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Keywords = sediment depletion

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24 pages, 9491 KiB  
Article
Provenance of the Upper Permian Longtan Formation in Southern Anhui Province in the Lower Yangtze Region, China: Insights from Sedimentary and Geochemical Characteristics
by Sizhe Deng, Dujie Hou and Wenli Ma
Minerals 2025, 15(8), 831; https://doi.org/10.3390/min15080831 (registering DOI) - 5 Aug 2025
Abstract
There are many controversies over the material sources of the Late Paleozoic strata in the Lower Yangtze region, and there is a lack of consensus on the basin source–sink system, which hinders the reconstruction of Late Paleozoic paleogeography and exploration of energy and [...] Read more.
There are many controversies over the material sources of the Late Paleozoic strata in the Lower Yangtze region, and there is a lack of consensus on the basin source–sink system, which hinders the reconstruction of Late Paleozoic paleogeography and exploration of energy and mineral resources in the area. This study aimed to clarify the sedimentary provenance and tectonic background of the Upper Permian Longtan Formation in the Chizhou area of southern Anhui Province. The key objectives were to: (i) analyze the geochemical characteristics of sandstones using major, trace, and rare earth elements; (ii) determine the tectonic setting of the sediment source region based on discrimination diagrams; and (iii) integrate geochemical, sedimentological, and paleocurrent data to reconstruct the source-to-sink system. The geochemical data suggest that the sandstone samples exhibit relatively high SiO2, Fe2O3, MgO, and Na2O content and relatively low TiO2, Al2O3, and K2O content, consistent with average values of post-Archean Australian shale (PAAS) and the upper continental crust (UCC). The chondrite-normalized rare earth element patterns resemble PAAS, with enrichment in light REEs and depletion in heavy REEs. Tectonic discrimination diagrams indicate a provenance from active continental margins and continental island arcs, with minor input from passive continental margins. Combined with regional tectonic context and paleocurrent measurements, the results suggest that the Longtan Formation sediments primarily originated from the Neoproterozoic Jiangnan orogenic belt and the Cathaysia Block, notably the Wuyi terrane. These research results not only provide new geological data for further clarifying the provenance of Late Paleozoic sedimentary basins in the Lower Yangtze region but also establish the foundation for constructing the Late Paleozoic tectonic paleogeographic pattern in South China. Full article
(This article belongs to the Special Issue Selected Papers from the 7th National Youth Geological Congress)
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22 pages, 7156 KiB  
Communication
Water Management, Environmental Challenges, and Rehabilitation Strategies in the Khyargas Lake–Zavkhan River Basin, Western Mongolia: A Case Study of Ereen Lake
by Tseren Ochir Soyol-Erdene, Ganbat Munguntsetseg, Zambuu Burmaa, Ulziibat Bilguun, Shagijav Oyungerel, Soninkhishig Nergui, Nyam-Osor Nandintsetseg, Michael Walther and Ulrich Kamp
Geographies 2025, 5(3), 38; https://doi.org/10.3390/geographies5030038 - 1 Aug 2025
Viewed by 368
Abstract
The depletion of water resources caused by climate change and human activities is a pressing global issue. Lake Ereen is one of the ten natural landmarks of the Gobi-Altai of western Mongolia is included in the list of “important areas for birds” recognized [...] Read more.
The depletion of water resources caused by climate change and human activities is a pressing global issue. Lake Ereen is one of the ten natural landmarks of the Gobi-Altai of western Mongolia is included in the list of “important areas for birds” recognized by the international organization Birdlife. However, the construction of the Taishir Hydroelectric Power Station, aimed at supplying electricity to the western provinces of Mongolia, had a detrimental effect on the flow of the Zavkhan River, resulting in a drying-up and pollution of Lake Ereen, which relies on the river as its water source. This study assesses the pollution levels in Ereen Lake and determines the feasibility of its rehabilitation by redirecting the flow of the Zavkhan River. Field studies included the analysis of water quality, sediment contamination, and the composition of flora. The results show that the concentrations of ammonium, chlorine, fluorine, and sulfate in the lake water exceed the permissible levels set by the Mongolian standard. Analyses of elements from sediments revealed elevated levels of arsenic, chromium, and copper, exceeding international sediment quality guidelines and posing risks to biological organisms. Furthermore, several species of diatoms indicative of polluted water were discovered. Lake Ereen is currently in a eutrophic state and, based on a water quality index (WQI) of 49.4, also in a “polluted” state. Mass balance calculations and box model analysis determined the period of pollutant replacement for two restoration options: drying-up and complete removal of contaminated sediments and plants vs. dilution-flushing without direct interventions in the lake. We recommend the latter being the most efficient, eco-friendly, and cost-effective approach to rehabilitate Lake Ereen. Full article
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26 pages, 12136 KiB  
Article
Integrated Analysis of Satellite and Geological Data to Characterize Ground Deformation in the Area of Bologna (Northern Italy) Using a Cluster Analysis-Based Approach
by Alberto Manuel Garcia Navarro, Celine Eid, Vera Rocca, Christoforos Benetatos, Claudio De Luca, Giovanni Onorato and Riccardo Lanari
Remote Sens. 2025, 17(15), 2645; https://doi.org/10.3390/rs17152645 - 30 Jul 2025
Viewed by 260
Abstract
This study investigates ground deformations in the southeastern Po Plain (northern Italy), focusing on the Bologna area—a densely populated region affected by natural and anthropogenic subsidence. Ground deformations in the area result from geological processes (e.g., sediment compaction and tectonic activity) and human [...] Read more.
This study investigates ground deformations in the southeastern Po Plain (northern Italy), focusing on the Bologna area—a densely populated region affected by natural and anthropogenic subsidence. Ground deformations in the area result from geological processes (e.g., sediment compaction and tectonic activity) and human activities (e.g., ground water production and underground gas storage—UGS). We apply a multidisciplinary approach integrating subsurface geology, ground water production, advanced differential interferometry synthetic aperture radar—DInSAR, gas storage data, and land use information to characterize and analyze the spatial and temporal variations in vertical ground deformations. Seasonal and trend decomposition using loess (STL) and cluster analysis techniques are applied to historical DInSAR vertical time series, targeting three representatives areas close to the city of Bologna. The main contribution of the study is the attempt to correlate the lateral extension of ground water bodies with seasonal ground deformations and water production data; the results are validated via knowledge of the geological characteristics of the uppermost part of the Po Plain area. Distinct seasonal patterns are identified and correlated with ground water production withdrawal and UGS operations. The results highlight the influence of superficial aquifer characteristics—particularly the geometry, lateral extent, and hydraulic properties of sedimentary bodies—on the ground movements behavior. This case study outlines an effective multidisciplinary approach for subsidence characterization providing critical insights for risk assessment and mitigation strategies, relevant for the future development of CO2 and hydrogen storage in depleted reservoirs and saline aquifers. Full article
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24 pages, 4663 KiB  
Article
Neoproterozoic Subduction Zone Fluids and Sediment Melt-Metasomatized Mantle Magmatism on the Northern Yangtze Block: Constraints from the Ca. 880 Ma Taoyuan Syenogranite
by Shilei Liu, Yiduo Li, Han Liu, Peng Wang, Shizhen Zhang and Fenglin Chen
Minerals 2025, 15(7), 730; https://doi.org/10.3390/min15070730 - 12 Jul 2025
Viewed by 191
Abstract
The Yangtze Block, with its widespread Neoproterozoic mafic–felsic magmatic rock series and volcanic–sedimentary rock assemblages, is one of the key windows for reconstructing the assembly and fragmentation process of Rodinia. This study focuses on the Taoyuan syenogranite from the Micangshan Massif on the [...] Read more.
The Yangtze Block, with its widespread Neoproterozoic mafic–felsic magmatic rock series and volcanic–sedimentary rock assemblages, is one of the key windows for reconstructing the assembly and fragmentation process of Rodinia. This study focuses on the Taoyuan syenogranite from the Micangshan Massif on the northern Yangtze Block, by conducting systematic chronology, mineralogy, and geochemistry analyses to investigate their source, petrogenesis, and tectonic setting. LA-ICP-MS U–Pb geochronology reveals that the medium- to coarse-grained and medium- to fine-grained syenogranites have crystallization ages of 878 ± 4.2 Ma and 880 ± 6.5 Ma, respectively. These syenogranites have aluminum saturation index (A/CNK) values ranging from 0.79 to 1.06, indicating quasi-aluminous to weakly peraluminous compositions, and are classified as calc-alkaline I-type granites. The geochemical indicators of these rocks, including Mg# (44–48, mean 46), Zr/Hf (40.07), Nb/La (0.4), and zircon εHf(t) values (+9.2 to +10.9), collectively indicate a depleted lithospheric mantle source. The mantle source was metasomatized by subduction-derived fluids and sediment melts prior to partial melting as evidenced by their higher Mg#, elevated Ba content, and distinctive ratios (Rb/Y, Nb/Y, Th/Yb, Th/Sm, Th/Ce, and Ba/La). Integrating regional data, this study confirms crust–mantle interaction along the northern Yangtze during the early Neoproterozoic, supporting a sustained subduction-related tectonic setting. Full article
(This article belongs to the Special Issue Selected Papers from the 7th National Youth Geological Congress)
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30 pages, 20045 KiB  
Article
Mineralogy and Geochemistry of Early Triassic Granite in South China: Insights into Source Region Characteristics and REE Mineralization
by Liya Yang, Yongfeng Cai, Jieting Ouyang, Fang Xu, Yankun Chen and Yun Zhou
Minerals 2025, 15(5), 530; https://doi.org/10.3390/min15050530 - 16 May 2025
Viewed by 409
Abstract
Regolith-hosted rare-earth element (REE) deposits are some of the most important types of REE deposits. The relationship between Late Paleozoic and Early Mesozoic granite and regolith-hosted REE deposits is still poorly studied. Detailed geochronology, geochemistry, and rare-earth mineralogy analyses of Early Triassic granite [...] Read more.
Regolith-hosted rare-earth element (REE) deposits are some of the most important types of REE deposits. The relationship between Late Paleozoic and Early Mesozoic granite and regolith-hosted REE deposits is still poorly studied. Detailed geochronology, geochemistry, and rare-earth mineralogy analyses of Early Triassic granite in the South China Block were conducted. The geochronological results showed that four representative granite samples yielded formation ages of 245 ± 1 Ma, 244 ± 1 Ma, 244 ± 1 Ma, and 244 ± 2 Ma, respectively. The granites show geochemical affinity to A-type granite. They are characterized by enrichment in Rb, Th, and U, are depleted in Ba, Sr, P, and Ti, and show obvious negative Nb and Ta anomalies. They have high light rare-earth element (LREE) and low heavy rare-earth element (HREE) contents, with obvious negative Eu anomalies. They were derived from the partial melting of a sediment source and underwent intense fractional crystallization during the magma evolution process. They contain a certain number of rare-earth-element-bearing minerals, such as monazite, xenotime, apatite, and zircon. Their REE compositions and mineral associations are similar to those of the parent rocks from typical regolith-hosted REE deposits in South China. The highly weathered horizon at the ridge of the granite weathering crust profile has the highest REE content. A comprehensive analysis indicated that the degree of magma evolution, geomorphology, and weathering are important factors controlling the formation of regolith-hosted REE deposits in the area. Full article
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28 pages, 10258 KiB  
Article
Microfluidic Chip for Quantitatively Assessing Hemorheological Parameters
by Yang Jun Kang
Micromachines 2025, 16(5), 567; https://doi.org/10.3390/mi16050567 - 8 May 2025
Viewed by 765
Abstract
The biomechanical properties of blood are regarded as promising biomarkers for monitoring early-stage abnormalities and disease progression. To detect any changes in blood, it is necessary to measure as many rheological properties as possible. Herein, a novel method is proposed for measuring multiple [...] Read more.
The biomechanical properties of blood are regarded as promising biomarkers for monitoring early-stage abnormalities and disease progression. To detect any changes in blood, it is necessary to measure as many rheological properties as possible. Herein, a novel method is proposed for measuring multiple rheological properties of blood using a microfluidic chip. The syringe pump turns off for 5 min to induce RBC (red blood cell) sedimentation in the driving syringe. RBC aggregation is determined by analyzing the time-lapse blood image intensity at stasis: I(t) = I1 exp (−k1t) + I2 exp (−k2t). RBC-rich blood and RBC-depleted blood are sequentially infused into the microfluidic chip. Based on blood pressure estimated with time-lapse blood velocity, blood viscosity is acquired with the Hagen–Poiseuille law. RBC sedimentation is quantified as RBC sedimentation distance (Xesr) and erythrocyte sedimentation rate (ESR). The proposed method provides a consistent viscosity compared with previous methods. Two of the four variables (I1, I2) exhibited a strong correlation with the conventional RBC aggregation index (AI). The indices Xesr and ESR showed consistent trends with respect to the blood medium and hematocrit. In conclusion, the proposed method is then regarded as effective for monitoring multiple rheological properties. Full article
(This article belongs to the Special Issue Microfluidic Chips for Biomedical Applications)
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21 pages, 15542 KiB  
Article
Postagrogenic Dynamics of Different-Aged Soils of Northwest Russia
by Vyacheslav Polyakov, Timur Nizamutdinov, Igor Popov, Egor Artyukhov and Evgeny Abakumov
Agronomy 2025, 15(5), 1141; https://doi.org/10.3390/agronomy15051141 - 7 May 2025
Viewed by 523
Abstract
The postagrogenic transformation of landscapes is one of the key problems leading to a decrease in soil fertility in the territory of Northwest Russia. In order to assess the degree of land degradation, field studies of soils from fallow lands in the Leningrad [...] Read more.
The postagrogenic transformation of landscapes is one of the key problems leading to a decrease in soil fertility in the territory of Northwest Russia. In order to assess the degree of land degradation, field studies of soils from fallow lands in the Leningrad Region were carried out. Different evolutionary trends of ontogenesis of soils with types of soil parent materials were revealed. At morphological and micromorphological levels, degradation processes of old-arable horizons were noted, including secondary podzolization and decreasing Ap horizon thickness. Using a CHN analyzer, the stock levels of soil organic carbon and nitrogen of the studied chronoseries were estimated. The data obtained show that the carbon stocks of old-arable soils are lower than the benchmark ones due to the weak development of the Oi horizon. Carbon dynamics varied substantially by parent materials: soils on silt–clay materials showed a low 7.1% carbon decrease, while soils on sandy and bottom sediments increased by 139% and 163%, respectively, in old-arable horizons by the accumulation of coarse forms of carbon. For nitrogen, it was revealed that the highest stocks are observed in old-ploughed soils, which is due to the input of a large amount of plant residues from small-leaved forests. The content of biogenic elements in the soil showed separate evolutionary direction depending on parent materials: soils on silt–clay materials showed 7.6% phosphorus depletion and 15% potassium loss over 15–30 years, while soils on sandy materials demonstrated 18% phosphorus loss and 114% potassium increase during 30–86 years of fallow state. On the contrary, the content of nitrate and ammonium forms of nitrogen was higher than in the benchmark zonal soils, with nitrate nitrogen increasing by 150 times on sandy parent materials and ammonium nitrogen increasing by 102% in soils formed on bottom sediments over 35–70 years, which is due to the transformation of grass and forest plant residues. The duration of transformation and regradation of soils of fallow land depends on geogenic and bioclimatic conditions that determine the direction and speed of changes. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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17 pages, 16149 KiB  
Article
Source, Transport, and Fractionation of Rare Earth Elements in Fluvial Sediments from a Typical Small Urban Basin (East Tiaoxi River, Eastern China)
by Kunhua Yang, Qian Zhang, Bei Wang, Bin Liang, Qiang Lin and Weijiao Wang
Water 2025, 17(9), 1279; https://doi.org/10.3390/w17091279 - 25 Apr 2025
Viewed by 563
Abstract
As emerging contaminants, rare earth elements (REEs) have undergone significant anthropogenic enrichment in aquatic systems. This study investigates the REE concentrations, major metal elements, and grain size in surface sediments from the East Tiaoxi (ETX) River in eastern China, a small urban river [...] Read more.
As emerging contaminants, rare earth elements (REEs) have undergone significant anthropogenic enrichment in aquatic systems. This study investigates the REE concentrations, major metal elements, and grain size in surface sediments from the East Tiaoxi (ETX) River in eastern China, a small urban river subjected to substantial anthropogenic influences. Total REE concentrations of surface sediments ranged from 133.62 to 222.92 mg/kg with MREE enrichment and HREE depletion. REE concentration and fractionation were strongly correlated with Ca, Fe, Mg, and Mn, which may reflect the control of clay minerals, Fe-Mn oxides, and specific heavy minerals, and differences in REE behavior between riparian sediments and riverbed sediments highlighted the impact of hydrodynamic sorting and chemical weathering on REE distribution. Anthropogenic activities, particularly urbanization, were found to increase REE concentrations, especially at urban-adjacent sites (e.g., RBS2 and RS2), while natural processes such as soil transport and chemical weathering primarily contributed to REE variation at other sites. The enrichment factor and ecological risk assessment revealed that the enrichment and moderate risks associated with REEs occurred in river sediments adjacent to urbanized areas, though agricultural impacts were less pronounced. The findings emphasize the combined influence of urbanization and natural processes on REE distribution and ecological risks in the ETX River basin and underscore the need to prioritize urban-derived REE contamination in environmental management strategies. Full article
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19 pages, 8968 KiB  
Article
Role of Hungry Water on Sediment Dynamics: Assessment of Valley Degradation, Bed Material Changes and Flood Inundation in Pamba River During Kerala Flood, 2018
by Sreelash Krishnan Kutty, Padmalal Damodaran, Jeenu Mathai, Micky Mathew, Asha Rani, Rajat Kumar Sharma and Maya Kesavan
Hydrology 2025, 12(4), 79; https://doi.org/10.3390/hydrology12040079 - 1 Apr 2025
Viewed by 759
Abstract
Flood frequencies, along with the associated loss of life and property, have risen significantly due to climate change and increasing human activities. While prior research has primarily focused on high-intensity rainfall events and reservoir management in flood management, the influence of sediment-starved water—termed [...] Read more.
Flood frequencies, along with the associated loss of life and property, have risen significantly due to climate change and increasing human activities. While prior research has primarily focused on high-intensity rainfall events and reservoir management in flood management, the influence of sediment-starved water—termed “hungry water”—released from dams in controlling flood dynamics has not gained much attention. The present study is aimed at exploring the potential role of sediment-starved water, or the “hungry water effect” on the valley degradation, bed material changes and flood inundation in the Pamba River during the Kerala Flood, 2018, through a detailed characterization of bed materials and their deposition in the channel bed. The release of sediment-starved water from the Kakki reservoir during the episodic precipitation event (15 to 17 August 2018) resulted in significant bed degradation and scouring of the valley slopes, leading to the deposition of large boulders and rock masses and the inundating of approximately 196 km2 of floodplains. This study highlights the need for integrated sediment management strategies in reservoir operations by providing essential insights into sediment transport dynamics during extreme weather events. Understanding these processes is crucial for formulating effective flood mitigation strategies and improving the resilience of riverine ecosystems, particularly as the interaction between intense rainfall and sediment-depleted releases significantly exacerbated the flood’s severity. Full article
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18 pages, 3086 KiB  
Article
Earth Fissures During Groundwater Depletion and Recovery: A Case Study at Shitangwan, Wuxi, Jiangsu, China
by Guang-Ya Wang, Jin-Qi Zhu, Greg G. You, Dan Zhang, Jun Yu, Fu-Gang Gou and Jian-Qiang Wu
Hydrology 2025, 12(3), 62; https://doi.org/10.3390/hydrology12030062 - 19 Mar 2025
Viewed by 582
Abstract
The Shitangwan earth fissure is a resultant geological hazard due to prolonged groundwater depletion and land subsidence in Wuxi, China, since the 1980s. Initially observed in 1991, the earth fissure experienced continuous development over the next several decades. Employing a diverse array of [...] Read more.
The Shitangwan earth fissure is a resultant geological hazard due to prolonged groundwater depletion and land subsidence in Wuxi, China, since the 1980s. Initially observed in 1991, the earth fissure experienced continuous development over the next several decades. Employing a diverse array of techniques, including field monitoring via multilayered borehole extensometers, earth fissure monitoring for lateral and vertical movements, advanced geophysical exploration, and conventional geological investigations, this study aims to mitigate the risks associated with land subsidence and earth fissures. It is found that the groundwater has recovered to the levels in the 1980s, land subsidence and earth fissuring have ceased, and the earth fissuring is closely linked to the land subsidence. A bedrock ridge and a river course are underlying porous Quaternary sediments beneath the earth fissure. The formation of the earth fissure is the result of a combination of factors, including spatial and temporal variations in strata compression, rugged bedrock terrain, and the heterogeneity of the strata profile. Land subsidence is primarily attributed to the deep pumping aquifer and its adjacent aquitards, which are responsive to groundwater recovery with a time lag of a decade, and the land rebound accounts for 2% of the accumulated land subsidence. Estimations suggest that the depth of the earth fissure may have reached the bedrock ridge. The mechanism of the earth fissuring is the coupled effect of tension from the rotation of shallow soil strata along the bedrock ridge and shearing of strata driven by the differential compression of deep strata below the ridge level. Full article
(This article belongs to the Section Soil and Hydrology)
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24 pages, 15411 KiB  
Article
A Comprehensive Study of the Spatial Variations in the Distribution of Rare Earth Elements (REE) and Their Potential in the Coals of the Shubarkol Deposit, Kazakhstan
by Gulim Blyalova, Altynay Amangeldykyzy, Aiman Kopobayeva, Valentin Zhirkov and Stanislav Ryzhkov
Minerals 2025, 15(2), 170; https://doi.org/10.3390/min15020170 - 12 Feb 2025
Viewed by 848
Abstract
Due to the gradual depletion of traditional metallic mineral resources, the search for new potential sources is an important issue. One such source is coal deposits. The extraction of metals from coal is a way to produce clean energy. This study presents the [...] Read more.
Due to the gradual depletion of traditional metallic mineral resources, the search for new potential sources is an important issue. One such source is coal deposits. The extraction of metals from coal is a way to produce clean energy. This study presents the results of detailed research on geochemical features and mineralogy to understand the processes of microelement enrichment in the coal-bearing deposit of Shubarkol, in Central Kazakhstan. Modern analytical techniques were used to obtain information about the conditions and processes of trace element accumulation in coal, as well as the modes of occurrence of these elements. Geochemical data were analyzed using multidimensional statistical methods, including correlation, clustering, and factor analysis, which allowed us to draw several scientific conclusions. Numerous factors indicate that the enrichment of trace elements in sediments is controlled by clastic terrigenous material and low-temperature hydrothermal solutions circulating in the coal basin. The main sources of removal of trace elements from coal are ancient igneous rock complexes located within deposits that were directly involved in coal enrichment through secondary geological processes. According to estimates, the degree of enrichment of Jurassic coals at Shubarkol was close to the average value for world coals (0.5 < CC < 2), and coal seams were enriched with lithophilic and chalcophilic elements such as Ba, U, Yb, Co, La, Nb, Hf, Sc, V, Sr, Cu, and Zn. A correlation analysis of coal deposits revealed a significant correlation between main oxides and rare earth elements (REEs). The strongest correlation was between Zr, Hf, Th/Ta, and REEs. The positive correlations between Zr and Al2O3, Nb and Al2O3 indicate that these elements (Zr, Hf, Nb, Ta, and REY) are probably related to Al. The results obtained make it possible to consider coal as a potential mineral resource for the production of rare metals and serve as a guide for the industrial processing of the most important elements found in coal. Full article
(This article belongs to the Section Mineral Deposits)
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40 pages, 14218 KiB  
Article
Geochemistry and Petrogenesis of Permo–Triassic Silicic Volcanic Rocks from the Circum-Rhodope Belt in the Vardar/Axios Zone, Northern Greece: An Example of a Post-Collision Extensional Tectonic Setting in the Tethyan Realm
by Argyro Asvesta
Geosciences 2025, 15(2), 48; https://doi.org/10.3390/geosciences15020048 - 2 Feb 2025
Viewed by 989
Abstract
The western side of the Vertiskos Unit crystalline basement in northern Greece is fringed by a Permo–Triassic low-grade metamorphic volcano-sedimentary complex that belongs to the Circum-Rhodope Belt (CRB), which is an important part of the Vardar/ Axios oceanic suture zone. The silicic volcanic [...] Read more.
The western side of the Vertiskos Unit crystalline basement in northern Greece is fringed by a Permo–Triassic low-grade metamorphic volcano-sedimentary complex that belongs to the Circum-Rhodope Belt (CRB), which is an important part of the Vardar/ Axios oceanic suture zone. The silicic volcanic rocks from the CRB are mainly rhyolitic to rhyodacitic lavas with aphyric and porphyritic textures as well as pyroclastic deposits. In this study, geochemical data obtained with X-ray fluorescence (XRF) for the CRB silicic volcanic rocks are reported and discussed to constrain their petrogenesis and tectonic setting. The rocks are peraluminous and show enrichment in K, Rb, Th, Zr, Y, and Pb while being depleted in Ba, Sr, Nb, P, and Ti, and they have Zr + Nb + Y + Ce > 350 ppm, which are characteristic features of anorogenic A-type granites. They have a Y/Nb ratio > 1.2 and belong to A2-subtype granitoids, implying crust-derived magma in a post-collisional tectonic setting. The high Rb/Sr ratio (3.45–39.14), the low molar CaO/(MgO + FeOt) ratio, and the CaO/Na2O ratio (<0.5), which they display, indicate that metapelites are the magma sources. Their low Al2O3/TiO2 ratio (<100), consistent with their high zircon saturation temperatures (average TZr = 886 °C), and their low Pb/Ba ratio (average 0.06) reveal that they were generated by biotite dehydration melting. The increased Rb/Sr ratio relative to that of presumable parental metapelites of the Vertiskos Unit, coupled with their low Sr/Y ratio (0.12–1.08), reflects plagioclase and little or no garnet in the source residue, indicating magma derivation at low pressures of 0.4–0.8 GPa that correspond to a depth of ~15–30 km. The nearby tholeiitic basalts and dolerites, interstratified with the Triassic pelagic sediments, indicate bimodal volcanism in the region. They also support a model involving an upwelling asthenosphere that underplated the Vertiskos Unit basement, supplying the heat required for crustal melting at low pressures. The Permo–Triassic magmatism marks the transition from an orogenic to an anorogenic environment during the initial stage of continental breakup of the Variscan basement in a post-collision extensional tectonic framework, leading to the formation of the nascent Mesozoic Neo-Tethyan Maliac–Vardar Ocean. This apparently reveals that the Variscan continental collision between the Gondwana-derived Vertiskos and Pelagonian terranes must have been completed by at least the earliest Late Permian. Full article
(This article belongs to the Section Geochemistry)
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42 pages, 21453 KiB  
Article
Clay Mineralogy and Major and Trace Element Geochemistry of Recent Sediments in Rivers Along the West Coast of India: Implications for Provenance and Chemical Weathering
by Shaik Sai Babu, Venigalla Purnachandra Rao and Mekala Ram Mohan
Minerals 2025, 15(1), 43; https://doi.org/10.3390/min15010043 - 31 Dec 2024
Cited by 1 | Viewed by 1652
Abstract
The clay mineralogy and major and trace element geochemistry of the sediments deposited at the lower reaches of 90 medium and minor rivers from five states along the west coast of India indicate distinct clay mineral assemblages in the Archean–Proterozoic (A-P) terrain and [...] Read more.
The clay mineralogy and major and trace element geochemistry of the sediments deposited at the lower reaches of 90 medium and minor rivers from five states along the west coast of India indicate distinct clay mineral assemblages in the Archean–Proterozoic (A-P) terrain and Deccan Trap (DT) terrain. The sediments from A-P terrain are dominated by kaolinite, with minor illite and gibbsite and traces of goethite, and those from DT terrain are dominated by smectite with minor illite, kaolinite and chlorite. The sediments are depleted of Si, Ca, Mg, Na and K relative to those of Post-Archean average Australian Shale. The SiO2/Al2O3 ratio of the sediments suggests lateritic soils in the A-P terrain and non-lateritic, chemically weathered soils in the DT terrain. Weathering indices indicate strong weathering in the clay fractions of all sediments. The silt fractions of sediments from Goa, Maharashtra and Gujarat exhibit intermediate to weak weathering and influence by hydraulic sorting processes and source rock characteristics. The total trace element content (∑TE) was higher in the silt fractions than in clay fractions of all sediments, and peaks of high ∑TE occur in the silt fractions of Kerala and Maharashtra. The silt fractions exhibit relatively high Th, U, La, Zr and Hf from A-P terrain, and high Sc, Cr, Co, Ni, V and Ga from DT terrain. The Th/U and Rb/Sr ratios are controlled by the intensity of weathering and lithology of source rocks. The standard plots using trace elements reveal that the clay fractions of sediments are more mafic from both the terrains, while silt fractions exhibit intermediate provenance between felsic and mafic sources. Since mafic component-dominated clays are transported to the adjacent seas and oceans, it would be a challenge to identify the provenance of clays from granitic terrain in the oceans using trace element chemistry. Full article
(This article belongs to the Special Issue Chemical Weathering Studies)
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17 pages, 15255 KiB  
Article
The Genesis of Cs-Rich Geyserite in the Chabu Geothermal Field in Southern Tibet
by Ruo-Ming Li, Yu-Bin Li, Chang-Jin Yang, Jin-Shu Zhang, Cong Shen, Lin Yuan, Can Yang, Guo-Miao Xu, Duo Liu, Lin-Chao Yang, Ze-Lin Zhang and Zhe-Wei Sun
Minerals 2025, 15(1), 36; https://doi.org/10.3390/min15010036 - 30 Dec 2024
Cited by 1 | Viewed by 850
Abstract
Recent studies have shown that the geothermal systems in Tibet are rich in rare metal elements such as lithium (Li), boron (B), rubidium (Rb), and cesium (Cs). However, the understanding of the origin of Cs-rich geyserite formed by hot springs remains unclear. In [...] Read more.
Recent studies have shown that the geothermal systems in Tibet are rich in rare metal elements such as lithium (Li), boron (B), rubidium (Rb), and cesium (Cs). However, the understanding of the origin of Cs-rich geyserite formed by hot springs remains unclear. In this study, a detailed petrological, elemental geochemical, and strontium–neodymium (Sr–Nd) isotopic investigation on Cs-rich geyserite in the Chabu region revealed that opal was the main mineral component of Chabu geyserite; here, some samples were rich in terrigenous clastic material, and well-developed diatom fossils were also present. Chabu geyserite had high contents of SiO2 (78.95%–94.72%) and Al2O3 (3.02%–8.14%) and low contents of Fe2O3 (0.21%–1.94%), TiO2 (0.01%–0.20%), MnO (0.01%–0.15%); additionally, the Fe/Ti ratio, the Al/(Al + Fe) ratio, and the Al/(Al + Fe + Mn) ratio showed large variations. These results indicated different degrees of participation by the terrigenous materials, hydrothermal deposition, and biogenic processes. Chabu geyserite was depleted in transition metal elements (e.g., Sc, V, and Cr) and high field strength elements (e.g., Nb, Zr, and Hf), relatively enriched in large-ion lithophile elements (e.g., Li, Rb, Sr, and Ba), and strongly enriched in Cs, (by up to 100 times the Cs content in the upper crust); in addition, it had low V/Y (1.30–2.00) and U/Th ratios. Chabu geyserite exhibited a right-dipping rare earth element (REE) distribution pattern and had significant negative Eu anomalies (0.26–0.72) and no or weak positive Ce anomalies (0.97–1.36). These results further indicated the influence of terrigenous clastic materials and nonhydrothermal sedimentation factors. The Sr–Nd isotopic composition of Chabu geyserite was significantly different from that of the mantle, with relatively high 87Sr/86Sr ratios (0.7070–0.7076) and low 143Nd/144Nd ratios (0.512223–0.512314). These ratios were similar to those of the crust. Combined with previous studies, the results from this study indicated that Chabu geyserite was a Cs-rich geyserite and was formed in an intracontinental post-collisional orogenic environment, mainly from crustal material, with the participation of biological and hydrothermal processes. Full article
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23 pages, 6055 KiB  
Article
Assessing the Geological Environment Resilience Under Seawater Intrusion Hazards: A Case Study of the Coastal Area of Shenzhen City
by Dong Su, Jinwei Zhou, Maolong Huang, Wenlong Han, Aiguo Li, Enzhi Wang and Xiangsheng Chen
J. Mar. Sci. Eng. 2025, 13(1), 18; https://doi.org/10.3390/jmse13010018 - 27 Dec 2024
Viewed by 978
Abstract
Revealing geological environment resilience (GER) under seawater intrusion (SWI) hazards is a prerequisite for solving groundwater resource depletion, land salinization, and ecological degradation in coastal cities. This study applies the resilience design approach based on urban complex adaptive systems theory to understand the [...] Read more.
Revealing geological environment resilience (GER) under seawater intrusion (SWI) hazards is a prerequisite for solving groundwater resource depletion, land salinization, and ecological degradation in coastal cities. This study applies the resilience design approach based on urban complex adaptive systems theory to understand the impact of SWI on the geological environment. Taking SWI as the research object, the GER evaluation method under SWI disaster was established by selecting five elastic indexes: disturbance intensity, geological environment vulnerability, stress resistance, recovery, and adaptability. This method is used to evaluate the GER level of the coastal areas of Shenzhen in recent years under the impact of SWI hazards. The study found that there is a negative correlation between the intensity of disturbance and precipitation amount. The vulnerability is greater the closer the distance to the coastline and the shallower the depth of bedrock burial. Resistance is composed of early warning ability and disaster prevention ability, and the result is 10.07, which belongs to the medium level. The recovery is 1.49, which is at a relatively high level, indicating a high capacity for restoration ability. The adaptability increased from 3.03 to 3.13, so that the area of seawater intrusion is becoming smaller. GER is affected by precipitation amount and depth of bedrock burial; the greater the precipitation and the shallower the bedrock burial, the lower the GER. Precipitation amount significantly impacts the SWI situation in the eastern coastal area of Shenzhen. In the central region, the impact of precipitation on GER is less significant. However, in the western region, the depth of bedrock burial primarily affects GER. Compared to completely weathered granite, Pleistocene fluvial plain sediments are more susceptible to SWI effects in freshwater environments. This study contributes to a deeper understanding of the impact of SWI on the geological environment in coastal areas, providing decision-makers with the necessary knowledge to develop targeted and effective governance and prevention strategies. Full article
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