Geosciences

30 pages, 9985 KB

Open AccessArticle

3D Response Characteristics Analysis of Vertical Electric Dipole Transient Electromagnetic Fields Under Complex Geological Conditions

by Xianxiang Wang, Zefan Hu, Shanmei Li and Qing Sun

Geosciences 2026, 16(5), 206; https://doi.org/10.3390/geosciences16050206 - 21 May 2026

Viewed by 158

Abstract

Vertical electric sources serve as an effective method for identifying deep hydrocarbon reservoirs. This involves the ability to generate transverse magnetic fields, concentrate currents at reservoir interfaces, and effectively emphasize resistivity anomalies in late-time domains. Marine geological conditions are often complex, marked by [...] Read more.

Vertical electric sources serve as an effective method for identifying deep hydrocarbon reservoirs. This involves the ability to generate transverse magnetic fields, concentrate currents at reservoir interfaces, and effectively emphasize resistivity anomalies in late-time domains. Marine geological conditions are often complex, marked by rugged topography and intricate structures. This complexity results in highly complicated electromagnetic response features, presenting significant challenges for data interpretation. This research employs the Time-Domain Finite Element Method (TDFEM) using unstructured meshes to accurately discretize complex geological models. Through the formulation of TDFEM equations, we successfully performed three-dimensional forward modeling of VED transient electromagnetic (VSTEM) responses in intricate geological environments. An analysis was conducted on the diffusion mechanisms and spatial distribution characteristics of VSTEM fields located beneath the seabed. A comparative analysis was conducted on the resolution capabilities of different fields stimulated by horizontal and VED sources. The findings show that the Ex provides enhanced boundary identification for the lateral extent of targets, whereas the Ez displays the greatest anomaly contrast, highlighting its exceptional results in anomaly detection. We investigated how complex seabed topography and geological structures affect the resolution of hydrocarbon targets. The research indicates that complex topography significantly influences electromagnetic fields; however, the proposed method can still effectively identify resistive hydrocarbon reservoirs, even in intricate model scenarios, thus confirming its reliability in challenging marine environments. Full article

(This article belongs to the Special Issue Advancements in Marine Geology: Underwater Exploration and Geophysical Insights)

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16 pages, 3257 KB

Open AccessArticle

GIS-Based Sliding Surface Reconstruction for Rapid Landslide Volume Estimation

by Qian Liu, Mingxin Yue and Lianghao Guan

Geosciences 2026, 16(5), 205; https://doi.org/10.3390/geosciences16050205 - 21 May 2026

Viewed by 176

Abstract

Landslides cause significant casualties and economic losses worldwide each year, creating an urgent demand for rapid and reliable volume estimation during emergency response. Conventional approaches often involve trade-offs among accuracy, efficiency, and data availability, particularly when pre-event topographic data are unavailable. This study [...] Read more.

Landslides cause significant casualties and economic losses worldwide each year, creating an urgent demand for rapid and reliable volume estimation during emergency response. Conventional approaches often involve trade-offs among accuracy, efficiency, and data availability, particularly when pre-event topographic data are unavailable. This study proposes a novel GIS-based method for rapid landslide volume estimation through sliding surface reconstruction. By integrating open-source geospatial data (post-landslide Digital Elevation Model and landslide boundary KML) with spline interpolation and spatial analysis, the method reconstructs the subsurface sliding surface and calculates volume by comparing this surface with the post-landslide DEM. Applied to the 2019 Shuicheng landslide (Guizhou Province, China), the method yielded a volume estimate of 1.58 × 10⁶ m³, which deviates by only ~5% from official survey data. The entire workflow can be completed within approximately one hour, demonstrating high efficiency, low operational cost, and acceptable accuracy for rapid post-disaster assessment during the critical “golden 72 h”. Full article

(This article belongs to the Section Natural Hazards)

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37 pages, 18498 KB

Open AccessArticle

Land Subsidence Identification in Gas Exploitation Area in Sidoarjo, East Java Using Integrated Geodetic Methods

by Akbar Kurniawan, Nurrohmat Widjajanti and Harintaka

Geosciences 2026, 16(5), 204; https://doi.org/10.3390/geosciences16050204 - 21 May 2026

Viewed by 188

Abstract

Land subsidence around the gas exploitation area in Sidoarjo Regency, East Java Province, Indonesia, located in the northeastern part of Java Island, has been detected since 2006. This subsidence occurs not only in the vicinity of the Sidoarjo mud eruption but also extends [...] Read more.

Land subsidence around the gas exploitation area in Sidoarjo Regency, East Java Province, Indonesia, located in the northeastern part of Java Island, has been detected since 2006. This subsidence occurs not only in the vicinity of the Sidoarjo mud eruption but also extends to the Wunut and Tanggulangin areas, where several gas production wells are located. This study identifies land subsidence using integrated geodetic methods, including InSAR (PS-InSAR and SBAS), GNSS, and levelling observations. InSAR provides spatially continuous measurements from satellite radar imagery, while GNSS and levelling observations at control points are used to evaluate and interpret the detected deformation. GNSS provides point-based three-dimensional displacement, whereas levelling offers high-accuracy vertical displacement information. The results show notable differences between the InSAR approaches. PS-InSAR indicates a maximum subsidence of −249.4 mm, with a velocity of −41.01 mm/year, whereas SBAS yields a maximum subsidence of −510.43 mm and a velocity of −86.08 mm/year. GNSS observations indicate an average subsidence rate of −52.2 mm/year during 2020–2022, while levelling results show an average subsidence rate of −205.4 mm/year during 2022–2023. These differences are primarily attributed to variations in spatial sampling, temporal coverage, and the measurement characteristics of each method, particularly under rural and wetland conditions with limited persistent scatterers. Overall, the integration of InSAR, GNSS, and levelling data provides a more comprehensive interpretation of land subsidence and highlights the importance of considering method-dependent uncertainties when comparing deformation results from different geodetic techniques. Full article

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21 pages, 4137 KB

Open AccessArticle

Seismic Fragility Assessment of Jointed Rock Slope Using Incremental Dynamic Analysis and Field-Characterized Barton–Bandis Parameters

by Hare Ram Timalsina and Krishna Kanta Panthi

Geosciences 2026, 16(5), 203; https://doi.org/10.3390/geosciences16050203 - 20 May 2026

Viewed by 227

Abstract

This study presents a probabilistic seismic fragility assessment of a jointed rock slope by integrating field characterization, incremental dynamic analysis (IDA), and numerical modeling. Dominant joint sets are identified through field mapping, and key discontinuity parameters are estimated for the Barton–Bandis non-linear shear [...] Read more.

This study presents a probabilistic seismic fragility assessment of a jointed rock slope by integrating field characterization, incremental dynamic analysis (IDA), and numerical modeling. Dominant joint sets are identified through field mapping, and key discontinuity parameters are estimated for the Barton–Bandis non-linear shear strength criterion. Dynamic simulations are performed using the distinct element method with the continuously yielding (C-Y) joint model to capture progressive shear degradation. Twenty real earthquake ground-motion records are scaled incrementally to perform IDA, with critical block displacement and cumulative joint slip adopted as engineering demand parameters (EDPs). A probabilistic seismic demand model (PSDM) is developed to correlate peak ground acceleration (PGA) with EDPs. Kinematic analysis indicates that planar failure along joint set 1 is the most likely failure mechanism (90% probability), followed by wedge failure along the intersection of joint sets 1 and 2 (52%). Fragility curves are derived for three displacement-based damage states: minor (1 cm), moderate (5 cm), and severe (15 cm). The results demonstrate that seismic deformation is strongly controlled by discontinuity geometry and progressive joint slip, with the slope exceeding the severe damage state at PGA levels as low as 0.4 g, indicating high seismic vulnerability. This highlights the importance of integrating field characterization with dynamic numerical modeling for reliable seismic stability assessment of such discontinuous rock mass. Future work should incorporate larger datasets, in situ testing, and 3D modeling to enhance assessment reliability. Full article

(This article belongs to the Section Natural Hazards)

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15 pages, 15538 KB

Open AccessArticle

Discovery of a Hidden Strike-Slip Fault from High-Resolution Analysis of the 2019 Wang Nua Earthquake Sequence, Lampang, Northern Thailand

by Saowapak Buphu, Passakorn Pananont, Kevin P. Furlong and Patinya Pornsopin

Geosciences 2026, 16(5), 202; https://doi.org/10.3390/geosciences16050202 - 19 May 2026

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Abstract

The M_L4.9 Wang Nua earthquake on 20 February 2019 is the largest earthquake to occur in Lampang Province in the past four decades and identifies the potential seismic hazard of previously unmapped faults in northern Thailand. We reanalyzed this earthquake sequence [...] Read more.

The M_L4.9 Wang Nua earthquake on 20 February 2019 is the largest earthquake to occur in Lampang Province in the past four decades and identifies the potential seismic hazard of previously unmapped faults in northern Thailand. We reanalyzed this earthquake sequence using waveform-based matched-filter detection and double-difference relocation techniques. The enhanced catalog increases the number of small earthquakes by 2.5 times compared with the official record. It also reveals microearthquakes down to M_L–0.3, including a previously unreported foreshock sequence beginning approximately four hours before the mainshock. Relocated hypocenters define an 8 km long, near-vertical N-S striking rupture zone at depths of 0.7–10.6 km. The focal mechanism of the mainshock indicates right-lateral strike-slip motion (strike ~189°, dip ~77°, rake ~–150°), aligned with the kinematics of other extensions of the Phayao Fault Zone. These results indicate that the sequence occurred on a previously unrecognized fault segment. This highlights the importance of high-resolution seismic analysis for improving hazard assessment in regions with concealed fault systems. Full article

(This article belongs to the Special Issue Earthquake Geology of Plate Margins and Plate Interiors: Integrating Classical Methods with New Approaches)

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20 pages, 8711 KB

Open AccessArticle

Late Cretaceous Intraplate Mafic Dyke Swarms in the East Kunlun Orogen, Northern Tibetan Plateau: Implications for Lithospheric Reactivation and Early Surface Uplift

by Denghui Chen, Hao Wu, Wei Wang, Yujie Zhao, Huajun Wen, Dongming Jiang, Xiaotong Sun and Fuhao Xiong

Geosciences 2026, 16(5), 201; https://doi.org/10.3390/geosciences16050201 - 19 May 2026

Viewed by 187

Abstract

The Cretaceous represents a key period in the geodynamic evolution of the Tibetan Plateau and the initial development of its paleotopography. While widespread orogenesis and magmatism associated with the Lhasa–Qiangtang collision are well documented in southern Tibet, coeval magmatic records in northern Tibet [...] Read more.

The Cretaceous represents a key period in the geodynamic evolution of the Tibetan Plateau and the initial development of its paleotopography. While widespread orogenesis and magmatism associated with the Lhasa–Qiangtang collision are well documented in southern Tibet, coeval magmatic records in northern Tibet are extremely limited, hindering constraints on the deep processes responsible for surface uplift. Zircon U–Pb ages, whole-rock geochemistry, and Sr–Nd–Hf isotopes are presented for two mafic dyke swarms from the East Kunlun Orogen, northern Tibet. The two dyke swarms were emplaced at 91.8 ± 2.0 Ma and 84.8 ± 0.6 Ma, indicating a previously underrecognized episode of Late Cretaceous mafic magmatism in northern Tibet. They are subalkaline tholeiites enriched in LILEs and LREEs, depleted in HFSEs, and characterized by negative Nb–Ta anomalies. Their decoupled Nd-Hf isotopes (εNd(t) = −4.96 to +0.94; εHf(t) = +3.75 to +5.76) indicate derivation from an enriched lithospheric mantle metasomatized by slab-related fluids during Permian-Triassic Paleo-Tethyan subduction. Partial melting modeling indicates that the magmas were generated by low-degree (1–5%) decompression melting of lherzolite within the spinel–garnet transition zone. We propose that these mafic dyke swarms formed in an intraplate extensional setting triggered by far-field stresses associated with the Lhasa–Qiangtang collision, which reactivated lithosphere-scale faults and induced localized mantle melting. These results provide new petrological constraints on Late Cretaceous intracontinental extension in northern Tibet and highlight mafic dyke swarms as key probes for linking lithospheric reactivation to early surface uplift of the Tibetan Plateau. Full article

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38 pages, 583 KB

Open AccessArticle

Radon and Thoron in Volcanic, Tectonic, and Hydrothermal Systems: A Critical Synthesis and Reduced Inference Framework

by Sebastiano Ettore Spoto

Geosciences 2026, 16(5), 200; https://doi.org/10.3390/geosciences16050200 - 16 May 2026

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Abstract

Radon (²²²Rn) and thoron (²²⁰Rn) are widely used to investigate diffuse degassing, fault-zone permeability, hydrothermal circulation, and subsurface unrest, but their signals are not direct proxies for a single process. This manuscript is a critical synthesis and methodological article [...] Read more.

Radon (²²²Rn) and thoron (²²⁰Rn) are widely used to investigate diffuse degassing, fault-zone permeability, hydrothermal circulation, and subsurface unrest, but their signals are not direct proxies for a single process. This manuscript is a critical synthesis and methodological article that develops a reduced inference framework for interpreting radon–thoron observations in volcanic, tectonic, and hydrothermal settings. The framework separates accessible support of the immediate radium parents ²²⁶Ra and ²²⁴Ra, recoil-scale release into the mobile phase, multiphase transport, geological carrier-gas throughput, and observational closure. It also distinguishes total activity flux from activity concentration and chamber throughput from natural carrier-gas dilution. Synthetic illustrative experiments test the internal behavior of the reduced operator; a concise re-reading of the public Upper Rhine Graben dataset illustrates the limits of concentration-only inference; and published volcanic and hydrothermal examples are used as literature-grounded vignettes. The purpose is not to validate a universal inversion model but to define what can be inferred from different observation packages. The paper, therefore, emphasizes three operational levels: anomaly reporting, mechanism discrimination, and local inversion. Full article

(This article belongs to the Special Issue Advancements in Geological Fluid Flow and Mechanical Properties)

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27 pages, 3526 KB

Open AccessArticle

Kelvin–Voigt and Boltzmann Viscoelastic Models for Footing’s Soil–Structure Interaction

by Ricardo Morais Lanes, Carolina Coelho de Magalhães Grossi and Marcelo Greco

Geosciences 2026, 16(5), 199; https://doi.org/10.3390/geosciences16050199 - 15 May 2026

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Abstract

This paper presents a practical numerical procedure for the study of structures on foundations subjected to soil consolidation settlements, using the Finite Element Method (FEM) coupled with the Boundary Element Method (BEM). A theoretical application is presented for a structure built on saturated [...] Read more.

This paper presents a practical numerical procedure for the study of structures on foundations subjected to soil consolidation settlements, using the Finite Element Method (FEM) coupled with the Boundary Element Method (BEM). A theoretical application is presented for a structure built on saturated soft soil, employing the Kelvin–Voigt and Boltzmann viscoelastic models. The Kelvin–Voigt model is suitable for situations where uniform or negligible initial settlements are assumed before the onset of soil consolidation, whereas the Boltzmann model allows for the consideration of differential movements, including both immediate and time-dependent displacements. This study shows that, although the same viscoelastic parameters are adopted for both models, the differences in internal forces and resulting displacements can be significant due to the distinct relative stiffnesses. The choice of viscoelastic model directly impacts the prediction of structural behavior. The analyses were conducted considering an iterative coupling between the FEM and BEM systems, using an MATLAB R2024a routine developed by the authors. Despite the differences between the models, the results obtained were consistent with the technical literature, reinforcing the applicability of the proposed procedure. Full article

(This article belongs to the Section Geomechanics)

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31 pages, 39069 KB

Open AccessArticle

Crustal Structure of the South Tibet Rift System from Receiver Function Analysis

by Junmeng Zhao, Junzhe Teng, Tsaiba Yangzin, Hongbing Liu, Sen Hu, Jihang Li, Taijin Su, Kangcheng Zhu and Tashi Jizong

Geosciences 2026, 16(5), 198; https://doi.org/10.3390/geosciences16050198 - 15 May 2026

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Abstract

The Tibetan Plateau, formed by the Indian-Eurasian collision, is dissected by the north-south trending South Tibet Rift system, but the formation mechanism of these rifts within a continuing compressional setting remains debated. Using P-wave receiver functions and joint inversion with surface wave dispersion [...] Read more.

The Tibetan Plateau, formed by the Indian-Eurasian collision, is dissected by the north-south trending South Tibet Rift system, but the formation mechanism of these rifts within a continuing compressional setting remains debated. Using P-wave receiver functions and joint inversion with surface wave dispersion along a ~230 km broadband seismic profile crossing the Nyima-Tingri Rift (NTR) and Xianza-Dingjie Rift (XDR), we investigated the detailed crustal structure beneath the Himalayan and Lhasa terranes. Our results reveal three key findings: (1) The crustal thickness ranges from 60 to 80 km, with the XDR exhibiting a pronounced Moho uplift (~10 km) beneath the rift axis, whereas the Moho beneath the NTR remains flat and continuous, indicating contrasting evolutionary stages. (2) A mid-crustal low-velocity layer at ~30 km depth is consistently observed west of 87.2° E, suggesting the presence of partial melt or fluids that decouple upper crustal deformation from mantle flow. (3) A prominent intracrustal discontinuity at 50–70 km depth produces a “Moho doublet” pattern; we interpreted this as the subducted Indian lower crust in the Himalayan terrane but as the relict Tibetan Moho in the Lhasa terrane, reflecting progressive northward modification. Collectively, these observations demonstrate that the north-south structures in southern Tibet lack the deep structural characteristics of mature rifts and instead represent an “infant stage” of extension. Their formation is best explained by east-west crustal stretching driven by an ongoing north-south convergence and eastward flow of lower crustal and upper mantle materials rather than by classical lithosphere-scale rifting. Full article

(This article belongs to the Special Issue Applied Geophysics for Geohazards Investigations)

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37 pages, 17890 KB

Open AccessArticle

Tectonic Control on Ultra-Deep Sub-Salt Trap Architecture: Insights from Multi-Detachment Modeling and Physical Simulations in the Kuqa Foreland Thrust Belt

by Yongxu Mei, Jinning Zhang, Yuan Neng, Wenjie Wang, Ke Xu, Honghan Xiang, Yanna Wu and Peiye Liu

Geosciences 2026, 16(5), 197; https://doi.org/10.3390/geosciences16050197 - 13 May 2026

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Abstract

Salt-bearing foreland fold–thrust belts represent a critical tectonic system for ultra-deep hydrocarbon exploration. In the Kalasu structural belt of the Kuqa Depression—characterized by the “four extremes” of ultra-high temperature, pressure, salinity, and stress—conventional single-detachment models fail to adequately resolve the complex subsalt structures. [...] Read more.

Salt-bearing foreland fold–thrust belts represent a critical tectonic system for ultra-deep hydrocarbon exploration. In the Kalasu structural belt of the Kuqa Depression—characterized by the “four extremes” of ultra-high temperature, pressure, salinity, and stress—conventional single-detachment models fail to adequately resolve the complex subsalt structures. To address this challenge, this study integrates high-resolution 3D seismic data, field outcrop observations, well logs, balanced cross-sections, and particle image velocimetry (PIV)-monitored physical modeling to propose a ramp–flat multi-detachment model. Our results demonstrate that deformation is governed by four regional detachment horizons: gypsum-salt layers, thick mudstones, coal-bearing strata, and the basement, which vertically partition the basin into six tectonic units: supra-salt, salt, subsalt, supra-coal, coal, and sub-coal basement. The structural architecture is controlled by five key factors: (1) paleo-uplift geometry, (2) distance from the South Tianshan orogenic front, (3) orientation of basin-bounding faults, (4) regional stress regime (pure compression versus transpression), and (5) rheological contrasts among detachment layers. The kinematic evolution follows a progressive sequence: basement-involved thrusting → multi-level ramp–flat detachment folding → cover detachment. Three primary trap levels are identified—subsalt, supra-coal, and sub-coal—hosting six distinct trap styles: pop-up anticlines, imbricate faulted anticlines, structural triangle zones, fault-bend fold anticlines, supra-coal anticlines, and inter-coal/sub-coal anticlines. Notably, under transpressional stress, oblique paleo-uplifts control the formation of enigmatic “fish-scale” arcuate trap belts composed of fault-bend fold anticlines. Full article

(This article belongs to the Topic Formation Mechanism and Quantitative Evaluation of Deep and Ultra-Deep Effective Reservoirs)

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20 pages, 6604 KB

Open AccessArticle

Modeling of Sediment Accumulation Upstream of Samarra Barrage and Assessment of Flushing Efficiency

by May Samir Saleh, Sherien Fadhel and Taghreed Khaleefa Mohammed Ali

Geosciences 2026, 16(5), 196; https://doi.org/10.3390/geosciences16050196 - 12 May 2026

Viewed by 283

Abstract

Sediment accumulates behind dams, thereby reducing their operational efficiency. In response to this issue, hydraulic flushing is considered an effective solution for its removal. A numerical model is used to provide a deep understanding of this process and its dynamics. It acts as [...] Read more.

Sediment accumulates behind dams, thereby reducing their operational efficiency. In response to this issue, hydraulic flushing is considered an effective solution for its removal. A numerical model is used to provide a deep understanding of this process and its dynamics. It acts as a low-cost virtual laboratory that eliminates the need for costly field experiments and provides a precise understanding of sedimentation and flushing behavior. This study used numerical modeling to examine sediment deposition in the Tigris River upstream of the Samarra Barrage. Within the iRIC framework, two models were used: NaysCUBE and Nays2DH. NaysCUBE is a three-dimensional solver that provides detailed simulations of partial gate openings and vertical flow distribution. This capability is crucial for a realistic analysis of the flushing process. Nays2DH is a two-dimensional solver that simulates full gate openings and captures general flow patterns. Results showed that sediment deposits were mostly concentrated within the first kilometer upstream of the dam, particularly when backwater effects caused the outflow to be lower than the inflow. Different gate operation schemes produced varied results: some configurations improved the balance between sediment movement and water flow, whereas others caused local erosion and uneven scouring. Results showed that lowering the water level at the barrage by 1 m increases shear stress on the riverbed by up to 25%, thereby improving the river’s ability to carry sediment without the need for additional discharge. High-discharge flushing operations are no longer feasible because of the reduced flow in the Tigris River since the operation of the Ilisu Dam in Turkey. This study recommends maintaining low water levels at the barrage with frequent and reasonable maintenance operations by partially opening the gates (40–60%). This strategy maintains a balance between the required water storage and sediment control, thereby ensuring the long-term sustainability of the hydraulic structure and the river ecosystem. Full article

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29 pages, 10822 KB

Open AccessArticle

Spatial Modelling of Groundwater Potential Zones Using GIS-Based Machine Learning Techniques: A Case Study of Abuja, Nigeria

by Danlami Ibrahim, Tatsuya Nemoto and Venkatesh Raghavan

Geosciences 2026, 16(5), 195; https://doi.org/10.3390/geosciences16050195 - 12 May 2026

Viewed by 440

Abstract

In many African nations, including Nigeria, groundwater remains the most readily available source of clean water. However, finding and developing these resources in heterogeneous terrain, such as the Federal Capital Territory (FCT), Abuja, is challenging due to the uneven distribution of the aquifers [...] Read more.

In many African nations, including Nigeria, groundwater remains the most readily available source of clean water. However, finding and developing these resources in heterogeneous terrain, such as the Federal Capital Territory (FCT), Abuja, is challenging due to the uneven distribution of the aquifers and complex geological settings. Using a GIS-based machine learning approach that incorporates surface and subsurface hydrogeological parameters, this study defines groundwater potential zones (GWPZ). Nine conditioning factors were derived from remote sensing, geophysical and climatic datasets. Aquifer thickness, depth to bedrock, geology, rainfall, slope, LULC, lineament density, drainage density and distance from river were among these variables. Three machine learning models: Extreme Gradient Boosting (XGBoost), Support Vector Machine (SVM) and Random Forest (RF) were trained and validated using 2410 borehole records (productive and abortive). Hold-out validation (80:20), 10-fold cross-validation, ROC-AUC, and confusion matrix were used to assess each model’s performance. The ensemble models outperformed the SVM, achieving higher predictive accuracy and better generalisation (XGBoost: 0.89, RF: 0.88 and SVM: 0.87). The generated maps categorised the study area into five GWPZs: very high, high, moderate, low and very low. These findings provide a scientific foundation for groundwater exploration and sustainable water resource management in the study area. Full article

(This article belongs to the Special Issue AI and Machine Learning in Hydrogeology)

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14 pages, 16451 KB

Open AccessArticle

Study on Flow Mechanisms in Shale Oil Horizontal Wells Using Fiber-Optic DTS Production Logging

by Hong Zhuo, Si Li, Shaohua Li, Zhangying Han, Xiuling He, Guishan Li and Jianwei Ren

Geosciences 2026, 16(5), 194; https://doi.org/10.3390/geosciences16050194 - 12 May 2026

Viewed by 355

Abstract

In response to the challenges in monitoring the production profile during the development of the Qingcheng shale oil field in the Changqing Oilfield, this study systematically investigates the application mechanism and practical effectiveness of Distributed Temperature Sensing (DTS) technology for dynamic monitoring in [...] Read more.

In response to the challenges in monitoring the production profile during the development of the Qingcheng shale oil field in the Changqing Oilfield, this study systematically investigates the application mechanism and practical effectiveness of Distributed Temperature Sensing (DTS) technology for dynamic monitoring in horizontal wells. By establishing a coupled model of fracture–matrix dual-porosity media flow and wellbore thermodynamics, which integrates mass, momentum, and energy conservation equations solved via the finite difference method, an interpretation method for the production profile based on the Joule–Thomson effect is proposed. The model was calibrated using shut-in temperature data and validated by comparing simulated temperature profiles with DTS measurements under constant-rate production. Field tests conducted in six horizontal wells in the Qingcheng oil field enabled the quantitative analysis of cluster-level production contributions along the horizontal section, with a water-producing zone localization accuracy of ±3.5 m. The results indicate that shale oil wells exhibit a non-uniform production characteristic of “high at the front and low at the rear” during the early production stage, where the production contribution from fully fractured segments can be up to 2.8 times that of adjacent segments. Inversion of the fiber-optic monitoring data reveals that differences in the conductivity of hydraulic fractures are the primary cause of flow heterogeneity. This research provides a theoretical foundation and technical support for the efficient development of shale oil, contributing to the transition of China’s continental shale oil development from “experience-driven” to “data-driven.” Full article

(This article belongs to the Topic Global Unconventional Shale Oil and Gas: Geological Mechanisms, Technological Innovations, and Economic–Environmental Sustainability Assessment)

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13 pages, 5139 KB

Open AccessArticle

Re-Evaluating Petroleum Play of the Late Triassic Sediments to Find Oil in the Upper Yangtze Region

by Bo Zheng, Jianwei Kang, Guilai Yang, Yongjie Qiu and Zhan Zhao

Geosciences 2026, 16(5), 193; https://doi.org/10.3390/geosciences16050193 - 11 May 2026

Viewed by 261

Abstract

The upper late Triassic Xujiahe Formation (T3x) is the most important terrigenous stratum gas province, with accumulated gas production over 3TCF, technical recoverable resources at 18TCF (500BCM) and geological reserve close to 50TCF (1TCM), in the Sichuan Basin (SCB). In the Southern Plateaus [...] Read more.

The upper late Triassic Xujiahe Formation (T3x) is the most important terrigenous stratum gas province, with accumulated gas production over 3TCF, technical recoverable resources at 18TCF (500BCM) and geological reserve close to 50TCF (1TCM), in the Sichuan Basin (SCB). In the Southern Plateaus of SCB (SP-SCB), Upper Yangtze Region also has the matching T3x, i.e., Baiguowan/T3b, often located in the folded smaller basins, i.e., Xichang Basin in this paper, which has not been explored as much. Past study of source rocks in T3x already found extracts to have non-terrestrial-humic biomarker values, and this work further adds the gas composition and isotope data from the T3x formations already producing and the T3b formation in two exploratory wells in the SPSCB, i.e., the Xichang basin/Zhaojue sub-basin, where oil stains and bubbled oil and bitumen are found in cores. Based on the geochemical analysis results of gas isotopes and biomarkers T3x/T3b (in SP-SCB) formations, this paper discusses the sedimentary environment and thermal evolution of source rocks of T3x & T3b, and possible transformation of the oil and gas generated, and the potential to find oil and gas in the T3x and T3b formations. We use latest isotope-maturity–wetness–Gas to Oil Ratio (GOR) templates for gas isotope data interpretation, and show the difference between T3x and T3b, and discuss the possibility of finding liquid in T3x and T3b. The conclusion is that T3b in Xichang basin should have oil and gas, and estimated Gas to Oil ratio is about 3~5:1 on a barrel of equivalent (BOE) basis. Full article

(This article belongs to the Section Geochemistry)

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17 pages, 5330 KB

Open AccessArticle

Finite Element Modeling of Spontaneous Potential Well Logs in Complex Near-Wellbore Environments

by Kirill Danilovskiy, Anastasia Glinskikh and Aleksey Petrov

Geosciences 2026, 16(5), 192; https://doi.org/10.3390/geosciences16050192 - 10 May 2026

Viewed by 317

Abstract

Spontaneous potential (SP) logging remains a widely used method in well geophysics. However, its interpretation is often limited by simplified physical models and correction charts that do not fully account for the processes governing SP generation, particularly in shaly and heterogeneous formations. In [...] Read more.

Spontaneous potential (SP) logging remains a widely used method in well geophysics. However, its interpretation is often limited by simplified physical models and correction charts that do not fully account for the processes governing SP generation, particularly in shaly and heterogeneous formations. In this study, we develop a finite element-based algorithm for modeling SP responses in complex near-wellbore environments, with the aim of providing a more physically consistent framework for interpretation. The proposed algorithm is based on the numerical solution of the Poisson equation with electrochemical source terms, incorporating the cation transport number to describe diffusion–adsorption processes and allowing for smooth variations in formation resistivity, fluid properties, and shale content. The numerical implementation is validated against published analytical solutions, correction charts, and previous numerical studies, showing good agreement in both the shape and amplitude of modeled SP responses across a range of geological scenarios, including thin beds and invasion zones. Application to real data from a Southeast Asia gas field demonstrates that the approach provides reliable estimates of formation water salinity and the cation transport number, with results consistent with independent estimates. The proposed method offers a flexible tool for SP response modeling and may complement existing interpretation techniques, particularly when working with heterogeneous formations and limited legacy datasets. Full article

(This article belongs to the Section Geophysics)

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18 pages, 47917 KB

Open AccessArticle

Monazite and Cassiterite Dating and Pyrite S Isotopes of the Helukou Tungsten-Tin Polymetallic Deposit of the Guposhan Ore District, Nanling Range: Implications for Ore Genesis

by Ying’ai Zhou, Yiping Chen, Lujun Peng, Dezhen Zou, Jinlun Cai, Hao Lei and Jingya Cao

Geosciences 2026, 16(5), 191; https://doi.org/10.3390/geosciences16050191 - 10 May 2026

Viewed by 434

Abstract

The Guposh an orefield within the western segment of the Nanling Range hosts a globally significant tungsten and tin metallogenic province whose formation is tied to the intense Middle Jurassic granitic magmatism. Nonetheless, critical ambiguities remain regarding the metallogenetic ages and origin of [...] Read more.

The Guposh an orefield within the western segment of the Nanling Range hosts a globally significant tungsten and tin metallogenic province whose formation is tied to the intense Middle Jurassic granitic magmatism. Nonetheless, critical ambiguities remain regarding the metallogenetic ages and origin of ore-related hydrothermal fluids for W-Sn polymetallic deposits in this orefield. Here, we integrate in situ U-Pb geochronology of monazite and cassiterite and sulfur isotope analyses of pyrite from the Helukou W-Sn polymetallic deposit to resolve this outstanding question. In situ monazite U-Pb geochronology yielded lower intercept ages of 164.4 ± 1.1 Ma and 162.0 ± 2.0 Ma for the fine-grained and medium- to coarse-grained biotite monzogranite phases of the Guposhan pluton, respectively, bracketing its formation during the Middle Jurassic era. The initial ²⁰⁷Pb/²⁰⁶Pb ratio of 0.85 for the monazite grains is within the range of crustal and mantle materials, likely indicating a mantle–crust mixing source for the magma. Cassiterite from skarn-type ores yields a lower intercept U-Pb age of 165.9 ± 3.2 Ma, confirming a genetic relationship between the Guposhan magmatism and Helukou W-Sn mineralization. In situ pyrite δ³⁴S_V-CDT values show a uniform range from −0.66‰ to +0.79‰, indicating a uniform magmatic-derived sulfur source for the ore-forming fluids. We further demonstrate that fluid-rock interaction, rather than fluid mixing, acts as a crucial factor in the ore precipitation of W-Sn metals of the Helukou deposit. Full article

(This article belongs to the Special Issue The Application of Accessory Mineral Geochemistry in Ore Deposit Studies)

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16 pages, 5144 KB

Open AccessReview

The Changing Concept of Habitability on Earth, the Solar System, and Beyond

by Christopher P. McKay

Geosciences 2026, 16(5), 190; https://doi.org/10.3390/geosciences16050190 - 10 May 2026

Viewed by 2349

Abstract

Our concept of where life can thrive on Earth has advanced over the past 70 years to include extreme ionizing radiation, high temperatures, the deep subsurface, hydrothermal vents on the deep ocean floor, extreme arid deserts, and the ice-covered lakes and high mountain [...] Read more.

Our concept of where life can thrive on Earth has advanced over the past 70 years to include extreme ionizing radiation, high temperatures, the deep subsurface, hydrothermal vents on the deep ocean floor, extreme arid deserts, and the ice-covered lakes and high mountain valleys of Antarctica. This expanding understanding of the biosphere has coincided with the development of space exploration programs, and it has informed those programs with regard to the search for life on other water worlds in our Solar System—especially Mars, Europa, and Enceladus. Titan presents a reverse of this approach. The interesting organic solids and fluids on that world have no analog in Earth habitability but have inspired suggestions of possible biological systems unlike any on Earth. If realized, the discovery of life on Titan would stretch the concept of habitability just as it stretches the concept of life as we know it. Habitability studies on exoplanets may follow both of these paths: we will look for habitability on exoplanets based on observed habitats on Earth, and we will also use observations of exoplanets as grist for contemplation of lifestyles different from anything we know on Earth. Full article

(This article belongs to the Special Issue Worlds of the Solar System: Geological Evolution and Habitability of Planets and Moons)

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30 pages, 21722 KB

Open AccessArticle

Wave-Resource Characterization Along the Coast of Vietnam

by Thi Thuy Dung Nguyen and Xiao Hua Wang

Geosciences 2026, 16(5), 189; https://doi.org/10.3390/geosciences16050189 - 9 May 2026

Viewed by 219

Abstract

A wave-resource characterization along the coast of Vietnam was performed based on the 12-year period from 2007 to 2018, using the structured-grid Simulating WAves Nearshore (SWAN) model with a ~2.3 km spatial resolution. Extensive model validations were performed using an observed nearshore dataset [...] Read more.

A wave-resource characterization along the coast of Vietnam was performed based on the 12-year period from 2007 to 2018, using the structured-grid Simulating WAves Nearshore (SWAN) model with a ~2.3 km spatial resolution. Extensive model validations were performed using an observed nearshore dataset and ERA5 offshore datasets. The wave parameters, significant wave height, wave period, total wave energy and omnidirectional wave power varied both spatially and temporally, with a strong seasonal pattern influenced by the northeast and southwest monsoons, with the impact of the northeast monsoon being stronger. Wave energy resources were highest in winter and lowest in summer, making the southcentral coast of Vietnam a prime location for wave energy harvesting. However, further feasibility and design studies are needed before wave farms can be established. The Gulf of Tonkin and the Gulf of Thailand had lower wave energy due to wind distribution, shadowing effects and changes in water depth. This study also noted the impact of ENSO phases on wave conditions. Year-round, El Niño generally weakened winds, leading to smaller waves and reduced wave energy, while La Niña had the opposite effect. Additionally, tropical cyclones can further amplify significant wave height, especially during both ENSO phases in July, thereby increasing wave energy. Full article

(This article belongs to the Special Issue Fluid Dynamics and Hydrological Processes)

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28 pages, 12703 KB

Open AccessArticle

Multi-Scale Attention Network for Landslide Susceptibility Assessment

by Zhao Zhan, Shanxiong Chen, Min Zhang, Wenzhong Shi, Yangjie Sun and Hongbo Luo

Geosciences 2026, 16(5), 188; https://doi.org/10.3390/geosciences16050188 - 7 May 2026

Viewed by 279

Abstract

Landslide susceptibility assessment (LSA) is crucial for regional landslide risk evaluation and mitigation strategy formulation. Previous studies mostly adopted single-scale features, while landslide formation is influenced by multi-scale factors, making multi-scale information extraction more appropriate for assessment. This study proposes a deep learning [...] Read more.

Landslide susceptibility assessment (LSA) is crucial for regional landslide risk evaluation and mitigation strategy formulation. Previous studies mostly adopted single-scale features, while landslide formation is influenced by multi-scale factors, making multi-scale information extraction more appropriate for assessment. This study proposes a deep learning framework integrating multi-scale and attention modules for object-based LSA. A multi-scale network extracts geo-environmental features at different scales, which are input into attention networks using multi-head attention and Squeeze-and-Excitation, termed MSMHA and MSSE, respectively, to enhance relevant features and suppress irrelevant ones. Finally, features are fused for classification and prediction. In a case study in Hong Kong, CNN-based and ML-based methods were compared using 9814 landslides and 11 influencing factors. Results show the proposed MSMHA (area under the curve, AUC 0.91) and MSSE (AUC 0.90) outperform conventional methods (e.g., random forest with AUC 0.86; multi-layer perceptron and support vector machine with AUC 0.85; DenseNet with AUC 0.86; CNN with AUC 0.88; VGG with AUC 0.87; GoogLeNet and ResNet with AUC 0.81). CNN-based methods outperformed ML-based ones, indicating that incorporating neighborhood information improves model performance. The rationality of the susceptibility map generated by MSMHA was verified via comparative analysis. Results confirm that the proposed multi-scale and attention-integrated framework outperforms traditional single-scale methods consistently. Equally importantly, the case study provides advanced CNN-based landslide susceptibility maps for Hong Kong, which can serve as a critical reference for regional landslide risk management and the formulation of targeted mitigation strategies. Full article

(This article belongs to the Special Issue Intelligent Landslide Early Warning: From Multi-Source Sensing to AI-Driven Forecasting)

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17 pages, 7760 KB

Open AccessArticle

Terahertz Time-Domain Spectroscopy in Molybdenum Exploration: A Case Study of the Dengshang Deposit, North China Craton

by Xiao-Xia Li, Shan-Shan Li, Murat Tamer, Zhuo-Er Teng, Qun-Feng Miao, Jia-Hui Zhou, Cheng-Xun Li, Ze-Hai Peng, Hao-Chong Huang, Zhi-Yuan Zheng and Kun-Feng Qiu

Geosciences 2026, 16(5), 187; https://doi.org/10.3390/geosciences16050187 - 7 May 2026

Viewed by 324

Abstract

Porphyry-type deposits are characterized by well-developed alteration zoning, among which potassic alteration is closely associated with mineralization and represents a key target for prospecting and exploration. The Dengshang molybdenum deposit is a porphyry-type deposit within the Yanliao molybdenum metallogenic belt. Characterized by deep [...] Read more.

Porphyry-type deposits are characterized by well-developed alteration zoning, among which potassic alteration is closely associated with mineralization and represents a key target for prospecting and exploration. The Dengshang molybdenum deposit is a porphyry-type deposit within the Yanliao molybdenum metallogenic belt. Characterized by deep burial and unclear alteration zoning, it presents challenges for prospecting and exploration. This study integrates field surveys, petrographic analysis, and terahertz time-domain spectroscopy (THz-TDS) to characterize the altered wall rocks and molybdenite ores, aiming to support deep prospecting. The main findings reveal a clear spatial gradient from potassic to propylitic alteration zones within and around the rhyolite porphyry intrusion. THz-TDS reveals that the THz spectral characteristics of potassic-altered wall rocks are closely related to the structure of minerals and the intensity of hydrothermal alteration. Propylitically altered wall rocks exhibit distinctive spectral signatures in the terahertz band. For molybdenite ores, the molybdenite content shows a negative correlation with THz amplitude and a positive correlation with both the absorption coefficient and refractive index. This study proposes that the lower refractive index and absorption coefficient of potassic wall rocks, coupled with the higher values in ores, reflect the spatial position of the ore body. Additionally, the characteristic THz spectral curve of propylitically altered rocks can aid in delineating ore body boundaries. These findings hold practical guiding significance for prospecting and exploration. Full article

(This article belongs to the Special Issue Isotope Geochemistry: New Techniques and Applications)

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17 pages, 10727 KB

Open AccessArticle

COSISA: A Python Tool for Co-Seismic Slope Instabilities Susceptibility Assessment Based on the Newmark Displacement and a Logic-Tree Computation Procedure

by José Carlos Román-Herrera, Martín Jesús Rodríguez-Peces and Julio Garzón-Roca

Geosciences 2026, 16(5), 186; https://doi.org/10.3390/geosciences16050186 - 6 May 2026

Viewed by 302

Abstract

Earthquake-induced landslides are a major secondary seismic hazard in mountainous regions and can cause significant human and economic losses. This study presents COSISA (Co-Seismic Slope Instabilities Susceptibility Assessment), a software tool developed in Python and GIS to automate the generation of co-seismic landslide [...] Read more.

Earthquake-induced landslides are a major secondary seismic hazard in mountainous regions and can cause significant human and economic losses. This study presents COSISA (Co-Seismic Slope Instabilities Susceptibility Assessment), a software tool developed in Python and GIS to automate the generation of co-seismic landslide susceptibility maps based on the Newmark displacement method combined with a logic-tree approach. The software integrates geomorphological, geotechnical, and seismic data to compute Newmark displacement using several available empirical equations. The logic-tree framework incorporates the variability and uncertainty of geotechnical parameters, failure depth, degree of saturation, and empirical models through weighted combinations of input variables. As a result, COSISA produces numerous susceptibility maps corresponding to different parameter combinations and generates a weighted susceptibility map. The tool was applied to a case study in the Granada Basin (southeastern Spain), an area affected by the 2021 Santa Fe seismic sequence. Results show that COSISA efficiently generates multiple susceptibility scenarios and identifies best- and worst-case conditions, significantly reducing the time and effort required compared with conventional step-by-step procedures. This approach supports seismic hazard assessment and can contribute to territorial planning and risk management strategies aimed at reducing damage from future co-seismic landslides. Full article

(This article belongs to the Special Issue Advances in Earthquake Hazard Assessment and Seismic Risk Mitigation Strategies)

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17 pages, 4828 KB

Open AccessArticle

Comparative Assessment of UAV and CoastSnap Data for Shoreline Change Monitoring Using DSAS Metrics: A Case Study from Southern Brazil

by Jade Moreira, João Luiz Nicolodi, Miguel da Guia Albuquerque, Breno Mello Pereira and Raíssa Magnan Scorsatto

Geosciences 2026, 16(5), 185; https://doi.org/10.3390/geosciences16050185 - 5 May 2026

Viewed by 461

Abstract

This study assesses the comparative performance of two geotechnologies for shoreline monitoring—Unmanned Aerial Vehicle (UAV) surveys and CoastSnap citizen-science imagery—at Guarita Beach, southern Brazil. The analysis was based on twelve paired monitoring dates distributed over a two-year interval. Shorelines were extracted from the [...] Read more.

This study assesses the comparative performance of two geotechnologies for shoreline monitoring—Unmanned Aerial Vehicle (UAV) surveys and CoastSnap citizen-science imagery—at Guarita Beach, southern Brazil. The analysis was based on twelve paired monitoring dates distributed over a two-year interval. Shorelines were extracted from the wet–dry line, manually digitized from UAV orthomosaics, and automatically detected from CoastSnap images with subsequent quality control. Shoreline change was quantified in the Digital Shoreline Analysis System (DSAS) using the Shoreline Change Envelope (SCE) and the Linear Regression Rate (LRR). The SCE showed the highest equivalence between methods, with a mean difference close to zero (−0.14 m) and no evidence of systematic bias. For LRR, values derived from CoastSnap tended to be lower than those derived from UAVs (mean difference = −2.14 m year⁻¹), although without statistically significant divergence at the adopted significance level. The results demonstrate that the agreement between CoastSnap and UAV data depends directly on the metric analyzed: SCE was more robust for inter-method comparison, whereas LRR was useful for medium-term trend interpretation but more sensitive to uncertainty propagation. Overall, CoastSnap did not replace UAV surveys, but it proved to be a valuable complementary tool for expanding temporal coverage in coastal monitoring programs. Full article

(This article belongs to the Section Climate and Environment)

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24 pages, 17172 KB

Open AccessArticle

Seismic Stratigraphy and Sedimentology of the Post-Rift Lower Paleogene Sedimentary Succession in the Northern Norwegian North Sea: Implications for New Potential Stratigraphic Petroleum Plays

by Ali Al Janabi, Camelia Knapp, Ziyad Albesher, Mohammad A. Abdelwahhab, Mahmoud Leila and Ahmed A. Radwan

Geosciences 2026, 16(5), 184; https://doi.org/10.3390/geosciences16050184 - 4 May 2026

Viewed by 599

Abstract

In the northern Norwegian North Sea, the Lower Paleogene post-rift succession constitutes an underexplored interval with considerable potential for stratigraphic petroleum plays. Nevertheless, predicting its subsurface prospectivity remains hindered by persistent uncertainties in facies architecture, depositional heterogeneity, and reservoir quality. To address these [...] Read more.

In the northern Norwegian North Sea, the Lower Paleogene post-rift succession constitutes an underexplored interval with considerable potential for stratigraphic petroleum plays. Nevertheless, predicting its subsurface prospectivity remains hindered by persistent uncertainties in facies architecture, depositional heterogeneity, and reservoir quality. To address these uncertainties, the present study integrates relative geologic time (RGT)-based seismic stratigraphic interpretation, spectral decomposition, sedimentary facies analysis, and litho-saturation assessment, primarily constrained by seismic and well-log datasets, to evaluate the Paleocene post-rift Lista Formation in the northern Norwegian North Sea. The results reveal the presence of Paleocene mass-transport deposit (MTD) complexes associated with axial lobe sandstones of submarine fan systems. These MTD complexes exhibit pronounced vertical and lateral facies transitions into low-density turbidites, debrites, and hemipelagic drapes, together forming an effective stratigraphic framework for hydrocarbon entrapment. Although the Lista submarine-fan sandstones are relatively thin, typically ranging from a few centimeters to decimeters in thickness, they display favorable reservoir characteristics. Litho-saturation analysis indicates preserved porosity and low water saturation (<20%), supporting their potential as effective hydrocarbon storage intervals. Distal fan-lobe sandstones, despite their limited thickness, show encouraging reservoir quality, whereas thicker low stand systems tract (LST) accumulations and time-equivalent carbonate mound complexes appear to have developed within more proximal structural domains. This proximal-to-distal facies organization reflects the dynamic interaction between tectonically inherited accommodation space and sediment-routing pathways during the early Paleocene. Overall, the findings highlight the significant petroleum prospectivity of the Paleocene post-rift succession in the northern Norwegian North Sea. The stratigraphic juxtaposition of sand-prone submarine-fan lobes against hemipelagic sealing intervals, combined with heterogeneity imposed by syn-rift structural inheritance, generates a highly favorable architecture for stratigraphic trapping. More broadly, the integrated workflow presented here enhances the predictive mapping of subtle stratigraphic traps within post-rift successions and provides a robust framework for reducing exploration uncertainty in analogous basins. Full article

(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)

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19 pages, 21845 KB

Open AccessArticle

Morphological Mimicry in Loess-Mantled Terrains: Re-Evaluating the Quaternary Activity of the Devene Fault

by Alexander Radulov, Yordanka Donkova, Nikolay Nikolov, Marlena Yaneva, Konstantin Kostov and Ivan Alexiev

Geosciences 2026, 16(5), 183; https://doi.org/10.3390/geosciences16050183 - 2 May 2026

Viewed by 524

Abstract

The Devene fault system, a major strike–slip structure at the boundary between the Balkan Range and the Moesian Platform in NW Bulgaria, remains a subject of debate regarding its Quaternary activity. This study investigates the shallow expression of the fault at two representative [...] Read more.

The Devene fault system, a major strike–slip structure at the boundary between the Balkan Range and the Moesian Platform in NW Bulgaria, remains a subject of debate regarding its Quaternary activity. This study investigates the shallow expression of the fault at two representative sites, Tri Kladentsi and Beli Breg, using high-resolution electrical resistivity profiling to differentiate tectonic deformation from climatically driven landscape evolution. At Tri Kladentsi, resistivity profiles confirm a steeply dipping structural boundary within the Miocene bedrock, juxtaposing limestone against sands. The overlying 25 m thick loess cover, however, remains sub-horizontal and undisturbed. Likewise, at Beli Breg, the complex architecture of stacked channel sequences and tributary deposits at the Ogosta River confluence reveals no identifiable fault displacement. Our results suggest a high degree of morphological mimicry, where asymmetric river valleys produced by selective erosion and differential loess accumulation superficially converge with tectonic signatures. The long-term left-lateral slip rate is estimated at 0.14–0.19 mm/yr based on a 20 km Miocene offset. Nevertheless, the lack of modern surface rupture indicates a deceleration of the fault slip rate and a transition to a buried fault top during the Quaternary. These findings necessitate a re-evaluation of regional seismic hazard assessments, because the absence of continuous surface traces physically constrains the maximum earthquake potential. Full article

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16 pages, 6881 KB

Open AccessArticle

Optimized Arrays for 2-D Resistivity Survey Lines Using a Multi-Step Compare R Method

by Yao Qu, Caide Lin, Hai Liu, Xiangtai Liu, Xu Meng, Shangyang Zhang, Zixin Yin and Hesong Hu

Geosciences 2026, 16(5), 182; https://doi.org/10.3390/geosciences16050182 - 1 May 2026

Viewed by 369

Abstract

The imaging quality of electrical resistivity tomography (ERT) crucially depends on the electrode array configuration. Although the symmetrical optimized ‘Compare R’ (CR) method improves computational efficiency, restricting the search to the symmetrical data set inherently limits the imaging accuracy. To address this limitation, [...] Read more.

The imaging quality of electrical resistivity tomography (ERT) crucially depends on the electrode array configuration. Although the symmetrical optimized ‘Compare R’ (CR) method improves computational efficiency, restricting the search to the symmetrical data set inherently limits the imaging accuracy. To address this limitation, this paper proposes a multi-step optimized CR method that progressively explores both symmetrical and asymmetrical arrays to extend the search space and further enhance imaging accuracy. Numerical experiments demonstrate that the multi-step optimized array yields the highest average relative model resolution (0.646) and structural similarity index measure (0.668), surpassing the symmetrical optimized array (0.615 and 0.630, respectively). Field experiments on pipeline detection confirm that the proposed array accurately identifies the location and geometry of underground anomalies and achieves superior imaging accuracy. Applications in karst cavity exploration further confirm that the proposed array effectively detects the deep karst caves and the bedrock interfaces, as validated by borehole drilling. Additionally, the detection performance of both optimized arrays is evaluated at different depths. The results indicate that the multi-step optimized array preserves anomaly geometry and resistivity more reliably at greater depths, attributed to the accumulation of asymmetrical data points in deep regions, which results in a significantly higher data density. Full article

(This article belongs to the Section Geophysics)

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19 pages, 20217 KB

Open AccessArticle

Permian Crustal Reworking and Rare-Metal Mineralization in the Halajun Area, the Southwest Tianshan, NW China

by Haiquan Li, Huanhuan Wu, He Huang, Guoqing Wang, Zhanlin Ge, Ming Liu and Di Hao

Geosciences 2026, 16(5), 181; https://doi.org/10.3390/geosciences16050181 - 1 May 2026

Viewed by 443

Abstract

Permian A-type granites and associated rare-metal mineralization are widespread in the Halajun area, southwestern Tianshan; however, petrogenetic controls on rare-metal enrichment and mineralization remain under-constrained. Here, we integrate zircon and monazite geochronology, whole-rock geochemistry, and zircon Hf-O isotopes from Halajun I and II [...] Read more.

Permian A-type granites and associated rare-metal mineralization are widespread in the Halajun area, southwestern Tianshan; however, petrogenetic controls on rare-metal enrichment and mineralization remain under-constrained. Here, we integrate zircon and monazite geochronology, whole-rock geochemistry, and zircon Hf-O isotopes from Halajun I and II plutons to constrain the origin of these granites and their metallogenic significance. Zircon U–Pb and monazite ages indicate emplacement at 274–273 Ma, coeval with regional magmatism associated with the Tarim large igneous province. Geochemical signatures—high SiO₂, alkali, and rare-earth element (REE) contents, enrichment of HFSE (e.g., Nb, Zr, and Hf), coupled with LILE (e.g., Ba and Sr) depletion—classify these granites as highly differentiated alkaline A-type rocks. Positive εHf(t) values and intermediate δ¹⁸O compositions of zircons suggest derivation from partial melting of Neoproterozoic lower crust with input from mantle-derived melts, reflecting significant crust–mantle mixing. Magmatic differentiation, in concert with regional crustal reworking driven by mantle plume activity, produced granites enriched in Nb, Ta, Zr, and REEs, which host the rare-metal mineralization in the region. These results indicate that Permian crustal reworking in the southwestern Tianshan was a driver of high-differentiation magmatism and rare-metal enrichment, highlighting the potential of similar A-type granitic systems in Central Asia for rare-metal exploration. Full article

(This article belongs to the Special Issue Critical Metals from Magmatic–Hydrothermal and Supergene Systems: From Genesis to Comprehensive Utilization)

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16 pages, 2626 KB

Open AccessArticle

Shear Strength and Size Effects of Completely Weathered Granite Residual Soil Under Laboratory and In Situ Direct Shear Testing

by Zhibo Chen, Jinduo Gao, Wei Huang, Ping Hu, Xuefeng Tang, Zhigang Zhao and Banglai Lü

Geosciences 2026, 16(5), 180; https://doi.org/10.3390/geosciences16050180 - 1 May 2026

Viewed by 381

Abstract

Completely weathered granite residual soil is a weathering-derived, soil-like geomaterial whose shear strength is difficult to characterize using only conventional small-scale laboratory tests. This study evaluated the effects of specimen size and material structure by comparing in situ direct shear tests, conventional laboratory [...] Read more.

Completely weathered granite residual soil is a weathering-derived, soil-like geomaterial whose shear strength is difficult to characterize using only conventional small-scale laboratory tests. This study evaluated the effects of specimen size and material structure by comparing in situ direct shear tests, conventional laboratory direct shear tests on undisturbed and remolded specimens, and large-scale laboratory direct shear tests on remolded specimens with box sizes of 150, 200, and 250 mm. The results show that undisturbed specimens exhibited higher shear strength than remolded specimens, indicating a clear structural contribution. With increasing specimen size, cohesion decreased from 41.2 to 31.4 kPa, whereas the friction angle increased from 35.3° to 40.6°. Compared with the conventional undisturbed test, the in situ tests yielded lower cohesion but higher friction angles. These results indicate that both size effect and structural disturbance significantly influence the interpretation of shear strength parameters in completely weathered granite residual soil. For engineering design in weathered-granite terrains, strength parameters derived from larger specimens or in situ tests are likely to be more representative than those obtained from conventional small-scale laboratory tests. Full article

(This article belongs to the Topic Control Mechanisms and Technological Applications for Surrounding Rock in Deep Mine Roadways)

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19 pages, 16669 KB

Open AccessArticle

Gravimetric Detection of Cave Space and Sinkhole Hazard with Growth Inversion: Valaská Village Case in Karst (Slovakia)

by Jozef Bódi, Peter Vajda, Pavol Zahorec, René Putiška, Juraj Papčo, Roman Pašteka and José Fernández

Geosciences 2026, 16(5), 179; https://doi.org/10.3390/geosciences16050179 - 29 Apr 2026

Viewed by 563

Abstract

Underground water flow in karst areas and changing water levels due to extreme rain can lead to the creation of caverns and sinkhole hazards. Such is the historical experience of the Valaská village in central Slovakia. To better understand the current sinkhole threat [...] Read more.

Underground water flow in karst areas and changing water levels due to extreme rain can lead to the creation of caverns and sinkhole hazards. Such is the historical experience of the Valaská village in central Slovakia. To better understand the current sinkhole threat in the village, we aim to detect shallow caverns using microgravimetry. Our broader objective is to examine the capabilities of the Growth inversion methodology to detect and characterize shallow cave space. In our study, we focus on the benefits and weak points of the Growth inversion approach, which is a free-geometry inversion method based on model exploration and growing source bodies. Since a sole gravimetric inversion produces ambiguous results, we pay attention to the role and setup of the several free user-adjustable inversion parameters of Growth. We examine tuning these parameters for the specific needs of shallow cavity detection. Valaská experienced sinkholes in 1964, 1968 and 2019. That of 1964 is known for a curious loss of a horse sunk into a karst chimney. Our gravimetric work shows that the sinkhole hazard at the exposed lot in Valaská is ongoing despite the mitigation construction measures. The Growth approach proved to be applicable and useful in microgravimetric identification of sinkhole threat and detection of shallow caverns in karst. Full article

(This article belongs to the Section Geophysics)

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29 pages, 9702 KB

Open AccessArticle

Seafloor to Borehole CSEM: A 3D Modelling Study of Survey Sensitivity to Small Resistive Targets in Shallow Water

by Vikas C. Baranwal, Martin C. Sinha, Lucy M. MacGregor, Anna C. Maxey and Yang Su

Geosciences 2026, 16(5), 178; https://doi.org/10.3390/geosciences16050178 - 29 Apr 2026

Viewed by 344

Abstract

Marine controlled source electromagnetic (CSEM) surveys have been proven to be an effective tool in hydrocarbon exploration, principally due to the method’s ability (in the right circumstances) to identify electrical resistivity contrasts between hydrocarbon-saturated and brine-saturated sedimentary units. However, the sensitivity of such [...] Read more.

Marine controlled source electromagnetic (CSEM) surveys have been proven to be an effective tool in hydrocarbon exploration, principally due to the method’s ability (in the right circumstances) to identify electrical resistivity contrasts between hydrocarbon-saturated and brine-saturated sedimentary units. However, the sensitivity of such surveys decreases in shallow water, for deeper targets, and for targets with limited horizontal extent. In principle, the resolution and sensitivity of a survey can be improved by moving either the transmitting or the receiving dipoles into the sub-surface. We have therefore investigated the sensitivity of Seafloor to Borehole CSEM (sbCSEM) survey geometries, specifically for the case of simplified targets with small lateral dimensions in shallow water areas—including targets whose depth of burial substantially exceeds their lateral extent. The results are encouraging. Neither small target size nor shallow water presents obstacles in principle to the use of this approach. Our models reveal distinct lobes in the patterns of electric field and current density amplitudes around a sub-seafloor transmitting dipole. The shape, positions and amplitudes of these lobes are all strongly modified by the presence of one or more small resistive targets, and they are strongly influenced by the positions of target edges. These effects significantly modify the pattern of electric fields at the seafloor and hence result in good sensitivity for realistic survey geometries. Small targets can be detected by seafloor receivers when the sub-seafloor transmitting dipole is located at some distance laterally outside the targets—leading to potential applications in ‘step-out’ prospecting. The asymmetry of responses at the seafloor from targets that are offset with respect to transmitter location has potential applications in field appraisal, while monitoring of reservoirs during production provides another possible application. Varying the depth of the transmitter down the borehole generates a Vertical EM Profiling (VEMP) survey—analogous to Vertical Seismic Profiling (VSP)—and we demonstrate that this too can have useful applications. Modelling for deeper (3 km sub-seafloor) targets continues to yield encouraging results and suggests that step-out sbCSEM may be effective at depths beyond the detection limit of conventional seafloor–seafloor CSEM. Full article

(This article belongs to the Section Geophysics)

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16 pages, 13436 KB

Open AccessArticle

The Internal Geometry of Microbial Shoal and Its Reservoir Heterogeneity: Insights from Core Samples of Well X1 in the Pre-Salt Santos Basin

by Demin Zhang, Fayou Li, Zhongmin Zhang and Chaonian Si

Geosciences 2026, 16(5), 177; https://doi.org/10.3390/geosciences16050177 - 29 Apr 2026

Viewed by 349

Abstract

Recently, a substantial quantity of oil and gas has been discovered in the pre-salt Lower Cretaceous microbialite successions of Brazil’s Santos Basin, thereby prompting a global surge in research related to microbialites. It has been demonstrated that microbial shoal reservoirs yield the highest [...] Read more.

Recently, a substantial quantity of oil and gas has been discovered in the pre-salt Lower Cretaceous microbialite successions of Brazil’s Santos Basin, thereby prompting a global surge in research related to microbialites. It has been demonstrated that microbial shoal reservoirs yield the highest hydrocarbon production, with optimal reservoir properties, as evidenced by experience in the field of oilfield production. However, as research progresses, it has become increasingly evident that significant heterogeneity exists in both the lithology and physical properties within microbial shoal bodies. In order to address the identified knowledge gap, the present study employs systematic petrological and petrophysical datasets. These include 30-m continuous core samples, thin-section analyses, routine petrophysical tests and mercury injection capillary pressure (MICP) measurements. The aim is to characterize the internal microfacies architecture and reservoir heterogeneity of microbial shoals. It is imperative to ascertain the principal factors that govern the heterogeneity observed in these reservoirs. This critical step is essential for a comprehensive understanding of the subject matter. The results of the study demonstrate that: the Barra Velha Formation microbial shoals in the Santos Basin can be subdivided into three microfacies, which are delineated from base to top. The foundation of the shoal is the shoal base. The rock composition is dominated by the presence of spherulites, with intracrystalline pores functioning as the primary reservoir spaces. The compositional rocks of the shoal flank are poorly sorted microbial debris, with intergranular and intragranular pores formed by penecontemporaneous dissolution. The sedimentary succession of the shoal core is characterized by well-sorted microbial debris rocks displaying multiple shallowing-upward sequences, with reverse-graded textures. The primary storage space is constituted by fabric-selective pores from penecontemporaneous dissolution, though these are subject to local disruption by destructive silicification. Meanwhile, the microbial shoals demonstrate wide porosity (8.8–26.4%, mean 16.8%) and permeability (0.13–839 mD, mean 169 mD) ranges, thus classifying them as medium-porosity, high-permeability reservoirs. The superimposition of microfacies and diagenetic processes gives rise to considerable reservoir heterogeneity. It is evident that the shoal core microfacies exhibits robust energy and substantial grain size, characteristics that facilitate its exposure above lake level during periods of high-frequency lake-level oscillation. This exposure is further compounded by the influence of atmospheric water dissolution, which remodels the microfacies during the quasi-contemporaneous period. The reservoir quality is optimal, exhibiting the highest proportion of large pores. The reservoir properties of the shoal flank are closely followed by medium and large pores, and those of the shoal base are the worst, with micro and medium pores. Full article

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Geosciences, Volume 16, Issue 5 (May 2026) – 41 articles

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