528985","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":"Remagnetisation of the Caerfai Group (lower Cambrian, SW Wales) in hot geothermal fluids during Caledonian (pre-Acadian) metamorphism","authors":"Peter Turner ,&nbsp;Rob Ixer ,&nbsp;Duncan Pirrie ,&nbsp;Matthew Power","doi":"10.1016/j.tecto.2024.230532","DOIUrl":"10.1016/j.tecto.2024.230532","url":null,"abstract":"<div><div>Palaeomagnetic data from the Lower Cambrian red beds of the Caerfai Group in Pembrokeshire, South Wales have been revisited. Original studies all produced closely similar directional data with the combined results yielding a palaeomagnetic pole at 21.8^oS; 355.5°E corresponding to a time of ∼430 Ma when compared with the APWP of Stable Europe and Baltica. The results of this study indicate that remagnetisation occurred during Caledonian metamorphism, prior to Acadian deformation in the area. The magnetic remanence is carried by fine grained hematite distributed throughout the sequence and which appears to have been acquired during the duration of a single chron. This time zone is traditional early Silurian (late Llandovery) and corresponds to the docking of Baltica and east Avalonia with the Laurentian continent. The proposed age of the remagnetisation event is consistent with radiometric ages from epizonal authigenic illites in overlying Middle Cambrian bentonites at Porth-y-Rhaw and elsewhere in the Welsh Basin and other parts of Avalonia including Charnwood block and Brabantia. The Caerfai Group comprises texturally immature litharenites with a mineral assemblage including chlorite, biotite, muscovite, graphite, and epidote consistent with a greenschist facies source area which remains unidentified. A key component of the Caerfai mineral assemblage are magnetite crystals (typically 30–60 μm) deposited during contemporaneous volcanic activity. Deep burial during the drift of Avalonia, indicated by clay transformations and overpressure in the Caerfai Bay Mudstone, was associated with the alteration of iron-bearing minerals and the dissolution of magnetite. During collision of Avalonia/Baltica with Laurentia a geothermal cell with epizonal metamorphic conditions (&gt;300 °C) and fluids enriched in iron, probably in the form of iron chloride complexes was established. The remagnetisation event was triggered when the geothermal cell was cooled, most likely by the infiltration of meteoric water, and the reaction of iron chloride with water produced the widespread precipitation of fine-grained hematite and the formation of a chemical remanent magnetisation (CRM).</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"891 ","pages":"Article 230532"},"PeriodicalIF":2.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528987","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":"Crustal imaging and characterization of active faults with a large-N nodal deployment - Application to the Chaînons Béarnais region (western Pyrenees foothills, France)","authors":"Sébastien Chevrot ,&nbsp;Matthieu Sylvander ,&nbsp;Nicolas Saspiturry ,&nbsp;Amine Ourabah ,&nbsp;Sébastien Benahmed ,&nbsp;Benoît Derode ,&nbsp;Frank Grimaud ,&nbsp;Jean Letort ,&nbsp;Hélène Pauchet ,&nbsp;Guy Sénéchal ,&nbsp;Antonio Villaseñor ,&nbsp;Jean-Baptiste Ammirati","doi":"10.1016/j.tecto.2024.230531","DOIUrl":"10.1016/j.tecto.2024.230531","url":null,"abstract":"<div><div>Understanding the driving forces and nature of intraplate seismicity remains a major unsolved problem in seismology. In the western Pyrénées, seismicity is concentrated in a narrow region that follows the boundary between the Axial Zone and the North Pyrenean Zone. Despite the presence of a permanent network in the region, the geometry of active faults, and their relationship with crustal structures, remain elusive, owing to significant earthquake location uncertainties. Here, we exploit data recorded by a large-N nodal array deployed in the Chaînons Béarnais region during four weeks of 2022 in order to image crustal structures and characterize active faults. We automatically detected and picked P and S waves with PhaseNet, resulting in a catalog of over 500 events, half of which are located beneath the temporary deployment. Tomographic images obtained from the inversion of P and S arrival times provide detailed insight into the geometry of folds and thrusts in the sedimentary cover, as well as the presence of a main fault in the basement which dips northward with an angle of 65° (Chaînons Béarnais normal fault). Seismicity relocation within the 3D model obtained by tomography shows that earthquakes are concentrated along this main active fault, extending from the top of the basement to a depth of approximately 16 km. These results demonstrate that passive imaging approaches can offer cost-effective alternatives to traditional controlled source imaging for seismotectonic studies and natural resource exploration in regions with active seismicity.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"892 ","pages":"Article 230531"},"PeriodicalIF":2.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552846","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":"Insight into intracontinental deformation and crustal reworking of ancient continents implied by crustal structure imaging of the Yangtze Craton","authors":"Mingming Jiang ,&nbsp;Tianyu Zheng ,&nbsp;Yumei He","doi":"10.1016/j.tecto.2024.230537","DOIUrl":"10.1016/j.tecto.2024.230537","url":null,"abstract":"<div><div>The crustal imprints from multistage tectonic activities in cratons offer valuable insights into continental evolution. Utilizing seismic data from two densely deployed, nearly perpendicular linear arrays, and a newly developed stepwise joint inversion of depth-domain receiver function and surface wave dispersion, we constructed a detailed crustal layering model for the Yangtze Craton. Our analysis revealed elongated double velocity reversal zones as salient features of the crust, which likely record ancient crustal reworking and juvenile crustal growth associated with Neoproterozoic rift-related magmatic processes. The interlayering of low- and high-velocity structures may contribute to the enduring stability of the Yangtze Craton. Additionally, superimposed layers separated by east-dipping interfaces and abrupt changes in crustal thickness in the boundary belts surrounding the Yangtze Craton document the crust's structural responses to intracontinental deformation during continent assembly.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"892 ","pages":"Article 230537"},"PeriodicalIF":2.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552845","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":"Structural evolution of the Horoman peridotite complex in conjunction with the formation of the Hidaka Metamorphic Belt, Hokkaido","authors":"Kazuki Matsuyama ,&nbsp;Katsuyoshi Michibayashi","doi":"10.1016/j.tecto.2024.230535","DOIUrl":"10.1016/j.tecto.2024.230535","url":null,"abstract":"<div><div>We conducted crystal-fabric analyses of peridotites within the Horoman peridotite complex in the Hidaka metamorphic belt, Hokkaido, Japan. Over fifty oriented peridotite samples were collected and analyzed for olivine fabric strength (<em>J</em>-index) and crystallographic preferred orientations (CPOs). The peridotites contained four olivine CPOs: A, E, D, and AG types. We confirmed that olivine CPOs presented a transitional distribution from E to A to AG type from south to north. Previous experimental studies have demonstrated that E type CPO can merge under hydrous conditions. In addition, magnetotelluric observations suggested that the subducting oceanic plate supplies pore fluid to the basal thrust in the region (the Hidaka Main Thrust). Therefore, we infer that the E type CPO was originated from a local water infiltration event. AG type CPO, on the other hand, was considered as a secondary product enhanced by the synkinematic melts in the northern (geological upper) part, combined with the pressure-temperature path inferred by previous petrological studies. Furthermore, we reconstructed the senses of shear strain using the microstructure and olivine crystal-fabrics. Then we built the tectonic history of the Horoman peridotite complex integrating the structural development of the Hidaka metamorphic belt.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"892 ","pages":"Article 230535"},"PeriodicalIF":2.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552847","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":"New insight into the velocity and anisotropy structures of the subduction zone in northern Sumatra","authors":"Xueyuan Huang ,&nbsp;Ping Tong","doi":"10.1016/j.tecto.2024.230534","DOIUrl":"10.1016/j.tecto.2024.230534","url":null,"abstract":"<div><div>In this study, we conducted seismic tomographic inversions to investigate the velocity and anisotropy structures of northern Sumatra, using 9774 P-wave and 8405 S-wave arrivals from regional earthquakes. Isotropic P-wave velocity, isotropic S-wave velocity, P-wave azimuthal anisotropy, and P-wave radial anisotropy models were generated using eikonal equation-based traveltime tomography methods. The study identified low-velocity zones beneath the Toba and Sinabung volcanoes, potentially indicating the presence of magma reservoirs. Furthermore, low-velocity anomalies above the subduction slab were detected, which were likely caused by the dehydration of the slab and interpreted as channels of upwelling flow. The tomographic results revealed a trench-parallel high-velocity belt in the uppermost mantle, representing the subducting slab of the India-Australian plate. The trench-parallel fast velocity directions in the slab suggested that the subducted oceanic slab retains its frozen-in anisotropy formed at the mid-ocean ridge, or that the anisotropy is induced by the lattice-preferred orientation of the B-type olivine. Negative radial anisotropy in the mantle wedge was observed, reflecting hot upwelling flows and transitions of olivine fabrics in the presence of water due to slab dehydration. The results also indicated a multilevel magma plumbing system beneath the Toba Caldera. In summary, the results of this study provided new insights into the structure and dynamic processes of the northern Sumatra subduction zone.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"892 ","pages":"Article 230534"},"PeriodicalIF":2.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552850","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":"Deep plutonic bodies over low-frequency earthquakes revealed from receiver-side Green's functions","authors":"Yasunori Sawaki ,&nbsp;Yoshihiro Ito ,&nbsp;Emmanuel Soliman M. Garcia ,&nbsp;Ayumu Miyakawa ,&nbsp;Takuo Shibutani","doi":"10.1016/j.tecto.2024.230536","DOIUrl":"10.1016/j.tecto.2024.230536","url":null,"abstract":"<div><div>Seismological heterogeneity in subduction zones provides insights into slow earthquakes and potential megathrust earthquakes. Studies at the Kii Peninsula in the Nankai subduction zone suggest that there are high-density and high-velocity plutonic bodies in the accretionary prism over the subducting slab, potentially influencing megathrust earthquakes. The lateral variation of heterogeneity and the spatial extent of plutonic bodies remain to be investigated well. Our passive-source imaging of receiver-side Green's functions, from widely distributed campaign seismic observations, reveals a sharp negative S-wave velocity contrast on the top surface of the subducting Philippine Sea plate common to all along-dip profiles and a positive phase tilted upward in the forearc crust. The low permeability of the forearc crust prevents the infiltration of slab-dehydrated fluid further into the upper crust. In the western area, we also found positive phases tilted upward in the forearc crust. The negative phase extends towards the deeper extent of slow-earthquake sources. Meanwhile, the positive phase likely represents the top surface of plutonic rocks of the Kumano and Ohmine plutons that span all the way down to the plate interface. Together with observations of gravity anomaly, intraslab seismicity, and seismic tomography, our interpretation supports the presence of plutonic bodies which extend deep beneath the forearc crust as well as laterally over the subducting PHS slab, rather than a serpentinized mantle wedge. The upper plate is generally low in permeability, but areas with localized high permeability may exist on the updip side of tremor sources. This condition, wherein fluid can infiltrate upwards locally, may maintain the relatively less active slow earthquakes in the western area. The lateral variation of the upper-plate lithology likely influences fluid processes and slow earthquake activities.</div></div>","PeriodicalId":22257,"journal":{"name":"Tectonophysics","volume":"892 ","pages":"Article 230536"},"PeriodicalIF":2.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552848","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}