Analysis of fracture geometries, orientation, distribution, and connectivity is commonly conducted to characterise the mechanical and hydraulic properties of a fractured rock mass and to interpret its deformation history. These studies increasingly leverage high-resolution drone imagery (e.g., orthomosaics or orthophotographs). However, consistently and accurately extracting fracture traces from these large datasets remains a persistent challenge. In this contribution, we present a harmonised benchmarking dataset, FraXet, for pixel-wise fracture segmentation of combined high-resolution RGB orthophotographs and digital elevation models (DEMs) (ground sampling distance ranging from approximately 0.5 to 32 mm). FraXet curates images from three publicly available datasets, totalling 8953 256 × 256 RGB + DEM patches spanning diverse lithologies and imaging conditions (ground sampling distance, illumination, etc.) to systematically assess the effectiveness of conventional image-processing approaches for fracture extraction (Canny, Sobel, Gabor, Sato, and phase congruency) and two deep-learning (DL) models (U-Net and SegFormer). Quantitative comparisons using image-quality (e.g., MSE, PSNR), segmentation (e.g., Precision, Recall, F1, IoU), and new task-specific error metrics show that the deep models substantially outperform classical filters (F1 ≈ 0.3–0.5 vs. ± 0.29) and produce smoother, more continuous fracture traces. Training on the combined dataset (M_all) improves cross-site generalisation compared to models trained on individual sub-datasets used in this study. Probability maps derived from the DL approaches enable confidence-based triage and visualisation of model uncertainty. This work establishes a unified benchmark, curated dataset, and reproducible baseline for developing robust automated fracture-detection tools.
The geodynamic evolution of the post-Pan-African Anti-Atlas Orogeny (∼ 650 Ma) remains debated, particularly regarding the basement beneath the Central Anti-Atlas and the geological processes leading to the formation of the Ediacaran Saghro Group (SG) and Ouarzazate Group (OG). New LA-ICP-MS U-Pb± 3 Ma± 2 MaMaMaNb-TaTi anomalies, consistent with a back-arc basin setting; and (ii) an OG felsic-intermediate, high-KϵNd620 = +3.2 to +4.6, TDM = 1.02–0.91 GaϵNd570 = −0.8 to +1.1, TDM = 1.30–1.15 GaThese findings support a model in which early Ediacaran SG sediments and associated magmatic rocks were deposited in a back-arc basin. During this basin development, its shoulders were locally formed by the 2100 Ma
The Liqiao and Xianping plutons can provide crucial evidence for the collision-orogeny process of the Proto-Tethys Ocean in the western section of the North Qinling Orogen. In this study, we present petrological, zircon U-Pb geochronological, geochemical, and zircon Lu-Hf isotopic data for these plutons. Both the Liqiao and Xianping plutons are characterized as high-K, calc-alkaline, metaluminous to weakly peraluminous granites, with ages of 429 and 421 Ma, respectively. The Liqiao pluton was classified as I-type granite, displaying positive ϵHf(t)−0.1 to +3.4, and high Mg##ϵHf(t)−18.0 to −13.9), consistent with the geochemical characteristics of highly fractionated I-type granite. This suggests that the Xianping pluton formed through the partial melting of ancient felsic crust and followed by extensive fractional crystallization. We propose that the Liqiao pluton originated in a syn-collisional setting, while the Xianping pluton formed in a post-collisional environment. Both plutons are products of the collisional orogeny between the Yangtze Block and the North Qinling Orogen, which were associated with the closure of the Wushan-Shangdan Ocean, the northern of the Proto-Tethys Ocean.
The magnitude and location of vertical uplift in fold-thrust belts is a function of the geometry, duration, and timing of faults and how they have evolved over time. Yet in the Himalaya, uncertainties persist in whether vertical uplift and exhumation are driven by sustained displacement over mid-crustal ramps in the basal décollement, pulses of more rapid exhumation during periods of out-of-sequence fault displacement, or a combination of these drivers. In western Nepal, the well-defined zone of steep slopes and high relief that marks the high Himalaya in central Nepal splits into two zones: a northern zone ∼ 10 km∼ 80 km∼ 5–10 Ma
We analysed two rare earthquakes that occurred near Mirotice in south Bohemian Massif (Czechia) in March 2024 (ML 3.5) and April 2025 (ML 3.1), integrating seismological analyses with crowdsourced macroseismic observations. Both events originated at unusually large depths for the region (24.5 km) and were widely felt across southern and central Bohemia, attracting significant public attention. Independent of low population density, macroseismic effects were documented through extensive citizen participation, with over 1500 questionnaires for each event collected by the Institute of Geophysics, Czech Academy of Sciences. Maximum macroseismic intensities reached IV; however, the spatial distribution of observations was distinctly non-circular, forming a pattern controlled by major tectonic structures. Areas underlain by granitoids of the Central Bohemian Pluton exhibited dense and far-reaching macroseismic responses, consistent with low seismic energy attenuation of the Moldanubian, whereas regions dominated by early Palaeozoic sedimentary rocks of the Teplá–Barrandian showed sparse observations, indicating higher attenuation. The results indicate that crowdsourced data can constrain deep geological structures and effectively complement instrumental observations in regions with sparse seismicity.
Lithium brine systems are critical resources for the energy transition, yet the mechanisms governing lithium mobilization, transport, and concentration remain poorly constrained. In particular, the role of fault and fracture networks in controlling fluid flow and associated lithium distribution is not well resolved. New analyses of calcite-mineralized faults and opening-mode fractures, and paleo-spring deposits from Clayton Valley, Nevada are interpreted to record lithium-bearing fluid flow through > 10 Myr of Basin and Range extension. Calcite U–Pb ages related to Basin and Range extension range from 15.4 ± 6.4 to 4.2 ± 2.3 Ma. Clumped-isotope formation temperatures of vein calcites span 24.6 ± 4.1 to 139.2 ± 12.6 °C, and bulk lithium concentrations of veins and paleo-spring deposits span < 2 to 460 ppm. These results indicate that fault and fracture networks repeatedly served as conduits for lithium-bearing fluids through basement, along basin margins, and within basin-fill strata throughout basin evolution. Lithium concentrations vary systematically with host setting, with the highest values recorded in basin-fill-hosted veins and spring deposits and generally lower values in basement-hosted and basin-bounding fault veins. Several veins containing measurable lithium yield U–Pb ages older than the ∼ 6 Ma Rhyolite Ridge tuff, the dominant volcanic lithium source unit in the region, suggesting that structurally focused lithium-bearing fluid circulation locally predated its emplacement. The highest lithium concentrations, however, are generally associated with younger veins that postdate the tuff. Temperature and stable isotope constraints indicate dominantly meteoric fluids advected to depth and focused along faults, suggesting that lithium transport and enrichment in Clayton Valley does not necessarily require ascent of lithium-enriched magmatic fluids along deeply rooted crustal-scale faults. Although fault-controlled lithium enrichment has been recognized previously, this study provides direct evidence for long-lived structurally focused fluid flow associated with lithium transport over multi-Myr timescales.
Plate-like behavior in mantle convection models is commonly obtained using a strongly temperature-dependent viscosity together with a low yield stress that caps lithospheric strength. Yet, alternative mechanisms for limiting strength, including low-temperature plasticity, have been proposed. Here, we investigate how different rheological formulations promote lithospheric-scale strain localization, using 2-D thermo-mechanical simulations of upper mantle extension. We test a suite of olivine flow laws (diffusion creep and dislocation creep at low- and/or high-temperature), with and without a yield-stress cap, and introduce diagnostics that attribute plate weakening to either increasing strain rate (mechanical weakening) or increasing temperature (thermal weakening). Without a yield-stress cap, deformation remains distributed in all cases, indicating that weakening of the whole lithosphere is required for strain localization. In such simulations, a new extensional plate boundary develops in two stages: progressive narrowing of the deforming zone followed by rapid thinning of the weakened lithosphere. Across plate ages of 10–100 Myr, localization depends weakly on age but strongly on divergence rate, primarily through Stage-1 narrowing, and is controlled more by the stiffest lithospheric region than by the presence of a shallow weak layer. Including dislocation creep allows both mechanical and thermal weakening to operate within the deforming plate, enhancing feedbacks and accelerating localization relative to yield-stress plus diffusion creep. This implies that yield-stress/diffusion-only rheologies may overestimate break-up timescales in whole-mantle convection models. Low-temperature dislocation creep weakens the plate at 800–1000 K, providing a physically grounded mechanism for limiting strength in this temperature range. Finally, we propose that thermal weakening may in some cases promote rapid strength loss and accelerated extension during the late stages of natural rift evolution.
Gas hydrates and deltaic deep-sea fans are main features in continental margin systems, influencing slope stability, fluid migration, and carbon cycling. In the northwestern Black Sea, the Danube Fan remains poorly constrained with respect to subsurface structure, sediment strength, and hydrate dynamics. Here, we present high-resolution multichannel seismic (MCS) and ocean-bottom seismometer (OBS) data to characterise sedimentary structure and fluid-related features. Two integrated OBS–MCS profiles reveal under-consolidated, clay-rich levee deposits interspersed with mass-transport units, chaotic facies, and gas-related anomalies. Derived P- and S-wave velocity models indicate low shear strength and high
Middle Triassic felsic volcanic rocks exposed at Margečan and in the Kjumberk area, located along the Periadriatic Fault System and the Mid-Hungarian Shear Zone, have long been assigned to the Southern Alpine domain and interpreted mainly in terms of their magmatic affinity. This study demonstrates that ignimbritic rhyolites from the Margečan area record a previously unrecognized high-pressure, low-temperature metamorphic overprint reaching blueschist-facies conditions. Phengitic muscovite compositions indicate peak pressures of ∼1.1–1.2 GPa at temperatures around 300 °C, providing the first evidence that these felsic volcanic rocks were involved in Eoalpine subduction-related metamorphism and represent a part of the Austroalpine units. In contrast, felsic volcanic rocks from the nearby Kjumberk area, although compositionally and temporally similar, show no evidence of overprint and retain their Southern Alpine affinity, thus outlining a first order tectonic boundary between the two areas. U–Pb zircon ages constrain felsic volcanism to the Anisian–early Ladinian (∼246–240 Ma). Whole-rock geochemistry and Nd isotopic compositions indicate derivation from a subduction-modified mantle source with substantial crustal contribution, consistent with Triassic calc-alkaline magmatism along the Adriatic margin. These petrogenetic characteristics provide a framework for regional correlations but do not explain the contrasting metamorphic overprint. The recognition of Cretaceous Eoalpine blueschist-facies metamorphism in the Margečan ignimbrites therefore revises the tectonic interpretation of this sector of the Adriatic margin and implies large-scale eastward extrusion of the Austroalpine units into the Carpathian embayment, accommodated by high-offset right-lateral strike-slip faults.
Brunia is a distinctive crustal block within the European Variscides, composed of a late Neoproterozoic arc complex overlain by Ediacaran–early Cambrian cover sequences. Sparse preservation of early Paleozoic strata obscures its pre-Variscan paleogeography. Proposed models suggest Brunia either shared a crustal domain with adjacent parts of the Bohemian Massif, represented a far-eastern extension of Avalonia accreted to Baltica in the early Paleozoic, or maintained long-term connections to Baltica since the late Ediacaran.To address these uncertainties, we present the first systematic study of detrital zircons (both U–PbLu–HfThe Type-1 pattern reflects predominant recycling of local Brunia sources. Nearly-uniformly positive εHf(t)The Type-2 pattern broadly matches Devonian detrital zircon signatures from the British Isles, the Rhenish and Harz Mountains and parts of the Mid-German Crystalline Rise, the Dobrogea region of Romania, and NW Turkey delineating the northern margin of the Rheic Ocean. Strong similarity to Ordovician–Silurian Scandinavian datasets suggests original derivation from the Caledonides and confirms an Early Devonian connection between Brunia and Baltica.
Correlating late coda waves from large earthquakes produces stable waveforms that approximate inter-station core phases. However, the properties of these coda waves often violate the strict assumptions underlying classical Green's function retrieval, undermining confidence in interpreting the reconstructed arrivals as true inter-station phases and limiting their utility in seismic imaging. In this study, we present a perturbation analysis of core-phase interferometry and show that accurate travel-time information can be recovered under locally uniform wave incidence along the inter-station path. We introduce a dimensionless parameter – defined as the ratio of the seismic wave period to the inter-station travel time – which establishes a critical angular threshold. Our perturbation analysis reveals that the travel-time reconstruction accuracy scales with the cube of this threshold, allowing high-precision recovery of core phases, which naturally exhibit small threshold values due to their long propagation paths. Numerical simulations validate the theoretical predictions. By applying the proposed framework to real coda correlation data, we demonstrate that core phases can be reliably reconstructed using a sufficiently large number of global earthquakes – even without the traditionally assumed uniform source distribution. These results establish a rigorous theoretical foundation for extracting high-precision core-phase travel times from coda correlations, enhancing the reliability of seismological imaging of Earth's deep interior.
The deep, high-resolution regional-scale seismic profiles of the PolandSPAN®100+ km, are located at depth of ca. 6–7 to 19–20 km, and are far beyond the reach of the deepest wells. They are represented by packages of strong seismic reflectors, sometimes saucer-shaped, and are often characterized by step-wise geometry, sometimes diverging into several separate branches. Forward seismic modelling was used in order to provide insight – “educated guess” – regarding their lithology, exact lateral extent, and lateral thickness variations. It was concluded that most probably these are doleritic intrusions of thickness in the range of 60 to 200 m. Due to lithological coherence and close spatial relation to shallow sills and massifs recognized in wells, they have been interpreted as Mississippian (early Carboniferous) intrusions belonging to the recently recognized Lublin-Baltic Igneous Province. We applied a methodology that combines quantitative assessment of seismic data resolution and estimation of tuning thickness with 2D seismic forward modelling based on geological constraints that may be used to better understand, or estimate, parameters characterizing deep intrusions that are beyond the reach of deep wells.
We analyze the statistical characteristics of non-volcanic tremor (NVT) sequences in the Mexican subduction zone. To this end, we employ various techniques, including the Gutenberg–Richter relationship, non-extensive statistics, and multifractal detrended moving-average analysis, to extract information on magnitude and interevent-time distributions. The b-value results reveal that bq-value shows an inverse behavior, reaching its highest values in the interplate coupling region. Similar to tectonic earthquakes, NVT sequences exhibit a multifractal structure in both magnitude and interevent-time series. The multifractality analysis suggests that this behavior is associated with long-term correlations, the probability distribution of the data, and nonlinear dynamics. Both apparent and intrinsic multifractality are identified, with the former being dominant. Our estimates of the Hurst exponent (H) range from 0.65 to 1.06; most sequences indicate strong persistence (H>0.95), while values exceeding unity suggest a transition toward non-stationary behavior. These high temporal correlations may reflect localized fluid-perturbed regions, although this interpretation remains speculative. Regarding the distribution that best describes interevent sequences, we find that most sequences are well described by a Lognormal distribution and, to a lesser extent, by a Gamma distribution. Finally, observations of tectonic tremor duration exhibit substantial scatter, resulting in low coefficients of determination in scaling relationships. The source of this variability may be related to the NVT generation mechanism or to detection and characterization processes.
We present updated estimates of Basic Earth Parameters (BEP) from VLBI Celestial Pole Offset (CPO) time series spanning 1980-2025 using an ensemble Markov Chain Monte Carlo (MCMC) Bayesian inversion. Building upon Koot et al.2008), we incorporate recent advances in ocean tidal modeling (Cheng and Bizouard, 2025)(Lyard et al., 2021), without the empirical 0.7 scaling factor previously applied in the construction of the last adopted nutation model MHB2000; and (3) utilization of five diverse CPO series from different analysis centers spanning up to 45 years of observations.Our estimated mean values of the parameters show good consistency across different CPO series, with values of the Earth's dynamical ellipticity at the edge of the 1σ(Mathews et al., 2002; Buffett et al., 2002; Herring et al., 2002). Notable findings include a larger absolute value for the imaginary part of the core-mantle boundary (CMB) coupling constant (KCMB), approaching the 2σMathews et al.2002), which may reflect contributions from other coupling mechanisms in addition to electromagnetic coupling, including possible topographic coupling through “form drag” effect caused by wave interactions with irregular boundaries (Rekier et al., 2025). The real part of the Inner Core Boundary (ICB) coupling constant (KICB) is approximately half the MHB2000 value, potentially indicating the need to revisit hydrostatic assumptions for the inner core given recent seismic evidence of viscous deformation (Wang et al., 2024; Vidale et al., 2025). Compliance estimates suggest that frequency extrapolation methods from seismic to nutation bands may be considered unchanged in the mantle, but should be revised at the ICB. The enhanced FCN free-mode modeling captures amplitude variations that differ from empirical models, particularly after 2000, although the physical interpretation of these differences requires further investigation.The systematic discrepancies across multiple parameters suggest that current nutation theory needs substantial updates to incorporate more realistic models of core-mantle coupling and inner-core–outer-core coupling.
Remote sensing and field data suggest distributed right-lateral faulting at the northern edge of the Quito-Latacunga microblock in northern Ecuador and southern Colombia. Off the west coast of Ecuador and Colombia, oblique subduction of the Nazca Plate beneath the South America plate induces NE-motion of the Northern Andean Sliver relative to stable South America. Recent geodetic studies show this sliver comprises several independent microblocks, with strain accommodated at each of their boundaries. The Quito-Latacunga microblock, located in the densely populated Inter-Andean valley, shows approximately 3 mm yr−1M 5.6−1, suggesting geologic slip rates that could be higher than geodetic ones. Exposures of the Reservoir fault also show evidence for at least three surface rupturing earthquakes with magnitudes between M 6.3M 7.0. Inflation at the nearby Chile-Cerro Negro volcano may influence earthquakes on these faults, enhancing slip and earthquake rates. The Polylepis, Reservoir, and 25 July earthquake faults all overlap with the proposed area for the 15 August 1868, M 6.4–6.8 El Angel earthquake, indicating they could be associated with this damaging event.
The Carpathian Region, located at the edge of the East European Platform, presents a unique tectonic setting where major deformation associated with subduction and collision appears to have ceased around 8 million years ago. Yet vertical movements and seismicity continued afterward till the present day, suggesting ongoing crustal deformation and challenging our understanding of intraplate earthquakes and the processes driving these phenomena in an area considered a stable continental interior. In this study, we analyze over two decades of continuous GPS (cGPS) data from 143 permanent stations to estimate both horizontal and vertical crustal motions, constructing the most accurate model of crustal deformation in the region to date. The estimated velocity field indicates a southward drift of the South Carpathians and Moesia relative to Eurasia, with velocities ranging from 0.5 to 2 mm yr−1. We detect a more complex pattern of vertical uplift and subsidence in the foredeep, challenging a previously held view that this region is solely subsiding. This pattern may reflect localized uplift in response to processes such as the Vrancea Slab break-off beneath the South-East Carpathians. Crustal-scale active faults accommodate the observed differential motion, fragmenting the foreland. Furthermore, using a regularized horizontal velocity vector field, we estimate strain rate variations, maximum shear strain, and dilatation patterns across Romania, which align with observed stress regimes and earthquake mechanisms. This agreement validates our results and indicates an influence of surface plate kinematics on the observed seismicity, in addition to the deep Vrancea Slab dynamics. Our findings provide insights into the causes of crustal deformation at the transition between active collision zones and stable continental platforms, enhancing our understanding of intraplate seismicity in regions traditionally considered tectonically stable.
We investigated the crustal structure beneath the Lerma Valley in northwestern Argentina using data from a local seismic network deployed between 2017 and 2018. This geologically complex transition zone between the Eastern Cordillera and the Santa Bárbara system is characterized by moderate to high seismicity, yet remains largely understudied despite its strategic location within the Andean orogen. Its passive orogenic setting and evidence of inherited structures make it a natural laboratory for exploring intraplate deformation and foreland basin evolution. We combined local and teleseismic receiver functions with ambient noise tomography (ANT), jointly inverting Rayleigh wave phase velocities to obtain 1D shear-wave velocity profiles. The results reveal a stratified crust with four main discontinuities at
Knowledge of the present-day stress field of the Earth's crust is essential for understanding geodynamic processes, as well as for the exploration and management of geo-reservoirs. The World Stress Map (WSM) project provides the only open-access global database of crustal stress information. To mark the project's 40th anniversary, the WSM database has been substantially updated, and now contains more than twice the number of data records on the orientation of maximum horizontal stress (SHmax) in comparison to the previous release in 2016. The new database includes 100 842 quality-ranked data records documenting the SHmaxSHmaxSHmaxSHmax∼ 50° rotation of the SHmaxSHmax> 50° over distances of less than 100 km in eastern Australia.
Deep seismic reflection is a key method for investigating plate tectonics, as it enables detailed imaging of lithospheric structures – particularly within the crust and upper mantle. It plays a crucial role in understanding crustal evolution and identifying mineral enrichment zones. However, during data acquisition, deviations from the planned shot and receiver locations often occur due to surface constraints or other logistical challenges. These deviations result in irregular seismic data that can introduce significant migration artifacts during processing, ultimately reducing data quality and hindering the interpretation of deep geological structures. To address this issue, we evaluated four data regularization strategies based on anti-aliasing Matching Pursuit Fourier Interpolation using a 2D deep seismic reflection dataset from the central Jiangnan Orogenic Belt. Among these, the method that involves regularizing and infilling shot gathers at 100 m intervals produced the most effective results. Compared to legacy contractor-processed data, this method achieved a higher signal-to-noise ratio and improved seismic resolution. The superiority of that method was further confirmed through enhanced imaging in the pre-stack time migration results. These findings highlight the importance of shot domain regularization prior to migration in deep seismic reflection surveys.
The geometry, deep structural style, and seismotectonic setting of the outer Abruzzi thrust system are less understood than those of other segments of Italy's Late Pliocene–Quaternary contractional belt. This knowledge gap arises from the region's complex surface geology, low seismicity rates, and the limited resolution of existing geophysical data.Here, we present a local earthquake tomography of a large and previously unexplored area that encompasses the Abruzzi thrust system and spans from the Apennine extensional province in the west to the foreland strike-slip province in the east. The model is based on the inversion of 42 176 P-wave and 29 045 S-wave arrival times from earthquakes with MLOur results show low seismic velocities at upper crustal levels in the western sectors, correlating with continental basins of the extensional domain. In contrast, marked VpWe interpret the tomographic results in the context of geological, geophysical, and seismological data to construct a 3D conceptual model of the region. This includes the geometric reconstruction of the Abruzzi Arc basal thrust, an eastward convex arcuate structure extending ∼170 km and reaching depths of ∼24 km. The model also incorporates strike-slip faults in the footwall and east-dipping normal faults to the west.The structural affinity between the Abruzzi Arc basal thrust and other seismogenic structures of the Padan–Adriatic belt, located in the same structural position, suggests potential seismogenic behavior, although slow deformation rates and long recurrence intervals obscure its seismic expression. This conceptual model provides new insights into regional geodynamics and has significant implications for seismic hazard assessment in the central–southern Apennine transition zone.