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25 pages, 3845 KiB  
Article
Lagrangian Simulation of Sediment Erosion in Francis Turbines Using a Computational Tool in Python Coupled with OpenFOAM
by Mateo Narváez, Jeremy Guamán, Víctor Hugo Hidalgo, Modesto Pérez-Sánchez and Helena M. Ramos
Machines 2025, 13(8), 725; https://doi.org/10.3390/machines13080725 - 15 Aug 2025
Viewed by 181
Abstract
Hydraulic erosion from suspended sediment is a major degradation mechanism in Francis turbines of sediment-laden rivers, especially in Andean hydropower plants. This study presents a Python3.9-based computational tool integrating the empirical Oka erosion model within a Lagrangian particle tracking framework, coupled to single-phase [...] Read more.
Hydraulic erosion from suspended sediment is a major degradation mechanism in Francis turbines of sediment-laden rivers, especially in Andean hydropower plants. This study presents a Python3.9-based computational tool integrating the empirical Oka erosion model within a Lagrangian particle tracking framework, coupled to single-phase CFD in OpenFOAM 10. The novelty lies in a reduced-domain approach that omits the spiral casing and replicates its particle-induced swirl via a custom algorithm, lowering meshing complexity and computational cost while preserving erosion prediction accuracy. The method was applied to a full-scale Francis turbine at the San Francisco hydropower plant in Ecuador (nominal discharge 62.4 m3/s, rated output 115 MW, rotational speed 34.27 rad/s), operating under volcanic and erosive sediment loads. Maximum erosion rates reached ~1.2 × 10−4 mm3/kg, concentrated on runner blade trailing edges and guide vane pressure sides. Impact kinematics showed most collisions at near-normal angles (85°–98°, peak at 92°) and 6–9 m/s velocities, with rare 40 m/s impacts causing over 50× more loss than average. The workflow identifies critical wear zones, supports redesign and coating strategies, and offers a transferable, open-source framework for erosion assessment in turbines under diverse sediment-laden conditions. Full article
(This article belongs to the Special Issue Sustainable Manufacturing and Green Processing Methods, 2nd Edition)
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21 pages, 5958 KiB  
Article
Removal of As from Tambo River Using Sodium Alginate from Lessonia trabeculata (Aracanto)
by Diana M. Villanueva, Aldo G. Gonzales, Claudio A. Saez and Antonio M. Lazarte
Plants 2025, 14(14), 2173; https://doi.org/10.3390/plants14142173 - 14 Jul 2025
Viewed by 424
Abstract
Arsenic (As) contamination in the Tambo River (Perú), linked to mining activities and volcanic eruptions, poses significant health and agricultural risks. This study evaluated sodium alginate extracted from the brown macroalgae Lessonia trabeculata (LT) as a biosorbent for As removal. Water samples from [...] Read more.
Arsenic (As) contamination in the Tambo River (Perú), linked to mining activities and volcanic eruptions, poses significant health and agricultural risks. This study evaluated sodium alginate extracted from the brown macroalgae Lessonia trabeculata (LT) as a biosorbent for As removal. Water samples from three river points revealed As concentrations up to 0.309 mg/L, exceeding regulatory limits (0.1 mg/L). Sodium alginate was obtained via a simplified alkaline method, yielding an average of 21.44% (w/w relative to dry algae biomass) and characterized by Fourier Transform Infrared Spectroscopy (FTIR), showing structural similarity to industrial alginate (A1). Biosorption assays under simulated environmental conditions (neutral pH, 20 °C) demonstrated that LT alginate (A2) reduced As by 99% at 48 h with a 1.0 g/L dose, outperforming A1. Langmuir (qmax = 0.0012 mmol/g; b = 506.9 L/mg) and Freundlich (n = 1.94) isotherms confirmed favorable adsorption, while kinetics followed a Pseudo-Second-Order Model, suggesting physisorption. These results highlight LT alginate as a sustainable and scalable solution for remediating As-contaminated water, promoting the conservation of a vulnerable marine resource. This study underscores the potential of algal biopolymers in bioremediation strategies aligned with environmental and socioeconomic needs. Full article
(This article belongs to the Section Plant Ecology)
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17 pages, 2692 KiB  
Article
Distribution of Thallium in Sediments of the Fiora River Catchment, Central Italy: Implications for Its Sources
by Alessia Nannoni, Pierfranco Lattanzi, Guia Morelli, Cesare Fagotti, Rossella Friani, Valentina Rimondi and Pilario Costagliola
Minerals 2025, 15(7), 678; https://doi.org/10.3390/min15070678 - 24 Jun 2025
Viewed by 880
Abstract
Previous studies documented the contribution of toxic elements (Hg, As, and Sb) from the dismissed Monte Amiata Mining District (Italy), the third largest Hg producer worldwide, to the Mediterranean Sea. Another highly toxic element, thallium (Tl), received less attention. Here we report a [...] Read more.
Previous studies documented the contribution of toxic elements (Hg, As, and Sb) from the dismissed Monte Amiata Mining District (Italy), the third largest Hg producer worldwide, to the Mediterranean Sea. Another highly toxic element, thallium (Tl), received less attention. Here we report a reconnaissance study of the spatial variability of Tl content in stream sediments across the Fiora River catchment, which drains part of the Hg and Sb mining districts. Thallium contents are comparatively low (≤0.4 mg/kg) in sediments of creeks directly draining the mining areas, whereas they increase up to 2 mg/kg in the catchment section that drains the Vulsini ultrapotassic volcanic province, where no known mineral deposits occur. Results suggest that Hg and Sb deposits cannot be the only Tl source in the catchment. The most likely alternative/additional candidate are the high-K volcanic rocks. Although no specific data for the Vulsini district exist, a distinct Tl geochemical anomaly linked to the Latium volcanic province is present. The total Tl mass contained in sediments discharged yearly into the Mediterranean Sea from the Fiora River is estimated in the order of 0.1 t. This reconnaissance study indicates a non-negligible potential release of Tl from the mining districts and volcanic catchments in Central Italy and suggests the opportunity of further investigation on Tl distribution and speciation in the area. Full article
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15 pages, 5838 KiB  
Article
Design and Performance Verification of Deep Learning-Based River Flood Prediction System Design and Digital Twin-Based Its Application
by Heesang Eom, Younghun Kim and Jongho Paik
Mathematics 2025, 13(11), 1696; https://doi.org/10.3390/math13111696 - 22 May 2025
Viewed by 733
Abstract
This paper presents a digital twin-based river management and flood prediction system designed for hydrological environments, including volcanic geology. To address the problems of rapid runoff and complex terrain, a deep learning-based hybrid model is proposed that integrates a Convolutional Neural Network (CNN) [...] Read more.
This paper presents a digital twin-based river management and flood prediction system designed for hydrological environments, including volcanic geology. To address the problems of rapid runoff and complex terrain, a deep learning-based hybrid model is proposed that integrates a Convolutional Neural Network (CNN) for spatial feature extraction and a Recurrent Neural Network (RNN) with Long Short-Term Memory (LSTM) units for temporal sequence modeling. The performance evaluation results show that the proposed CNN-RNN hybrid model outperforms individual CNN and RNN baselines. The hybrid model achieves a macro-average precision of 0.97, a recall of 0.99, and an F1 score of 0.98, significantly outperforming existing methods. The system is also integrated with a 3D digital twin visualization platform to enable real-time monitoring and data-driven decision-making. Full article
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19 pages, 6430 KiB  
Article
Groundwater–River Water Interaction in an Urban Setting (Rome, Italy) Using a Multi-Method Approach (Hydrogeological and Radon Analyses)
by Martina Mattia, Gianmarco Mondati, Roberto Mazza, Carlo Rosa, Cristina Di Salvo and Paola Tuccimei
Water 2025, 17(10), 1555; https://doi.org/10.3390/w17101555 - 21 May 2025
Viewed by 595
Abstract
The interaction of the Almone River with groundwater in the Caffarella area (Rome, Italy) was investigated using a multi-method approach based on hydrogeological and radon analyses. Eleven measurement stations were established along the river at distances of approximately 270 m from one another. [...] Read more.
The interaction of the Almone River with groundwater in the Caffarella area (Rome, Italy) was investigated using a multi-method approach based on hydrogeological and radon analyses. Eleven measurement stations were established along the river at distances of approximately 270 m from one another. Stream discharge, water physicochemical properties, and radon levels were measured from June 2024 to March 2025. The contribution of two tributaries of the Almone was evaluated, but it was found to be negligible in terms of radon contribution. Except for an average increase of 40 L/s between stations 1A and 2A, the Almone’s discharge (corrected for the streams input) was constant (around 150 L/s) in June and slightly increasing from 6A to 11A in March due to heavier rainfalls. The increased discharge between stations 1A and 2A was interpreted as groundwater overflow from the volcanic aquifer into the alluvial body and in turn into the river due to a change in geometry and volume of the volcanic aquifer. In that part of the river, radon concentration increased only in March, due to the fast transition of the groundwater from a high to a lower radon emanation unit. Radon decreased along the valley due to atmospheric evasion, as confirmed by pH growth due to CO2 degassing. Full article
(This article belongs to the Special Issue Research on Hydrogeology and Hydrochemistry: Challenges and Prospects)
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17 pages, 35407 KiB  
Article
Crustal Structure of Hainan Island and Surrounding Seabed Based on High-Resolution Airborne Gravity
by Xiao Li, Xuanjie Zhang, Wan Zhang, Ruohan Wu, Yanyun Sun, Guotao Yao and Huaichun Wu
Appl. Sci. 2025, 15(10), 5564; https://doi.org/10.3390/app15105564 - 15 May 2025
Viewed by 615
Abstract
Hainan Island and its surrounding seabed are located at the intersection of the Eurasian, Indochina, and South China Sea tectonic plates with active Quaternary volcanism and intensive seismicity, such as the 7.6-magnitude earthquake that occurred in northern Hainan in 1605. Based on the [...] Read more.
Hainan Island and its surrounding seabed are located at the intersection of the Eurasian, Indochina, and South China Sea tectonic plates with active Quaternary volcanism and intensive seismicity, such as the 7.6-magnitude earthquake that occurred in northern Hainan in 1605. Based on the newest airborne gravity data of Hainan Island and its adjacent areas, this paper uses wavelet multiscale decomposition followed by power spectral analysis to estimate the average depth of each layer of the source field. We use the Parker–Oldenburg method to invert the Moho structure, incorporating constraints from seismic data to investigate the fine crustal structure and deformation characteristics to elucidate the deep seismogenic mechanism. The regional Moho depth decreases from 30 km in the northwest to 16 km in the southeast. The map of the Moho surface shows three Moho uplift zones, located in the northern Hainan Island, the southern Qiongdongnan Basin, and the southwestern tip of Hainan Island. The following findings are revealed: Firstly, a series of northeastward high-gravity anomaly strips are discovered for the first time in the middle and lower crust of Hainan Island, which may be the remnants within the continental crust of the ancient Pacific northwestward subduction during the Mesozoic era. Secondly, under the Leiqiong volcanic rocks, there is a pronounced northeastward high-value anomaly and shallower Moho depth, which may indicate the deep-seated mantle material that rose and intruded during the activity of the Hainan mantle plume. Thirdly, the seismogenic structure is discussed by combining the wavelet multiscale decomposition results with natural seismic data. The results show that earthquakes occur in the place where the NE-trending gravity anomaly is cut by the NW-trending fault in the upper crust. That place also lies in the gravity anomaly gradient or high-value anomaly in the middle and lower crust. These features reveal that the earthquakes on Hainan Island are controlled by the left strike-slip activity of the Red River Fault and deep mantle upwelling caused by Hainan Plume. Full article
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26 pages, 27571 KiB  
Article
Nutrient Fluxes from the Kamchatka and Penzhina Rivers and Their Impact on Coastal Ecosystems on Both Sides of the Kamchatka Peninsula
by Pavel Semkin, Galina Pavlova, Vyacheslav Lobanov, Kirill Baigubekov, Yuri Barabanshchikov, Sergey Gorin, Maria Shvetsova, Elena Shkirnikova, Olga Ulanova, Anna Ryumina, Ekaterina Lepskaya, Yuliya Fedorets, Yi Xu and Jing Zhang
J. Mar. Sci. Eng. 2025, 13(3), 569; https://doi.org/10.3390/jmse13030569 - 14 Mar 2025
Viewed by 916
Abstract
Catchment areas on volcanic territories in different regions are of great interest since they are enriched with nutrients that contribute significantly to coastal ecosystems. The Kamchatka Peninsula is one of the most active volcanic regions of the world; however, to date, the chemistry [...] Read more.
Catchment areas on volcanic territories in different regions are of great interest since they are enriched with nutrients that contribute significantly to coastal ecosystems. The Kamchatka Peninsula is one of the most active volcanic regions of the world; however, to date, the chemistry of its river waters and the state of its coastal ecosystems remain understudied in connection with volcanism. The two rivers under study are the largest in this region. The Kamchatka River, unlike the Penzhina River, drains volcanic territories, including the areas of the most active volcanoes of the Klyuchevskaya group of volcanoes and the Shiveluch Volcano. The mouth of the Kamchatka River has been shown to have DIP and DIN concentrations of 2.79–3.87 and 10.0–23.8 µM, respectively, during different seasons, which are comparable to rivers in urbanized areas with sewerage and agricultural sources of nutrients. It has been established that volcanoes form high concentrations of nutrients in the catchment area of the Kamchatka River. The Penzhina River has had very low DIP and DIN concentrations of 0.2–0.8 and 0.17–0.35 µM, respectively, near the mouth during different seasons, but high concentrations of DOC, at 5.9 mg/L in spring, which may be due to seasonal thawing of permafrost. During the period of increasing river discharge, seasonal phytoplankton blooms occur in spring and summer in bays of the same name, as shown using satellite data. The biomass of zooplankton in Penzhina Bay is at a level of 100 mg/L, while in Kamchatka Gulf, it exceeds 2000 mg/L. Thus, the biomass of zooplankton in the receiving basin, which is influenced by the runoff of the Kamchatka River with a volcanic catchment area in eastern Kamchatka, is 20 times higher than in the basin, which has a small nutrient flux with the river runoff in northwestern Kamchatka. This study demonstrates the connection between nutrient fluxes from a catchment area and the formation of seasonal phytoplankton blooms and high zooplankton biomass in the coastal area. We also study seasonal, year-to-year, and climatic variability of water discharges and hydrometeorological conditions to understand how nutrient fluxes can change in the foreseeable future and influence coastal ecosystems. Full article
(This article belongs to the Special Issue Coastal Water Quality Observation and Numerical Modeling)
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44 pages, 14026 KiB  
Review
Coastal Environments: LiDAR Mapping of Copper Tailings Impacts, Particle Retention of Copper, Leaching, and Toxicity
by W. Charles Kerfoot, Gary Swain, Robert Regis, Varsha K. Raman, Colin N. Brooks, Chris Cook and Molly Reif
Remote Sens. 2025, 17(5), 922; https://doi.org/10.3390/rs17050922 - 5 Mar 2025
Viewed by 1846
Abstract
Tailings generated by mining account for the largest world-wide waste from industrial activities. As an element, copper is relatively uncommon, with low concentrations in sediments and waters, yet is very elevated around mining operations. On the Keweenaw Peninsula of Michigan, USA, jutting out [...] Read more.
Tailings generated by mining account for the largest world-wide waste from industrial activities. As an element, copper is relatively uncommon, with low concentrations in sediments and waters, yet is very elevated around mining operations. On the Keweenaw Peninsula of Michigan, USA, jutting out into Lake Superior, 140 mines extracted native copper from the Portage Lake Volcanic Series, part of an intercontinental rift system. Between 1901 and 1932, two mills at Gay (Mohawk, Wolverine) sluiced 22.7 million metric tonnes (MMT) of copper-rich tailings (stamp sands) into Grand (Big) Traverse Bay. About 10 MMT formed a beach that has migrated 7 km from the original Gay pile to the Traverse River Seawall. Another 11 MMT are moving underwater along the coastal shelf, threatening Buffalo Reef, an important lake trout and whitefish breeding ground. Here we use remote sensing techniques to document geospatial environmental impacts and initial phases of remediation. Aerial photos, multiple ALS (crewed aeroplane) LiDAR/MSS surveys, and recent UAS (uncrewed aircraft system) overflights aid comprehensive mapping efforts. Because natural beach quartz and basalt stamp sands are silicates of similar size and density, percentage stamp sand determinations utilise microscopic procedures. Studies show that stamp sand beaches contrast greatly with natural sand beaches in physical, chemical, and biological characteristics. Dispersed stamp sand particles retain copper, and release toxic levels of dissolved concentrations. Moreover, copper leaching is elevated by exposure to high DOC and low pH waters, characteristic of riparian environments. Lab and field toxicity experiments, plus benthic sampling, all confirm serious impacts of tailings on aquatic organisms, supporting stamp sand removal. Not only should mining companies end coastal discharges, we advocate that they should adopt the UNEP “Global Tailings Management Standard for the Mining Industry”. Full article
(This article belongs to the Special Issue GIS and Remote Sensing in Ocean and Coastal Ecology)
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28 pages, 20776 KiB  
Article
Innovative Approaches to Geoscientific Outreach in the Napo Sumaco Aspiring UNESCO Global Geopark, Ecuadorian Amazon Region
by Samantha-Solange Salazar-Del-Pozo, Felipe Carlosama-Morejón, Karla Freire-Quintanilla, Henry Grefa-Shiguango and Marco Simbaña-Tasiguano
Geosciences 2025, 15(2), 43; https://doi.org/10.3390/geosciences15020043 - 29 Jan 2025
Viewed by 1651
Abstract
The Napo Sumaco Aspiring UNESCO Global Geopark (NSAUGG) in Ecuador represents a genuine variety of geological, cultural, and natural heritage, which aims to promote sustainable development through geotourism. This study describes the significance of NSAUGG, emphasizing its geological diversity which includes a variety [...] Read more.
The Napo Sumaco Aspiring UNESCO Global Geopark (NSAUGG) in Ecuador represents a genuine variety of geological, cultural, and natural heritage, which aims to promote sustainable development through geotourism. This study describes the significance of NSAUGG, emphasizing its geological diversity which includes a variety of geosites, and focusing on three recently annexed geosites: the Wawa Sumaco Quarry, Puka Urku, and the Pucuno River, where geological analyses, including petrographic and mineralogical assessments, were conducted. To enhance community engagement and educational outreach, a multi-platform mobile application, “SumAppGeo”, was developed using ArcGIS and Flutterflow. This application serves as an interactive tool for visitors and local communities, providing detailed geological information, interactive maps, and educational content. The findings reveal the presence of significant geological features, such as haüyne-bearing alkaline rocks, which indicate specific volcanic activity in this region and are an element of geodiversity, validating the Wawa Sumaco Quarry, Puka Urku, and the Pucuno River as geosites. The implementation of SumAppGeo aims to foster a deeper understanding of the region’s geodiversity while promoting responsible tourism practices. This initiative not only supports the recognition of NSAUGG as part of the UNESCO Global Geoparks Network but also contributes to the socio-economic development of local communities through sustainable tourism practices. Full article
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21 pages, 8154 KiB  
Article
Bedrock Origins from Petrology and Geochemistry: Volcanic Gravel Clasts from the Rawhide Terrace in the Pleistocene Ancestral Mississippi River Pre-Loess Terrace Deposits
by Maxwell G. Pizarro, Jennifer N. Gifford, James E. Starnes and Brian F. Platt
Geosciences 2024, 14(12), 340; https://doi.org/10.3390/geosciences14120340 - 10 Dec 2024
Viewed by 1927
Abstract
Situated throughout the southeastern United States within the Laurentian craton are occurrences of various aged deposits (Late Proterozoic to Early Paleogene) that contain volcanics spanning from lamprophyres to carbonatites and basalts to rhyolites. Several are intrusive, while others have been reworked detritally, deposited [...] Read more.
Situated throughout the southeastern United States within the Laurentian craton are occurrences of various aged deposits (Late Proterozoic to Early Paleogene) that contain volcanics spanning from lamprophyres to carbonatites and basalts to rhyolites. Several are intrusive, while others have been reworked detritally, deposited as river gravels out onto the Gulf Coastal Plain. The earliest occurrence of igneous gravel clasts in the coastal plain of the lower Mississippi Valley lie along the Mississippi River’s eastern valley wall in the ancestral Mississippi River’s pre-loess terrace deposits (PLTDs). The coarse clastics of the PLTDs are dominantly chert gravels derived from Paleozoic carbonate bedrock, but also include clasts of Precambrian Sioux Quartzite, glacially faceted and striated stones, and ice-rafted boulders, which indicate a direct relationship between the PLTDs and glacial outwash during the cyclic glaciation of the Pleistocene Epoch. The PLTDs also contain the oldest known examples of igneous gravels exposed at the surface in Mississippi. An understanding of their igneous bedrock provenance and the timing of their contribution to the sedimentary record of the lower Mississippi River Valley sheds a valuable light onto the geologic history and evolution of the ancestral Mississippi River during the Pleistocene Epoch. The use of fusion inductively coupled plasma mass-spectroscopy (ICP-MS) in the identification of the igneous suites of one of the pre-loess terraces, well-delineated by geologic mapping, adds important geochemical source data from the gravel constituents for the further interpretation and correlation of the individual PLTD allounits. Gravel constituent geochemistry also offers a better understanding of the evolution of the ancestral Mississippi River watershed and the contributions of bedrock sources during Pleistocene glaciation. This petrological study suggests that the igneous gravels sampled from within the Rawhide PLTD allounit originated from the St. Francois Mountains (SFMs) in southwestern Missouri, with the implications that the SFM igneous terrain was in the direct path of the Independence “Kansan” glaciation. This could indicate a glacial extent further southwest than previously documented. Full article
(This article belongs to the Section Geochemistry)
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12 pages, 1823 KiB  
Article
The Study of Nitrogen and Phosphorus Removal Efficiency in Urbanized River Systems Using Artificial Wetland Systems with Different Substrates
by Ran Chi, Zhongqing Wei, Longcong Gong, Guosheng Zhang, Duo Wen and Weiying Li
Water 2024, 16(22), 3309; https://doi.org/10.3390/w16223309 - 18 Nov 2024
Cited by 1 | Viewed by 1515
Abstract
This study evaluated the effectiveness of five commercial substrates (zeolite, volcanic rock, gravel, magic rack, and ceramic pellets) in removing nitrogen (N) and phosphorus (P) from urban river systems using constructed wetlands. By employing X-ray CT and NGS technologies, we analyzed the physical [...] Read more.
This study evaluated the effectiveness of five commercial substrates (zeolite, volcanic rock, gravel, magic rack, and ceramic pellets) in removing nitrogen (N) and phosphorus (P) from urban river systems using constructed wetlands. By employing X-ray CT and NGS technologies, we analyzed the physical structure of the substrates and the microbial communities they harbor. The results indicated that volcanic rock and ceramic pellets, due to their high porosity and specific surface area, performed exceptionally well in nitrogen and phosphorus removal. Specifically, the microbial systems with these two substrates achieved ammonia nitrogen removal rates of 89.86% and 88.45%, total nitrogen removal rates of 78.78% and 74.97%, and total phosphorus removal rates of 92.67% and 80.82%, respectively, within a 7-day period. Furthermore, the microbial communities on volcanic rock and ceramic pellets were more diverse, which correlated with their high pollutant removal efficiency. The study further elucidated the synergistic role of substrate characteristics and microbial community structure and function in nitrogen and phosphorus removal, enhancing the understanding of the purification mechanisms in constructed wetlands. These findings provide a scientific basis for the ecological restoration of urban rivers and are significant for improving the quality of urban water environments. Full article
(This article belongs to the Special Issue Microbial Characteristics of Drinking Water)
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18 pages, 7145 KiB  
Review
Evolution of Auriferous Fluids in the Kraaipan-Amalia Greenstone Belts: Evidence from Mineralogical and Isotopic Constraints
by Kofi Adomako-Ansah, Napoleon Q. Hammond, Yuichi Morishita and Daizo Ishiyama
Minerals 2024, 14(11), 1171; https://doi.org/10.3390/min14111171 - 18 Nov 2024
Viewed by 1266
Abstract
The Kraaipan and Amalia greenstone belts in South Africa occur in the western part of the Kaapvaal Craton. The two belts stretch discontinuously in an approximately north–south orientation over a distance of about 250 km from southern Botswana in the north to the [...] Read more.
The Kraaipan and Amalia greenstone belts in South Africa occur in the western part of the Kaapvaal Craton. The two belts stretch discontinuously in an approximately north–south orientation over a distance of about 250 km from southern Botswana in the north to the Vaal River near Christiana in the south and are separated by a distance of about 90 km. Gold mineralization is hosted in banded iron formation at both the Kalahari Goldridge deposit (Kalgold) in the Kraaipan greenstone belt in the north and the Amalia deposit in the Amalia greenstone belt in the south, with the mineralization associated with quartz–carbonate veins. The footwalls of these deposits are generally composed of mafic volcanic schist and the hanging walls consisting of graywackes, schist and shale units. The Kalgold and Amalia gold deposits show some variation in the redox condition of the mineralizing system and fluid chemistry. The ore mineral assemblage is characterized by magnetite–pyrrhotite–pyrite at Kalgold, which is indicative of reducing conditions, and a magnetite–hematite–pyrite assemblage at Amalia that suggests a relatively oxidizing environment. Average mineralizing temperatures determined from chlorite geothermometry were relatively higher at the Kalahari Goldridge deposit ranging from 350 to 400 °C compared to the slightly cooler range of 330 to 390 °C at Amalia. The composition of the fluids derived from fluid inclusions is indicative of low salinity H2O--CO2±CH4-rich fluids at Kalgold against relatively H2O-CO2-rich fluids at Amalia. Evidence from strontium–carbon–oxygen isotopic ratios from carbonates suggests that differences in redox conditions in the deposits could be attributed to different flow pathways by an evolving fluid from a common source (with minimum 87Sr/86Sr = 0.70354) to the sites of gold deposition, with a significant ore fluid interaction with a thick sequence of carbonaceous meta-pelitic rock units at the Kalahari Goldridge deposit that is absent in the Amalia deposit. Full article
(This article belongs to the Special Issue Geochemistry and Genesis of Hydrothermal Ore Deposits)
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16 pages, 2724 KiB  
Article
A Simple Neural Network for Estimating Fine Sediment Sources Using XRF and XRD
by Selline Mutiso, Keisuke Nakayama and Katsuaki Komai
Hydrology 2024, 11(11), 192; https://doi.org/10.3390/hydrology11110192 - 12 Nov 2024
Cited by 1 | Viewed by 1600
Abstract
Suspended sediment (SS) has a wide range of negative effects such as increased water turbidity, altered habitat structures, sedimentation, and effects on hydraulic systems and environmental engineering projects. Nevertheless, the methods for accurately determining SS sources on a basin-scale are poorly understood. Herein, [...] Read more.
Suspended sediment (SS) has a wide range of negative effects such as increased water turbidity, altered habitat structures, sedimentation, and effects on hydraulic systems and environmental engineering projects. Nevertheless, the methods for accurately determining SS sources on a basin-scale are poorly understood. Herein, we used a simplified neural network analysis (NNA) model to identify the sources of SS in Japan’s Oromushi River Catchment Basin. Fine soil samples were collected from different locations of the catchment basin, processed, and separately analysed using X-ray fluorescence (XRF) and X-ray diffraction (XRD). The sampling stations were grouped according to the type of soil cover, vegetation type and land-use pattern. The geochemical components of each group were fed into the same neural network layer, and a series of equations were applied to estimate the sediment contribution from each group to the downstream side of the river. Samples from the same sampling locations were also analysed by XRD, and the obtained peak intensity values were used as the input in the NNA model. SS mainly originated from agricultural fields, with regions where the ground is covered with volcanic ash identified as the key sources through XRF and XRD analysis, respectively. Therefore, based on the nature of the surface soil cover and the land use pattern in the catchment basin, NNA was found to be a reliable data analytical technique. Moreover, XRD analysis does not incorporate carbon, and also provides detailed information on crystalline phases. The results obtained in this study, therefore, do not depend on seasonal uncertainty due to organic matter. Full article
(This article belongs to the Section Ecohydrology)
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20 pages, 5031 KiB  
Article
Rapid India–Asia Initial Collision Between 50 and 48 Ma Along the Western Margin of the Indian Plate: Detrital Zircon Provenance Evidence
by Muhammad Qasim, Junaid Ashraf, Lin Ding, Javed Iqbal Tanoli, Fulong Cai, Iftikhar Ahmed Abbasi and Saif-Ur-Rehman Khan Jadoon
Geosciences 2024, 14(11), 289; https://doi.org/10.3390/geosciences14110289 - 29 Oct 2024
Cited by 1 | Viewed by 2303
Abstract
Constraining the collision timing of India and Asia requires reliable information from the coeval geological record along the ~2400 km long collisional margin. This study provides insights into the India–Asia collision at the westernmost margin of the Indian Plate using combined U-Pb geochronological [...] Read more.
Constraining the collision timing of India and Asia requires reliable information from the coeval geological record along the ~2400 km long collisional margin. This study provides insights into the India–Asia collision at the westernmost margin of the Indian Plate using combined U-Pb geochronological data and sandstone petrography. The study area is situated in the vicinity of Fort Munro, Pakistan, along the western margin of the Indian Plate, and consists of the Paleocene Dunghan Formation and Eocene Ghazij Formation. The U-Pb ages of detrital zircons from the Dunghan Formation are mainly clustered between ~453 and 1100 Ma with a second minor cluster between ~1600 and 2600 Ma. These ages suggest that the major source contributing to the Dunghan Formation was likely derived from basement rocks and the cover sequence exposed mainly in Tethyan Himalaya (TH), Lesser Himalaya (LH), and Higher Himalayan (HH). Petrographic results suggest that the quartz-rich samples from the Dunghan Formation are mineralogically mature and have likely experienced log-distance transportation, which is possible in the case of an already established and well-developed river system delivering the sediments from the Craton Interior provenance. Samples of the overlying Ghazij Formation show a major detrital zircon age clustered at ~272–600 Ma in the lower part of the formation, comparable to the TH. In the middle part, the major cluster is at ~400–1100 Ma, and a minor cluster at ~1600–2600 Ma similar to the age patterns of TH, LH, and HH. However, in the uppermost part of the Ghazij Formation, ages of <100 Ma are recorded along with 110–166 Ma, ~400–1100 Ma, and ~1600–2600 Ma clusters. The <100 Ma ages were mainly attributed to the northern source, which was the Kohistan-Ladakh arc (KLA). The ~110–166 Ma ages are possibly associated with the TH volcanic rocks, ophiolitic source, and Karakoram block (KB). The Paleozoic to Archean-aged zircons in the Ghazij Formation represent an Indian source. This contrasting provenance shift from India to Asia is also reflected in the sandstone petrography, where the sample KZ-09 is plotted in a dissected arc field. By combining the U-Pb ages of the detrital zircons with sandstone petrography, we attribute this provenance change to the Asia–India collision that caused the provenance shift from the southern (Indian Craton) provenance to the northern (KLA and KB) provenance. In view of the upper age limit of the Ghazij Formation, we suggest the onset of Asian–Indian collision along its western part occurred at ca. 50–48 Ma, which is younger than the collision ages reported from central and northwestern segments of the Indian plate margin with 70–59 Ma and 56 Ma, respectively. Full article
(This article belongs to the Special Issue Zircon U-Pb Geochronology Applied to Tectonics and Ore Deposits)
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47 pages, 3839 KiB  
Article
Global Historical Megatsunamis Catalog (GHMCat)
by Mercedes Ferrer and Luis I. González-de-Vallejo
GeoHazards 2024, 5(3), 971-1017; https://doi.org/10.3390/geohazards5030048 - 23 Sep 2024
Cited by 1 | Viewed by 5957
Abstract
The Global Historical Megatsunamis Catalog (GHMCat) is presented for the first time, including events with the largest waves recorded in historical times. An objective criterion is established to identify megatsunamis based on the maximum wave height (runup) of all recorded events. A threshold [...] Read more.
The Global Historical Megatsunamis Catalog (GHMCat) is presented for the first time, including events with the largest waves recorded in historical times. An objective criterion is established to identify megatsunamis based on the maximum wave height (runup) of all recorded events. A threshold value of 35 m for maximum wave height is proposed based on the analysis of the statistical distribution of the maximum wave heights documented. The catalog was compiled through a systematic review and verification of tsunami events from the two existing Global Historical Tsunami Databases (GHTDs). A list of 40 megatsunamis from 1674 to the present is presented, including descriptions of their maximum wave heights, causes and sources according to the available and verified information, along with the main bibliographical references that support the data gathered in the catalog. The majority of megatsunamis have originated from large landslides, predominantly subaerial, with fewer caused by submarine landslides or associated with volcanic explosions. The geographical distribution of source locations shows that megatsunamis most frequently occur in bays and fjords in glaciated areas and in inland bodies of water, such as lakes and rivers. Notably, certain regions of Alaska and Norway experienced an unusual frequency of megatsunamis, particularly in the early 20th century. The information provided by the GHMCat allows for a comprehensive historical overview of megatsunamis, establishing relationships between their causes, wave heights, and geographic distribution over the past 350 years. This may contribute to advancing the study of the causes and origins of megatsunamis and aid in their prevention in high-risk regions. Full article
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