Geosystems and Geoenvironment最新文献

{"title":"Geochemistry of the metavolcanic rocks from the Archean Bikélélé greenstone belt (Chaillu Massif, Republic of the Congo): Petrogenesis and tectonic implications","authors":"Yarsé Brodivier Mavoungou ,&nbsp;Noël Watha-Ndoudy ,&nbsp;Hardy Medry Dieu-Veill Nkodia ,&nbsp;Anthony Temidayo Bolarinwa ,&nbsp;Aliyu Ohiani Umaru ,&nbsp;Georges Muhindo Kasay","doi":"10.1016/j.geogeo.2025.100429","DOIUrl":"10.1016/j.geogeo.2025.100429","url":null,"abstract":"<div><div>The Bikélélé greenstone belt belongs to the Chaillu Massif, which corresponds to the northwestern part of the Congo Craton outcropping in the southwestern Republic of the Congo. It mainly consists of metavolcanic lithological sequences composed of amphibolites, clinopyroxene amphibolites, epidote amphibolites, amphibole gneisses and amphibole-chlorite schists. These rocks show granoblastic to grano-nematoblastic textures, and contain amphibole, plagioclase, alkali feldspar, quartz, chlorite, clinopyroxene, biotite, sericite, sphene and opaque minerals. They have high contents in SiO₂, Fe₂O₃, Al₂O₃, CaO and MgO, with subordinate Na₂O and K₂O. In the REE chondrite-normalised diagrams, the metavolcanic rocks show flat to LREE-enriched and flat HREE patterns. However, in the primitive mantle-normalised diagrams, most of the samples show depletion in Nb, Ta and Ti. Trace and rare earth element (REE) data suggest that their protoliths correspond to basalts and basaltic andesites of tholeiitic and calc-alkaline affinity. The metavolcanic rocks likely formed by 2.5–4 % partial melting of a subcontinental lithospheric mantle source that was enriched through metasomatism involving sediment-derived melts and subduction-related fluids. The results of this study suggest that the protoliths of the Bikélélé metavolcanic rocks were emplaced in a subduction-related back-arc environment, during the second magmatic episode recorded in the Chaillu Massif and underwent metamorphic grade up to amphibolite facies during the Neoarchean tectono-metamorphic event.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 4","pages":"Article 100429"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accessory graphite in phyllites as indicator of metamorphic grade and stage (Szendrő Mts., NE Hungary)","authors":"Lívia Leskóné Majoros ,&nbsp;Máté Zs. Leskó ,&nbsp;Krisztián Fintor ,&nbsp;Ferenc Móricz ,&nbsp;Délia Bulátkó-Debus ,&nbsp;Sándor Szakáll ,&nbsp;Ferenc Kristály","doi":"10.1016/j.geogeo.2025.100431","DOIUrl":"10.1016/j.geogeo.2025.100431","url":null,"abstract":"<div><div>The metamorphic temperature of rock bodies can be estimated from the degree of graphitization of carbonaceous material, best determined by Raman spectroscopy. Graphite-bearing rocks from intensely folded black phyllites (black schists) near Meszes village in the Szendrő Mts., NE-Hungary, were analyzed using ore microscopy, scanning electron microscopy (SEM-EDX), X-ray powder diffraction (XRD), Raman spectroscopy and X-ray fluorescence spectrometry (XRF). The exposed Szendrő Phyllite Formation is of Carboniferous age, represents a gradually deepening basin fill, metamorphosed under greenschist facies conditions. Due to its low quantity and the presence of significant muscovite (± illite) 2M₁, clinochlore and quartz content, graphite is not directly detectable by XRD. Graphite occurs as intensely deformed 50–150 μm sized flakes persistently with kink-band microstructure and undulose extinction. The absence of S and Cl (confirmed by EDX) indicates a total maturation of the carbonaceous material into pure, disordered graphite with higher crystal ordering supported also by the initial splitting of S2 Raman band. The average formation temperature is estimated at 425°C (±50°C) by the Beyssac-method and 417°C (±50°C) by the Aoya-method.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 4","pages":"Article 100431"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-subduction Ichara adakite-like rocks from West Sakhalin (Russian Far East) versus supra-subduction Daisen adakites from SW Japan: Insight from trace-element modelling of sources","authors":"Tatyana A. Yasnygina ,&nbsp;Sergei V. Rasskazov ,&nbsp;Irina S. Chuvashova ,&nbsp;Elena V. Saranina","doi":"10.1016/j.geogeo.2025.100358","DOIUrl":"10.1016/j.geogeo.2025.100358","url":null,"abstract":"<div><div>The Ichara Complex of small intrusions is located on the Late Cenozoic Orlov volcanic field of West Sakhalin, in the area of Lamanon Cape. Andesites and dacites of the Ichara Complex and Orlov volcanic field show adakite-like signature (high Sr/Y, low HREE and Y, and high La/Yb) that is associated with magma generation at a crust-mantle transition. Trace element partial melting modelling shows that sources of the adakite-like rocks are the primitive mantle with admixtures of lower crustal (7–12 %) and minor fluid (0.5–1 %) components. Garnet and amphibole contents as well as the degree of partial melting in model sources increase from the older adakite-like andesites of the Orlov volcanic field to the younger andesites and dacites of Ichara Complex. Decreasing ⁸⁷Sr/⁸⁶Sr and increasing Sr/Y values from adakite-like andesites to dacites of West Sakhalin correspond to an increasing role of lower crustal and supra-subduction fluid components. The most pronounced adakite-like signature is characteristic of dacites derived from a clinopyroxene-amphibole-garnet source with maximal lower crustal addition. No young slab (MORB-type) material is detected in the modeled sources. In contrast to Ichara adakite-like rocks, the modelling of Daisen adakites from Southwest Honshu yields evidence on melting of the upper part of the Philippine Sea slab with significant contribution of the supra-subduction fluid component.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 4","pages":"Article 100358"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial distribution and source apportionment of potentially toxic elements in residential soil from Nsuta, a typical manganese mine community in Tarkwa, Southwestern Ghana","authors":"Eric Gyimah ,&nbsp;Samuel Kwamena ,&nbsp;Shadrack Fosu ,&nbsp;Emmanuel Daanoba Sunkari ,&nbsp;David Edem Dinku ,&nbsp;Yao Yevenyo Ziggah","doi":"10.1016/j.geogeo.2025.100435","DOIUrl":"10.1016/j.geogeo.2025.100435","url":null,"abstract":"<div><div>The environmental quality of residential areas of urban communities has been threatened by rapid industrial growth, substantial technological innovation, and urban expansion. The present study provides chemometric receptor model-based source apportionment, the ecotoxicological status, and the spatial distribution of arsenic, cadmium, lead, mercury, manganese and iron in residential soils in a mining community in Tarkwa. The distributions of the heavy metals showed a widespread pattern, while the eastern fringe of the study area was identified as a hotspot for mercury contamination. Agreement among the cluster analysis (CA), principal component analysis (PCA), and positive matrix factorization (PMF) along with the correlation matrix (CM) reasonably identified the sources of arsenic, manganese, and iron contamination of residential soils of the Nsuta community to be governed by geogenic influences such as the weathering and hydromorphic dispersion from the metavolcanic rocks. Noteworthily, atmospheric deposition is considered a prioritized source for mercury contamination, with a PMF contribution of 78.50%. Vehicular emission as well as other anthropogenic activities contribute to lead (48.00%) and cadmium (66.20%) contamination of the residential soil within the study area. Ecotoxicological assessment reveals a combined toxic risk index (TRI) of 29.80, with mercury contributing to about 97.50% of the total risk. Moreover, the modified hazard quotient (mHQ_i) for the single metals also indicated that mercury (Hg) has the highest ecological toxicity level with a mHQ_i value of 7.00. The present study provides baseline data that could be valuable for proper environmental management and policy-making to reduce the myriad influx of heavy metal contamination in the study area. To provide a thorough understanding of metal pollution in the Nsuta community, future research on metal speciation, bioavailability, bioaccumulation, potential modes of action in soils, and the implications for human health is also necessary.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 4","pages":"Article 100435"},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of depth to basement using natural electric field method (NEFM) in a proposed weir at Iju-Itaogbolu, SW Nigeria","authors":"Philomina Nkeonye Okanigbuan ,&nbsp;Edore Festus Omozeje ,&nbsp;Oluwatoyin Francis Ijasan ,&nbsp;Uyiosa Osagie Aigbe","doi":"10.1016/j.geogeo.2025.100403","DOIUrl":"10.1016/j.geogeo.2025.100403","url":null,"abstract":"<div><div>Natural electric field traverses (3) consisting of eighteen (18) VEMs points in each traverse 1 m apart were conducted across the proposed weir axis at Ogbesse River in the Iju-Itaogbolu area, to determine the thickness of overburden materials and depth to bed rock at the proposed weir site. Field investigations were conducted using the PQWT GT 500 series. Results revealed five (5) geo-electric layers with varying thickness in place, which included the topsoil, clayey unit, sand unit, and significantly weathered and fractured basement. The result also showed the presence of alluvium deposits in the area which is approximately 118 m² and varies between 3 and 18 m beneath the study area. The average thickness and saturation of the subsurface materials are particularly significant, with consequences leaning toward a high permeability of the sandy layer below the clay bed which has been partly exposed at the surface in the south-eastern section of the proposed weir axis. The proposed weir axis exhibited a regolith thickness ranging from 3.86 to 16.22 m, notably fractured at shallow and deep sections. These characteristics were observed across the proposed weir axis, increasing in magnitude and numbers upstream of the proposed weir axis. The conductivity of these fractured zones is indicative of a significant saturation. Depth to bed rock and thickness of overburden materials in the study area is however not uniform as observed from the results, indicating the fairly undulating surface of the bed rock in the study area. This study has provided useful information on the cause of failure experienced in the previous weir located 100 m upstream of the proposed weir in the past.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 3","pages":"Article 100403"},"PeriodicalIF":0.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144306453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geotechnical analysis and landslide susceptibility of overburden slope material in the Jammu and Kashmir, Western Himalaya","authors":"Zahid Habib ,&nbsp;Ajay Kumar ,&nbsp;Riyaz Ahmad Mir ,&nbsp;Irfan Maqbool Bhat ,&nbsp;Waseem Qader ,&nbsp;Rosan Kumar Mallik","doi":"10.1016/j.geogeo.2025.100413","DOIUrl":"10.1016/j.geogeo.2025.100413","url":null,"abstract":"<div><div>This study examines the geotechnical properties of slope overburden material from Banihal to Ramban road section of National Highway-44 (NH44), Jammu and Kashmir, Western Himalaya. This region consists of Early Palaeozoic rock formations and is prone to mass wasting. Extensive development activities have exacerbated slope instability in this area. For geotechnical analysis, 40 undisturbed soil samples (USS) were collected and assessed for various parameters. Average values indicate moderate natural moisture content (11.6%), liquid limit (32%), plastic limit (24%), and plasticity index (7%), bulk density (1.6 g/cm³), dry density (1.4 g/cm³), cohesion (0.25 kg/cm²), internal friction angle (38°), void ratio (0.8), porosity (0.44%), and specific gravity (2.5%). The observed geotechnical results suggest moderate bearing capacity of the studied slopes, but increased landslide risk due to low cohesion in high moisture conditions. Therefore, these results may act as a policy document, aiding in land-use planning and identifying suitable sites for engineering structures.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 3","pages":"Article 100413"},"PeriodicalIF":0.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial distribution and health implications of particulate matter concentrations across diverse land use types in Dinajpur District, Bangladesh","authors":"Ahmad Kamruzzaman Majumder ,&nbsp;Kazi Khaled Mahmud ,&nbsp;Marziat Rahman ,&nbsp;Md. Nasir Ahmmed Patoary ,&nbsp;Sneha Gautam ,&nbsp;Kaspia Rahman Tanima","doi":"10.1016/j.geogeo.2025.100397","DOIUrl":"10.1016/j.geogeo.2025.100397","url":null,"abstract":"<div><div>This study investigates the concentrations of particulate matter (PM₁, PM_2.5 and PM₁₀) across various land use types in Dinajpur District, Bangladesh, highlighting significant spatial variations in PM concentrations in sensitive, residential, mixed, commercial, road intersection, industrial, and village areas. Along with this, examines the health consequences linked to increased levels of particulate matter (PM).The investigation was carried out in sites within the area of Dinajpur district town, utilising a portable Air Quality Monitor, Portable Air Quality Detector (Model: DM106) and Garmin ETrex 10. To examine and illustrate the differences in pollutant concentrations among various locations, whisker box plots and descriptive statistics were used. Likewise, ArcGIS software was used for spatial analysis, and a dendrogram plot was created to classify and interpret data clusters, providing a deeper understanding of the spatial distribution of pollutants. PM_2.5 levels in worst affected sensitive area, Dinajpur General Hospital (77.00 µg/m³), exceeded the Bangladesh National Ambient Air Quality Standards (NAAQS) level (65 µg/m³) by 1.18 times and WHO standards (25 µg/m³) by 3.08 times. Besides, residential areas like Gabgash Residential (78.50 µg/m³) showed PM_2.5 concentrations 1.20 and 3.14 times higher than NAAQS and WHO standards respectively. Moreover, commercial zones, particularly around AB Bank, exhibited the highest pollution levels with PM_2.5and PM₁₀ concentrations 2.44 and 1.28 times higher than NAAQS norms, respectively. However, road intersections such as Bahadur Mor (113.25 µg/m³) recorded PM_2.5 concentrations 1.74 times higher than NAAQS while industrial areas like Sonali Brick Field showed PM_2.5 levels exceeding NAAQS by 1.46 times.</div><div>Finally, the study calculated an Attributable Mortality value of 892 owing to PM_2.5, highlighting the significant impact of particle pollution on human health in Dinajpur Sadar. These findings contribute to the understanding of local air quality patterns, emphasizing the critical need for targeted interventions to protect public health and reduce exposure to harmful particulate matter in Dinajpur District.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 3","pages":"Article 100397"},"PeriodicalIF":0.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144106439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Georesistivity assessment of lithological and hydrodynamic factors in groundwater sanitation of Akwa Ibom river channel aquifer system","authors":"Kufre Richard Ekanem,&nbsp;Nyakno Jimmy George,&nbsp;Aniekan Martin Ekanem,&nbsp;Ndifreke Inyang Udosen,&nbsp;Jewel Emem Thomas","doi":"10.1016/j.geogeo.2025.100411","DOIUrl":"10.1016/j.geogeo.2025.100411","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This study deploys methods of vertical electrical sounding (VES), electrical resistivity tomography (ERT), and georesistivity-hydrodynamic correlation to evaluate groundwater quality and lithological changes in the river channel aquifer system of Akwa Ibom State, Southern Nigeria. In addition to revealing groundwater recharge and discharge zones, resistivity anomalies combined with borehole lithology also highlight the potential for contamination from rivers, landfills, and agricultural runoff. According to georesistivity studies, there are four different subsurface layers. The topmost layer shows resistivity fluctuations between 14.1 and 2345.4 Ωm (mean: 501.1 Ωm, CV: 105%), which are caused by human activity and surface erosion. High thickness variations (1.8–102.8 m) and resistivity values (8.1–1847.1 Ωm) are observed in the second layer, a fine sand aquifer. Medium to coarse sands make up the third layer, which exhibits resistivity values ranging from 1.1 to 2408.9 Ωm (CV: 124%). Although the thickness of the fourth layer is unknown, its resistivity values range from 12.3 to 2128.2 Ωm. 40.7% of the region is made up of high-energy aquifers (HK: &lt;em&gt;ρ&lt;/em&gt;&lt;sub&gt;1&lt;/sub&gt; &gt; &lt;em&gt;ρ&lt;/em&gt;&lt;sub&gt;2&lt;/sub&gt; &lt; &lt;em&gt;ρ&lt;/em&gt;&lt;sub&gt;3&lt;/sub&gt; &gt; &lt;em&gt;ρ&lt;/em&gt;&lt;sub&gt;4&lt;/sub&gt;), 14.8% are Q-type (&lt;em&gt;ρ&lt;/em&gt;&lt;sub&gt;1&lt;/sub&gt; &gt; &lt;em&gt;ρ&lt;/em&gt;&lt;sub&gt;2&lt;/sub&gt; &gt; &lt;em&gt;ρ&lt;/em&gt;&lt;sub&gt;3&lt;/sub&gt;), and 14.8% are H-type (&lt;em&gt;ρ&lt;/em&gt;&lt;sub&gt;1&lt;/sub&gt; &lt; &lt;em&gt;ρ&lt;/em&gt;&lt;sub&gt;2&lt;/sub&gt; &gt; &lt;em&gt;ρ&lt;/em&gt;&lt;sub&gt;3&lt;/sub&gt;), according to VES curve classifications. These conditions imply high permeability, transmissivity, and groundwater flow, all of which jeopardize groundwater sanitation. The percentage of sampling sites with low-energy aquifers with limited storage capacity is just 3.7%. High-resistivity zones correlate to compacted formations, whereas low-resistivity zones near river channels are identified as active recharging locations using resistivity mapping. It is confirmed by borehole lithology that fine, gravelly sands predominate in groundwater-bearing units. Hydraulic conductivity, permeability, and transmissivity range from 0.52 to 31.45 m/day, 788.39 to 51,681.97 mD, and 18.72 to 1988.27 m²/day, respectively, according to hydrodynamic study. The Dar Zarouk characteristics, which range from 0.015 to 7.194 Ω⁻¹ for longitudinal conductance, categorize protective capacities as dominantly weak (63%), moderate (15%), good (11%), or very good (11%). Overall, this study demonstrates how intricately groundwater quality, hydrodynamics, and lithology interact within the river channel aquifer system. As inferred from the results, significant binary correlations exist between depth and aquifer thickness, water resistivity and bulk resistivity, transverse resistance and bulk resistivity, longitudinal conductance and bulk resistivity, as well as water resistivity and transverse resistance. Moreover, hydraulic conductivity exhibits a strong correlation with both permeability and transmissibility. In Nigeria's","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 3","pages":"Article 100411"},"PeriodicalIF":0.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144653474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uranium uptake by phosphate minerals from Ca-containing technogenic solutions: Experimental study","authors":"А.Е. Boguslavsky ,&nbsp;O.L. Gaskova ,&nbsp;S.M. Sofronova ,&nbsp;А.А. Saraev ,&nbsp;Z.S. Vinokurov ,&nbsp;А.V. Safonov","doi":"10.1016/j.geogeo.2025.100415","DOIUrl":"10.1016/j.geogeo.2025.100415","url":null,"abstract":"<div><div>Since apatite is capable to adsorb and retain radionuclides, the removal of uranyl (UO₂²⁺) ions from two Ca-containing technogenic and model solutions (1–2 g/L of Ca) was studied when neutralized with sodium hydrogen phosphate solution Na₂HPO₄. Chemical composition of the sediments was analyzed by XPS and their structure was refined by XRD. The hydroxyapatite formation was confirmed. XRD proves that the two samples contained additional CaH(PO₄) ∙ (H₂O)₂ (brushite), in which calcium changes to uranium of up to 15 % in a model solution. When identifying the oxidation state of uranium the presence of U⁴⁺, U⁵⁺ and U⁶⁺ was noticed with U⁵⁺ of up to 30–35 at. % from the total.</div><div>SEM-EDS did not allow to determine location of the phases with an uranium content over 14 %, for example Ca(UO₂)₂(PO₄)₂·11H₂O (autunite) or other uranium phosphates. Uranium is detected at the grain rims, indicating a sorption nature of its accumulation. At the same time, thermodynamic computations showed the possible formation of independent uranium phases, such as ß-UO_2.333, ß-UO₂(OH)₂ and NaUO₂O(OH) (clarkeite), at the measured Eh-pH. We believe that the supersaturation of solutions and the spontaneous formation of hydroxyapatite and brushite solid particles led to a change in the initial Ca/PO₄ ratio, where the P/Ca and Ca/O ratios, as well as the elemental composition in the near-surface layer of three sediments, are not strictly constant. There have been no similar studies on uranium, and our results demonstrate the need for further studies on the influence of uranium on apatite crystallization. Stability of phosphate phases shows the high efficiency of phosphate safety barriers for the uranium recovery facilities and these processes can be used for the water purification of polluted aquifers.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 3","pages":"Article 100415"},"PeriodicalIF":0.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144262857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Holocene climate variability deciphered from Chilika Lagoon sediments: Implication for anthropogenic activity or paleocyclones?","authors":"Barnita Banerjee ,&nbsp;Monalisa Mallick ,&nbsp;Mohd Amir ,&nbsp;Abdul Hameed ,&nbsp;Luan Ozelim ,&nbsp;Nihar Ranjan Kar ,&nbsp;E.V.S.S.K. Babu ,&nbsp;K. Venkatesham ,&nbsp;M. Venkateshwarlu ,&nbsp;Tanveer Hassan ,&nbsp;Vireswar Samanta ,&nbsp;Prem Chand Kisku ,&nbsp;Debajyoti Paul ,&nbsp;Pankaj Kumar ,&nbsp;Aurovinda Panda","doi":"10.1016/j.geogeo.2025.100390","DOIUrl":"10.1016/j.geogeo.2025.100390","url":null,"abstract":"<div><div>Coastal lagoons, acting as a link between land and sea, serve as valuable archives for past climate variations, human activities, and paleo-cyclonic events. In this study, we employ a multi-proxy approach to analyze sedimentary records and uncover climatic shifts influenced by both monsoonal and non-monsoonal factors. Our analysis incorporates sediment characteristics such as grain size, magnetic susceptibility (MS), and clay mineralogy to infer high-energy conditions within the Chilika Lagoon. Additionally, we utilize Rock-Eval pyrolysis and deconvolution of flame ionization detector (FID) signals to determine the type of organic matter (OM) present.</div><div>Findings reveal that during the Early Holocene, a high sand percentage and elevated MS indicate an intensified monsoon, coinciding with a dominance of terrestrial OM. However, as monsoonal intensity declined after the Early Holocene, marine OM became more prevalent, likely linked to the formation of an estuary around ∼7.7 Ka. Despite a weakening monsoon around ∼4 Ka, MS values remained high, possibly due to increased aeolian input, which transported titanomagnetite, contributing to elevated MS in the sediment record. After ∼4 Ka, the sedimentary record indicates a greater influx of terrestrial OM, likely due to the formation of a barrier spit that limited marine influence. From this period onward, monsoonal intensity gradually increased, peaking around ∼1.1 Ka, coinciding with the Medieval Warm Period. Following ∼1.1 Ka, sedimentation rates rose, accompanied by low magnetic susceptibility (MS) and high sand content. This phase also shows an increase in both terrestrial and marine OM, along with higher CaCO₃ and illite concentrations, suggesting the impact of high-energy events, possibly cyclones. The intensification of cyclonic activity after ∼1.1 Ka may be associated with a weakening of El Niño–Southern Oscillation (ENSO) intensity during this period.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 3","pages":"Article 100390"},"PeriodicalIF":0.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143852121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}