Geosciences

19 pages, 3019 KiB

Open AccessArticle

Composition of Pre-Salt Siliciclastic Units of the Lower Congo Basin and Paleogeographic Implications for the Early Stages of Opening of the South Atlantic

by João Constantino, Pedro A. Dinis, Ricardo Sousa Gomes and Mário Miguel Mendes

Geosciences 2025, 15(5), 189; https://doi.org/10.3390/geosciences15050189 - 21 May 2025

Viewed by 218

Abstract

The Lower Congo Basin (LCB) is a rift-type basin with petroleum systems that developed at the western African margin in association with the opening of the South Atlantic. Two pre-salt siliciclastic units of the LCB, Lucula (uppermost Jurassic to Lower Cretaceous) and Chela [...] Read more.

The Lower Congo Basin (LCB) is a rift-type basin with petroleum systems that developed at the western African margin in association with the opening of the South Atlantic. Two pre-salt siliciclastic units of the LCB, Lucula (uppermost Jurassic to Lower Cretaceous) and Chela (Aptian) formations, were sampled in deep wells and outcrops. Heavy mineral assemblages, XRD mineralogy and geochemistry indicate prevailing source in high rank metamorphic rocks from western regions of the Lower Congo Belt. However, sediment composition reveals some provenance heterogeneity. For the Chela Formation, occasionally abundant amphibole in the heavy mineral fraction, coupled with relatively high Fe and Ti proportions, suggest that it formed when deeper crustal units were exhumed. The Lucula Formation collected in outcrops have composition substantially different from Lucula and Chela samples collected in deep wells, indicating distinct provenance and the incorporation of recycled material. A significant diagenetic overprint compromises the interpretation of compositional features in terms of paleoclimate. The presence of a chemical component with dolomite, halite and diverse sulphates and the stratigraphic position of the Chela Formation at the transition to a thick evaporitic succession are compelling evidence of deposition under warm and dry conditions, which are probably more extreme than those associated with the original stages of rifting recorded by the Lucula Formation. Full article

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

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16 pages, 2249 KiB

Open AccessArticle

Challenges in Interpreting ⁴⁰Ar/³⁹Ar Age Spectra: Clues from Hydrothermally Altered Alkali Feldspars

by Yinzhi Wang, Liekun Yang, Wenbei Shi, Lin Wu and Fei Wang

Geosciences 2025, 15(5), 188; https://doi.org/10.3390/geosciences15050188 - 21 May 2025

Viewed by 136

Abstract

Integrated ⁴⁰Ar/³⁹Ar and U-Pb geochronology, combined with microstructural analysis of Early Cretaceous volcanics from eastern China, challenge conventional interpretations of flat ⁴⁰Ar/³⁹Ar age spectra. K-feldspar sample JD-1K (122.12 ± 0.81 Ma) preserves magmatic sanidine characteristics (homogeneous composition, [...] Read more.

Integrated ⁴⁰Ar/³⁹Ar and U-Pb geochronology, combined with microstructural analysis of Early Cretaceous volcanics from eastern China, challenge conventional interpretations of flat ⁴⁰Ar/³⁹Ar age spectra. K-feldspar sample JD-1K (122.12 ± 0.81 Ma) preserves magmatic sanidine characteristics (homogeneous composition, disordered monoclinic structure), while hydrothermally altered perthite JD-2K yields a flat plateau age of 99.83 ± 0.73 Ma (~20 Ma younger than coeval K-feldspar, biotite, and zircon samples). Microstructural analyses using energy dispersive spectroscopy (SEM−EDS), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) methods unequivocally demonstrate that the concordant ⁴⁰Ar/³⁹Ar age spectrum of sample JD-2K is a result of isotopic resetting during fluid-mediated recrystallization processes, rather than primary post-crystallization thermal stability. In step-heating experiments, contrasting argon release patterns correlate with microstructural heterogeneities. This study challenges the paradigm that flat ⁴⁰Ar/³⁹Ar spectra uniquely signify post-crystallization thermal histories, demonstrating that hydrothermal alteration can fully reset argon systems to produce misleadingly concordant ages. This study highlights the complexity of interpreting isotopic data in hydrothermally altered rocks, emphasizing the necessity of integrated petrological-geochemical analyses to differentiate primary magmatic signals from secondary overprints. Full article

(This article belongs to the Section Geochemistry)

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18 pages, 5654 KiB

Open AccessCase Report

The Influence of Pre-Existing Tension Cracks on the Stability of Unsupported Temporary Excavations in Stratified Hard Clays: Case Study of Corfu Island, Northwestern Greece

by Panagiotis Pelekis, Anastasios Batilas, Spyridon Lainas and Nikolaos Depountis

Geosciences 2025, 15(5), 187; https://doi.org/10.3390/geosciences15050187 - 21 May 2025

Viewed by 199

Abstract

Slope failures in overconsolidated hard clays present significant geotechnical challenges, particularly in stratified formations prone to pre-existing discontinuities. Despite extensive research on residual shear strength and fissuring in stiff clays, the role of undetected tension cracks and their interaction with hydrogeological conditions in [...] Read more.

Slope failures in overconsolidated hard clays present significant geotechnical challenges, particularly in stratified formations prone to pre-existing discontinuities. Despite extensive research on residual shear strength and fissuring in stiff clays, the role of undetected tension cracks and their interaction with hydrogeological conditions in temporary excavations remains underexplored. This study addresses this research gap through a detailed case study of a slope failure during an unsupported residential excavation on Corfu Island, Greece. The investigation aimed to identify the failure mechanism, assess the influence of geological discontinuities and groundwater conditions, and evaluate the contribution of residual shear strength to slope stability. The methodology combined field observations, laboratory testing (including unconfined compression and ring shear tests), and numerical modelling using both finite element (FEM) and limit equilibrium (LEM) approaches. The results revealed that a nearly vertical, pre-existing fissure—acting as a tension crack—and water infiltration along the clay–sandstone interface significantly reduced the factor of safety, triggering a planar slide. Both FEM and LEM analyses indicated that critical conditions for failure were reached with a residual friction angle of 19°, inclined sandstone layers at 15–17°, and hydrostatic pressure from groundwater accumulation. This study demonstrates the compounded destabilizing effects of undetected discontinuities and water pressures in stratified hard clays and underscores the necessity of comprehensive geotechnical assessments for temporary excavations, even in seemingly stable formations. Full article

(This article belongs to the Topic Database, Mechanism and Risk Assessment of Slope Geologic Hazards)

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20 pages, 6304 KiB

Open AccessArticle

Projected Meteorological Drought in Mexico Under CMIP6 Scenarios: Insights into Future Trends and Severity

by Juan Alberto Velázquez-Zapata and Rodrigo Dávila-Ortiz

Geosciences 2025, 15(5), 186; https://doi.org/10.3390/geosciences15050186 - 21 May 2025

Viewed by 159

Abstract

Meteorological droughts are a complex and recurring phenomenon in Mexico, posing significant challenges for water availability, ecosystems, and socio-economic activities. Furthermore, several worldwide studies highlight that the impacts of droughts may intensify due to the potential effects of climate change. Using projections from [...] Read more.

Meteorological droughts are a complex and recurring phenomenon in Mexico, posing significant challenges for water availability, ecosystems, and socio-economic activities. Furthermore, several worldwide studies highlight that the impacts of droughts may intensify due to the potential effects of climate change. Using projections from global climate models in the Coupled Model Intercomparison Project Phase 6 (CMIP6), this study evaluates future trends in drought frequency and severity across the Mexican hydrological regions. We applied the Standardized Precipitation Index (SPI) to assess meteorological drought indicators under two Shared Socio-economic Pathway (SSP) scenarios (SSP2-4.5 and SSP5-8.5) for the periods 2040–2069 and 2070–2099. Climate models show high variability in projected precipitation changes between the reference and future periods. The SSP5-8.5 scenario indicates the greatest decrease, with reductions of at least 5 to 10%, and even larger declines projected for hydrological regions along the Pacific and Gulf of Mexico coasts, as well as the Yucatán Peninsula. Changes in drought indicators vary depending on the time horizon and scenario considered. For instance, projections for the period 2070–2099 under the high-emission scenario SSP5-8.5 suggest more frequent (three to four events) and prolonged (15 to 18 months) droughts in central and southern hydrological regions. These insights highlight the urgency of strengthening water management policies and adaptive strategies to mitigate the anticipated impacts of climate change on Mexico’s water resources. Full article

(This article belongs to the Section Climate and Environment)

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13 pages, 2059 KiB

Open AccessArticle

Co-Extrusive Magma Transport and Volcanic Dome Formation: Implications for Triggering Explosive Volcanic Eruptions

by Charles R. Carrigan and John C. Eichelberger

Geosciences 2025, 15(5), 185; https://doi.org/10.3390/geosciences15050185 - 21 May 2025

Viewed by 189

Abstract

Polymer co-extrusion experiments are described simulating the dynamics of two different magmas (e.g., silicic and mafic having different viscosities) flowing simultaneously in a vertical volcanic pipe or conduit which results in the effusion of composite lava domes on the surface. These experiments, involving [...] Read more.

Polymer co-extrusion experiments are described simulating the dynamics of two different magmas (e.g., silicic and mafic having different viscosities) flowing simultaneously in a vertical volcanic pipe or conduit which results in the effusion of composite lava domes on the surface. These experiments, involving geologically realistic conduit length-to-diameter aspect ratios of 130:1 or 380:1, demonstrate that co-extrusion of magmas having different viscosities can explain not only the observed normal zoning observed in planar dikes and the pipelike conduits that evolve from dikes but also the compositional layering of effused lava domes. The new results support earlier predictions, based on observations of induced core-annular flow (CAF), that dike and conduit zoning along with dome layering are found to depend on the viscosity contrast of the non-Newtonian (shear-thinning) magmas. Any magma properties creating viscosity differences, such as crystal content, bubble content, water content and temperature may also give rise to the CAF regime. Additionally, codependent flow behavior involving the silicic and mafic magmas may play a significant role in modifying the nature of volcanic eruptions. For example, lubrication of the flow by an annulus of a more mafic, lower-viscosity component allows a more viscous but more volatile-charged magma to be injected rapidly to greater vertical distances along a dike into a lower pressure regime that initiates exsolving of a gas phase, further assisting ascent to the surface. The rapid ascent of magmas exsolving volatiles in a dike or conduit is associated with explosive silicic eruptions. Full article

(This article belongs to the Special Issue Structural Analysis in Volcanic Areas: Towards a Multidisciplinary Approach and Small- to Large-Scale Observations)

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39 pages, 14246 KiB

Open AccessArticle

Comparison of PlanetScope and Sentinel-2 Spectral Channels and Their Alignment via Linear Regression for Enhanced Index Derivation

by Christian Massimiliano Baldin and Vittorio Marco Casella

Geosciences 2025, 15(5), 184; https://doi.org/10.3390/geosciences15050184 - 20 May 2025

Viewed by 493

Abstract

Prior research has shown that for specific periods, vegetation indices from PlanetScope and Sentinel-2 (used as a reference) must be aligned to benefit from the experience of Sentinel-2 and utilize techniques such as data fusion. Even during the worst-case scenario, it is possible [...] Read more.

Prior research has shown that for specific periods, vegetation indices from PlanetScope and Sentinel-2 (used as a reference) must be aligned to benefit from the experience of Sentinel-2 and utilize techniques such as data fusion. Even during the worst-case scenario, it is possible through histogram matching to calibrate PlanetScope indices to achieve the same values as Sentinel-2 (useful also for proxy). Based on these findings, the authors examined the effectiveness of linear regression in aligning individual bands prior to computing indices to determine if the bands are shifted differently. The research was conducted on five important bands: Red, Green, Blue, NIR, and RedEdge. These bands allow for the computation of well-known vegetation indices like NDVI and NDRE, and soil indices like Iron Oxide Ratio and Coloration Index. Previous research showed that linear regression is not sufficient by itself to align indices in the worst-case scenario. However, this paper demonstrates its efficiency in achieving accurate band alignment. This finding highlights the importance of considering specific scaling requirements for bands obtained from different satellite sensors, such as PlanetScope and Sentinel-2. Contemporary images acquired by the two sensors during May and July demonstrated different behaviors in their bands; however, linear regression can align the datasets even during the problematic month of May. Full article

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20 pages, 14821 KiB

Open AccessArticle

Seismic Facies Classification of Salt Structures and Sediments in the Northern Gulf of Mexico Using Self-Organizing Maps

by Silas Adeoluwa Samuel, Camelia C. Knapp and James H. Knapp

Geosciences 2025, 15(5), 183; https://doi.org/10.3390/geosciences15050183 - 19 May 2025

Viewed by 341

Abstract

Proper geologic reservoir characterization is crucial for energy generation and climate change mitigation efforts. While conventional techniques like core analysis and well logs provide limited spatial reservoir information, seismic data can offer valuable 3D insights into fluid and rock properties away from the [...] Read more.

Proper geologic reservoir characterization is crucial for energy generation and climate change mitigation efforts. While conventional techniques like core analysis and well logs provide limited spatial reservoir information, seismic data can offer valuable 3D insights into fluid and rock properties away from the well. This research focuses on identifying important structural and stratigraphic variations at the Mississippi Canyon Block 118 (MC-118) field, located on the northern slope of the Gulf of Mexico, which is significantly influenced by complex salt tectonics and slope failure. Due to a lack of direct subsurface data like well logs and cores, this area poses challenges in delineating potential reservoirs for carbon storage. The study leveraged seismic multi-attribute analysis and machine learning on 3-D seismic data and well logs to improve reservoir characterization, which could inform field development strategies for hydrogen or carbon storage. Different combinations of geometric, instantaneous, amplitude-based, spectral frequency, and textural attributes were tested using Self-Organizing Maps (SOM) to identify distinct seismic facies. SOM Models 1 and 2, which combined geometric, spectral, and amplitude-based attributes, were shown to delineate potential storage reservoirs, gas hydrates, salt structures, associated radial faults, and areas with poor data quality due to the presence of the salt structures more than SOM Models 3 and 4. The SOM results presented evidence of potential carbon storage reservoirs and were validated by matching reservoir sands in well log information with identified seismic facies using SOM. By automating data integration and property prediction, the proposed workflow leads to a cost-effective and faster understanding of the subsurface than traditional interpretation methods. Additionally, this approach may apply to other locations with sparse direct subsurface information to identify potential reservoirs of interest. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: “New Horizons in Geophysics: From Theory to Applications”)

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20 pages, 2173 KiB

Open AccessArticle

Advancing the Prediction and Evaluation of Blast-Induced Ground Vibration Using Deep Ensemble Learning with Uncertainty Assessment

by Sinem Bozkurt Keser, Mahmut Yavuz and Gamze Erdogan Erten

Geosciences 2025, 15(5), 182; https://doi.org/10.3390/geosciences15050182 - 19 May 2025

Viewed by 254

Abstract

Ground vibration is one of the most dangerous environmental problems associated with blasting operations in mining. Therefore, accurate prediction and controlling the blast-induced ground vibration are imperative for environmental protection and sustainable development. The empirical approaches give inaccurate results, as evident in the [...] Read more.

Ground vibration is one of the most dangerous environmental problems associated with blasting operations in mining. Therefore, accurate prediction and controlling the blast-induced ground vibration are imperative for environmental protection and sustainable development. The empirical approaches give inaccurate results, as evident in the literature. Hence, numerous researchers have started to use fast-growing soft computing approaches that are satisfying in prediction performance. However, achieving high-prediction performance and detecting prediction uncertainty is crucial, especially in blasting operations. This study aims to propose a deep ensemble model to predict the blast-induced ground vibration and quantify the prediction uncertainty, which is usually not addressed. This study used 200 published data from ten granite quarry sites in Ibadan and Abeokuta areas, Nigeria. The empirical equation (United States Bureau of Mines-based approach) was applied for comparison. The comparison of the models demonstrated that the proposed deep ensemble model achieved superior performance, offering more accurate predictions and more reliable uncertainty quantification. Specifically, it exhibited the lowest root mean square error (22.674), negative log-likelihood (4.44), and mean prediction interval width (1.769), alongside the highest

R^{2}

value (0.77) and prediction interval coverage probability (0.95). The deep ensemble model reached the desired coverage of 95%, demonstrating that uncertainty was not underestimated or overestimated. Full article

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19 pages, 8986 KiB

Open AccessArticle

Stability Assessment of the Tepehan Landslide: Before and After the 2023 Kahramanmaras Earthquakes

by Katherine Nieto, Noha I. Medhat, Aimaiti Yusupujiang, Vasit Sagan and Tugce Baser

Geosciences 2025, 15(5), 181; https://doi.org/10.3390/geosciences15050181 - 17 May 2025

Viewed by 231

Abstract

This study focuses on the investigation of the Tepehan landslide triggered by the 6 February 2023, Kahramanmaraş earthquake in Türkiye. The overall goal of this study is to understand the slope condition and simulate the failure considering pre- and post-event geometry. Topographic variations [...] Read more.

This study focuses on the investigation of the Tepehan landslide triggered by the 6 February 2023, Kahramanmaraş earthquake in Türkiye. The overall goal of this study is to understand the slope condition and simulate the failure considering pre- and post-event geometry. Topographic variations in the landslide area were analyzed using digital elevation models (DEMs) derived from the Sentinel-1 Synthetic Aperture Radar (SAR) satellite data and geospatial analysis. Slope stability analyses were conducted over a representative alignment, including assessments of soil structure, geological history, and field features. A limit equilibrium back-analysis was performed under both static and pseudo-static conditions, where an earthquake load coefficient was considered in the analyses. A total of five scenarios were evaluated to determine factors of safety (FoS) based on fully softened and residual strength parameters. The resulting critical slip surfaces from the simulations were compared with the geomorphometric analysis, necessitating the adjustment of the subsurface hard clay layer for residual conditions. The analyses revealed that the slope behaves as a delayed first-time landslide, with bedding planes acting as localized weak layers, reducing mobilized shear strength. This integrated remote sensing–geotechnical approach advances landslide hazard evaluation by enhancing the precision of slip surface identification and post-seismic slope behavior modeling, offering a valuable framework for similar post-disaster geohazard assessments. Full article

(This article belongs to the Section Geomechanics)

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14 pages, 3042 KiB

Open AccessArticle

Application of LiDAR Differentiation and a Modified Savage–Hutter Model to Analyze Co-Seismic Landslides: A Case Study of the 2024 Noto Earthquake, Japan

by Christopher Gomez and Danang Sri Hadmoko

Geosciences 2025, 15(5), 180; https://doi.org/10.3390/geosciences15050180 - 15 May 2025

Viewed by 269

Abstract

This study investigates co-seismic landslides triggered by the 1 January 2024 Mw 7.6 Noto Peninsula earthquake in Japan using LiDAR differentiation and a modified Savage–Hutter model. By analyzing pre- and post-earthquake high-resolution topographic data from 13 landslides in a geologically homogeneous area of [...] Read more.

This study investigates co-seismic landslides triggered by the 1 January 2024 Mw 7.6 Noto Peninsula earthquake in Japan using LiDAR differentiation and a modified Savage–Hutter model. By analyzing pre- and post-earthquake high-resolution topographic data from 13 landslides in a geologically homogeneous area of the peninsula, we characterized distinct landslide morphologies and dynamic behaviours. Our approach combined static morphological analysis from LiDAR data with simulations of granular flow mechanics to evaluate landslide mobility. Results revealed two distinct landslide types: those with clear erosion-deposition zonation and complex landslides with discontinuous topographic changes. Landslide dimensions followed power-law relationships (H = 7.51L^0.50, R² = 0.765), while simulations demonstrated that internal deformation capability (represented by the μ parameter) significantly influenced runout distances for landslides terminating on low-angle surfaces but had minimal impact on slope-confined movements. These findings highlight the importance of integrating both static topographic parameters and dynamic flow mechanics when assessing co-seismic landslide hazards, particularly for predicting potential runout distances on gentle slopes where human settlements are often located. Our methodology provides a framework for improved landslide susceptibility assessment and disaster risk reduction in seismically active regions. Full article

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19 pages, 7639 KiB

Open AccessArticle

Triple Filtering of Terrain Conductivity Data for Precise Tracing of Underground Utilities

by Mohamed Rashed, Abdulaziz Alqarawy, Nassir Al-Amri, Riyadh Halawani, Milad Masoud and Maged El Osta

Geosciences 2025, 15(5), 179; https://doi.org/10.3390/geosciences15050179 - 15 May 2025

Viewed by 168

Abstract

Terrain conductivity meters (TCMs) are efficient devices for different sorts of subsurface investigations, including detecting and tracing buried utilities, such as metallic pipes and cables. However, data collected using TCMs are usually ambiguous and hard to interpret. This ambiguity originates from the complex [...] Read more.

Terrain conductivity meters (TCMs) are efficient devices for different sorts of subsurface investigations, including detecting and tracing buried utilities, such as metallic pipes and cables. However, data collected using TCMs are usually ambiguous and hard to interpret. This ambiguity originates from the complex shape of apparent conductivity anomalies, the influence of irrelevant conductive bodies, and the interference of random noise with the collected data. To overcome this ambiguity and produce more interpretable apparent conductivity maps, a three-step filtering routine is proposed and tested using different real datasets. The filtering routine begins with applying a Savitzky–Golay (SG) filter to reduce the effect of random noise. This is followed by a modified rolling ball (MRB) filter to convert the complex M-shape of the anomaly into a single trough pointing to the underground utility. Finally, a virtual resolution enhancement (VRE) filter is applied to enhance the pinpointing apex of the trough. The application of the proposed filtering routine to apparent conductivity data collected using different terrain conductivity meters over different utilities in different urban environments shows a significant improvement of the data and an effective ability to reveal masked underground utilities. The proposed triple filtering routine can be a starting point for a new generation of TCMs with a built-in operation mode for instantaneous delineation and characterization of underground utilities in real time. Full article

(This article belongs to the Section Geophysics)

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21 pages, 6759 KiB

Open AccessArticle

Changes in Land Use and Land Cover Patterns in Two Desert Basins Using Remote Sensing Data

by Abdullah F. Alqurashi and Omar A. Alharbi

Geosciences 2025, 15(5), 178; https://doi.org/10.3390/geosciences15050178 - 15 May 2025

Viewed by 272

Abstract

Land use and land cover (LULC) changes can potentially impact natural ecosystems and are considered key components of global environmental change. The majority of LULC changes are related to human activities. Anthropogenic modifications have resulted in significant changes in the structure and fragmentation [...] Read more.

Land use and land cover (LULC) changes can potentially impact natural ecosystems and are considered key components of global environmental change. The majority of LULC changes are related to human activities. Anthropogenic modifications have resulted in significant changes in the structure and fragmentation of landscapes. This research aimed to analyze LULC changes using satellite images in the following two main basins in the Makkah region: the Wadi Fatimah and Wadi Uranah fluvial systems. First, image classification was conducted using remote sensing data from different satellite platforms, namely the Multispectral Scanner, the Landsat Thematic Mapper, the Enhanced Thematic Mapper Plus, and the Operational Land Imager. Images from these platforms were acquired for the years 1972, 1985, 1990, 2000, 2014, and 2022. A combination of object-based image analysis and a support vector machine classifier was used to produce LULC thematic maps. The obtained results were then used to calculate landscape metrics to quantify landscape patterns and fragmentation. The results showed that the landscape has undergone remarkable changes over the past 46 years. Built-up areas exhibited the most significant increase, while vegetation cover was the most dynamic land cover type. This was attributed mainly to the dry climatic conditions in the study area. These results suggest that LULC changes have influenced the natural environment in the studied area and are likely to contribute to further environmental impacts in the future. Measuring the spatial LULC distribution will help planners and ecologists to develop sustainable management strategies to mitigate future environmental consequences. Full article

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27 pages, 49480 KiB

Open AccessArticle

Analyzing Recent Tectonic Activity Along the Karak Wadi Al Fayha Fault System Using Seismic, Earthquake, and Remote Sensing Data

by Mu’ayyad Al Hseinat, Malek AlZidaneen and Ghassan Sweidan

Geosciences 2025, 15(5), 177; https://doi.org/10.3390/geosciences15050177 - 14 May 2025

Viewed by 513

Abstract

The Karak Wadi Al Fayha Fault (KWF) is a major NW-trending intraplate wrench fault system extending over 325 km from Western Karak in Jordan to Wadi Al Fayha in Saudi Arabia. Structurally linked to the Precambrian Najd Fault System, the KWF has been [...] Read more.

The Karak Wadi Al Fayha Fault (KWF) is a major NW-trending intraplate wrench fault system extending over 325 km from Western Karak in Jordan to Wadi Al Fayha in Saudi Arabia. Structurally linked to the Precambrian Najd Fault System, the KWF has been previously mapped using field observations, gravity, magnetic, and reflection seismic methods. However, these approaches lacked the vertical resolution necessary to characterize its shallow structure, leaving its influence on recent deposits and surface topography poorly understood. This study employs reflection seismic sections integrated with a Digital Elevation Model to refine terrain analysis and enhance fault mechanism solutions for determining the regional stress field pattern. Our results provide compelling evidence of the KWF’s upward propagation into the surface, as demonstrated by deformation of the uppermost Cretaceous and Cenozoic successions, distinct geomorphic features in the Digital Elevation Model, alignment of earthquake epicenters along the fault, and active landslides associated with its movement. We suggest that the reactivation of the KWF has been influenced by changing stress fields from the Late Cretaceous (Turonian) to the present. The Northwestern Arabian plate has undergone multiple tectonic stress transitions, including WNW–ESE compression associated with the Syrian Arc Fold-Belt system (Turonian–Plio-Pleistocene) and subsequent NNE–SSW extension linked to Red Sea rifting (Neogene–present). The analysis of fault mechanism solutions suggests that the latest fault movements result from the continued activity of the Irbid Rift event (Eocene) and the Dead Sea Transform Fault since the Miocene. Full article

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

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15 pages, 3559 KiB

Open AccessArticle

Evaluation of the Shear Modulus Degradation by a Modified Hyperbolic Function for Unconventional Geomaterials

by Hernán Patiño, Fausto Molina-Gómez and Rubén Ángel Galindo-Aires

Geosciences 2025, 15(5), 176; https://doi.org/10.3390/geosciences15050176 - 14 May 2025

Viewed by 233

Abstract

The characterisation of shear modulus degradation is essential for understanding the dynamic response of geomaterials. This article presents a modified hyperbolic model that evaluates the shear modulus for various angular strains and effective confining stresses. The model has been calibrated and validated using [...] Read more.

The characterisation of shear modulus degradation is essential for understanding the dynamic response of geomaterials. This article presents a modified hyperbolic model that evaluates the shear modulus for various angular strains and effective confining stresses. The model has been calibrated and validated using data from 108 resonant-column tests conducted on three different types of tailings from the Riotinto mines in Huelva, Spain. These tests were conducted on saturated samples that were consolidated at effective stresses of 50, 100, 150, 200, 250, and 300 kPa, accompanied by various combinations of torsional excitations to induce distinct angular strains. The results show that the hyperbolic model effectively predicts the shear modulus degradation in unconventional geomaterials, characterising the shear modulus under the testing conditions for the three types of Riotinto tailings. Additionally, the model can identify and confirm both the initial (or maximum) shear modulus and the reference angular strain as functions of the effective confining stress. The findings and model presented in this article contribute to enhancing the stability and resilience of geotechnical structures, including tailings storage facilities, that are subjected to dynamic loading, leading to safer designs and improved infrastructure performance. Full article

(This article belongs to the Section Geomechanics)

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17 pages, 10398 KiB

Open AccessArticle

Application of Machine Learning Methods for Gravity Anomaly Prediction

by Katima Zhanakulova, Bakhberde Adebiyet, Elmira Orynbassarova, Ainur Yerzhankyzy, Khaini-Kamal Kassymkanova, Roza Abdykalykova and Maksat Zakariya

Geosciences 2025, 15(5), 175; https://doi.org/10.3390/geosciences15050175 - 14 May 2025

Viewed by 359

Abstract

Gravity anomalies play critical roles in geological analysis, geodynamic monitoring, and precise geoid modeling. Obtaining accurate gravity data is challenging, particularly in inaccessible or sparsely covered regions. This study evaluates machine learning (ML) methods—Support Vector Regression (SVR), Gaussian Process Regression (GPR), and Ensemble [...] Read more.

Gravity anomalies play critical roles in geological analysis, geodynamic monitoring, and precise geoid modeling. Obtaining accurate gravity data is challenging, particularly in inaccessible or sparsely covered regions. This study evaluates machine learning (ML) methods—Support Vector Regression (SVR), Gaussian Process Regression (GPR), and Ensemble of Trees—for predicting gravity anomalies in southeastern Kazakhstan and compares their effectiveness with traditional Kriging interpolation. A dataset, consisting of the simple Bouguer anomaly values, latitude, longitude, elevation, normal gravity, and terrain corrections derived from historical maps at a scale of 1:200,000, was utilized. Models were trained and validated using cross-validation techniques, with performance assessed by statistical metrics (RMSE, MAE, R²) and spatial error analysis. Results indicated that the Exponential GPR model demonstrated the highest predictive accuracy, outperforming other ML methods, with 72.9% of predictions having errors below 1 mGal. Kriging showed comparable accuracy and superior robustness against extreme errors. Most prediction errors from all methods were spatially associated with mountainous regions featuring significant elevation changes. While this study demonstrated the effectiveness of machine learning methods for gravity anomaly prediction, their accuracy decreases in complex terrain, indicating the need for further research to improve model performance in such environments. Full article

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23 pages, 13284 KiB

Open AccessArticle

Reconstruction of a 3D Bedrock Model in an Urban Area Using Well Stratigraphy and Geophysical Data: A Case Study of the City of Palermo

by Alessandro Canzoneri, Raffaele Martorana, Mauro Agate, Maurizio Gasparo Morticelli, Patrizia Capizzi, Alessandra Carollo and Attilio Sulli

Geosciences 2025, 15(5), 174; https://doi.org/10.3390/geosciences15050174 - 14 May 2025

Viewed by 563

Abstract

A multidisciplinary approach was employed to construct a three-dimensional model of the bedrock top surface within the Palermo Plain, Sicily, Italy. This urban area is characterized by a dense and extensive built environment that largely obscures its geological features, thereby emphasizing the value [...] Read more.

A multidisciplinary approach was employed to construct a three-dimensional model of the bedrock top surface within the Palermo Plain, Sicily, Italy. This urban area is characterized by a dense and extensive built environment that largely obscures its geological features, thereby emphasizing the value of geophysical methods for enhancing subsurface understanding. In this sector, Numidian Flysch deposits constitute the geological bedrock of the plain. The morphology of the top surface of this unit was reconstructed by integrating borehole stratigraphic data with both passive and active seismic surveys. Ambient noise recordings were analyzed using the Horizontal-to-Vertical Spectral Ratio (HVSR) method to obtain spectral curves. These were then inverted into seismostratigraphic models using shear wave velocity profiles derived by Multichannel Analysis of Surface Waves (MASW) and lithostratigraphic information from borehole logs. Finally, the depth of the top of the Numidian Flysch, determined from both the borehole data and the inverted seismic models, was interpolated to generate a comprehensive 3D model of the bedrock top surface. Full article

(This article belongs to the Section Geophysics)

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27 pages, 5497 KiB

Open AccessArticle

Experimental Studies to Evaluate the Effects of Different Unloading Stress Paths on Strength Properties of Unconsolidated Sands

by Sabyasachi Prakash, Michael Myers, George Wong, Lori Hathon and Duane Mikulencak

Geosciences 2025, 15(5), 173; https://doi.org/10.3390/geosciences15050173 - 13 May 2025

Viewed by 248

Abstract

The mechanical behavior of rocks under loading conditions depends on stress path and magnitude. With increasing load, rocks have an elasto-plastic behavior. Within the loading yield surface, constitutive models assume that rocks behave elastically and are independent of the stress path and magnitude [...] Read more.

The mechanical behavior of rocks under loading conditions depends on stress path and magnitude. With increasing load, rocks have an elasto-plastic behavior. Within the loading yield surface, constitutive models assume that rocks behave elastically and are independent of the stress path and magnitude (e.g., Mohr–Coulomb models). We performed tests on unconsolidated sands (no cementation), and under both loading and unloading conditions. We mapped the loading yield surface using a multi-stage triaxial test with the yield criterion as the point of positive dilatancy. We studied the yield behavior of the two different unloading stress paths: a constant axial stress unloading test (reducing mean effective stress and increasing shear stress) and a constant shear stress unloading test (reducing mean effective stress and keeping shear stress constant). The results show that unloading-based tests reach yield point at a lower shear stress than expected from the loading-based yield surface. The unloading-based yield surface is also dependent on the stress path. The application of this research includes a prediction of the geomechanical behavior of unconsolidated sands under injection conditions. Often, a constitutive model derived from loading stress paths is used for injection with the ad hoc assumption that the loading and unloading models are identical. These constitutive models provide results for injector design parameters, injection performance prediction, and safe injection envelopes. Therefore, it is essential to have accurate constitutive models that are representative of unloading stress paths. In calibrating these models, we demonstrated that the yield criterion (point of positive dilatancy) is reached before the loading-based yield surface during injection (decrease in mean effective stress) is reached. We also developed a minimum yield surface model. With a calibration using three tests, this model can predict the yield point for any stress path and at any initial stress state (within the bounds of the experiments). Full article

(This article belongs to the Section Geomechanics)

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21 pages, 10338 KiB

Open AccessArticle

A Comparative Analysis of Avalanche Risk Assessment for Local Mountain Roads

by Matteo Dalmasso, Barbara Frigo and Bernardino Chiaia

Geosciences 2025, 15(5), 172; https://doi.org/10.3390/geosciences15050172 - 13 May 2025

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Abstract

For avalanche risk management, local authorities need streamlined and quantitative approaches to define the risk of exposed elements. In this paper, two quantitative avalanche risk assessment approaches are compared: (1) Wilhelm’s method, referring exclusively to transport routes, defines numerically the risk, and (2) [...] Read more.

For avalanche risk management, local authorities need streamlined and quantitative approaches to define the risk of exposed elements. In this paper, two quantitative avalanche risk assessment approaches are compared: (1) Wilhelm’s method, referring exclusively to transport routes, defines numerically the risk, and (2) the multi-criteria risk assessment (McRA) (Italian avalanche risk guidelines), which defines the risk through categorical results. It provides a degree of avalanche risk to which the element is exposed, according to the definition of a risk class (RC). This method allows a simplified avalanche risk analysis for different types of buildings or infrastructures. The paper presents a comparison of the two methods for studying avalanche risk on a stretch of road that reaches the village of Planpincieux in Val Ferret (Aosta Valley, IT), highlighting their advantages and drawbacks. Additionally, to demonstrate the flexibility of the multi-criteria risk assessment, a risk analysis was performed on the hotel in Planpincieux hamlet. The key findings illustrate that Wilhelm’s method shines in defining the risk posed by diverse avalanche paths, but is hampered by imprecise parameter definition. McRA, by means of the RC, allows hierarchical and direct assessment of the risk severity at the territory scale but requires hazard intensity maps. Full article

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20 pages, 3615 KiB

Open AccessArticle

Long-Term and Interannual Changes in the Land Area of a Barrier Using Multiple Satellite Images

by Hsien-Kuo Chang, Wei-Wei Chen and Jin-Cheng Liou

Geosciences 2025, 15(5), 171; https://doi.org/10.3390/geosciences15050171 - 12 May 2025

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Abstract

The Waisanding Barrier (WSDB) in Taiwan faces problems with regard to beach erosion and land area (LA) reduction. Due to the small amount of data generated and insufficient time periods used, the results of previous studies are only local rather than long term [...] Read more.

The Waisanding Barrier (WSDB) in Taiwan faces problems with regard to beach erosion and land area (LA) reduction. Due to the small amount of data generated and insufficient time periods used, the results of previous studies are only local rather than long term in nature. This study used 207 satellite images over 20 years to explore long-term and interannual changes in the LA of the WSDB. We developed both a surface fitting method (SFM) and a two-step interpolation method (TSIM) to reliably determine the LA of each image. When the tidal level of WSDB at the image acquisition is within ±0.25 m of the zero-meter shoreline, the LA obtained via the TSIM is similar to that of the SFM, while the other ones are quite different. The long-term decaying rate of the WSDB’s LA determined via both methods is about −0.40 × 10⁶ m²/year. The consistent differences in LA obtained from LiDAR and image data and the interannual variation in excess area (EA) are discussed, and the causes of these differences are land subsidence (LS) in the WSDB and excess wave energy (AEWE). Full article

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19 pages, 5233 KiB

Open AccessArticle

Two-Stage Systematic Forecasting of Earthquakes

by Valery Gitis and Alexander Derendyaev

Geosciences 2025, 15(5), 170; https://doi.org/10.3390/geosciences15050170 - 11 May 2025

Viewed by 240

Abstract

Earthquakes cause enormous social and economic damage. Consequently, the seismic process requires regular monitoring and systematic forecasting of strong earthquakes. This study introduces an enhanced iteration of the method of the minimum area of alarm (MMAA), refined to advance earthquake forecasting technology closer [...] Read more.

Earthquakes cause enormous social and economic damage. Consequently, the seismic process requires regular monitoring and systematic forecasting of strong earthquakes. This study introduces an enhanced iteration of the method of the minimum area of alarm (MMAA), refined to advance earthquake forecasting technology closer to its practical application. In the new version, a forecast is considered successful when all target earthquake epicenters within a specified time interval are contained within predefined alarm zones. Our updated algorithm optimizes the probability of successfully detecting earthquakes across forecast cycles and the probability for subsequent periods. A case study from the Kamchatka region demonstrates the practical application of this systematic forecasting approach. We propose that this computational technology can serve as an operational tool for generating early warnings of potential seismic hazards, and a research platform for conducting detailed investigations of precursor phenomena. Full article

(This article belongs to the Special Issue Precursory Phenomena Prior to Earthquakes (2nd Edition))

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18 pages, 5531 KiB

Open AccessArticle

A Comparative Study of Solvers and Preconditioners for an SPE CO₂ Storage Benchmark Reservoir Simulation Model

by Cenk Temizel, Gökhan Karcıoğlu, Ali Behzadan, Coşkun Çetin and Yusuf Ziya Pamukçu

Geosciences 2025, 15(5), 169; https://doi.org/10.3390/geosciences15050169 - 8 May 2025

Viewed by 294

Abstract

This study analyzes and evaluates the performance of various solvers and preconditioners for reservoir simulations of CO₂ injection and long-term storage using the model 11B of SPE CSP (Society of Petroleum Engineers, 11th Comparative Solution Project) and the MATLAB Reservoir Simulation Toolbox [...] Read more.

This study analyzes and evaluates the performance of various solvers and preconditioners for reservoir simulations of CO₂ injection and long-term storage using the model 11B of SPE CSP (Society of Petroleum Engineers, 11th Comparative Solution Project) and the MATLAB Reservoir Simulation Toolbox (MRST). The SPE CSP 11 model serves as a benchmark for testing numerical methods for solving partial differential equations (PDEs) in reservoir simulations. The research focuses on the Biconjugate Gradient Stabilized (BiCGSTAB) and Loose Generalized Minimum Residual (LGMRES) solver methods, as well as multiple preconditioning techniques designed to improve convergence rates and reduce computational effort for CO₂ storage. Extensive simulations were performed to compare the performance of different solver-preconditioner combinations under varying reservoir conditions, leveraging MRST’s flexible simulation capabilities. Key performance metrics, including iteration counts and computational time, were analyzed for the project. The results reveal trade-offs between computational efficiency and solution accuracy, providing valuable insights into the effectiveness of each approach. This study offers practical guidance for reservoir engineers and researchers seeking to analyze and optimize simulation workflows within MRST by identifying the strengths and limitations of specific solver-preconditioner combinations for complex linear systems. Full article

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30 pages, 200218 KiB

Open AccessArticle

Tectonic Evolution and Structural Control of Dike-Hosted Orogenic Gold Deposits in the Yana–Kolyma Collision Orogen (Eastern Siberia): Insights from the Eastern Margin of the Siberian Craton

by Valery Yurievich Fridovsky and Maxim Vasilievich Kudrin

Geosciences 2025, 15(5), 168; https://doi.org/10.3390/geosciences15050168 - 7 May 2025

Viewed by 235

Abstract

The Yana–Kolyma collision orogen, Eastern Siberia, is one of world-class gold economic belts, where large gold deposits are localized, mainly in the Upper Paleozoic and Lower Mesozoic clastic rocks. Dike-hosted orogenic gold deposits are found and to a lesser extent studied, but they [...] Read more.

The Yana–Kolyma collision orogen, Eastern Siberia, is one of world-class gold economic belts, where large gold deposits are localized, mainly in the Upper Paleozoic and Lower Mesozoic clastic rocks. Dike-hosted orogenic gold deposits are found and to a lesser extent studied, but they are important for understanding the structural control of mineralization within the framework of the orogen. Orogenic gold deposits of the Vyun ore field are hosted in Kimmeridgian–Titonian mafic, intermediate and felsic dikes, but they have no genetic connection with dikes. The late formation of deposits led to the fact that previously reactivated polydeformed structures were subsequently mineralized. The study of the structural control of mineralization is also complicated by superimposed late tectonic events. Based on the analysis of collected field materials, this paper presents the results of the study of deformation structures of the Vyun ore field within the framework of the Mesozoic evolution history throughout the geological time of the eastern convergent margin of the Siberian Craton. Four stages of deformations are identified. The pre-mineralization deformations and metamorphic and magmatic events share a common NE-SW shortening (D1 phase), which is related to the subduction of the Oymyakon oceanic slab and collision of the Kolyma–Omolon superterrane from the eastern margin of the Siberian Craton. This first stage is characterized by the superposition of several tectonic events under conditions of compression and progressive deformations (D1/1 and D1/2). Ore mineralization was formed at the end of compression in the same stress field (D1/2). Its structural control is determined by reactivation of older dikes and faults. Dikes are areas of heterogeneous stress and heterogeneous strain, being favorable for the concentration of ore fluids. The metallogenic time of formation of the gold mineralization is synchronous with the tectonic event, which likely reflects the final stages of the Kolyma–Omolon microcontinent–Siberian Craton collision of the Valanginian during crustal thickening. The main impulse of the Au mineralization D1/2 phase coincided with a slowdown in convergence. The post-mineralization tectonic regime was related to the Aptian–Late Cretaceous tectonic transition from compression to transpression. Transpressional tectonics were determined accordingly by W-E (D2 phase) and N-S (D3 phase) stress fields caused by several accretion events in the Cretaceous on the northern and eastern margins of Siberia. D4 phase extensional structures were caused by the opening of the Eurasian Oceanic basin in the Arctic in the Paleocene. The obtained results have a first-order impact on the understanding of the structural control of orogenic gold deposits and their relationship to the evolution of the host orogen. The new findings improve the tectonic knowledge of an area of interest for ore deposit exploration targeting orogenic gold deposits in Phanerozoic terranes of craton margins. Full article

(This article belongs to the Section Structural Geology and Tectonics)

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20 pages, 11450 KiB

Open AccessArticle

Glacier Recession and Climate Change in Chitral, Eastern Hindu Kush Mountains of Pakistan, Between 1992 and 2022

by Zahir Ahmad, Farhana Altaf, Ulrich Kamp, Fazlur Rahman and Sher Muhammad Malik

Geosciences 2025, 15(5), 167; https://doi.org/10.3390/geosciences15050167 - 7 May 2025

Viewed by 494

Abstract

Mountain regions are particularly sensitive and vulnerable to the impacts of climate change. Over the past three decades, mountain temperatures have risen significantly faster than those in lowland areas. The Hindu Kush–Karakoram–Himalaya region, often referred to as the “water tower of Asia”, is [...] Read more.

Mountain regions are particularly sensitive and vulnerable to the impacts of climate change. Over the past three decades, mountain temperatures have risen significantly faster than those in lowland areas. The Hindu Kush–Karakoram–Himalaya region, often referred to as the “water tower of Asia”, is the largest freshwater source outside the polar regions. However, it is currently undergoing cryospheric degradation as a result of climatic change. In this study, the Normalized Difference Glacier Index (NDGI) was calculated using Landsat and Sentinel satellite images. The results revealed that glaciers in Chitral, located in the Eastern Hindu Kush Mountains of Pakistan, lost 816 km² (31%) of their total area between 1992 and 2022. On average, 27 km² of glacier area was lost annually, with recession accelerating between 1997 and 2002 and again after 2007. Satellite analyses also indicated a significant increase in both maximum (+7.3 °C) and minimum (+3.6 °C) land surface temperatures between 1992 and 2022. Climate data analyses using the Mann–Kendall test, Theil–Sen Slope method, and the Autoregressive Integrated Moving Average (ARIMA) model showed a clear increase in air temperatures from 1967 to 2022, particularly during the summer months (June, July, and August). This warming trend is expected to continue until at least 2042. Over the same period, annual precipitation decreased, primarily due to reduced snowfall in winter. However, rainfall may have slightly increased during the summer months, further accelerating glacial melting. Additionally, the snowmelt season began consistently earlier. While initial glacier melting may temporarily boost water resources, it also poses risks to communities and economies, particularly through more frequent and larger floods. Over time, the remaining smaller glaciers will contribute only a fraction of the former runoff, leading to potential water stress. As such, monitoring glaciers, climate change, and runoff patterns is critical for sustainable water management and strengthening resilience in the region. Full article

(This article belongs to the Section Cryosphere)

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22 pages, 998 KiB

Open AccessReview

Review of Correlations Between Soil Electrical Resistivity and Geotechnical Properties

by Kornkanok Sangprasat, Avirut Puttiwongrak and Shinya Inazumi

Geosciences 2025, 15(5), 166; https://doi.org/10.3390/geosciences15050166 - 6 May 2025

Viewed by 346

Abstract

This review presents a comprehensive synthesis of existing studies on the correlations between soil electrical resistivity and fundamental geotechnical properties, with the aim of improving the applicability of resistivity testing in geotechnical engineering. Based on both laboratory and field research, the analysis highlights [...] Read more.

This review presents a comprehensive synthesis of existing studies on the correlations between soil electrical resistivity and fundamental geotechnical properties, with the aim of improving the applicability of resistivity testing in geotechnical engineering. Based on both laboratory and field research, the analysis highlights moisture content as the most influential factor inversely affecting resistivity, followed by plasticity index, clay content, and dry unit weight. Statistical approaches—including regression analysis and Spearman’s rank correlation—and artificial neural networks (ANNs) were evaluated for their effectiveness in modeling these nonlinear relationships. ANNs demonstrated superior predictive performance, particularly in heterogeneous and fine-grained soils. The review also examines the influence of temperature and salinity, emphasizing the need for multivariable models for robust interpretation. While resistivity testing shows great potential for non-destructive soil classification and compaction assessment, limitations related to soil type specificity, environmental variability, and model generalizability are noted. This work provides an important foundation for the development of data-driven, non-invasive techniques for subsurface characterization and outlines directions for future research, including field validation and hybrid modeling. Full article

(This article belongs to the Section Geomechanics)

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18 pages, 2383 KiB

Open AccessArticle

A Digital Analysis of the ‘Phoenix Trackway’ at the Hanxi Cretaceous Dinosaur Tracksite, China

by Anthony Romilio and Lida Xing

Geosciences 2025, 15(5), 165; https://doi.org/10.3390/geosciences15050165 - 3 May 2025

Viewed by 2229

Abstract

Long dinosaur trackways provide valuable records of trackmaker behaviour, yet their study is often hindered by logistical challenges in documentation and analysis. This study addresses these limitations by employing digital methodologies to re-analyse the Lower Cretaceous HX-T3 theropod trackway, originally mapped in 2015. [...] Read more.

Long dinosaur trackways provide valuable records of trackmaker behaviour, yet their study is often hindered by logistical challenges in documentation and analysis. This study addresses these limitations by employing digital methodologies to re-analyse the Lower Cretaceous HX-T3 theropod trackway, originally mapped in 2015. At nearly 70 m in length, this is the longest documented theropod trackway in China. Using digital mapping, 81 footprints were examined, revealing a consistent southward orientation between 163° and 187° azimuth, a trackway width of 0.008 to 0.300 m, and pace and stride lengths ranging from 0.707 to 1.176 m and 1.408 to 2.043 m, respectively. A potential trackmaker, Yutyrannus, was used to estimate a hip height of 1.13 m in a bent-legged stance, with relative stride values indicating a consistent walking gait at a median speed of 5.3 km/h. A digital life reconstruction animated in a bent-legged stance allowed the translation of ichnological data into a real-time reconstruction of trackmaker locomotion, providing dynamic insight into behavioural movement and avoiding unrealistic limb dislocations associated with straight-leg models. This study highlights the efficacy of digital methods in overcoming field-based limitations, integrating trace and body fossil evidence to enhance previous research. Full article

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27 pages, 13123 KiB

Open AccessArticle

The Didactic Potential of Paleontological Immovable Heritage for Secondary Education (Middle School and High School) Students in Spain: Assessment from Learning and Research Approaches

by Abel Acedo, Omid Fesharaki and Alejandra García-Frank

Geosciences 2025, 15(5), 164; https://doi.org/10.3390/geosciences15050164 - 2 May 2025

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Abstract

This study explores the didactic potential of paleontological immovable heritage in Secondary Education in Spain, focusing on how paleontological sites can enrich the educational curriculum. It is based on a survey of experts to identify key aspects to consider when developing educational activities [...] Read more.

This study explores the didactic potential of paleontological immovable heritage in Secondary Education in Spain, focusing on how paleontological sites can enrich the educational curriculum. It is based on a survey of experts to identify key aspects to consider when developing educational activities at paleontological sites, aligning learning based on the official educational curriculum with the 2030 Agenda for Sustainable Development. The goal is, on the one hand, to improve awareness of natural heritage conservation and foster meaningful and interdisciplinary learning and, on the other hand, to optimize the use of paleontological sites as valuable and accessible educational resources. The research highlights the importance of direct contact of students with the natural environment, proposing activities before and after the visits that seek greater involvement of students with the territory in which they live, and that serve to consolidate and strengthen their knowledge. In this context, the key competences of the educational curriculum are also analyzed, based on the official competences proposed by the European Union, which can be reinforced in paleontological contexts, considering both the benefits and the difficulties of integrating these sites into formal education. Full article

(This article belongs to the Section Geoheritage, Geoparks and Geotourism)

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18 pages, 9668 KiB

Open AccessArticle

Superdeep Diamond Genesis Through Fe-Mediated Carbonate Reduction

by Jing Gao, Bin Chen, Xiang Wu, Xiaojing Lai, Changzeng Fan, Yun Liu and Junfeng Zhang

Geosciences 2025, 15(5), 163; https://doi.org/10.3390/geosciences15050163 - 1 May 2025

Viewed by 358

Abstract

Superdeep diamonds and their syngenetic inclusions are crucial for understanding Earth’s deep carbon cycle and slab–mantle redox dynamics. The origins of these diamonds, especially their links to iron (Fe) carbides and ferropericlase with varying Mg# [=Mg/(Mg+Fe)_at], however, remain elusive. In this [...] Read more.

Superdeep diamonds and their syngenetic inclusions are crucial for understanding Earth’s deep carbon cycle and slab–mantle redox dynamics. The origins of these diamonds, especially their links to iron (Fe) carbides and ferropericlase with varying Mg# [=Mg/(Mg+Fe)_at], however, remain elusive. In this study, we performed high pressure–temperature (P-T) experiments (10–16 GPa and 1200–1700 K) across cold-to-warm subduction zones using a multi-anvil press. The results reveal a stepwise Fe-mediated carbonate reduction process for the formation of superdeep diamonds: MgCO₃ → Fe-carbides (Fe₃C/Fe₇C₃) → graphite/diamond. This mechanism explains two phenomena regarding superdeep diamonds: (1) anomalous ¹³C depletion results from kinetic isotope fractionation during ¹²C enrichment into the intermediate Fe-carbides; (2) nitrogen scarcity is due to Fe-carbides acting as nitrogen sinks. Ferropericlase [(Mg,Fe)O] formed during the reactions in our experiments shows Mg# variations (0.2–0.9), similar to those found in natural samples. High Mg# (>0.7) variants from lower temperature experiments indicate diamond crystallization from carbonatitic melts in the shallow lower mantle, while the broad Mg# range (0.2–0.9) from experiments at higher temperatures suggests multi-depth formation processes as found in Brazilian diamonds. These findings suggest that slab–mantle interactions produce superdeep diamonds with distinctive Fe-carbides and ferropericlase assemblages as inclusions, coupled with their ¹³C- and nitrogen-depleted signatures, which underscore thermochemical carbon cycling as a key factor in deep carbon storage and mantle mineralogy. Full article

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24 pages, 4388 KiB

Open AccessArticle

Closed-System Magma Degassing and Disproportionation of SO₂ Revealed by Changes in the Concentration and δ³⁴S Value of H₂S_(g) in the Solfatara Fluids (Campi Flegrei, Italy)

by Luigi Marini, Claudia Principe and Matteo Lelli

Geosciences 2025, 15(5), 162; https://doi.org/10.3390/geosciences15050162 - 1 May 2025

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Abstract

The use of a conceptual model of reference and modelling of relevant processes is mandatory to correctly interpret chemical and isotopic data. Adopting these basic guidelines, we have interpretated the unprecedented increase in the H₂S_(g) concentration and the concurrent unexpected [...] Read more.

The use of a conceptual model of reference and modelling of relevant processes is mandatory to correctly interpret chemical and isotopic data. Adopting these basic guidelines, we have interpretated the unprecedented increase in the H₂S_(g) concentration and the concurrent unexpected decrease in the δ³⁴S value of H₂S_(g) recorded since 2018 in the fumarolic effluents of the Bocca Grande fumarolic vent at Solfatara, Campi Flegrei caldera, in the framework of our conceptual model of the Solfatara magmatic–hydrothermal system. Assuming that the magma chamber situated at depths ≥ 8 km was filled at the end of the 1982–1984 bradyseismic crisis and no refilling episodes took place afterwards, as suggested by gas geochemistry, the concentration and the δ³⁴S value of H₂S_(g) of the Bocca Grande fumarolic effluents are controlled by closed-system degassing of the melt at depths ≥ 8 km and disproportionation of SO₂ in the deep hydrothermal reservoir (6.5–7.5 km depth) hosted in carbonate rocks where H₂S equilibrates. These processes have been active during the last 40 years, but 41.1% (±6.4%) of the sulfur initially stored in the melt (2200 mg/kg) was lost in the 4-year period of April 2018–April 2022. This marked loss of S from the melt in 2018–2022 might be due to the high solubility of sulfur in the melt, which caused its preferential separation during the late degassing stages. These findings are of utmost importance for the surveillance of the Solfatara magmatic–hydrothermal system during the ongoing bradyseismic crisis. Full article

(This article belongs to the Special Issue Geochemistry in the Development of Geothermal Resources)

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22 pages, 4303 KiB

Open AccessArticle

Comparative Analysis of Fracturing Definitions in Boreholes and Underground Workings

by Vassilyi Portnov, Nazym Askarova, Vladislav Medvedev, Serhii Vyzhva, Vitalii Puchkov, Gulnara Dosetova, Tatyana Kryazheva and Galiya Rakhimova

Geosciences 2025, 15(5), 161; https://doi.org/10.3390/geosciences15050161 - 1 May 2025

Viewed by 279

Abstract

This article presents a comparative analysis of rock mass fracturing at the Karasu gold deposit, located approximately 400 km northwest of Karaganda, Kazakhstan. The analysis is based on core drilling data and measurements from underground workings, including an old mine that was explored [...] Read more.

This article presents a comparative analysis of rock mass fracturing at the Karasu gold deposit, located approximately 400 km northwest of Karaganda, Kazakhstan. The analysis is based on core drilling data and measurements from underground workings, including an old mine that was explored and investigated to gather missing information. The spatial characteristics of fractures and their relationship with tectonic faults are identified. The feasibility of using the Rock Quality Designation (RQD) index for classifying fracture systems is assessed. Engineering and geological studies include the identification of major fracture systems and their characteristics using Leapfrog and Rocscience software, chosen for their ease of use and extensive functionality. The stability parameters of open-pit slopes are calculated, considering the physical and mechanical properties of rocks, the degree of fracturing, and the influence of groundwater. Key engineering and geological elements of the rock mass are identified, emphasizing the necessity of integrating fracture data from various sources to improve the accuracy of mine design and ensure the safe operation of open pits. These studies are part of the exploration phase to assess the geological situation and the physico-mechanical properties of these rocks for further quarry design. Full article

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19 pages, 6521 KiB

Open AccessArticle

Hydrological Characteristics of Columnar Basalt Aquifers: Measuring and Modeling Skaftafellsheiði, Iceland

by Roel Dijksma, Victor Bense, Eline Zweers, Lisette Avis and Martine van der Ploeg

Geosciences 2025, 15(5), 160; https://doi.org/10.3390/geosciences15050160 - 25 Apr 2025

Viewed by 443

Abstract

Basalt with columnar jointing can act as a good groundwater conductor. In areas with limited water resources in sedimentary rock, such as the Deccan Traps in India and the Columbia River basalt formations in Washington State (USA), large quantities of groundwater are abstracted [...] Read more.

Basalt with columnar jointing can act as a good groundwater conductor. In areas with limited water resources in sedimentary rock, such as the Deccan Traps in India and the Columbia River basalt formations in Washington State (USA), large quantities of groundwater are abstracted from such basalt formations for drinking water supply and irrigation. The hydraulic properties of basaltic formations are difficult to quantify. To obtain a better understanding of their hydraulic properties, intensive field campaigns in Iceland were combined with a conceptual groundwater model in MODFLOW. The field experiments enabled us to derive the upper boundary conditions, like precipitation surplus, and obtain reliable ranges for the k_h (0.01–0.3 m d⁻¹) and k_v (0.01–10 m d⁻¹) of the basalt formations. The main objective was to test the concept of representative elementary volumes (REVs) for such basaltic regions. Precipitation excess for the Vestragil and Eystragil catchments was calculated by taking into account the orographic effect of precipitation. It was found that at higher elevations (600 m + msl) the precipitation was twice the amount compared to the base camp rain gauge at 100 m + msl. Calculated evapotranspiration (1–2 mm d⁻¹) is in line with the literature. In the MODFLOW model, best results were obtained when the top layer (organic soil, peat, and regolith) was considered to be most conductive (up to 10 m d⁻¹), with a gradual reduction in hydraulic conductivity with depth in the basaltic aquifers. This study shows that, when larger elementary volumes are used, a good model representation of basaltic regions can be created. Full article

(This article belongs to the Section Hydrogeology)

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