Geosystems and Geoenvironment最新文献

{"title":"Critical metals: Their mineral systems and exploration","authors":"Daniel Müller , David I. Groves , M. Santosh , Cheng-Xue Yang","doi":"10.1016/j.geogeo.2024.100323","DOIUrl":"10.1016/j.geogeo.2024.100323","url":null,"abstract":"<div><div>Complex geological formation processes under a variety of tectonic regimes have led to a heterogeneous global distribution of the critical metal resources that will be increasingly in demand due to Net Zero and the clean energy transition. Although brownfield exploration around existing mines can add to inventories of some critical metals, including copper in the short to medium term, all mines have a finite life with many historical giants already exhausted. Therefore, without a revolution in metal recycling, successful global greenfield exploration is of key importance.</div><div>If greenfield exploration is to supply a significant proportion of critical metals to meet future supply for a sustainable economic future, it is imperative that superior conceptual models are employed for initial ground selection. This requires an understanding of the critical components of the wide variety of metallic mineral systems that contain these critical metals and their temporal distribution and tectonic settings. Greenfield exploration faces numerous challenges as new discoveries are commonly concealed by younger sedimentary cover and they occur in increasingly remote terrains and at greater depths, resulting in declining discovery rates despite rising budgets.</div><div>Some mineral systems have high preservation potential and are distributed within well-established temporal ranges in Earth history. These systems include orogenic gold, VMS-type Cu-Pb-Zn, intrusion-hosted Ni-Cu±PGE, carbonatite REE, and SEDEX, MVT, Broken Hill-type, and Zambian-type base-metal systems. Understanding the temporal range and tectonic setting of such critical mineral systems aids conceptual targeting to define new exploration spaces. However, many of the Precambrian critical mineral deposits within these systems are now situated in subdued topography and have experienced regolith development such that they have thick cover ranging from desert sands to thick complex regolith, to glacial till. All scenarios represent technical and financial challenges in terms of successful exploration using increasingly sophisticated remote sensing, geophysical, and geochemical survey methodologies.</div><div>A contrasting conceptual targeting scenario is provided by critical mineral systems that formed in convergent margin arc settings or in marginal terrestrial sedimentary basins. These include widespread porphyry-skarn Cu-Au-Mo systems, both high- and low-sulfidation epithermal Au-Ag systems, and more geographically restricted IRGD and Carlin-type systems. Where tectonic uplift rates are high, critical metal deposits of these systems are rapidly eroded and have low preservation potential and hence are largely confined to the Cenozoic with only rare systems beyond the late Mesozoic. Conceptual exploration is less challenging for this group as they are commonly situated in mountainous terrains where remote sensing spectral surveys are effective and deposit footprints are large due to v","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 1","pages":"Article 100323"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143131630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal impact of particulate matter exposure on urinary health of mine workers in iron ore mining environment","authors":"Vibhanshu Vaibhav Singh ,&nbsp;Aron Rodrick Lakra ,&nbsp;Sneha Gautam","doi":"10.1016/j.geogeo.2024.100342","DOIUrl":"10.1016/j.geogeo.2024.100342","url":null,"abstract":"<div><div>Exposure to particulate matter (PM) in opencast iron ore mines poses a significant health risk to mine workers, particularly impacting urinary health. This study specifically examines how mining activities influence urinary parameters in employees, with a focus on how seasonal variations – such as shifts between monsoon and winter – intensify these effects. Through real-time analysis of air pollutants including PM₁, PM_2.5, PM₁₀, CO₂, and HCHO, we captured critical seasonal fluctuations in pollutant concentrations across different mining departments.</div><div>Urine samples from workers in diverse departments were rigorously analyzed for glucose levels, elemental concentrations, and other health indicators. Advanced regression and correlation analyses revealed strong associations between urine markers and PM exposure, with exceptionally high R² values across departments: 0.984 for excavation, 1.000 for crushing, 0.969 for downhill, 0.963 for screening, and 0.992 for loading, indicating a precise relationship. Low mean squared error (MSE) and root mean squared error (RMSE) values further underscored the model's predictive accuracy. Seasonal variations showed a clear impact on exposure levels, with the overall relevance percentage between monsoon and winter seasons approximating 39.24%, underscoring the added health burden during seasonal transitions. The results indicate that workers' health is clearly affected by exposure to mining-related air pollutants, as shown by the urine analysis, which revealed elevated levels of occupationally relevant elements. These findings highlight the need for proactive air quality monitoring and targeted mitigation strategies in mining environments to protect worker health, offering critical insights for policymakers and occupational health professionals focused on improving safety standards in mining operations.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 1","pages":"Article 100342"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploration of quality groundwater through lineament delineation in Okene and its surroudings","authors":"Oluwatoyin Khadijat Olomo,&nbsp;Onimisi Abdulmalik Danga,&nbsp;Abdullateef O. Aliyu","doi":"10.1016/j.geogeo.2024.100350","DOIUrl":"10.1016/j.geogeo.2024.100350","url":null,"abstract":"<div><div>This research addresses the issue of unproductive boreholes in the study area and the limited information on productive aquifers. The challenging geological terrain and dense urbanization necessitate the use of integrated airborne data, namely Landsat remote sensing, geographic information systems, and aeromagnetic data, to map potential groundwater zones in Okene and its surrounding areas. The analysis utilizes remote sensing and geospatial datasets, which are slope, drainage density, and lineament density, along with aeromagnetic data interpretation. Techniques employed are first and second-order derivatives, tilt derivative, and total horizontal derivative to identify groundwater productive zones. Observations of remotely sensed lineaments indicate intersections with aeromagnetic composite lineaments, suggesting the presence of shallow and deeper lineaments in proximity. These intersection points are identified as potential zones for groundwater accumulation and development due to their characteristics of secondary porosity and high permeability. The depth to the aquiferous zone, as determined by 3-D Euler deconvolution and spectral analysis, ranges from 60 to 150 m, which is proposed as the depth for borehole drilling in the study area. The central and southeastern regions of the study area exhibit higher groundwater potential because of the high density of lineament intersection and are recommended for future groundwater development. This study illustrates the effectiveness of geospatial and aerogeophysical techniques in regional groundwater exploration to provide insights into subsurface structural disposition for locating aquiferous zones and improving groundwater management.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 1","pages":"Article 100350"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143131356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"College bus commuter exposures to air pollutants in Indian city: The urban-rural transportation exposure study","authors":"Aron Rodrick Lakra ,&nbsp;Sneha Gautam ,&nbsp;Cyril Samuel ,&nbsp;Robert Blaga","doi":"10.1016/j.geogeo.2024.100346","DOIUrl":"10.1016/j.geogeo.2024.100346","url":null,"abstract":"<div><div>This study analyzes air quality along the Kavundampalayam transit route and across three urban regions in Coimbatore, India – Kavundampalayam, Ganapathy and Kovaiputhur – over five days during morning and evening commutes. Key pollutants monitored include PM₁, PM_2.5, PM₁₀, CO₂, formaldehyde (HCHO), and the Air Quality Index (AQI). Results show that PM_2.5 levels often exceeded the WHO's 24-hour limit, with Kovaiputhur peaking at 120.33 µg/m³ and PM₁₀ concentrations reaching 259.08 µg/m³ in Kavundampalayam. CO₂ levels varied significantly, with Ganapathy recording the highest at 1942.42 ppm, indicating traffic and industrial sources. Morning commutes exhibited higher PM levels due to vehicular emissions, while evenings showed reduced pollution. HCHO concentrations, though low (&lt;0.023 mg/m³), spiked in the evenings, suggesting emission sources later in the day. A strong correlation between CO₂ and AQI underscores the impact of anthropogenic activities on air quality. The study identifies pollution hotspots using heatmaps and temporal patterns, emphasizing the need for interventions like emission control, dust regulation, and green infrastructure. Continuous air quality monitoring is essential for sustainable urban planning, helping policymakers design strategies to reduce exposure risks and improve public health.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 1","pages":"Article 100346"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143131371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heavy metal (Pb, Cd and Cr) contamination and human health risk assessment of groundwater in Kuakata, southern coastal region of Bangladesh","authors":"Ali Newaz Chowdhury ,&nbsp;Samsun Naher ,&nbsp;Md. Nur Alam Likhon ,&nbsp;Jubairul Hassan ,&nbsp;Zannati Nur Fariha ,&nbsp;Md. Raisul Hasan ,&nbsp;Tanha Dewan Apon ,&nbsp;Md. Anwar Hossain Bhuiyan ,&nbsp;Md Mesbah Uddin Bhuiyan","doi":"10.1016/j.geogeo.2024.100325","DOIUrl":"10.1016/j.geogeo.2024.100325","url":null,"abstract":"<div><div>This study investigates the quality of groundwater in Kuakata, a coastal area in southwestern Bangladesh, by analyzing the levels of lead (Pb), cadmium (Cd), and chromium (Cr) in 50 groundwater samples. The concentrations of these heavy metals were determined using atomic absorption spectrometry. The results indicated that while cadmium was not detected, significant levels of lead and chromium exceeded recommended safety thresholds. The contamination was evaluated using several indices, including the heavy metal evaluation index (HEI), heavy metal pollution index (HPI), and degree of contamination (C_d). Health risk assessments for adults and children revealed potential non-carcinogenic and carcinogenic risks, particularly from lead. This study provides essential data to guide groundwater management and improve public health in the region. The groundwater samples contain traces of additional heavy metals including lead and chromium. The lead concentration ranges from 0.0003 to 0.1049 mg/L, while chromium ranges from 0.00074 to 0.1828 mg/L. The levels of certain substances in groundwater exceeded the maximum limit set by international and local health authorities for safe drinking water. Heavy metal evaluation index (HEI), along with the degree of contamination (C_d) and heavy metal pollution index (HPI), were used to assess the pollution load. The results of HEI and HPI revealed that a significant portion of the samples in the study area, specifically 34% and 38%, were found to be strongly and seriously affected, whereas 38% samples were within the highest values (&gt;4) of C_d. Based on the hazard index (HI) and incremental lifetime cancer risk (ICLR) values, the deep groundwater in the coastal area presents a notable health risk to the local population, particularly children. This study provides essential data that can be used as a foundation for developing effective groundwater management strategies in the coastal region, with the ultimate goal of ensuring the availability of safe drinking water.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 1","pages":"Article 100325"},"PeriodicalIF":0.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143131366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geospatial assessment of soil erosion in the Basantar and Devak watersheds of the NW Himalaya: A study utilizing USLE and RUSLE models","authors":"Ajay Kumar Taloor ,&nbsp;Varun Khajuria ,&nbsp;Gurnam Parsad ,&nbsp;Shikha Bandral ,&nbsp;Sugandha Mahajan ,&nbsp;Sachchidanand Singh ,&nbsp;Meenakshi Sharma ,&nbsp;Girish Ch Kothyari","doi":"10.1016/j.geogeo.2025.100355","DOIUrl":"10.1016/j.geogeo.2025.100355","url":null,"abstract":"<div><div>Soil erosion poses a substantial threat to environmental and human sustainability, intensified by anthropogenic interference, climate fluctuations, and socio-economic modifications. This study presents a meticulous and systematic analysis of soil erosion within the Basantar and Devak watersheds of the north-western Himalaya, employing geospatial technologies integrated with the USLE (Universal Soil Loss Equation) and RUSLE (Revised Universal Soil Loss Equation) modeling techniques. To derive the USLE and RUSLE based soil loss, various equation-based parameters such as rainfall (R), length slope factor (LS), cover management (C), conservation practice factor (P), and slope erodibility factor (K) were derived to assess the spatial soil loss in the study area. Based on both model outputs spatial maps have been derived in the Geographic Information System (GIS) platform to determine the soil loss in the study area. The results have been classified into five categories: very high, high, medium, low, and very low areas of soil erosion. Further, the analytical approach also involved the derivation of various satellite data-based soil indices to juxtapose remotely sensed soil loss results, enabling a more detailed understanding of soil loss dynamics in the watersheds. The comprehensive analysis demonstrated the practicality of the employed models in formulating geospatial soil erosion databases, aiding future research, planning, conservation strategies, and climate impact assessment, therefore, laying a foundation for informed environmental decision-making and sustainable land-use practices. The multifaceted exploration of soil erosion in the Basantar and Devak watersheds through intricate modeling and geospatial technologies accentuates the study's significance in advancing soil conservation research, and the potential applications of these models in varied environmental contexts.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100355"},"PeriodicalIF":0.0,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predicting urban landslides in the hilly regions of Bangladesh leveraging a hybrid machine learning model and CMIP6 climate projections","authors":"Md․ Ashraful Islam ,&nbsp;Musabbir Ahmed Arrafi ,&nbsp;Mehedi Hasan Peas ,&nbsp;Tanvir Hossain ,&nbsp;Md Mehedi Hasan ,&nbsp;Sanzida Murshed ,&nbsp;Monira Jahan Tania","doi":"10.1016/j.geogeo.2025.100354","DOIUrl":"10.1016/j.geogeo.2025.100354","url":null,"abstract":"<div><div>Landslides pose significant risks to infrastructure and human lives in cities, exacerbated by climate change. Therefore, a reliable predictive landslide model is crucial for mitigation, especially in resource-limited nations. This study employs hybrid machine learning (ML) techniques and climate projections to predict landslides in the Chattogram development area (CDA) of Bangladesh – a rapidly growing urban city in Bangladesh. The model was trained using diverse geospatial parameters including topographical, hydrological, soil, and geological parameters, along with an updated landslide inventory, enabling spatially explicit predictions of landslide susceptibility. To incorporate future climate scenarios, we utilized the Coupled Model Intercomparison Project Phase 6 (CMIP6) Global Climate Model (GCM), projecting climate impacts under SSP1-2.6 and SSP5-8.5 scenarios for the periods of 2021–2040, 2041–2060, 2061–2080, and 2081–2100, respectively. These scenarios reflect different pathways of greenhouse gas emissions, providing a range of possible future climate conditions. We tested six ML classifiers: random forest (RF), extra trees (ExT), support vector machine (SVM), logistic regression (LR), Bernoulli Naïve Bayes (bNB), and K-nearest neighbor (KNN). Each base model demonstrated high accuracy (&gt;90 %) but combining them improved both accuracy and computational efficiency. The LR-bNB hybrid model outperformed all others, effectively mapping landslide susceptibility in the study area for the current timeframe and future projections. Our results revealed significant variability in landslide-prone areas across the area, with 12 % of the region categorized as high to very high risk, a figure that slightly rises with predicted increased rainfall due to climate change. The present study demonstrates the efficacy of a hybrid ML model for nowcasting as well as forecasting landslide susceptibility under future climate scenarios. These findings offer valuable insights for proactive risk management and infrastructure planning in the CDA, helping to safeguard communities and improve resilience against future landslide events.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"4 2","pages":"Article 100354"},"PeriodicalIF":0.0,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Composition of olivines and spinel group minerals in aillikites from the Bushkanay dyke, South Siberian Craton: Insights into alkaline melt sources and evolution","authors":"Yazgul Nugumanova ,&nbsp;Anna Doroshkevich ,&nbsp;Anastasia Starikova ,&nbsp;Jonathan Garcia","doi":"10.1016/j.geogeo.2023.100247","DOIUrl":"10.1016/j.geogeo.2023.100247","url":null,"abstract":"<div><div>The potential sources and conditions that control the formation and evolution of alkaline melts are far from being fully understood. To address some of these fundamental questions, we have focused on the composition of olivines and spinel group minerals in aillikites from the Bushkanay dyke in the Siberian Craton. These ultramafic carbonate-rich lamprophyres contain 40–50 vol% fresh olivine macrocrysts (200–600 µm) within a groundmass consisting of phlogopite (60%), magnetite (15%), perovskite (10%), apatite (5%), calcite (3%), chromite (1%), clinopyroxene (up to 1%), barite (up to 1%), serpentine and chlorite (up to 4%). Two types of compositional zoning in olivine have been recognized: (1) Mg-rich cores consisting of a relatively high #Mg (86-89) and NiO (0.25–0.4 wt%); (2) Fe-rich cores with a relatively low #Mg (82-86) and NiO (0.10–0.25 wt%). Both types of olivine cores are igneous and crystallize from an ultramafic carbonate-rich melt. The Mg#-poor (Fe-rich) cores were derived from an early and more evolved aillikitic melt and were later entrained by a more primitive melt, responsible for the formation of the Mg#-rich (Mg-rich) cores. The spinels exhibit a more complex zoning with four major growth zones: (1) an aluminum chromite core; (2) an Fe-chromite and Cr-magnetite transitional zone; and (3) a Ti-magnetite rim. The most primitive spinels of Al-chromite compositions crystallized directly from undifferentiated pulse of the melt, while further growth involved a gradual decrease in Cr due to the crystallization of Cr-rich spinels, while Al remained the same due to the absence of early phlogopite. Our results on olivines and spinels suggest that the aillikites of the Bushkanay dyke were derived from a phlogopite-bearing carbonatized peridotite source. This idea is also supported by the presence of phlogopite, calcite, and amphibole as major phases in the chromite melt inclusions.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"3 4","pages":"Article 100247"},"PeriodicalIF":0.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138991160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical evolution of major and minor minerals in rocks of the Arbarastakh complex (Aldan shield, Republic of Sakha, Yakutia)","authors":"Mikhail Nikolaevich Kruk ,&nbsp;Anna Gennadievna Doroshkevich ,&nbsp;Ilya Romanovich Prokopyev ,&nbsp;Ivan Aleksandrovich Izbrodin","doi":"10.1016/j.geogeo.2024.100271","DOIUrl":"10.1016/j.geogeo.2024.100271","url":null,"abstract":"<div><div>The alkaline-ultrabasic carbonatite complex Arbarastakh is located in the southwestern part of the Siberian Craton. In addition to ultrabasic rocks such as pyroxenites and ijolites, various types of carbonatite dikes, phoscorites, and aillikites are present in the massif. Based on their modal and compositional characteristics, as well as the chemical composition of minerals, the rocks of the Arbarastakh complex have been divided into three groups: \"aillikite\", \"phoscorite\", and \"alkaline-silicate and carbonatite\" groups. The chemical compositions of olivines, phlogopites and spinellides indicate that aillikites are the least differentiated rocks in the complex. The compositional differences of micas from the \"phoscorite\" and \"alkaline-silicate and carbonatite\" groups support the liquation of the aillikite melt into two immiscible silicates and CPIO (carbonate-phosphate/iron-oxide-rich) melts. After liquation, for the \"phoscorite\" and \"alkaline-silicate and carbonatite\" groups, evolution follows fractional crystallization. Pyroxene-phlogopite-calcite and calcite carbonatites probably resulted from metasomatic alteration of silicate phases by apatite-dolomite carbonatites, which is confirmed by structural-textural features and the overlapping compositions of phlogopites, apatites and pyroxenes from calcite carbonatites and those from pyroxenites and ijolites.</div></div>","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"3 4","pages":"Article 100271"},"PeriodicalIF":0.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140282740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconstructions of mantle structure beneath the Anabar Shield kimberlites – Similarities and differences","authors":"Igor V. Aschepkov ,&nbsp;Sergei I. Kostrovitsky ,&nbsp;Svetlana A. Babushkina ,&nbsp;Nikolai S. Medvedev","doi":"10.1016/j.geogeo.2024.100282","DOIUrl":"10.1016/j.geogeo.2024.100282","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Comparisons of mantle xenocrysts from Lower Triassic kimberlites in the Anabar Shield (Ary-Mastakh, Dyuken, Kuranakh and Orto-Yargyn fields) have shown essential differences from the xenocrysts in the Olenek River Basin (Chomurdakh field). Xenoliths in the Anabar Shield and its northern fields are very rare; they include mainly garnet dunites and harzburgites, and less commonly, pyroxenites and eclogites.&lt;/div&gt;&lt;div&gt;PTXFO&lt;sub&gt;2&lt;/sub&gt; diagram reconstructions for the Boomerang pipe in the Ary-Mastakh field located in the suture zone of the Daldyn and Magan terranes have used monomineral thermobarometry to show that the Opx in rare lherzolitic pyropes formed between 6 and 7.5 GPa. Eclogites represent the mantle heated to the middle pyroxenite layer, and in these terranes the formation of Cr-less pyroxenites are linked to plume melt interactions with the eclogites. In the Dyuken, Kuranakh and Orto-Yargyn fields, the garnet advective trend starts from 7.5 GPa, while the asthenosphere – lithosphere boundary is found at 6 GPa, suggesting that the middle pyroxenite layer was heated and metasomatized. The lower and particularly mid-mantle parts of these fields also contain abundant eclogites. In the Chomur field, lherzolitic and pyroxenitic pyropes form from 7 GPa, while the captured materials mainly represent the upper mantle (4 GPa). All pipes show a similar mantle layering, consisting of seven parts and determined by the clustering of PT estimates for garnets, Cr-spinels, and pyroxenes. In the Boomerang pipe, the Cr-clinopyroxenes and pyropes show REE spectra with varying fan-shaped slopes, (La/Yb)n of 10–100 for pyropes, and HREE for garnets. Spider diagrams reveal peaks for Th, and troughs for U, Nb, Ta, and Pb. Eclogitic garnets and omphacites show minimum values of Eu and Nb, Ta, Zr, and Hf. REEs in ilmenites show a joint increase in LREE and HFSE for Mg to Fe-rich varieties with the degree of differentiation. Most depleted pyropes from Kuranakh have V-U shaped REE patterns, Ba and U peaks. The HFSE minima represents dunites from the arc and back-arc mantle, and the fertilization produces an increase in incompatible elements and sometimes large ion lithophile element (LILE) levels for lherzolitic pyropes. The pyroxenitic garnets display happed REE and the Cpx shows varying LILE and HFSE correlating with the (La/Yb)&lt;sub&gt;n&lt;/sub&gt;.&lt;/div&gt;&lt;div&gt;The Chomur pipe contains predominantly harzburgite-lherzolite garnets with minima Ba and Sr, in addition to various incompatible elements. Cpx shows similar variations with mainly depleted HFSE patterns. The marginal parts of the subcratonic lithospheric mantle (SCLM) of the Anabar Shield are extremely enriched in eclogitic deep-seated material. This is especially seen in the lower SCLM parts, demonstrating thermobarometric trends and features similar to the diamond inclusions from the Ebelyakh (Mayat) placers. The mantle column beneath several pipes (Los’, Universitetskaya, Kuranakh) contain Cr amphiboles","PeriodicalId":100582,"journal":{"name":"Geosystems and Geoenvironment","volume":"3 4","pages":"Article 100282"},"PeriodicalIF":0.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142704345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}