Geosystems and Geoenvironment最新文献

{"title":"Identification of structurally controlled potential mineralization zones in Chhotanagpur Gneissic Complex, Eastern India from gravity and magnetic data","authors":"Afaque Karim ,&nbsp;Anurag Tripathi ,&nbsp;Upananda Low ,&nbsp;Mohd Tabish Ansari ,&nbsp;Deepak Yadav ,&nbsp;Kashi Nath Prasad","doi":"10.1016/j.geogeo.2025.100470","DOIUrl":"10.1016/j.geogeo.2025.100470","url":null,"abstract":"<div><div>The present study delineates zones of potential mineralization within the Chhotanagpur Gneissic Complex (CGC) using integrated geophysical methods. Comprehensive gravity and magnetic surveys were conducted across ∼3500 km² revealing seven high–priority blocks characterized by distinct Bouguer gravity anomalies (–46 to –19 mGal) and magnetic intensity variations (–246 to +710 nT). These geophysical anomalies are linked to surface lithologies like mica–schist belts, amphibolites and intrusive bodies which are indicative of economically significant mineral deposits. In this study, structural analysis highlights NE–SW and NW–SE trending lineaments and faults that may play a key control on mineralization in the area. Depth estimations from radially averaged power spectrum (RAPS) and Euler 3D solutions shows causative bodies are deeper (∼4 km) in western region than the eastern region (∼1–2 km). The integration of geophysical data with geological interpretations enhances understanding of the CGC in the context of possible influence on mineralization processes. The present findings provide a strategic pathway for guiding further mineral exploration initiatives in seven potential zones identified in the study area.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 2","pages":"Article 100470"},"PeriodicalIF":0.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145618353","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":"Analysis of the trend of dry spells and how ocean factors affect their patterns during the summer monsoon in Bangladesh using the Mann-Kendall and frontier atmospheric general circulation model","authors":"Md. Moniruzzaman Monir ,&nbsp;Subaran Chandra Sarker ,&nbsp;Md. Mostafizur Rahman ,&nbsp;Md. Nazrul Islam","doi":"10.1016/j.geogeo.2025.100472","DOIUrl":"10.1016/j.geogeo.2025.100472","url":null,"abstract":"<div><div>To assess drought risk, susceptibility to food security, and water resource utilization, it is crucial to comprehend dry spell patterns from a hydrological perspective. Some regional studies have noted an extension of dry spells on a global and regional scale, but it is still unclear how often dry spells occur during the summer monsoon season, which is dominated by rainfall. This study uses the Mann-Kendall trend test to examine the trend of dry spells during Bangladesh's summer monsoon from 1985 to 2022 to close this gap. Using the frontier atmospheric general circulation model and remote sensing methods to examine the effects of ocean elements such as Indian Ocean Dipole (IOD), sea surface temperature (SST), El Niño-southern oscillation (ENSO) conditions, and the zonal wind. Daily rainfall data for 34 weather stations were obtained from the Bangladesh Meteorological Department, while surface water occurrence and change intensity data were retrieved from the JRC Global Surface Water Mapping Layers, v1.3 (FAO, UN). The NOAA Physical Sciences Laboratory (PSL) and the Tokyo Climate Center/WMO Regional Climate Centre in RA II (Asia) provided the IOD, SST, ENSO, and zonal wind data. A notable dry spell anomaly over Bangladesh was also observed in this research, with short, medium-length, and long dry spells increasing at 82.35 %, 73.53 %, and 50 % of the weather stations, respectively. Dry spells become less frequent during El Niño but more during La Niña. The climatic variability of IOD events and SST anomalies in the eastern and western tropical Indian Ocean was also noted by this study to be connected to these anomalous events. The correlation coefficient between summer monsoon rainfall and DMI is 0.34. Throughout the study period, there were changes in the upper atmosphere's and lower troposphere's wind circulation. The study allows the prioritization of regions for drought, effective water resource management, and food scarcity preparedness.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 2","pages":"Article 100472"},"PeriodicalIF":0.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145618486","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":"Landslide susceptibility assessment and slope stability analysis of cut slopes along Dumre-Paudhi Bazar road section, western Nepal","authors":"Suraj Adhikari,&nbsp;Subodh Dhakal","doi":"10.1016/j.geogeo.2026.100499","DOIUrl":"10.1016/j.geogeo.2026.100499","url":null,"abstract":"<div><div>Cut slopes in Nepal pose significant threats in hilly regions due to weak geology, steep slopes, rainfall, and seismic activity ultimately causing landslide events. This study aims to assess landslide susceptibility and rainfall-induced cut slope stability analysis along the Dumre-Paudhi Bazar road section using geographic information system (GIS) and the GeoStudio package as this approach of accessing the stability has never been performed in the study area. A total of 36 landslides were mapped, and a landslide susceptibility map was developed using the information value method. Ten key causative factors: slope, aspect, curvature, elevation, rainfall, distance from roads, distance from drainage, topographic wetness index (TWI), land use/land cover, and rock and soil distribution were selected based on field observations, geomorphological conditions, and statistical screening using Pearson and Spearman correlation analyses. The study classified the region into five susceptibility zones: very low, low, medium, high and very high using the natural breaks method. Validation was performed using receiver operating characteristics (ROC) curve, where an area under curve (AUC) values of 0.796 for training data sets and 0.762 for testing data sets were obtained indicating a success rate of 79.6% and a prediction rate of 76.2%.</div><div>To further assess rainfall-induced slope stability, five road cut slopes within medium to very high susceptibility zones were analyzed using the coupled SEEP/W and SLOPE/W approach in GeoStudio under different rainfall scenario. Sensitivity analysis was performed under dry conditions and under rainfall intensities ranging from 50% to 150% of the recorded maximum daily rainfall. The results reveal a consistent reduction in the factor of safety with increasing rainfall intensity due to increased pore water pressure highlighting increased failure potential during heavy precipitation. The integrated approach adopted in this study provides a comprehensive understanding of landslide-prone areas and cut-slope behavior under different rainfall conditions and provides valuable insights for hazard mitigation and road infrastructure planning.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 2","pages":"Article 100499"},"PeriodicalIF":0.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146187354","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":"Spectral dispersion matching technique for multi-class spatial-spectral feature detection of REE-fertile lithology in the Samalpatti alkaline–carbonatite complex (SACC) using Hyperion data","authors":"P. Abishek ,&nbsp;N.K. Libeesh ,&nbsp;S. Arivazhagan ,&nbsp;C. Sreejith","doi":"10.1016/j.geogeo.2025.100488","DOIUrl":"10.1016/j.geogeo.2025.100488","url":null,"abstract":"<div><div>The Proterozoic alkaline carbonatite complex, lies along the Samalpatti shear zone, is linked to a post-collisional rift setting in the Southern Granulitic Terrain (SGT), provides a geologically intriguing and economically prospective terrain for rare earth element (REE) exploration. This study involves a multiproxy approach by integrating the hyperspectral remote sensing, machine learning, and field validation techniques to delineate the REE fertile lithology units using the EO-1 Hyperion imagery. The pre-processed dataset was subjected to noise reduction and dimensionality reduction using spectral dispersion matching (SDM) methods. SDM was performed in 3 steps; initially, noise reduction algorithms such as principal component analysis (PCA), independent component analysis (ICA), minimum noise fraction (MNF), and band ratio combinations (BRC) were applied to enhance data quality. This was followed by correlation-based feature selection using support vector machines (SVM), focusing on spectral behaviour. Subsequently, mineralogical characteristics were integrated and validated to emphasize their spectrochemical properties. Among the reduction algorithms, ICA achieved the highest spectral class separability, as confirmed by Jeffries–Matusita distance analysis, with values &gt;1.9 for key lithological pairs. The correlation-based feature selection was performed with a radial basis function (RBF) kernel, yielding an overall accuracy of 85.56% and a Kappa coefficient of 0.80. The multiproxy approach using SDM highlights the efficacy of imaging spectroscopy combined with advanced classification techniques in complex lithological terrains and offers a scalable framework for mineral exploration targeting REE-fertile zones.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 2","pages":"Article 100488"},"PeriodicalIF":0.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976558","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":"Investigating structural controls on groundwater potential in parts of southeastern Ghana using geophysical tools to improve access to sustainable groundwater resources","authors":"Elikplim A. Dzikunoo,&nbsp;Yvonne S.A. Loh,&nbsp;Daniel Kwayisi,&nbsp;Prospera S. Sungpour","doi":"10.1016/j.geogeo.2026.100498","DOIUrl":"10.1016/j.geogeo.2026.100498","url":null,"abstract":"<div><div>Groundwater development in crystalline basement rocks is complex due to the discrete variations in the fractures, weathered zones and other geologic constraints which determine groundwater flow. To maximize groundwater exploration in such areas, it is imperative to understand the significance of the interplay between fracture systems as well as weathered zone thicknesses. To characterize these factors that underpin groundwater access in crystalline rocks, a geophysical assessment of parts of the Pan-African Dahomeyide rocks underlying the Akatsi district and parts of the Central Tongu district in southeastern Ghana was completed. Characterization of the fracture or lineament systems together with the weathered zone thickness was done using a multi-scale approach of interpreting airborne magnetic data together with limited direct current (DC) 2D electrical resistivity tomography (2D ERT) data. Based on the magnetic signatures, linear features at different depths and of different lengths were identified with the dominant trends being NE-SW. Inversion of the resistivity data aided in defining the weathered zone thicknesses in connection with established soil types including planosols, cambisols, luvisols, solonetz, gleysols and vertisols found in the area. The combined effects of lineaments and weathered zone thicknesses as a dual-porosity model are discussed in terms of their impact on groundwater development.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 2","pages":"Article 100498"},"PeriodicalIF":0.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077527","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":"Origin and paleoenvironmental conditions of iron duricrust in the Paleogene N’kapa Formation, Douala sub-basin, Cameroon","authors":"Kevin Jorex Voufor Tsafack ,&nbsp;Ngong Roger Ngia ,&nbsp;Christopher Fuanya ,&nbsp;Christopher M. Agyingi ,&nbsp;Elie Fosso Menkem ,&nbsp;Alexandrine N’nanga ,&nbsp;Median Yongye ,&nbsp;Ligbwah Victor Wotanie","doi":"10.1016/j.geogeo.2025.100486","DOIUrl":"10.1016/j.geogeo.2025.100486","url":null,"abstract":"<div><div>This paper unravels rarely studied paleoenvironmental conditions and origin of iron duricrust in the Paleogene N’kapa Formation, Douala sub-basin, Cameroon. It integrates petrographic and geochemical techniques (mineralogy, trace, major and REEs elements) and isotope of δ¹⁸O, δD and ⁸⁷Sr/⁸⁶Sr to reconstruct paleoclimate, paleoweathering, paleoredox and paleosalinity, and established mechanisms of formation of iron duricrust. The textures and mineralogy of iron duricrust indicates that they are ferricretes with brecciated to colloform textures composed of hematite, siderite, kaolinite and detrital quartz grains. Paleoclimate proxies revealed humid to semi-arid climate and variation in climatic conditions caused intense-chemical weathering, favouring a change in weathering processes from kaolinitisation to ferricretization. Paleoredox and paleosalinity proxies indicate that the iron duricrust was formed under dysoxic to dominantly oxic conditions in shallow freshwater to somewhat brackish water body with intermediate salinity. The δ¹⁸O, δD and ⁸⁷Sr/⁸⁶Sr composition of the samples indicate post-depositional alteration due to influx of meteoric waters during the duricrusting process. The equilibration with meteoric water reveals that the iron duricrusts formed primarily through supergene enrichment and diagenetic reworking of detrital sediments. However, some contribution from hydrogenous input occurred in lagoonal settings with fluctuating salinity, which probably facilitated the precipitation of iron directly from water. The remobilization of iron led to the formation of secondary hematite, which could possibly be link to early Paleogene climatic variations and eustatic sea-level changes. These findings provide valuable insights into sedimentary mineral enrichment in response to Paleogene environmental dynamics and offer a reference for comparable iron-rich deposits in African basins and other parts of the world.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 2","pages":"Article 100486"},"PeriodicalIF":0.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840235","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":"Petrogenesis and tectonomagmatic environment of Naranag granites from Northwestern Kashmir Himalaya, India","authors":"Akhtar R. Mir ,&nbsp;Shamim A. Dar ,&nbsp;Adil A. Bhat ,&nbsp;Naseer A. Bhat ,&nbsp;Irfan M. Bhat ,&nbsp;J. Ukasha ,&nbsp;Vikash Kumar ,&nbsp;Shabber H. Alvi ,&nbsp;V. Balaram ,&nbsp;Santosh Kumar","doi":"10.1016/j.geogeo.2026.100490","DOIUrl":"10.1016/j.geogeo.2026.100490","url":null,"abstract":"<div><div>Granites represent a fundamental component of the continental crust and provide valuable insights into crustal growth, recycling, and tectono-magmatic evolution through Earth’s history. The Early Paleozoic granitoids in the Himalaya are of particular significance as they record the influence of the Pan-African event (ca. 600–500 Ma), a major tectono-thermal event related with the assembly of Gondwana. Despite the occurance of numerous Pan-African granitoids across the Himalaya, several intrusions remain poorly characterized. One such body is the Naranag granites (NG) of the northwestern Himalaya, exposed over ∼15 km² in Ganderbal District, Kashmir. This study integrates detailed field relationships, petrographic observations, and whole-rock geochemistry to investigate the petrogenesis, source characteristics, and tectonic setting of the Naranag pluton. Field observations reveal that the Naranag granites are medium to coarse grained, whitish grey, and largely undeformed, with quartz, k-feldspar, plagioclase, and biotite ± muscovite minerals present. Pegmatitic and aplitic veins with tourmaline reflect late-stage magmatic evolution. Petrographic features, including graphic textures, perthitic intergrowths, and the presence of garnet and tourmaline, confirm a peraluminous, two-mica (S-type) affinity. Geochemical analyses show high SiO₂ (68.7–70.5 wt.%), elevated alkalis (Na₂O + K₂O = 8.3–9.1 wt.%), high alumina saturation indices (ASI =1.65–1.77), and enrichment in large ion lithophile elements (e.g., Rb, Ba, K, Pb) with depletion in high-field-strength elements (e.g., Nb, Ta, Ti). These features, along with negative Ba–Sr anomalies and negative trends of MgO, Al₂O₃, TiO₂, and CaO with SiO₂, reflect partial melting of metagraywacke-dominated lower crust under water-undersaturated conditions, followed by fractional crystallization of feldspars and biotite. Tectonic setting plots (Rb–Y–Nb; Rb vs. Y + Nb) and calc-alkaline affinity indicate emplacement in a syn-collisional to volcanic arc setting, consistent with other Early Paleozoic granitoids of the Himalaya, such as the Hant and Dalhousie granites, and comparable Pan-African intrusions globally. The Naranag granites thus represent a crust-derived melt generated during crustal thickening and orogenic heating associated with the Pan-African tectono-thermal regime. Their geochemical affinity and mineralogical signatures provide evidence for widespread Early Paleozoic granitic magmatism across the Himalaya linked to the assembly of Gondwana. This study highlights the significance of the Naranag granites as a key but previously underexplored record of Pan-African magmatism in the northwestern Himalaya. Future isotopic and geochronological investigations are recommended to refine their emplacement age and further constrain the relative contributions of crustal versus mantle sources in their genesis.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 2","pages":"Article 100490"},"PeriodicalIF":0.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037330","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":"Prioritization of sub-watersheds based on hydro-morphometric assessment in relation to soil erosion: A case study in Haora Drainage Basin, Tripura","authors":"Sudipta Pal,&nbsp;Nibedita Das Pan","doi":"10.1016/j.geogeo.2025.100471","DOIUrl":"10.1016/j.geogeo.2025.100471","url":null,"abstract":"<div><div>Among all the environmental issues of the world, soil erosion is of significant concern in terms of watershed management. For proper planning and management of watersheds in terms of soil erosion, characterization and prioritization of sub-watersheds (SWs) through appropriate techniques is crucial. Thus the present study focuses on prioritizing the erosion prone sub-watersheds of Haora Drainage Basin, Tripura using Hydro-Morphometric analysis. Remote sensing (RS) and geographical information system (GIS) play a vital role for providing cost-effective and accurate data of the study area. The generation of drainage networks and delineation of sub-watersheds has been done using ASTER DEM of 30 m resolution in the Arc-GIS 10.8 software. On one hand, nineteen vital morphometric parameters among the linear, areal and relief aspects in relation to soil erodibility were computed using pre-defined mathematical formulae and methods using the DEM and on the other hand, field surveys with necessary equipment for three consecutive water years (2021–2024) helped in evaluating six important hydrological parameters. The study area consists of nine sub-watersheds in order of SW1-SW9. The prioritization of the sub-watersheds has been done on the basis of compound value of each sub-watershed calculated by using the Preliminary Rankings of the parameters and weighted sum approach (WSA). As a result, SW5, SW7 and SW3 have been categorized into high priority and SW9 and SW1 comes under moderate priority. Four sub-watersheds namely SW6, SW4, SW8 and SW2 have been assigned low priority, suggesting that these are more sustainable than others. The study provides scientific information for decision makers toward effective soil and watershed management.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 2","pages":"Article 100471"},"PeriodicalIF":0.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840234","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":"Stable isotopes and palynological analyses of the Campanian-Maastrichtian Mamu shales, western flank of the Anambra Basin, Nigeria: A paleoenvironmental investigation","authors":"Olugbenga T. Fajemila ,&nbsp;Tesleem O. Kolawole ,&nbsp;Jorge E. Spangenberg ,&nbsp;Moshood A. Olayiwola ,&nbsp;Kehinde O. Akinterinwa ,&nbsp;Kabirat T. Adebiyi ,&nbsp;Rafiu A. Salako","doi":"10.1016/j.geogeo.2026.100492","DOIUrl":"10.1016/j.geogeo.2026.100492","url":null,"abstract":"<div><div>The Mamu Formation is an important sedimentary unit within the Anambra Basin, southern Nigeria. The presence of coal seams and carbonaceous shales within this formation has implications on its hydrocarbon potential and paleoenvironment of deposition. This study integrated stable isotopes of organic carbon and total nitrogen (<em>δ</em>¹³C_org, <em>δ</em>¹⁵N_TN) and palynology to characterize the depositional environment of the Mamu Shales located at the western flank of the Anambra Basin in Nigeria. The <em>δ</em>¹³C_org values ranged from -25.9 to -24.6‰ VPDB, while the <em>δ</em>¹⁵N_TN values varied from 3.0 to 5.6‰ Air-N₂. Additionally, the carbon-to-nitrogen molar ratios (C/N) fell between 10.8 and 19.3. These findings suggest that the organic matter primarily originated from terrestrial C₃ grasses and trees. The range of TOC, HI and T_max values suggested that these shales are good hydrocarbon source rocks. The palynomaceral (PM) assemblages were characterized by abundant, poorly sorted small and medium-sized PM-1 and PM-2, alongside relatively common lath-shaped PM-4. These assemblages were associated with lower occurrences of PM-3, structureless organic matter, and land-derived palynomorphs. Together, these observations indicate a predominantly terrestrial paleoenvironment marked by rainforest vegetation. From the <em>δ</em>¹⁵N_TN values, it appears that symbiotic nitrogen-fixing plants served as the primary nitrogen source for the black shales, which formed in a continental marginal environment. Overall, our results suggest that the episodic incursions of the Trans-Saharan Seaway were minimal at the western flank of the basin, indicating a carbonate-starved paleoenvironment during the Late Cretaceous.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 2","pages":"Article 100492"},"PeriodicalIF":0.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037329","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":"Peridotite pyroxenite and granulite xenoliths from Cenozoic Shavaryn Tsaram volcanic center (Mongolia): New data","authors":"I.V. Ashchepkov ,&nbsp;A.A. Tsygankov ,&nbsp;G.N. Burmakina","doi":"10.1016/j.geogeo.2025.100484","DOIUrl":"10.1016/j.geogeo.2025.100484","url":null,"abstract":"<div><div>Mantle lherzolites (spinel- and garnet-bearing), megacrysts and pyroxenites from Moho and lower crust xenoliths of the Cenozoic basalts of Shavaryn-Tsaram volcanic center were newly studied by the EPMA, SEM and LA-ICP methods to define more precisely their geochemical features for genetic purposes.</div><div>Thermal conditions in sampled mantle are close to the Southeastern Australian (SEA) mantle plume geotherm in 1.2–2.5 GPa divided into three intervals according to orthopyroxene-garnet barometry. The monomineral thermobarometry for ortho-, clinopyroxenes and garnets gives wider PT range to 3.0 GPa deviating to lower temperature clusters at 2–2.4 GPa. Black megacrysts show ascending from 3.0 to 1.0 GPa trend for pyroxenes and garnet accompanied by increase of Fe# for equilibrated with olivine (Ol) from 0.15 to 35 %. The intermediate Cr-bearing transitional pyroxenites are locating between the lherzolitic and black pyroxenite trends. They are referring to the primitive or slightly depleted associations according to petrographic and trace element (TRE) compositions. According to TRE of clinopyroxenes from spinel peridotites were divided into 5 groups: primitive, slightly depleted, deeply depleted; metasomatized by light rare earth (LREE); rich-Th-U (reactions with carbonatite melt) and in addition rare garnet-bearing types. Orthopyroxenes reveal decreasing to LREE straight line REE patterns and in TRE spiderdiagrams U, Ta and high Hf peaks. Some clinopyroxenes have Sr peaks and jagged left part of multicomponent spiderdiagrams (MSD). Olivines show and concaved from Eu to Tm in spider diagrams they reveal minima in Th, Nb, Pb, Zr. The Cr- bearing amphiboles reveal slightly inclined to LREE pattern at 90–60/CI (chondrite). And garnet show LREE depleted patters from Lu at 10/CI to 0.1 for La and depleted all left part at spider diagram, The pyroxenitic clinopyroxenes have flattened REE pattern or rarely depleted in heavy (HREE) and the hump from La to Sm. They reveal minima in Zr, Hf, Sr, Pb and left part starting from Nb. Garnets in black pyroxenites have higher HREE at 80/CI (chondrite) and Hf peaks and lowered jugged left part in MSD. The clinopyroxenes from black garnets pyroxenites reveal asymmetric bell- like REE with the depleted HREE to 1/CI and middle rare earth (MREE) at 12/CI. The clinopyroxenes from plagioclase-bearing varieties show flattened REE pattern at 100–80/CI and Eu minima and the MSD for megacrystic pyroxenes. Rare mantle metasomatites contain mica or amphiboles and are LREE enriched. Peridotites from Shavaryn Tsaram have no signs of essential mantle diapirism and represent ancient MORB mantle.</div><div>Determined with LA-ICP-MS age of zircon in granulite 322 ± 8 Ma refer to rifting processes in Central Mongolia and be-modal volcanism while 42 ± 0.4 Ma to Early Cenozoic plume magmatism.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"5 2","pages":"Article 100484"},"PeriodicalIF":0.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737650","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}