Journal of Geophysical Research: Solid Earth最新文献

{"title":"Mechanisms of Transient Postseismic Deformation Following the 2024 Mw 7.5 Noto Peninsula Earthquake Inferred From Horizontal and Vertical GNSS Data","authors":"Jeonghyeop Kim,&nbsp;Fred F. Pollitz,&nbsp;David A. Schmidt","doi":"10.1029/2025JB032097","DOIUrl":"https://doi.org/10.1029/2025JB032097","url":null,"abstract":"<p>The 2024 M_w 7.5 Noto Peninsula earthquake provided an opportunity to investigate postseismic deformation in a tectonically complex back-arc region in central Japan, where Miocene normal faults are reactivated under present-day compression. Results show that neither viscoelastic relaxation nor afterslip alone fully explains the GNSS data. However, a simple integrated model combining viscoelastic relaxation and kinematically inferred afterslip on a single planar fault reproduces the first-order postseismic deformation despite the region's tectonic complexity. Systematic model evaluation demonstrates that viscoelastic relaxation dominates far-field observations and near-field vertical deformation, whereas afterslip is essential for near-field horizontal signals. Their relative contributions depend on the weighting between horizontal and vertical data and the assumed viscoelastic structure. Assuming a 30 km-thick elastic top layer, the preferred model suggests that the best underlying 1D structure consists of a mantle asthenosphere with transient (Kelvin) and steady-state (Maxwell) viscosities of ∼4.0 × 10¹⁷ and ∼4.0 × 10¹⁸ Pa <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>·</mo>\u0000 </mrow>\u0000 <annotation> $cdot $</annotation>\u0000 </semantics></math> s, respectively, consistent with a Burgers body. The preferred model estimates afterslip concentrated northeast of the coseismic rupture, diminishing within 6 months and releasing ∼8% additional moment. Resolution tests, together with sensitivity analyses using multi-plane fault geometries, confirm that inferred afterslip on the southeast-dipping fault offshore northeast of the Noto Peninsula is robust. Investigation of the spatiotemporal relationship between afterslip and on-fault aftershocks reveals that the aftershock distribution corresponds spatially with total cumulative fault slip rather than afterslip alone, whereas aftershock activity decreases with afterslip moment decay over time, indicating that aftershock occurrence is controlled by multiple processes.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB032097","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved Half-Space Cooling Model Reconciles Bathymetry and Thermal Evolution of the Southwest Subbasin, South China Sea","authors":"Penggao Fang,&nbsp;Weiwei Ding","doi":"10.1029/2026JB034423","DOIUrl":"10.1029/2026JB034423","url":null,"abstract":"<p>The bathymetry of marginal sea basins commonly deviates from depths calculated by classical lithospheric cooling models, yet the controlling mechanisms remain debated. Here, using 19 seismic profiles and corrected local heat-flow data, we apply an improved half-space cooling model within a two-stage reconstruction to reassess thermal subsidence of the Southwest Subbasin (SWSB), South China Sea (SCS). By correcting for sediment and crustal loading, dynamic topography, sea-level change, and post-spreading cooling, we reconstruct paleobathymetry at seafloor spreading cessation (∼16 Ma) and isolate water-loaded subsidence during active spreading. Paleobathymetric reconstructions yield mean depths of 2.70–2.86 km at ∼16 Ma, compared with a present-day sediment-corrected mean of 4.55 km, implying 1.69–1.85 km of integrated post-spreading subsidence. We interpret this deepening primarily as cooling and contraction following the rapid cessation of magmatic heat input, potentially amplified by dense recycled mantle components. Removing post-spreading effects restores cessation-age bathymetry comparable to normal oceanic lithosphere. Syn-spreading age–depth coefficients are ∼188–287 m/Ma^1/2 lower than open-ocean reference values, indicating a pronounced subsidence deficit. We attribute this to enhanced magma supply linked to subduction-driven mantle flow, which maintained thermal and dynamic support during spreading. Along-strike variations reflect heterogeneous magma supply influenced by southern slab breakoff and westward spreading propagation over heterogeneous lithosphere. Our results reveal a two-stage evolution linking magma-supported shallow bathymetry during spreading to substantial post-spreading subsidence. This framework provides new constraints on the coupled roles of mantle dynamics, magma supply, and lithospheric cooling in shaping SWSB bathymetry.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JB034423","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterizing the Forearc Basement and Subducting Structures of the Northern Ecuadorian Margin","authors":"Arnaud Delsuc,&nbsp;Audrey Galve,&nbsp;Mireille Laigle,&nbsp;Andreas Rietbrock,&nbsp;Laure Schenini,&nbsp;Hans Agurto-Detzel,&nbsp;Alexandra Skrubej,&nbsp;Boris Marcaillou,&nbsp;Sandro Vaca,&nbsp;Annika Maier,&nbsp;Michele Paulatto","doi":"10.1029/2026JB033929","DOIUrl":"10.1029/2026JB033929","url":null,"abstract":"<p>We present 2D P-wave velocity (Vp) models from the northern Ecuadorian subduction zone, north of the Carnegie Ridge. Data were collected during the HIPER2 3D wide-angle seismic experiment, both onshore and offshore. Key seismic profiles were manually picked to determine P-wave first-arrival times, which were used for a traveltime tomographic inversion based on a Bayesian approach. Interpreting these 2D Vp models jointly with existing multi-channel seismic (MCS) data reveals a high vertical Vp gradient (&gt;0.85 km/s/km) consistent with the position of the forearc basement defined by MCS data, allowing us to map the basement along the margin. In addition, two notable low-velocity zones are identified. The first zone observed across all profiles within the inner margin wedge, is interpreted as resulting from rock fracturation and/or alteration near the trench. The second one present in the subducting oceanic crust, is characterized by a Vp reduction of 0.5–1.0 km/s relative to the surrounding areas and marks the northern termination of a previously identified trench-parallel velocities anomaly. As a possible origin of this distinctive anomaly, we propose the entry into subduction of an unmapped fracture zone (FZ), potentially reactivated by the increased plate bending due to the presence of the 2 km-high Carnegie Ridge. Three FZ are proposed as possible sources of this anomaly that would southwards extend fossil transform faults for 100–150 km.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JB033929","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Spatiotemporal Evolution of Creep on the Southern San Andreas Fault Between 2015–2021","authors":"Ellis J. Vavra,&nbsp;Yuri Fialko","doi":"10.1029/2026JB034392","DOIUrl":"10.1029/2026JB034392","url":null,"abstract":"<p>The Southern San Andreas fault (SSAF) in the Coachella Valley experiences shallow creep and slow slip events (SSE), which re-distribute stresses in the seismogenic zone and affect the potential of future earthquakes. Although average creep rates are relatively well-constrained, untangling the details of spatiotemporal variation in creep along the SSAF has been challenging due to limited data coverage. In this study, we use 7 years of Interferometric Synthetic Aperture Radar data from the dense Sentinel-1 catalog to image and model the evolution of shallow creep along the SSAF. We generate time series of fault parallel displacements and isolate the signal associated with shallow creep. We apply a network inversion filter approach to invert the surface displacements for the full slip history on the shallow creeping part of the SSAF and simultaneously characterize model uncertainties. Although some quasi-steady creep may have been occurring at the southern end of the SSAF prior to 2017, the slip history during 2015–2021 is dominated by a multi-year SSE where the elevated creep rate along nearly the entire SSAF was dynamically triggered by the 2017 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>w</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${M}_{w}$</annotation>\u0000 </semantics></math> 8.2 Chiapas earthquake. The SSE exhibited pulse-like bilateral propagation, with the total moment release equivalent to a <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>w</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${M}_{w}$</annotation>\u0000 </semantics></math> 5.2 earthquake. The dynamic triggering and the subsequent slow fall-off of slip and moment rate are suggestive of the low fault strength and healing rates.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JB034392","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inception and Plate Evolution of the Lau Back-Arc Basin From Plate Boundary Refinements","authors":"Alan T. Baxter,&nbsp;Mark D. Hannington,&nbsp;Kaitlyn Breker,&nbsp;Christopher Galley,&nbsp;Marc L. Fassbender,&nbsp;Erin Bethell","doi":"10.1029/2025JB033736","DOIUrl":"10.1029/2025JB033736","url":null,"abstract":"<p>Back-arc basins are important settings for crustal growth that form in response to both near and far-field tectonic influences. To better understand the processes that control back-arc basin initiation and evolution, we present a refined model of the kinematics of opening of the Lau Basin, embedded in a global plate model. The model, which runs from 10 Ma to the present, includes three previously unrecognized paleoplates, five microplates and 10 active spreading centers. Collision of the Ontong Java Plateau with the active Vitiaz arc between 25 and 15 Ma blocked subduction of the Pacific Plate and resulted in the formation of a Subduction-Transform Edge Propagator, or STEP fault, along the Vitiaz Trench. Fragmentation and rotation of the Vitiaz arc crust and the formation of new intrabasinal transform structures such as Peggy Ridge were fundamental in promoting back-arc rifting. Our model suggests that Peggy Ridge was originally an arc-parallel extensional fault, reactivated between 7 and 5 Ma as a strike-slip fault that allowed initial opening of the back-arc basin and propagation of early rifting into the southern Lau Basin. Multiple drivers, in addition to the dominant control of slab rollback, initiated this rapid change in basin opening, including transcurrent structures in the northern Lau Basin. As a result, the evolution of the basin was highly asymmetric and non-linear, in contrast to previously-proposed models. The model strongly supports upper plate processes as important drivers of back-arc basin development, including collisions, STEP fault formation, forearc extension, fault propagation and block rotation.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JB033736","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mapping Global GNSS Vertical Velocities to Solid Earth Figure Change","authors":"C. Kotsakis","doi":"10.1029/2026JB034224","DOIUrl":"10.1029/2026JB034224","url":null,"abstract":"<p>The Earth's figure evolves in response to glacial isostatic adjustment (GIA), surface-mass redistribution, and rotational and mantle-driven processes. While temporal changes in the geoid's flattening are monitored through low-degree gravity field harmonics, the geometric response of the solid Earth can be assessed independently from GNSS-derived vertical velocities. We develop a geometric framework to estimate Earth figure change (EFC) parameters from global vertical velocity fields and their gridded representations, focusing on the degree-2 zonal component that depicts the rate-of-change of solid Earth's flattening. The methodology links polar and equatorial mean radial deformation rates to this coefficient and evaluates gridding-related biases through synthetic experiments based on GIA models. For the non-GIA component of radial deformation, an elastic Earth response is assumed to translate GNSS-derived vertical displacements into the corresponding contribution to the temporal evolution of J2. The approach is applied to ITRF2014/ITRF2020 vertical velocities over 1997–2015 to derive time-resolved EFC estimates, their accelerations, and the contribution to the J2-rate under an elastic Earth loading framework after removal of the modeled GIA signal. Results indicate an increase in polar uplift from ∼0.5 to ∼1.0 mm/yr and concurrent equatorial subsidence of similar magnitude, producing an accelerating signal of solid Earth's flattening change. In addition, the inferred J2-rate due to elastic Earth response exhibits a positive linear trend consistent with enhanced surface-mass redistribution toward lower latitudes. Overall, the results demonstrate that geodetic vertical velocities provide a robust geometric complement to gravity-based assessments of ongoing global change of Earth's figure.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JB034224","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Building the Andean Crust at ∼35°S: Arc Geochemistry Reveals Cretaceous Thinning and Rapid Neogene Thickening","authors":"Chance B. Ronemus,&nbsp;Caden J. Howlett,&nbsp;Peter G. DeCelles,&nbsp;Barbara Carrapa,&nbsp;Andrés Echaurren,&nbsp;Matías Barrionuevo,&nbsp;Jesse G. Mosolf,&nbsp;Michelle L. Foley,&nbsp;Mihai N. Ducea","doi":"10.1029/2026JB034002","DOIUrl":"10.1029/2026JB034002","url":null,"abstract":"<p>Quantification of the timing and mechanisms of crustal thickening in Cordilleran orogenic hinterlands remains challenging. We address this in the Andes using whole-rock geochemistry and zircon petrochronology from a &gt;70 Myr volcanic record in the Tinguiririca valley of Chile (∼35<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>S), which captures a pivotal transition from extensional to contractional deformation. Zircon (Sm, Gd, Dy)/Yb ratios generally track trends in whole-rock geochemical crustal thickness (paleomohometry) models across this record, with Dy/Yb showing the most consistent correspondence. Our results indicate modest crustal thinning coeval with Late Cretaceous normal faulting and oblique plate convergence. Eocene and Early Miocene samples yield similar crustal thicknesses (∼35 km), suggesting limited local net attenuation during proposed intra-arc rifting (Abanico basin). The crust then thickened by ∼10 km to near-modern values (∼46 km) during the Neogene; Quaternary estimates match modern geophysical constraints, validating the paleomohometry approach. Thickening was most rapid between ca. 17 and 13 Ma, coinciding with accelerated retroarc shortening and plate convergence. Additional zircon geochronologic and geochemical proxies (Th/U, phosphorus content, and oxygen fugacity) indicate enhanced Miocene crustal melting and magmatic productivity. Along-strike comparisons reveal north-to-south younging and decreasing magnitude of thickening, mirroring trends in retroarc shortening. These findings indicate that underthrusting of foreland lithosphere during retroarc shortening drove crustal thickening, magmatic flare-up, and generation of orogenic topography in the southern Central Andes.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JB034002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Present-Day Kinematics of Continental Greece and Balkans Revealed by Sentinel-1 InSAR Data","authors":"A. Meridi,&nbsp;M. Métois,&nbsp;C. Lasserre,&nbsp;M.-P. Doin,&nbsp;P. Durand","doi":"10.1029/2026JB033831","DOIUrl":"10.1029/2026JB033831","url":null,"abstract":"<p>The Balkan Peninsula hosts the highest seismic activity in Europe, marked by numerous Mw6+ earthquakes in diverse tectonic settings. Assessing tectonic surface deformation is crucial to understand the forces controlling kinematics and, ultimately, constraining geodynamic models. However, because measuring slow velocity rates (a few mm/yr) with a sparse GNSS network is challenging, the Balkans surface deformation remain less studied than surrounding areas. We use Sentinel-1 radar images (2014–2021) processed by the FLATSIM program, providing InSAR time series extending over 360 000 km², at 240 m spatial resolution. By adapting a referencing method requiring minimal use of GNSS data, we produce a regional-scale InSAR velocity field for western Balkans, referenced to ITRF14 and showing strong agreement with GNSS (&lt;1 mm/yr). We decompose LOS velocities into horizontal and vertical components, constrain the location and amplitude of velocity gradients across active structures, and resolve both long- and short-wavelength signals. Horizontal velocities are dominated by large-scale tectonic motion, while vertical velocities are more heterogeneous, likely influenced by hydrology and anthropogenic processes. Kinematic analysis highlights key features: 4–5 mm/yr extension over 80 km in the inner Albanides and a major 250 km-wide lithospheric shear zone in Greece, accommodating &gt;2 cm/yr dextral motion, potentially linked to the North Anatolian Fault activity and Hellenic subduction rollback. Finally, we provide new constraints on compression going on in the Dinarides and Pannonian Basin. This study confirms the capability of InSAR to capture large-wavelength plate motions in slowly deforming regions, providing a robust basis for future surface deformation and seismic hazard studies.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JB033831","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiscale Surface Wave Tomography of the Bhutan Himalaya: MHT Imaging and Evidence of Crustal Tear of the MHT Below Central Bhutan","authors":"Gaurav Kumar,&nbsp;Ashwani Kant Tiwari,&nbsp;Anne Obermann,&nbsp;Sandeep Gupta","doi":"10.1029/2025JB033084","DOIUrl":"10.1029/2025JB033084","url":null,"abstract":"<p>The Bhutan Himalaya, within the India-Eurasia collision zone, is characterized by active deformation and significant seismic hazard. We image the Main Himalayan Thrust (MHT), the primary structure accommodating convergence, using surface wave dispersion derived from ambient noise and teleseismic earthquake recordings from the GANSSER network. Ambient noise data constrain shear wave velocities in the upper crust, whereas teleseismic Rayleigh waves extend resolution to ∼50 km depth. The resultant shear-wave velocity model reveals pronounced lateral heterogeneity in the upper crust, including high-velocity domains (<i>V</i>_<i>s</i> &gt; 3.6 km/s) consistent with quartzite-dominated lithologies. The MHT is imaged as a laterally continuous low-velocity layer (LVL) exhibiting a flat-ramp geometry: in western Bhutan a ramp emerges at ∼10 km, whereas in eastern Bhutan, the structure dips more gently to ∼20 km. In central Bhutan, disruption of the LVL, together with a concave-upward lower-crustal anomaly, suggest possible tear or segmentation of the thrust system.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Why Does the Broken Hill Deposit Sit in Resistive Crust? Magnetotelluric Evidence for Metamorphic Decoupling of a World-Class Mineral System","authors":"Yahya AlQahtani,&nbsp;Sinan Özaydın,&nbsp;Vasileios Chatzaras,&nbsp;Patrice F. Rey,&nbsp;Tiago Passos","doi":"10.1029/2026JB035666","DOIUrl":"10.1029/2026JB035666","url":null,"abstract":"<p>The spatial association between electrical conductors and ore deposits underpins the widespread use of magnetotellurics (MT) in mineral exploration, yet not all mineral systems preserve a diagnostic conductive signature. Here, we present a high-resolution MT study of the region hosting the world-class Broken Hill Pb-Zn-Ag deposit (NSW, Australia). Our MT model reveals a predominantly resistive upper crust <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mo>&gt;</mo>\u0000 <mn>1000</mn>\u0000 <mspace></mspace>\u0000 <mi>Ω</mi>\u0000 <mi>m</mi>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $( &gt; 1000 {Omega }mathrm{m})$</annotation>\u0000 </semantics></math> containing spatially discrete conductive anomalies that coincide with the Broken Hill lode and the sulphide-rich Broken Hill Group (specifically the Hores Gneiss). These anomalies show no robust vertical electrical connection to lower-crustal conductors. Nevertheless, we interpret the Broken Hill mineral system as genetically linked to a deep-seated anomaly in the lower crust related to the ore-forming rifting event and subsequent orogenesis. We propose that the shallow conductivity anomalies related to mineralization may have electrically and structurally decoupled from this deep-seated conductor during high-grade metamorphism. Consistent with this interpretation, larger-scale MT models of the region show that the Broken Hill deposits sit within a predominantly resistive domain in the shallow crust. Had its geology been obscured by the sedimentary cover, exploration strategies favoring conductive anomalies at a larger scale would have missed Broken Hill entirely. Our results caution against dismissing resistive crust as unprospective, and show how tectono-metamorphic overprinting and survey scale can obscure the primary signatures of major ore systems.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"131 9","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JB035666","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148932948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}