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Geosciences, Volume 14, Issue 6 (June 2024) – 33 articles

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41 pages, 6914 KiB  
Article
Trend Analysis of Climatic Variables in the Cross River Basin, Nigeria
by Ndifon M. Agbiji, Jonah C. Agunwamba and Kenneth Imo-Imo Israel Eshiet
Geosciences 2024, 14(6), 172; https://doi.org/10.3390/geosciences14060172 (registering DOI) - 18 Jun 2024
Abstract
There have been several incidences of flood recently, which are believed to be aggravated by increased climatic variables as a result of perceived changes in climatic conditions (due to climate change) in the Cross River Basin. The basin is the most extensively developed [...] Read more.
There have been several incidences of flood recently, which are believed to be aggravated by increased climatic variables as a result of perceived changes in climatic conditions (due to climate change) in the Cross River Basin. The basin is the most extensively developed and used river basin in the management of the water resources of the Cross River and Akwa Ibom States in Nigeria. In this paper, 30 years (from 1992 to 2021) of hydro-meteorological data (annual average rainfall, maximum and minimum temperatures, hu midity, duration of sunlight (sunshine hours), evaporation, wind speed, soil temperature, cloud cover, solar radiation, and atmospheric pressure) from four stations in the Cross River Basin were obtained from the Nigerian Meteorological Agency (NIMET), Abuja and subjected to trend detection analysis using the Mann–Kendall test to determine the trend in climatic parameters. The results indicate that there is a significant upward trend in annual rainfall in Ogoja but a downward trend in Calabar. The evaporation trend is significantly downward in Eket, whereas in Calabar, there is an upward trend in solar radiation. Generally, there is a significant rise in annual maximum temperature across the basin. Serial correlation and segmented regression analyses were performed to measure the impact of fluctuations in monthly and long-term Tahiti and Darwin’s Sea level pressures on the climatic variables at the Cross River Basin catchment. These analyses were necessary to determine the extent of the influence of the El Nino Southern Oscillation climatic cycle. The analyses show no significant association between the El Niño Southern Oscillation (ENSO) and rainfall or between the ENSO and runoff in the catchment. This implies that the impact of the ENSO on rainfall and runoff in the Cross River Basin catchment is not considerable. The intercepts derived from the segmented regression in Eket and Ogoja show significant positive trends in both areas for rainfall and runoff. The trends in intercepts suggest that there are external factors influencing rainfall and runoff other than ENSO events, thus strengthening the assertion of climate change. Results from this study will facilitate the understanding of the variability in climatic parameters by stakeholders in the basin, researchers, policymakers, and water resource managers. Full article
(This article belongs to the Section Climate)
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31 pages, 23478 KiB  
Article
Landslide Susceptibility Assessment by Machine Learning and Frequency Ratio Methods Using XRAIN Radar-Acquired Rainfall Data
by Dos Santos Rodrigues Neto José Maria and Netra Prakash Bhandary
Geosciences 2024, 14(6), 171; https://doi.org/10.3390/geosciences14060171 (registering DOI) - 18 Jun 2024
Viewed by 121
Abstract
This study is an efficiency comparison between four methods for the production of landslide susceptibility maps (LSMs), which include random forest (RF), artificial neural network (ANN), and logistic regression (LR) as the machine learning (ML) techniques and frequency ratio (FR) as a statistical [...] Read more.
This study is an efficiency comparison between four methods for the production of landslide susceptibility maps (LSMs), which include random forest (RF), artificial neural network (ANN), and logistic regression (LR) as the machine learning (ML) techniques and frequency ratio (FR) as a statistical method. The study area is located in the Southern Hiroshima Prefecture in western Japan, a locality known to suffer from rainfall-induced landslide disasters, the most recent one in July 2018. The landslide conditioning factors (LCFs) considered in this study are lithology, land use, altitude, slope angle, slope aspect, distance to drainage, distance to lineament, soil class, and mean annual precipitation. The rainfall LCF data comprise XRAIN (eXtended RAdar Information Network) radar records, which are novel in the task of LSM production. The accuracy of the produced LSMs was calculated with the area under the receiver operating characteristic curve (AUROC), and an automatic hyperparameter tuning and result comparison system based on AUROC scores was utilized. The calculated AUROC scores of the resulting LSMs were 0.952 for the RF method, 0.9247 for the ANN method, 0.9016 for the LR method, and 0.8424 for the FR. It is also noteworthy that the ML methods are substantially swifter and more practical than the FR method and allow for multiple and automatic experimentations with different hyperparameter settings, providing fine and accurate outcomes with the given data. The results evidence that ML techniques are more efficient when dealing with hazard assessment problems such as the one exemplified in this study. Although the conclusion that the RF method is the most accurate for LSM production as found by other authors in the literature, ML method efficiency may vary depending on the specific study area, and thus the use of an automatic multi-method LSM production system with hyperparameter tuning such as the one utilized in this study is advised. It was also found that XRAIN radar-acquired mean annual precipitation data are effective when used as an LCF in LSM production. Full article
(This article belongs to the Special Issue Landslide Monitoring and Mapping II)
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15 pages, 50410 KiB  
Article
Hydroacoustic Monitoring of Mayotte Submarine Volcano during Its Eruptive Phase
by Aude Lavayssière, Sara Bazin and Jean-Yves Royer
Geosciences 2024, 14(6), 170; https://doi.org/10.3390/geosciences14060170 - 17 Jun 2024
Viewed by 203
Abstract
Submarine volcanoes are more challenging to monitor than subaerial volcanoes. Yet, the large eruption of the Hunga Tonga-Hunga Ha’apai volcano in the Tonga archipelago in 2022 was a reminder of their hazardous nature and hence demonstrated the need to study them. In October [...] Read more.
Submarine volcanoes are more challenging to monitor than subaerial volcanoes. Yet, the large eruption of the Hunga Tonga-Hunga Ha’apai volcano in the Tonga archipelago in 2022 was a reminder of their hazardous nature and hence demonstrated the need to study them. In October 2020, four autonomous hydrophones were moored in the sound fixing and ranging channel 50 km offshore Mayotte Island, in the North Mozambique Channel, to monitor the Fani Maoré 2018–2020 submarine eruption. Between their deployment and July 2022, this network of hydrophones, named MAHY, recorded sounds generated by the recent volcanic activity, along with earthquakes, submarine landslides, marine mammals calls, and marine traffic. Among the sounds generated by the volcanic activity, impulsive signals have been evidenced and interpreted as proxy for lava flow emplacements. The characteristics and the spatio-temporal evolution of these hydroacoustic signals allowed the estimation of effusion and flow rates, key parameters for volcano monitoring. These sounds are related to the non-explosive quenching of pillow lavas due to the rapid heat transfer between hot lava and cold seawater, with this process releasing an energy equivalent to an airgun source as used for active seismic exploration. Volcano observatories could hence use autonomous hydrophones in the water column to detect and monitor active submarine eruptions in the absence of regular on-site seafloor survey. Full article
(This article belongs to the Section Geophysics)
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7 pages, 3932 KiB  
Article
Representing Zooplankters: An Example from the Foraminifera
by George H. Scott
Geosciences 2024, 14(6), 169; https://doi.org/10.3390/geosciences14060169 - 14 Jun 2024
Viewed by 223
Abstract
Because of their excellent preservation record, testate zooplankters provide valuable proxy ocean climate data through the Quaternary–Recent. Commonly, specimen abundances are sought, which are time-consuming to collect manually and require taxonomic expertise. While machine learning models obviate these problems, it is questioned whether [...] Read more.
Because of their excellent preservation record, testate zooplankters provide valuable proxy ocean climate data through the Quaternary–Recent. Commonly, specimen abundances are sought, which are time-consuming to collect manually and require taxonomic expertise. While machine learning models obviate these problems, it is questioned whether the current use of specimens selected by experts to train the models impartially captures the variation within the source populations. To illustrate the potential value of the latter and their relevance to the selection of representative specimens, the 2D outline shape of the planktonic foraminifer Truncorotalia crassaformis from four globally distributed, late-Quaternary–modern collections is examined. Large intra-sample variation is attributed to changes in the size and shape of the last-formed chamber, which often departs radically from its predecessors. Similar outlines occur in each collection, and no single axial shape is dominant when the aggregated data, aligned on their centroids and adjusted for size and position, are projected onto their principal components. Several partitions based on distance from the centroid of the standardized data are considered as sources of representative specimens, with that at ±1.645σ (standard deviations, nominally 90%) suggested as suitable. This procedure obviates the need for expert-based consensus sampling; for greater environmental resolution, it can be applied to individual water mass samples. It assists, but does not fully resolve, the following basic diagnostic question: which characters separate Truncorotalia crassaformis from its relatives? Full article
(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)
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23 pages, 16272 KiB  
Article
A Comparative Study of Susceptibility and Hazard for Mass Movements Applying Quantitative Machine Learning Techniques—Case Study: Northern Lima Commonwealth, Peru
by Edwin Badillo-Rivera, Manuel Olcese, Ramiro Santiago, Teófilo Poma, Neftalí Muñoz, Carlos Rojas-León, Teodosio Chávez, Luz Eyzaguirre, César Rodríguez and Fernando Oyanguren
Geosciences 2024, 14(6), 168; https://doi.org/10.3390/geosciences14060168 - 14 Jun 2024
Viewed by 295
Abstract
This study addresses the importance of conducting mass movement susceptibility mapping and hazard assessment using quantitative techniques, including machine learning, in the Northern Lima Commonwealth (NLC). A previous exploration of the topographic variables revealed a high correlation and multicollinearity among some of them, [...] Read more.
This study addresses the importance of conducting mass movement susceptibility mapping and hazard assessment using quantitative techniques, including machine learning, in the Northern Lima Commonwealth (NLC). A previous exploration of the topographic variables revealed a high correlation and multicollinearity among some of them, which led to dimensionality reduction through a principal component analysis (PCA). Six susceptibility models were generated using weights of evidence, logistic regression, multilayer perceptron, support vector machine, random forest, and naive Bayes methods to produce quantitative susceptibility maps and assess the hazard associated with two scenarios: the first being El Niño phenomenon and the second being an earthquake exceeding 8.8 Mw. The main findings indicate that machine learning models exhibit excellent predictive performance for the presence and absence of mass movement events, as all models surpassed an AUC value of >0.9, with the random forest model standing out. In terms of hazard levels, in the event of an El Niño phenomenon or an earthquake exceeding 8.8 Mw, approximately 40% and 35% respectively, of the NLC area would be exposed to the highest hazard levels. The importance of integrating methodologies in mass movement susceptibility models is also emphasized; these methodologies include the correlation analysis, multicollinearity assessment, dimensionality reduction of variables, and coupling statistical models with machine learning models to improve the predictive accuracy of machine learning models. The findings of this research are expected to serve as a supportive tool for land managers in formulating effective disaster prevention and risk reduction strategies. Full article
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30 pages, 41921 KiB  
Article
Petrographic and Textural Characterization of Beach Sands Contaminated by Asbestos Cement Materials (Cape Peloro, Messina, Italy): Hazardous Human-Environmental Relationships
by Roberta Somma
Geosciences 2024, 14(6), 167; https://doi.org/10.3390/geosciences14060167 - 14 Jun 2024
Viewed by 217
Abstract
In the past fifteen years, the contamination of the Italian marine coastal environments by asbestos cement materials (ACMs) represents a known crux mostly reported or denounced by mass media and environmental associations. A recent research reporting compositional and textural data related to ACMs [...] Read more.
In the past fifteen years, the contamination of the Italian marine coastal environments by asbestos cement materials (ACMs) represents a known crux mostly reported or denounced by mass media and environmental associations. A recent research reporting compositional and textural data related to ACMs found in the beach deposits of a protected natural reserve (Cape Peloro, Messina, Italy) induced the author to perform new petrographic and textural analyses on the Cape Peloro beach sands, pebbles, cobbles (BSPC), and technofossils (bricks, tails, slab, concrete), associated with the previously studied ACMs, in order to compare the data with those of the ACMs previously reported in the literature. The petrographic investigations allowed the author to determine that beach sands and weakly gravelly sands were characterized by a quartzo–lithic signature, being mainly composed of metamorphic grains of quartz (50–60%) and metamorphic lithics (40–50%, mainly composed of polymineral quartz + microcline, quartz + plagioclase, quartz + biotite, quartz + muscovite grains, and monomineral opaque minerals, plagioclase, k-feldspar, and almandine garnet grains), whereas the pebbles and cobbles were made of acid intrusive (granitoids) and metamorphic rocks (gneiss, augen gneiss prevailing). Pebbles and cobbles made up of porphyroids could derive from the cannibalization of the underlying lower to middle Pleistocene siliciclastic deposits of the Messina Formation. Differently, the gneiss, augen gneiss, and granitoids forming the beach pebbles and cobbles, being present both in the crystalline rocks of the Aspromonte Unit and in the clasts of the SGMF, could originate from both of them. Textural investigations allowed the author to characterize grain size, shape parameters, and roundness in the beach deposits. These were mostly composed of sands and weakly gravelly sands with medium grains. Parameters, such as elongation and flatness, showed higher values in the BSPC than in the technofossils. The shapes of the BSPC were mostly from oblate to equant, whereas the shapes of the technofossils were mostly from bladed to oblate. The main differences depended on the original shape of the technofossils, being mostly platy, and their softer composition. The roundness was from angular to sub-rounded. In the Ionian coast of the Cape Peloro peninsula, the source areas for the well-rounded ACM found on the beach and in the beach deposits could have at least four different origins: (i) Possible landfills widespread since the 1970s in the intensively urbanized coastal areas. (ii) Direct abandonment in the coastal area. (iii) Direct abandonment in the streams. (iv) Activities to counteract the erosion/lack of sediment using non-conforming materials. Considering the diffused damage caused by the coastal erosion affecting most of the Italian coast and the obvious increasing dispersion of the asbestos fibers from the ACMs over time, effectual counter actions to prevent further contamination and guidelines for clean-up efforts are necessary. Full article
(This article belongs to the Section Sedimentology, Stratigraphy and Palaeontology)
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19 pages, 3684 KiB  
Article
Energy-Based Pore Pressure Generation Models in Silty Sands under Earthquake Loading
by Giuseppe Tomasello and Daniela Dominica Porcino
Geosciences 2024, 14(6), 166; https://doi.org/10.3390/geosciences14060166 - 13 Jun 2024
Viewed by 322
Abstract
During an earthquake, excess pore water pressure generation in saturated silty sands causes a reduction in shear strength and even liquefaction of the soil. A comprehensive experimental program consisting of undrained cyclic simple-shear tests was undertaken to explore the key factors affecting the [...] Read more.
During an earthquake, excess pore water pressure generation in saturated silty sands causes a reduction in shear strength and even liquefaction of the soil. A comprehensive experimental program consisting of undrained cyclic simple-shear tests was undertaken to explore the key factors affecting the energy-based excess pore water pressure generation models for non-plastic silty sands. The examined influencing factors were non-plastic fines content (less than and greater than the threshold value ≅ 25%), packing density, vertical effective stress, applied cyclic stress ratio, and soil fabric. The relationship between excess pore water pressure ratio and dissipated energy per unit volume was found to be mainly dependent on the relative density and fines content of soil, whereas the cyclic stress ratio, initial vertical effective stress, and soil fabric (i.e. the reconstitution method) appeared to have a minor impact. A revision of the original energy-based model developed for clean sand by Berrill and Davis was proposed to improve prediction accuracy in terms of residual excess pore water pressures versus normalised cumulative dissipated energy. Nonlinear multivariable regression analyses were performed to develop correlations for the calibration parameters of the revised model. Lastly, these correlations were validated through additional cyclic simple-shear tests performed on different silty sands recovered at a site where liquefaction occurred after the 2012 Emilia Romagna (Italy) earthquake. Full article
(This article belongs to the Section Natural Hazards)
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24 pages, 1837 KiB  
Article
Quantifying Aperiodic Cliff Top and Cliff Face Retreat Rates for an Eroding Drumlin on Ireland’s Atlantic Coast Using Structure-from-Motion
by Gregor M. Rink, Eugene J. Farrell and Gordon R. M. Bromley
Geosciences 2024, 14(6), 165; https://doi.org/10.3390/geosciences14060165 - 12 Jun 2024
Viewed by 302
Abstract
Globally, the rapid retreat of coastal cliffs poses a profound risk to property, transport infrastructure, and public safety. To quantify and compare cliff top and cliff face retreat and identify erosion processes, this study combines historical (1842–2000) maps and orthophotos with contemporary UAV [...] Read more.
Globally, the rapid retreat of coastal cliffs poses a profound risk to property, transport infrastructure, and public safety. To quantify and compare cliff top and cliff face retreat and identify erosion processes, this study combines historical (1842–2000) maps and orthophotos with contemporary UAV surveys (2019–2023) to quantify cliff top and cliff face retreat along a 240 m wide coastal drumlin in Galway Bay, Ireland. Retreat rates for the cliff top and cliff face were calculated using 2D mapping and 3D modelling, respectively. Critically, the choice of method has a significant impact on calculated rates of cliff top retreat, with output from the 2D mapping approach (0.14 +/− 0.02 m yr−1) being double that of the 3D modelling approach (0.08 +/− 0.02 m year−1). The aperiodic development of a talus cone, which temporarily protects the cliff from storm waves, also influences estimates of cliff retreat. The repeat cycles of talus slope formation and removal in this high wave energy environment suggest that the drumlin scarp transitions between a periodically transport-limited and supply-limited system over short- and long-time periods, respectively, on the continuum of cliff types. These results warrant further research to identify and quantify the rates, patterns, drivers (marine and subaerial processes), and timing of cliff retreat in response to climate change. Full article
22 pages, 56468 KiB  
Article
Effect of Depositional Environment and Climate on Organic Matter Enrichment in Sediments of the Upper Miocene—Pliocene Kampungbaru Formation, Lower Kutai Basin, Indonesia
by Jamaluddin, Kateřina Schöpfer, Michael Wagreich, Maria, Susanne Gier and Douaa Fathy
Geosciences 2024, 14(6), 164; https://doi.org/10.3390/geosciences14060164 - 12 Jun 2024
Viewed by 253
Abstract
The Upper Miocene–Pliocene Kampungbaru Formation crops out in the easternmost part of the Lower Kutai Basin, Indonesia. The sedimentological analysis of seven outcrops was carried out, and a total of twenty-five samples from these outcrops was analyzed for bulk geochemistry, organic petrography, and [...] Read more.
The Upper Miocene–Pliocene Kampungbaru Formation crops out in the easternmost part of the Lower Kutai Basin, Indonesia. The sedimentological analysis of seven outcrops was carried out, and a total of twenty-five samples from these outcrops was analyzed for bulk geochemistry, organic petrography, and bulk and clay mineralogy to assess the effect of the climate and depositional environment on organic matter enrichment. The Kampungbaru Formation consists of interbedded sandstone, siltstone, claystone, and thick coal beds, which were classified into eleven lithofacies. Subsequently, seven facies associations were identified, namely the fluvial-dominated distributary channel, sheet-like sandstone, tide-influenced distributary channel, mouth bar, crevasse splay, delta plain, and delta front. The coal facies generally have a high amount of total organic carbon (TOC, 5.1–16.9; avg. 10.11 wt.%), and non-coal layers range from 0.03 to 4.22 wt.% (avg. 1.54 wt.%). The dominant maceral is vitrinite, while liptinite occurs only rarely in the samples. Organic matter is inferred to have originated from terrestrial plants growing in mangrove swamps. Identified clay minerals include varying proportions of kaolinite, illite, chlorite, and mixed layer illite/smectite (I/S). Kaolinite, which commonly constitutes up to 30% of the clay volume, indicates intensive chemical weathering during a warm and humid climate. In accordance with the Köppen climate classification, the paleoclimate during the deposition of the Kampungbaru Formation is classified as type Af, which is a tropical rainforest. Tropical climate was favorable for the growth of higher plants and deposition of organic matter under anoxic conditions and led to higher amounts of TOC in the Kampungbaru Formation. Full article
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37 pages, 29588 KiB  
Article
Pixel-MPS: Stochastic Embedding and Density-Based Clustering of Image Patterns for Pixel-Based Multiple-Point Geostatistical Simulation
by Adel Asadi and Snehamoy Chatterjee
Geosciences 2024, 14(6), 162; https://doi.org/10.3390/geosciences14060162 - 12 Jun 2024
Viewed by 347
Abstract
Multiple-point geostatistics (MPS) is an established tool for the uncertainty quantification of Earth systems modeling, particularly when dealing with the complexity and heterogeneity of geological data. This study presents a novel pixel-based MPS method for modeling spatial data using advanced machine-learning algorithms. Pixel-based [...] Read more.
Multiple-point geostatistics (MPS) is an established tool for the uncertainty quantification of Earth systems modeling, particularly when dealing with the complexity and heterogeneity of geological data. This study presents a novel pixel-based MPS method for modeling spatial data using advanced machine-learning algorithms. Pixel-based multiple-point simulation implies the sequential modeling of individual points on the simulation grid, one at a time, by borrowing spatial information from the training image and honoring the conditioning data points. The developed methodology is based on the mapping of the training image patterns database using the t-Distributed Stochastic Neighbor Embedding (t-SNE) algorithm for dimensionality reduction, and the clustering of patterns by applying the Density-based Spatial Clustering of Applications with Noise (DBSCAN) algorithm, as an efficient unsupervised classification technique. For the automation, optimization, and input parameter tuning, multiple stages are implemented, including entropy-based determination of the template size and a k-nearest neighbors search for clustering parameter selection, to ensure the proposed method does not require the user’s interference. The proposed model is validated using synthetic two- and three-dimensional datasets, both for conditional and unconditional simulations, and runtime information is provided. Finally, the method is applied to a case study gold mine for stochastic orebody modeling. To demonstrate the computational efficiency and accuracy of the proposed method, a two-dimensional training image with 101 by 101 pixels is simulated for 100 conditional realizations in 453 s (~4.5 s per realization) using only 361 hard data points (~3.5% of the simulation grid), and the resulting average simulation has a good visual match and only an 11.8% pixel-wise mismatch with the training image. Full article
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22 pages, 10169 KiB  
Article
Effect of Vehicle Cyclic Loading on the Failure of Canal Embankment on Soft Clay Deposit
by Kuo Chieh Chao, Tanawoot Kongsung and Krit Saowiang
Geosciences 2024, 14(6), 163; https://doi.org/10.3390/geosciences14060163 - 11 Jun 2024
Viewed by 448
Abstract
Road embankments along irrigation canals, constructed on soft Bangkok clay, have always been unstable. Numerous studies have shown that rapid drawdown of water level may be one of the main causes, while vehicle cyclic loading may also contribute to embankment failure. This study [...] Read more.
Road embankments along irrigation canals, constructed on soft Bangkok clay, have always been unstable. Numerous studies have shown that rapid drawdown of water level may be one of the main causes, while vehicle cyclic loading may also contribute to embankment failure. This study aims to investigate the impact of vehicle loading on the failure of embankments built on Bangkok soft clay. The behavior of soft Bangkok clay under vehicle load has been investigated by employing conventional and dynamic triaxial techniques, and finite element method (FEM). This study also examined the effects of soft clay thickness and cyclic loading with different magnitudes and frequencies. The laboratory testing results indicate that the threshold stress of the soft clay is estimated to be approximately three-fourths of the undrained shear strength of the soil. The reduction in effective stress in the soft clay is caused by varied frequencies and thicknesses of the clay. Based on the analysis results, it has been proven that the cyclic loads exerted by vehicles solely are insufficient to cause the embankment to collapse. Nevertheless, the repetitive loading of vehicles may result in a one-quarter decrease in the embankment’s factor of safety. Full article
(This article belongs to the Special Issue Computational Geodynamic, Geotechnics and Geomechanics)
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1 pages, 128 KiB  
Correction
Correction: Salvini et al. Ground Displacements Estimation through GNSS and Geometric Leveling: A Geological Interpretation of the 2016–2017 Seismic Sequence in Central Italy. Geosciences 2022, 12, 167
by Riccardo Salvini, Claudio Vanneschi, Chiara Lanciano and Renzo Maseroli
Geosciences 2024, 14(6), 161; https://doi.org/10.3390/geosciences14060161 - 11 Jun 2024
Viewed by 156
Abstract
Change of Affiliation [...] Full article
16 pages, 51049 KiB  
Article
UAV, GNSS, and GIS for the Rapid Assessment of Multi-Occurrence Landslides
by Konstantinos G. Nikolakopoulos, Aggeliki Kyriou and Ioannis K. Koukouvelas
Geosciences 2024, 14(6), 160; https://doi.org/10.3390/geosciences14060160 - 9 Jun 2024
Viewed by 845
Abstract
Intense long-duration rainfall or extreme precipitation in a few hours can provoke many simultaneous shallow landslides. In the past, the term multi-occurrence regional landslides (MORLEs) was proposed to describe such phenomena. In the current study, unmanned aerial vehicles in combination with a global [...] Read more.
Intense long-duration rainfall or extreme precipitation in a few hours can provoke many simultaneous shallow landslides. In the past, the term multi-occurrence regional landslides (MORLEs) was proposed to describe such phenomena. In the current study, unmanned aerial vehicles in combination with a global navigation satellite system sensor and geographical information systems seem to be the ideal solution for the rapid assessment of many landslides occurring in Aitoloakarnania Prefecture, Western Greece. Fourteen landslides were accurately mapped within a few working days, and precise orthophotos and reports were created and submitted to the local authorities. The analysis of meteorological data proved that there is a peak in precipitation height that triggers the MORLEs in the specific area. Specifically, the value of the daily precipitation was defined at 80 mm. Full article
(This article belongs to the Special Issue Landslide Monitoring and Mapping II)
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18 pages, 7532 KiB  
Article
On the Impact of Geospace Weather on the Occurrence of M7.8/M7.5 Earthquakes on 6 February 2023 (Turkey), Possibly Associated with the Geomagnetic Storm of 7 November 2022
by Dimitar Ouzounov and Galina Khachikyan
Geosciences 2024, 14(6), 159; https://doi.org/10.3390/geosciences14060159 - 7 Jun 2024
Viewed by 855
Abstract
A joint analysis of solar wind, geomagnetic field, and earthquake catalog data showed that before the catastrophic M = 7.8 and M = 7.5 Kahramanmaras earthquake sequence on 6 February 2023, a closed strong magnetic storm occurred on 7 November 2022, SYM/H = [...] Read more.
A joint analysis of solar wind, geomagnetic field, and earthquake catalog data showed that before the catastrophic M = 7.8 and M = 7.5 Kahramanmaras earthquake sequence on 6 February 2023, a closed strong magnetic storm occurred on 7 November 2022, SYM/H = −117 nT. The storm started at 08:04 UT. At this time, the high-latitudinal part of Turkey’s longitudinal region of future epicenters was located under the polar cusp, where the solar wind plasma would directly access the Earth’s environment. The time delay between storm onset and earthquake occurrence was ~91 days. We analyzed all seven strong (M7+) earthquakes from 1967 to 2020 to verify the initial findings. A similar pattern has been revealed for all events. The time delay between magnetic storm onset and earthquake occurrence varies from days to months. To continue these investigations, a retrospective analysis of seismic and other geophysical parameters just after preceded geomagnetic storms in the epicenter areas is desirable. Full article
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20 pages, 5306 KiB  
Article
Conservative Evaluation of Fault Displacement Hazard for a Nuclear Site in Case of Insufficient Data on the Fault Activity
by Tamás János Katona
Geosciences 2024, 14(6), 158; https://doi.org/10.3390/geosciences14060158 - 7 Jun 2024
Viewed by 292
Abstract
The safety regulations require periodic reviews of the site hazards when operating nuclear power plants. If any indications of Quaternary fault activity are revealed, the fault displacement hazard should be evaluated. Signs of paleo-liquefaction were recently found at the nuclear site of Paks, [...] Read more.
The safety regulations require periodic reviews of the site hazards when operating nuclear power plants. If any indications of Quaternary fault activity are revealed, the fault displacement hazard should be evaluated. Signs of paleo-liquefaction were recently found at the nuclear site of Paks, Hungary, indicating the late-Pleistocene activity of the fault crossing the site. Except for this, there are no historical or instrumental records of earthquakes at the fault, and the micro-seismic and GPS monitoring results do not indicate activity either. Despite a thorough site investigation of over 40 years, the indications are uncertain and insufficient for defining the fault activity, as required for a probabilistic fault displacement hazard analysis. This paper develops and applies a simplified conservative hazard evaluation method of average fault displacement that allows an in-time decision regarding the safety relevance of the hazard. Geometrical simplification is possible since the fault crosses the site. The fault’s activity is evaluated using magnitude–frequency relations of the area sources developed for probabilistic seismic hazard analysis. The total probability theorem is applied, and different strike-slip fault scaling relations are considered while calculating the probability of non-zero surface displacement, fault rupture length, and average displacement. The fault displacement hazard curve is defined and compared with earlier studies for the same site. Since the late recognition of active faults cannot be excluded at several operating plant sites, the methodology can be applied in the future beyond a single application for the Paks site in Hungary. Full article
(This article belongs to the Special Issue New Trends in Earthquake Engineering and Seismotectonics)
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17 pages, 15831 KiB  
Article
Dipping Tidal Notch (DTN): Exposed vs. Sheltered Morphometry
by Stefano Furlani, Mauro Agate, Eleonora de Sabata, Renato Chemello, Valeria Vaccher, Giulia Visconti and Fabrizio Antonioli
Geosciences 2024, 14(6), 157; https://doi.org/10.3390/geosciences14060157 - 6 Jun 2024
Viewed by 239
Abstract
Tidal notches, long regarded as reliable indicators of mean sea level, have been extensively studied along carbonate coasts in the central Mediterranean Sea. Previous studies revealed a correlation between the genesis of tidal notches and tidal range, lithology, cliff foot depth, and wave [...] Read more.
Tidal notches, long regarded as reliable indicators of mean sea level, have been extensively studied along carbonate coasts in the central Mediterranean Sea. Previous studies revealed a correlation between the genesis of tidal notches and tidal range, lithology, cliff foot depth, and wave energy. In the 2020 Geoswim campaigns at Lampedusa, the southernmost island of the Pelagie archipelago (Italy), and in Gozo Island (Malta), ‘anomalous’ tidal notches were identified. Unlike normal notches observed elsewhere, those in Lampedusa’s southern bays exhibited a particular behaviour —constantly deepening in the inner part of the bays, reaching a maximum depth of approximately 30 cm below sea level and narrowing inwards. Similar phenomena were previously observed near Marseille (France). As confirmed by the literature, all these areas are tectonically stable. Time-lapse images, alongside measurements of morphometric parameters, were collected during the survey. Our hypothesis indicates that a combination of marine factors influenced by local marine conditions driven by the local morphology of the small bays exposed to southern quadrants contribute to the formation of these unique landforms. The latter manifests higher lowering erosion rates slightly below the mean sea level in sheltered areas, challenging conventional notions about tidal notch formation. Full article
23 pages, 2619 KiB  
Article
Prediction of Soil Liquefaction Triggering Using Rule-Based Interpretable Machine Learning
by Emerzon Torres and Jonathan Dungca
Geosciences 2024, 14(6), 156; https://doi.org/10.3390/geosciences14060156 - 6 Jun 2024
Viewed by 722
Abstract
Seismic events remain a significant threat, causing loss of life and extensive damage in vulnerable regions. Soil liquefaction, a complex phenomenon where soil particles lose confinement, poses a substantial risk. The existing conventional simplified procedures, and some current machine learning techniques, for liquefaction [...] Read more.
Seismic events remain a significant threat, causing loss of life and extensive damage in vulnerable regions. Soil liquefaction, a complex phenomenon where soil particles lose confinement, poses a substantial risk. The existing conventional simplified procedures, and some current machine learning techniques, for liquefaction assessment reveal limitations and disadvantages. Utilizing the publicly available liquefaction case history database, this study aimed to produce a rule-based liquefaction triggering classification model using rough set-based machine learning, which is an interpretable machine learning tool. Following a series of procedures, a set of 32 rules in the form of IF-THEN statements were chosen as the best rule set. While some rules showed the expected outputs, there are several rules that presented attribute threshold values for triggering liquefaction. Rules that govern fine-grained soils emerged and challenged some of the common understandings of soil liquefaction. Additionally, this study also offered a clear flowchart for utilizing the rule-based model, demonstrated through practical examples using a borehole log. Results from the state-of-practice simplified procedures for liquefaction triggering align well with the proposed rule-based model. Recommendations for further evaluations of some rules and the expansion of the liquefaction database are warranted. Full article
(This article belongs to the Special Issue Geotechnical Earthquake Engineering and Geohazard Prevention)
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13 pages, 2557 KiB  
Article
Selection of the Value of the Power Distance Exponent for Mapping with the Inverse Distance Weighting Method—Application in Subsurface Porosity Mapping, Northern Croatia Neogene
by Uroš Barudžija, Josip Ivšinović and Tomislav Malvić
Geosciences 2024, 14(6), 155; https://doi.org/10.3390/geosciences14060155 - 6 Jun 2024
Viewed by 208
Abstract
The correct selection of the value of p is a complex and iterative procedure that requires experience in the interpretation of the obtained interpolated maps. Inverse Distance Weighting is a method applied to the porosities of the K and L hydrocarbon reservoirs discovered [...] Read more.
The correct selection of the value of p is a complex and iterative procedure that requires experience in the interpretation of the obtained interpolated maps. Inverse Distance Weighting is a method applied to the porosities of the K and L hydrocarbon reservoirs discovered in the Neogene (Lower Pontian) subsurface sandstones in northern Croatia (Pannonian Basin System). They represent small and large data samples. Also, a standard statistical analysis of the data was made, followed by a qualitative–quantitative analysis of the maps, based on the selection of different values for the power distance exponent (p-value) for the K and L reservoir maps. According to the qualitative analysis, for a small data set, the p-value could be set at 1 or 2, giving the optimal result, while for a large data set, a p value of 3 or 4 could be applied. For quantitative analysis, in the case of a small data set, p = 2 is recommended, resulting in a root mean square error value of 0.03458, a mean absolute error of 0.02013 and a median absolute deviation of 0.00546. In contrast, a p-value of 3 or 4 is selected as appropriate for a large data set, with root mean square errors of 0.02435 and 0.02437, mean square errors of 0.01582 and 0.01509 and median absolute deviations 0.00896 and 0.00444. Eventually for a small data set, it is recommended to use a p-value of 2, and for a large data set, a p-value of 3 or 4. Full article
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20 pages, 37893 KiB  
Article
Identification, Characterization, and Deposit Model of Calcite Mineralization in the Middle Atlas Belts, Morocco
by Abdelkhiar Ait Ali, Mohammed Charroud, Jaouad Choukrad, Youssef Ouahzizi, Hicham Si Mhamdi, Nacir El Moutaouakkil, Naoufal Saoud and Abdellah Mechaqrane
Geosciences 2024, 14(6), 154; https://doi.org/10.3390/geosciences14060154 - 6 Jun 2024
Viewed by 1018
Abstract
The Middle Atlas hosts calcite veins of considerable economic value, being found in the Mahdi and Bou Naceur ridges in the eastern part of the Moroccan Middle Atlas. In this study, we aim to identify the fundamental factors controlling mineralization, which could be [...] Read more.
The Middle Atlas hosts calcite veins of considerable economic value, being found in the Mahdi and Bou Naceur ridges in the eastern part of the Moroccan Middle Atlas. In this study, we aim to identify the fundamental factors controlling mineralization, which could be essential for the exploration of calcite minerals. Jurassic dolomites and limestones host calcite deposits. Mineralization is controlled by the NE-SW sinistral fault system of the Mahdi Ridge as well as by the NW-SE dextral fault system of the Bou Naceur Ridge. These veins exhibit a Riedel shear system. The edges of the veins display different textures, such as banded and brecciated calcite. At the heart of the veins are deposits of massive, automorphic, pure crystalline calcite. Geochemical analyses revealed carbonate rock dissolution and carbonate fluid infiltration, indicating the presence of a low-temperature hydrothermal system. These mineralizations are a response to the evolution of the geodynamic uplift of the Middle Atlas during the Neogene, which occurred during the Alpine orogeny. Full article
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19 pages, 7861 KiB  
Review
Geosites and Climate Change—A Review and Conceptual Framework
by Piotr Migoń
Geosciences 2024, 14(6), 153; https://doi.org/10.3390/geosciences14060153 - 5 Jun 2024
Viewed by 496
Abstract
Geosites are windows into the geological past, which may be recorded in rocks and their properties, the fossil content, and landform produced by processes no longer operating. Since the histories of sedimentation, life, and landscape evolution are to a certain extent controlled by [...] Read more.
Geosites are windows into the geological past, which may be recorded in rocks and their properties, the fossil content, and landform produced by processes no longer operating. Since the histories of sedimentation, life, and landscape evolution are to a certain extent controlled by climatic conditions, some geosites may be used as illustrations of various themes linked to the issue of climate change. In this paper, a coherent systematic framework is proposed for how to look at geosites through the lens of climate change. Four major aspects of relevance are recognized: (i) geosites providing evidence of changing climatic conditions in the past; (ii) geosites providing evidence of an environment different than that of today at the place; (iii) geosites providing evidence of extreme weather events; and (iv) dynamic geosites, subject to change as a response to ongoing climate change. The use of geosites to raise awareness and educate the public about climate change faces various interpretation challenges. In particular, linking with ongoing climate change requires caution and balanced presentation as most geosites record changes which occurred without any anthropogenic component. The preferred focus should be on environmental instability in general rather than on any specific reasons for change. Full article
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31 pages, 10514 KiB  
Article
Google Earth Engine and Machine Learning for Flash Flood Exposure Mapping—Case Study: Tetouan, Morocco
by EL Mehdi SELLAMI and Hassan Rhinane
Geosciences 2024, 14(6), 152; https://doi.org/10.3390/geosciences14060152 - 4 Jun 2024
Viewed by 1000
Abstract
Recently, the earth’s climate has changed considerably, leading to several hazards, including flash floods (FFs). This study aims to introduce an innovative approach to mapping and identifying FF exposure in the city of Tetouan, Morocco. To address this problem, the study uses different [...] Read more.
Recently, the earth’s climate has changed considerably, leading to several hazards, including flash floods (FFs). This study aims to introduce an innovative approach to mapping and identifying FF exposure in the city of Tetouan, Morocco. To address this problem, the study uses different machine learning methods applied to remote sensing imagery within the Google Earth Engine (GEE) platform. To achieve this, the first phase of this study was to map land use and land cover (LULC) using Random Forest (RF), a Support Vector Machine (SVM), and Classification and Regression Trees (CART). By comparing the results of five composite methods (mode, maximum, minimum, mean, and median) based on Sentinel images, LULC was generated for each method. In the second phase, the precise LULC was used as a related factor to others (Stream Power Index (SPI), Topographic Position Index (TPI), Slope, Profile Curvature, Plan Curvature, Aspect, Elevation, and Topographic Wetness Index (TWI)). In addition to 2024 non-flood and flood points to predict and detect FF susceptibility, 70% of the dataset was used to train the model by comparing different algorithms (RF, SVM, Logistic Regression (LR), Multilayer Perceptron (MLP), and Naive Bayes (NB)); the rest of the dataset (30%) was used for evaluation. Model performance was evaluated by five-fold cross-validation to assess the model’s ability on new data using metrics such as precision, score, kappa index, recall, and the receiver operating characteristic (ROC) curve. In the third phase, the high FF susceptibility areas were analyzed for two-way validation with inundated areas generated from Sentinel-1 SAR imagery with coherent change detection (CDD). Finally, the validated inundation map was intersected with the LULC areas and population density for FF exposure and assessment. The initial results of this study in terms of LULC mapping showed that the most appropriate method in this research region is the use of an SVM trained on a mean composite. Similarly, the results of the FF susceptibility assessment showed that the RF algorithm performed best with an accuracy of 96%. In the final analysis, the FF exposure map showed that 2465 hectares were affected and 198,913 inhabitants were at risk. In conclusion, the proposed approach not only allows us to assess the impact of FF in this study area but also provides a versatile approach that can be applied in different regions around the world and can help decision-makers plan FF mitigation strategies. Full article
(This article belongs to the Special Issue Flood Risk Reduction)
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20 pages, 5082 KiB  
Article
Stabilization of Pavement Subgrade Clay Soil Using Sugarcane Ash and Lime
by Abrar Ahmed, Magdi El-Emam, Naveed Ahmad and Mousa Attom
Geosciences 2024, 14(6), 151; https://doi.org/10.3390/geosciences14060151 - 2 Jun 2024
Viewed by 367
Abstract
Soft to medium clay soil possesses major sources of damages to the pavement layers overlying them because of their potential failure under moisture changes and external heavy traffic load. In such situations, soil stabilization methods can be used to improve the soil properties [...] Read more.
Soft to medium clay soil possesses major sources of damages to the pavement layers overlying them because of their potential failure under moisture changes and external heavy traffic load. In such situations, soil stabilization methods can be used to improve the soil properties and satisfy the desired engineering requirements. This study presents the use of sugarcane bagasse ash (SBA) and lime as chemical stabilizers for a clay soil subbase. Sugarcane bagasse ash and lime are used individually and as mixtures at varying percentages to stabilize a clay soil from Taxila, Pakistan. Various geotechnical laboratory tests such as Atterberg limits, compaction test, and California Bearing Ratio (CBR) are carried out on both pure and stabilized soils. These tests are performed at 2.5%, 5%, and 7.5% of either SBA or lime by weight of dry soil. In addition, mixtures of lime and SBA in ratios of 1:1, 2:1, 3:1, 1:2, and 1:3 are used in 5%, 7.5%, and 10% of dry soil weight, respectively. Results indicate that soil improved with 7.5% SBA showed a 28% increase in the liquid limit, while soil mixed with 2.5% lime in combination with 7.5% SBA showed an increase of 40% in the plastic limit. For the plasticity index, the soil mixed with 7.5% SBA showed an increase of 42%. Moreover, 2.5% lime in combination with 2.5% SBA showed the best improvement in soil consistency as this mixture reduced the soil plasticity from high to low according to the plasticity chart. Furthermore, 2.5% SBA in combination with 5% lime demonstrated the largest improvement on the CBR value, which is about a 69% increase above that of the pure soil. Finally, the cost analysis indicates a promising improvement method that reduces pavement cost, increases design life, and mitigates issues of energy consumption and pollution related to SBA as a solid waste material. Full article
(This article belongs to the Collection New Advances in Geotechnical Engineering)
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17 pages, 9041 KiB  
Article
Innovative Assessment of Mun River Flow Components through ANN and Isotopic End-Member Mixing Analysis
by Phornsuda Chomcheawchan, Veeraphat Pawana, Phongthorn Julphunthong, Kiattipong Kamdee and Jeerapong Laonamsai
Geosciences 2024, 14(6), 150; https://doi.org/10.3390/geosciences14060150 - 1 Jun 2024
Viewed by 210
Abstract
This study innovatively assesses the Mun River flow components in Thailand, integrating artificial neural networks (ANNs) and isotopic (δ18O) end-member mixing analysis (IEMMA). It quantifies the contributions of the Upper Mun River (UMR) and Chi River (CR) to the overall flow, [...] Read more.
This study innovatively assesses the Mun River flow components in Thailand, integrating artificial neural networks (ANNs) and isotopic (δ18O) end-member mixing analysis (IEMMA). It quantifies the contributions of the Upper Mun River (UMR) and Chi River (CR) to the overall flow, revealing a discrepancy in their estimated contributions. The ANN method predicts that the UMR and CR contribute approximately 70.5% and 29.5% respectively, while IEMMA indicates a more pronounced disparity with 84% from UMR and 16% from CR. This divergence highlights the distinct perspectives of ANN, focusing on hydrological data patterns, and IEMMA, emphasizing isotopic signatures. Despite discrepancies, both methods validate UMR as a significant contributor to the overall flow, highlighting their utility in hydrological research. The findings emphasize the complexity of river systems and advocate for an integrated approach of river flow analysis for a comprehensive understanding, crucial for effective water resource management and planning. Full article
(This article belongs to the Section Hydrogeology)
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9 pages, 1892 KiB  
Technical Note
Tremors—A Software App for the Analysis of the Completeness Magnitude
by Anna Figlioli, Giovanni Vitale, Matteo Taroni and Antonino D’Alessandro
Geosciences 2024, 14(6), 149; https://doi.org/10.3390/geosciences14060149 - 31 May 2024
Viewed by 168
Abstract
This paper introduces a software tool developed within the MATLAB environment, called Tremors, aimed at streamlining the pre-processing and analysis of seismic catalogues, with a particular emphasis on determining the Magnitude of Completeness. It will outline the criteria for event selection, as well [...] Read more.
This paper introduces a software tool developed within the MATLAB environment, called Tremors, aimed at streamlining the pre-processing and analysis of seismic catalogues, with a particular emphasis on determining the Magnitude of Completeness. It will outline the criteria for event selection, as well as various techniques to derive the Magnitude of Completeness values, including the recent and widely used Lilliefors statistical method. The study also addresses the important issue of short-term aftershock incompleteness and proposes solutions for managing it. Moreover, the software generates high-quality, customizable figures, and georeferenced raster images in .tif format as output. A standalone version of the App is also available (i.e., the users do not need a MATLAB license on their PC/laptop). Full article
(This article belongs to the Collection Advances in Statistical Seismology)
25 pages, 5625 KiB  
Article
A Hyperelastic Bounding Surface Plasticity Model for Unsaturated Granular Soils
by Mehdi Kadivar, Kalehiwot Nega Manahiloh and Victor N. Kaliakin
Geosciences 2024, 14(6), 148; https://doi.org/10.3390/geosciences14060148 - 30 May 2024
Viewed by 257
Abstract
In this paper, a state-dependent, bounding surface plasticity model that simulates the behavior of unsaturated granular soils is presented. An unsaturated, soil mechanics-compatible elastoplastic response is adopted in which no part of the response occurs in a purely elastic fashion. To create an [...] Read more.
In this paper, a state-dependent, bounding surface plasticity model that simulates the behavior of unsaturated granular soils is presented. An unsaturated, soil mechanics-compatible elastoplastic response is adopted in which no part of the response occurs in a purely elastic fashion. To create an appropriate hydro-mechanical coupling, a newer generation stress framework, consisting of the Bishop-type effective stress and a second stress variable, is used in conjunction with a soil-water characteristic curve function. Details regarding the model development, parameter estimation, and assessment of the model’s predictive capabilities are outlined. With a single set of parameter values, the model realistically simulates the main features that characterize the shear and volumetric behavior of unsaturated granular soils over a wide range of matric suction, density, and net confining pressure. Full article
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23 pages, 14722 KiB  
Article
Origin of Early Triassic Hornblende Gabbro from the Yunkai Massif, South China: Constraints from Mineral and Bulk-Rock Geochemistry
by Yaqian Wen, Feng Guo and Liang Zhao
Geosciences 2024, 14(6), 147; https://doi.org/10.3390/geosciences14060147 - 29 May 2024
Viewed by 442
Abstract
The early Triassic (~250 Ma) hornblende gabbro from the Tengxian area of Yunkai Massif, South China, contains a mineral assemblage of clinopyroxene, hornblende, biotite, plagioclase, K-feldspar and quartz and accessory apatite, and zircon and ilmenite. Based on mineral association and crystallization sequence, two [...] Read more.
The early Triassic (~250 Ma) hornblende gabbro from the Tengxian area of Yunkai Massif, South China, contains a mineral assemblage of clinopyroxene, hornblende, biotite, plagioclase, K-feldspar and quartz and accessory apatite, and zircon and ilmenite. Based on mineral association and crystallization sequence, two generations of the mineral assemblage have been identified: clinopyroxene + plagioclase + apatite (zircon) in Generation I and ilmenite + hornblende + biotite + K-feldspar + quartz in Generation II. The high crystallization temperature (T = 999–1069 °C) of clinopyroxene and its coexistence with labradorite (An = 52–58) indicate that Generation I crystallized in a basaltic magma, while the hornblende’s relatively low crystallization temperature (T = 780–820 °C) and coexistence with K-feldspar and quartz suggest that Generation II formed in an evolved alkaline melt. The mineralogical records are likely attributed to pulsed intrusion of the late-stage evolved magma into a crystal mush, like in Generation I. The bulk-rock geochemical data include a sub-alkaline affinity, arc-type trace element features, and highly enriched Sr-Nd-Pb-Hf isotopic compositions, consistent with the isotopic records from the accessory minerals, e.g., the very high δ18O values in both zircon and apatite and significantly negative εHf(t) in zircon. The combined mineral and bulk-rock geochemical data suggest that the primary magma for the Tengxian hornblende gabbro was derived from a mantle wedge that had been metasomatized by voluminous subducted terrigenous sediment-derived melts in response to subduction of the Paleo-Tethys Ocean. Full article
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50 pages, 6025 KiB  
Article
Carbon Dioxide Capture and Storage (CCS) in Saline Aquifers versus Depleted Gas Fields
by Richard H. Worden
Geosciences 2024, 14(6), 146; https://doi.org/10.3390/geosciences14060146 - 28 May 2024
Viewed by 1546
Abstract
Saline aquifers have been used for CO2 storage as a dedicated greenhouse gas mitigation strategy since 1996. Depleted gas fields are now being planned for large-scale CCS projects. Although basalt host reservoirs are also going to be used, saline aquifers and depleted [...] Read more.
Saline aquifers have been used for CO2 storage as a dedicated greenhouse gas mitigation strategy since 1996. Depleted gas fields are now being planned for large-scale CCS projects. Although basalt host reservoirs are also going to be used, saline aquifers and depleted gas fields will make up most of the global geological repositories for CO2. At present, depleted gas fields and saline aquifers seem to be treated as if they are a single entity, but they have distinct differences that are examined here. Depleted gas fields have far more pre-existing information about the reservoir, top-seal caprock, internal architecture of the site, and about fluid flow properties than saline aquifers due to the long history of hydrocarbon project development and fluid production. The fluid pressure evolution paths for saline aquifers and depleted gas fields are distinctly different because, unlike saline aquifers, depleted gas fields are likely to be below hydrostatic pressure before CO2 injection commences. Depressurised depleted gas fields may require an initial injection of gas-phase CO2 instead of dense-phase CO2 typical of saline aquifers, but the greater pressure difference may allow higher initial injection rates in depleted gas fields than saline aquifers. Depressurised depleted gas fields may lead to CO2-injection-related stress paths that are distinct from saline aquifers depending on the geomechanical properties of the reservoir. CO2 trapping in saline aquifers will be dominated by buoyancy processes with residual CO2 and dissolved CO2 developing over time whereas depleted gas fields will be dominated by a sinking body of CO2 that forms a cushion below the remaining methane. Saline aquifers tend to have a relatively limited ability to fill pores with CO2 (i.e., low storage efficiency factors between 2 and 20%) as the injected CO2 is controlled by buoyancy and viscosity differences with the saline brine. In contrast, depleted gas fields may have storage efficiency factors up to 80% as the reservoir will contain sub-hydrostatic pressure methane that is easy to displace. Saline aquifers have a greater risk of halite-scale and minor dissolution of reservoir minerals than depleted gas fields as the former contain vastly more of the aqueous medium needed for such processes compared to the latter. Depleted gas fields have some different leakage risks than saline aquifers mostly related to the different fluid pressure histories, depressurisation-related alteration of geomechanical properties, and the greater number of wells typical of depleted gas fields than saline aquifers. Depleted gas fields and saline aquifers also have some different monitoring opportunities. The high-density, electrically conductive brine replaced by CO2 in saline aquifers permits seismic and resistivity imaging, but these forms of imaging are less feasible in depleted gas fields. Monitoring boreholes are less likely to be used in saline aquifers than depleted gas fields as the latter typically have numerous pre-existing exploration and production well penetrations. The significance of this analysis is that saline aquifers and depleted gas fields must be treated differently although the ultimate objective is the same: to permanently store CO2 to mitigate greenhouse gas emissions and minimise global heating. Full article
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19 pages, 4602 KiB  
Article
Investigating Students’ Perception with an Online Dynamic Earth Course during COVID-19: A Quantitative Inquiry
by Md Iftekhar Alam, Jian Su, Hongwei Yang and Jacob Benner
Geosciences 2024, 14(6), 145; https://doi.org/10.3390/geosciences14060145 - 28 May 2024
Viewed by 375
Abstract
This study investigated Earth science students’ experiences with online education during the COVID-19 pandemic at the University of Tennessee, Knoxville, in the US. We used an existing survey from the online education literature, the Online Learning Environment Survey (OLES), which consists of three [...] Read more.
This study investigated Earth science students’ experiences with online education during the COVID-19 pandemic at the University of Tennessee, Knoxville, in the US. We used an existing survey from the online education literature, the Online Learning Environment Survey (OLES), which consists of three instruments: (a) community of inquiry (CoI), (b) Institutional Support (IS), and (c) Self-Directed Online Learning Scale (SDOLS). The survey rating subscales ordered from highest to lowest are autonomous learning, asynchronous online learning, institutional support, teaching presence, social presence, and cognitive presence, respectively, indicating interest for the online learning environment. Among all of the subscales, the asynchronous online category was rated the highest by the students. The data were then analyzed using Rasch modeling. According to the Rasch analyses, asynchronous online teaching represents the most favorable course delivery technique for geoscience education. Overall, the survey data show a general interest in online delivery and the effectiveness of the modality, thus indicating potential for evolving into an online Earth science program. Finally, also discussed are possible future extensions of the research (e.g., extending the research to other introductory online geoscience courses). Full article
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30 pages, 18820 KiB  
Article
Geological and Geochemical Characterization of Variscan Pegmatites in the Sidi Bou Othmane District, Central Jebilet Province, Morocco
by Amina Wafik, Nouamane El Aouad, Youssef Daafi, Yousra Morsli, Marouane Chniouar, Rosalda Punturo, Aida Maria Conte, Daniela Guglietta and Wissale Aba Sidi
Geosciences 2024, 14(6), 144; https://doi.org/10.3390/geosciences14060144 - 24 May 2024
Viewed by 628
Abstract
The Sidi Bou Othmane (SBO) pegmatite district is situated in the Central Jebilet massif, Western Meseta domain, Morocco. The SBO district is hosted essentially in a volcano-sedimentary series composed of Late-Devonian Sarhlef shales. Pegmatite bodies crop out as dykes, which are oriented from [...] Read more.
The Sidi Bou Othmane (SBO) pegmatite district is situated in the Central Jebilet massif, Western Meseta domain, Morocco. The SBO district is hosted essentially in a volcano-sedimentary series composed of Late-Devonian Sarhlef shales. Pegmatite bodies crop out as dykes, which are oriented from N-S to E-W and are generally variably deformed with ductile and/or brittle structures with ante, syn- or post-kinematic criteria. Petrographic observations of pegmatite dykes show that feldspars (i.e., albite, microcline) are the most abundant mineral phases, followed by quartz and micas, with tourmaline and accessory minerals such as garnet, and zircon also featuring heavily, as well as secondary minerals such as clinochlore, sericite, and illite. The geochemical study of the SBO pegmatites indicates that they have mainly S-type granitic compositions, which are peraluminous granites with calc-alkalic affinities. The study of trace elements indicates that SBO pegmatites were formed in post-orogenic syn-collision context during the Variscan orogeny by the partial melting of argilliferous sediment. They can be ascribed to the muscovite-bearing pegmatite; moreover, they have good potential regarding ceramics. They also contain minerals, such as feldspar, which have been recently assessed as critical raw materials by the European Union. Full article
(This article belongs to the Section Structural Geology and Tectonics)
21 pages, 9618 KiB  
Article
Trace Elements Distribution in the k7 Seam of the Karaganda Coal Basin, Kazakhstan
by Aiman Kopobayeva, Irina Baidauletova, Altynay Amangeldikyzy and Nazym Askarova
Geosciences 2024, 14(6), 143; https://doi.org/10.3390/geosciences14060143 - 24 May 2024
Viewed by 407
Abstract
We investigated the distribution patterns and evaluated the average contents of trace elements in the k7 seam of the Karaganda coal basin in Central Kazakhstan. This paper presents the results of studying the geochemistry of 34 elements in 85 samples of the [...] Read more.
We investigated the distribution patterns and evaluated the average contents of trace elements in the k7 seam of the Karaganda coal basin in Central Kazakhstan. This paper presents the results of studying the geochemistry of 34 elements in 85 samples of the k7 seam. The study employed a suite of advanced high-resolution analytical methods, including atomic emission spectrometry with inductively coupled plasma (ICP–OES) and mass spectrometry with inductively coupled plasma (ICP–MS), along with their processing and interpretation. It was determined that the concentrations of trace elements in the k7 seam are primarily associated with lithophile elements, revealing high concentrations of Li, V, Sc, Zr, Hf, and Ba. Additionally, increased concentrations of Nb, Ta, Se, Te, Ag, and Th were observed compared to the coal Clarke. Specific Nb(Ta)–Zr(Hf)–Li mineralization accompanied by a group of associated metals (Ba, V, Sc, etc.) was identified. The study revealed lateral and vertical heterogeneity of the rare elements’ distributions in coals, attributed to the formation dynamics of the coal basin. A correlation between Li and Al2O3 with a less positive relationship with K2O suggests the affinity of certain elements (Li, Ta, Nb, and Ba) to kaolinite. Clay layers showed increased radioactivity, with Th—13.2 ppm and U—2.6 ppm, indicating the possible presence of volcanogenic pyroclastic rocks characterized by radioactivity. Taken together, these data reveal the features of the rock composition of the source area, which is considered a mineralization source. According to geochemical data, it was found that the source area mainly consists of igneous felsic rocks, indicating that the formation occurred under conditions of a volcanic arc. This study’s novelty lies in estimating the average trace elements in the k7 seam, with elevated concentrations of certain elements that suggest promising prospects for industrial extraction from coals and coal wastes. These findings offer insights into considering coal as a potential source of raw material for rare metal production, guiding the industrial processing of key elements within coal. The potential extraction of metals from coal deposits, including from dumps, holds significance for industrial and commercial technologies, as processing critical coal elements can reduce disposal costs and mitigate their environmental impact. Full article
(This article belongs to the Topic Petroleum Geology and Geochemistry of Sedimentary Basins)
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