Journal of Geochemical Exploration最新文献

{"title":"Fe, Cu and S isotopes as tracers of microbial reduction in the shale-hosted VMS deposits of the Iberian Pyrite Belt","authors":"S. García de Madinabeitia ,&nbsp;J. Velasco-Acebes ,&nbsp;J.I. Gil Ibarguchi ,&nbsp;G. Layne ,&nbsp;Y. Lahaye ,&nbsp;F. Molnár ,&nbsp;F. Tornos","doi":"10.1016/j.gexplo.2025.107819","DOIUrl":"10.1016/j.gexplo.2025.107819","url":null,"abstract":"<div><div>This study represents an exploration of the geochemistry of sulphide minerals from prominent shale-hosted volcanogenic massive sulphide deposits of the Iberian Pyrite Belt, including Sotiel-Migollas, Tharsis, Neves Corvo and Lousal using the non-traditional heavy stable isotopes of Fe and Cu along with the S light isotope. Sampling encompassed a diverse range of styles of mineralization, including the dominant fine-grained massive sulphides sometimes exhibiting sedimentary layering, carbonate-rich mounds dominated by sulphides-siderite and formed by the superposition of microbial mats in anoxic bottoms, underlying subseafloor feeder structures (stockworks) and disseminated pyrite within the altered host shales. The δ⁵⁶Fe_IRMM-014 values of pyrite exhibit a range from −2.62 to +2.58 ‰, while those of pyrrhotite range from −1.93 to −0.40 ‰. Chalcopyrite δ⁶⁵Cu_SRM-976 signature varies between −1.11 and + 0.95 ‰, while the measured δ³⁴S_V-CDT values fluctuate from −45.0 to +9.4 ‰ in pyrite, −6.8 to +2.1 ‰ in pyrrhotite, and − 10.1 to +6.2 ‰ in chalcopyrite. Notably, pyrite grains within massive sulphides consistently exhibit more negative and variable δ⁵⁶Fe and δ³⁴S values than those in the hydrothermally altered host shales (apart from Neves Corvo) and stockworks. These findings strongly imply that the exhalative mineralization incorporated substantial amounts of iron derived from the dissimilatory reduction of aqueous Fe⁺³, attributable to low-temperature (&lt;100–120 °C) microbial reduction and contemporaneous with biogenic sulphate reduction. Consequently, Fe in pyrite is likely inherited from both the reduced hydrothermal fluids venting on the seafloor and the microbial reduction of oxidized iron dissolved in ambient seawater. While the microbial influence on Cu isotope signatures is less evident, we infer its potential significance. Superimposed hydrothermal refining during the late percolation of hot hydrothermal fluids reveals a non-biogenic kinetic fractionation, with partial overprinting of the early mineralization and neoformation of sulphides depicting isotopically heavy δ⁵⁶Fe, δ⁶⁵Cu, and δ³⁴S signatures that are interpreted as of deep derivation.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"277 ","pages":"Article 107819"},"PeriodicalIF":3.4,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling the enrichment mechanisms of U, Re, Se and V in the Bayinqinggeli Deposit, Northern Ordos Basin through in situ mineralogical analysis","authors":"Xiao-Wen Hu ,&nbsp;Ming-Xing Ling ,&nbsp;Jian-Bing Xu ,&nbsp;Fei Xia ,&nbsp;De-Ru Xu ,&nbsp;Ya-Lun Li ,&nbsp;Xiao-Yong Yang ,&nbsp;Chao Lu ,&nbsp;Hua-Ming Li ,&nbsp;Zhen-Cheng Li ,&nbsp;Long-Hui Wang ,&nbsp;Feng Zhang ,&nbsp;Xiao-Jie Jiang","doi":"10.1016/j.gexplo.2025.107821","DOIUrl":"10.1016/j.gexplo.2025.107821","url":null,"abstract":"<div><div>The Bayinqinggeli uranium (U) deposit, located in the northern Ordos Basin, is rich in U and co-enriched with valuable elements such as rhenium (Re), selenium (Se), and vanadium (V). This study presents new data of whole-rock geochemistry, as well as in situ analysis of authigenic minerals in the Bayinqinggeli deposit using Electron Probe Microanalyzer (EPMA) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), to elucidate the enrichment mechanisms of U and associated elements in the sandstone-hosted U deposit. The clay minerals and pyrites (abbreviated as Py for classification purposes) are each categorized into two types: those associated with U mineralization (Clay1 and Py1) and those not associated (Clay2 and Py2). Rhenium is primarily hosted within clay minerals and some in U minerals. Selenium is present either as discrete minerals such as clausthalite and ferroselite, or as a lattice substitute within Py1. Vanadium is enriched in unaltered U minerals and Clay1, likely existing as lattice substitutions. Uranium predominantly occurs as coffinite that is largely cemented by ore-stage calcite, which is indicative of an alkaline, carbonate-rich ore-forming fluid. The intimate association of coffinite with iron-rich montmorillonite (FeO up to 14.14 wt%), a typically neutral-environment mineral, and their extensive replacement for the dissolved Py1 demonstrate that localized abrupt changes in redox and pH facilitate U mineralization. The dissolution of pyrite resulted in a localized acidic and reducing environment and triggered U precipitation from the ore-bearing fluids. The Bayinqinggeli deposit was controlled by multiple sources of fluids. During the ore-forming stage, the early low-temperature alkaline oxidizing fluid introduced redox-sensitive elements, including U, Re, Se, and V, into a redox transition zone, leading to their enrichment. Calcite cementation partially preserved primary U minerals from oxidation. The persistent interaction of oxidizing fluids could remobilize U minerals and extract V in permeable sandstones. During the post-ore-forming stage, changes in the sources and nature of fluids within the deposit led to increased levels of Sc, Y, and P in altered coffinite, as well as the formation of low-Se Py2 and organically derived calcite. This profound understanding on mineralization mechanism of sandstone-hosted U deposits, and occurrence of U, Re, Se, and V, is crucial for mineral exploration and resource utilization in the Ordos Basin.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"277 ","pages":"Article 107821"},"PeriodicalIF":3.4,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144189967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rb-Sr dating of pyrite, Zircon U-Pb geochronology, and Sr-Nd-Hf isotopic geochemistry of the Baiyun Au deposit in the Qingchengzi Orefield, Liaodong Peninsula, Northeast China","authors":"Peng Zhang ,&nbsp;Junchao Lü ,&nbsp;Yan Zhao ,&nbsp;Linlin Kou ,&nbsp;Wei Pang","doi":"10.1016/j.gexplo.2025.107809","DOIUrl":"10.1016/j.gexplo.2025.107809","url":null,"abstract":"<div><div>The Baiyun Au deposit (&gt;20 t/5.86 g/t) is situated in the eastern Liaodong Peninsula.</div><div>(LP). More than 68 orebodies are found in the Precambrian metamorphic rocks and include altered rock type (ART) and quartz vein type (QVT). Pyrite Rb-Sr and zircon U-Pb dating, the elements and Sr-Nd-Hf isotopic geochemical data, and trace element contents of pyrite are adopted to control the ore genesis, petrogenesis, and the tectonic dynamics background of the Baiyun Au deposit. Isotopic chronology reveals that the magmatism can be divided into the Late Triassic (226–216 Ma), the Middle Jurassic (164.4 ± 0.4 Ma), and the Early Cretaceous (129.0–95.0 Ma). The 218.6 ± 0.4 Ma, which is obtained by pyrite Rb-Sr dating, represents the ore-forming age of the Baiyun Au deposit. Geochemically, the granite porphyry is enriched in K, Rb, and light rare earth elements (LREEs), and depleted in Nb, Ti, Ta, P, and heavy rare earth elements (HREEs), which belong to metaluminous adakite rocks. In addition, the initial ⁸⁷Sr/⁸⁶Sr ratios of the granite porphyry are between 0.71053 and 0.71141, the εNd(<em>t</em>) values and two-stage model ages (TDM₂) of granite porphyry range from −17.9 to −17.1 and 2.458 to 2.387 Ga, respectively. Its εHf(<em>t</em>) values and TDM₂ range from −14.46 to −12.48 and 2.159 to 2.054 Ga, respectively. Therefore, we proposed that the granite porphyry may be derived from ancient crustal sources. The quartz porphyry is enriched in Pb, K, Sr, and LREEs, and depleted in Ti, Nb, P, Ta, and HREEs, which belongs to the high-K Cal-alkaline and metaluminous to weakly peraluminous series. The initial ⁸⁷Sr/⁸⁶Sr ratios of quartz porphyry are between 0.71537 and 0.71690, εNd(t) values are between −17.1 and − 15.6, TDM₂ values are between 2.405 Ga and 2.295 Ga, and its εHf(<em>t</em>) values range from −17.58 to −14.07, TDM₂ ages range from 2.262 to 2.159 Ga, suggesting that the quartz porphyry mainly derived from ancient crustal sources. Three generations of pyrite (PyI, PyII, and PyIII) are identified. PyI and PyII occur in the first and second stages, respectively, and Py III occurs in schist (host strata). Py II has higher Au concentrations than Py I and Py III, indicating that gold is mainly deposited in the second stage. The pyrite has a medium-high proportion of Co and Ni, indicating a mixed fluid of magmatic water and other fluid origins. Combined with regional tectonic evolution, we classified the Baiyun Au deposit as a Late Triassic intrusion-related gold deposit. The Baiyun gold deposit and Late Triassic intrusions were formed during the Yangtze Craton (YC) subducted beneath the North China Craton (NCC). The rocks that formed during the Middle Jurassic and the Early-Late Cretaceous may be related to the subduction of the Paleo-Pacific Plate.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"277 ","pages":"Article 107809"},"PeriodicalIF":3.4,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144189871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distribution and speciation of uranium in pristine Tethyan phosphorites, Ionian Zone, Albania: Insights from synchrotron XRF/XANES analyses","authors":"Ayetullah Tunc ,&nbsp;Yakup Çelik ,&nbsp;Ana Fociro ,&nbsp;Reza Deevsalar ,&nbsp;Xinyi Wang ,&nbsp;Viorica F. Bondici ,&nbsp;Renfei Feng ,&nbsp;Ning Chen ,&nbsp;Yuanming Pan","doi":"10.1016/j.gexplo.2025.107808","DOIUrl":"10.1016/j.gexplo.2025.107808","url":null,"abstract":"<div><div>Tethyan phosphorites are globally the most important source of phosphate fertilizers and occasionally contain elevated contents of uranium (U) and rare-earth elements (REE). Extensive research has been conducted to elucidate Tethyan phosphorite occurrences, geochemistry, and formation mechanisms. However, the distribution and primary speciation of uranium in Tethyan phosphorites, during sedimentation and early diagenesis, remain unclear due to the scarcity of pristine phosphorites. This contribution integrates field and laboratory studies of Tethyan phosphorites of the Ionian Zone from Albania, including petrography, paragenetic relationships, chemical compositions, and bulk and microbeam synchrotron U <em>L</em>₃-edge X-ray absorption near-edge structure (XANES) and microbeam synchrotron X-ray fluorescence (μsXRF) mapping. These data provide a molecular-level understanding of the distribution, speciation, and enrichment mechanisms of uranium in pristine (primary) phosphorites. The phosphorites in the Ionian Zone of Albania occur as stratiform beds reaching several meters thick, lateral extension of up to 200 m, and U concentrations of up to 210 ppm. The phosphorites show three stages of mineral assemblages: primary mineralization dominated by carbonate-rich fluorapatite, organic matter, and phosphatized thin bivalve shells; followed by vein-filling calcite and pyrite; and finally, pyrite oxidation to iron oxides during surface weathering. The μsXRF mapping reveals positive correlations between U vs. P, S, and Sr, while bulk and microbeam U <em>L</em>₃-edge XANES data indicate dominant U⁴⁺ species in carbonate-rich fluorapatite. The results collectively suggest that uranium occurs as U⁴⁺ in pristine carbonate-rich fluorapatite, formed in a low-energy, oxygen-minimum marine environment. These findings not only enhance our understanding of the formation mechanisms of uranium-bearing Tethyan phosphorites but also provide a baseline for determining uranium enrichment mechanisms in marine phosphorites worldwide.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"277 ","pages":"Article 107808"},"PeriodicalIF":3.4,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144185666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry of trace elements of pyrite and its implications in intermediate sulfidation epithermal systems: Case study based on the Zhengguang Au–Zn deposit, North-East China","authors":"Zhang-Wei Qin ,&nbsp;Le Wang ,&nbsp;Ke-Zhang Qin ,&nbsp;Guang-Ming Li ,&nbsp;Sheng-Chao Xue ,&nbsp;Guo-Xue Song","doi":"10.1016/j.gexplo.2025.107810","DOIUrl":"10.1016/j.gexplo.2025.107810","url":null,"abstract":"<div><div>With the growing interest in intermediate sulfidation epithermal deposits, the mineral geochemistry of pyrite (FeS₂), the main gold-bearing mineral, has received increasing attention. This study integrates detailed petrographic analysis and in situ laser ablation inductively coupled plasma mass spectrometry–based trace element measurements of pyrite grains from the Zhengguang intermediate sulfidation epithermal Au<img>Zn deposit (Au &gt; 13.23 Mt @ 2.59 g/t, Zn &gt; 7.08 Mt @ 1.05 wt%, Ag &gt; 7.09 Mt @ 12.03 g/t). This deposit is located in the southeastern part of the Duobaoshan orefield in the eastern part of the Central Asian Orogenic Belt. This study aims to comprehensively characterize the behaviour of typical trace elements (e.g., Te, Co, Ni) during ore-forming processes and to derive insights into the fluid evolution. Three ore stages and corresponding pyrites are identified in the Zhengguang deposit: early porphyry stage (Py1), epithermal mineralized stage (Py2), and late deformed-stage (Py3). The ratios of certain trace elements (e.g., Ag/Co, Se/Te) and micro-textures of pyrite and coexisting gangue minerals suggest that early porphyry pyrites (Py1) are generally euhedral, pristine, and trace-element-poor, suggesting formation under relatively steady gentle boiling conditions and crystallization under a dominant magmatic fluid. Epithermal pyrites (Py2) are mainly porous and inclusion-rich and display elevated concentrations of trace elements, indicating rapid crystallization driven by vigorous boiling events and the addition of meteoric fluids. Compared with early pyrite and epithermal pyrite, late-stage pyrite (Py3) exhibits significant changes in several elements (Se, Te, As, Tl, and Au), indicating that the entire ore zone of the Duobaoshan orefield underwent regional metamorphism. This research clarifies the evolution processes of Au-rich fluids in the intermediate sulfidation epithermal system, and the outcomes can facilitate the exploration of epithermal deposits.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"277 ","pages":"Article 107810"},"PeriodicalIF":3.4,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144195134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stream sediment and soil geochemistry of the largest volcanogenic massive sulfide deposit in Türkiye, Karaburun deposit (Central Pontides)","authors":"Buğra Çavdar ,&nbsp;Kurtuluş Günay ,&nbsp;Halim Mutlu","doi":"10.1016/j.gexplo.2025.107816","DOIUrl":"10.1016/j.gexplo.2025.107816","url":null,"abstract":"<div><div>The recently discovered and potentially economic Karaburun deposit stands out as the largest VMS deposit in Türkiye, with a geological resource of ~125 Mt. at 1.16 wt% Cu, 0.25 wt% Zn, and 0.05 wt% Co. The pelitic-mafic type mineralization occurs within the low-grade greenschist facies metamorphic rocks in the Central Pontides Orogenic Belt. It is associated with volcaniclastic, clastic detrital sedimentary, and deep marine sedimentary rocks and cross-cutting submarine mafic dikes and/or sills. This study reports the statistical evaluation of stream sediment and soil geochemistry surveys, providing a well-documented example of preliminary surficial geochemical studies prior to the discovery of the Karaburun mineralization. Statistical analysis of 166 stream sediment samples shows that copper is the most reliable indicator of potential mineralization. Soil sampling was subsequently conducted in the source area of Cu anomalies, and a total of 2306 samples were collected. Both the median-median absolute deviation and the concentration-number (C<img>N) fractal methods yielded reliable results in determining spatial distributions; however, the fractal method provided more robust threshold values. The positive moderate to strong correlations between As–Pb–Zn and Cu–Zn–Bi indicate that these elements can be used to determine potential areas exhibiting anomalies. The distribution of selected elements in the “B” soil horizon is mostly consistent with the gossan formation. Anomalies in Cu, Zn and Co as the best indicator and pathfinder elements suggest weathering processes through pre-existent outcropping mineralized zones. The weathering, oxidation, and possibly erosion in the upper section of pre-existing Pb-enriched mineralization may have caused some Pb enrichments and local anomalies. Bismuth has been highlighted for the first time in soil geochemistry studies in the Central Pontides and could serve as a pathfinder element. However, structural features largely control the spatial distribution of elements and gossan zones; therefore, physical dispersion should also be considered alongside geochemical patterns. Factor analysis was applied to samples from Cu- and Zn-dominant zones identified through anomaly maps. The extracted factors collectively indicate associations with immobile elements during weathering processes, mineralization content, mafic volcanic or volcaniclastic rocks, and absorption onto Fe-oxides or newly formed compounds. Finally, we applied the robust weathering index, which indicates temperate climatic conditions during the weathering processes.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"277 ","pages":"Article 107816"},"PeriodicalIF":3.4,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144189968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the effects of Fe/Al on the distribution and fate of rare earth elements during the mixing of acid mine drainage with karst river water","authors":"Yuanyuan Yang ,&nbsp;Shichan Qin ,&nbsp;Qingguang Li ,&nbsp;Pan Wu ,&nbsp;Xuexian Li","doi":"10.1016/j.gexplo.2025.107813","DOIUrl":"10.1016/j.gexplo.2025.107813","url":null,"abstract":"<div><div>The geochemical behavior of rare earth elements (REEs) in acid mine drainage (AMD) has been extensively studied. However, the transport and fate of REEs during rapid mixing of AMD with karst river water (KRW), along with the factors influencing this process, remain uncertain. This study aimed to characterize the effects of hydrochemical parameters, particularly Fe and Al, on the distribution and fate of REEs in typical AMD-affected karst watersheds in northern Guizhou, China using geochemical modeling and structural equation modeling (SEM), Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). The results showed that the pH of AMD was as low as 2.77, with the highest concentrations of Fe, Al and REEs were 428.50 mg/L, 57.68 mg/L and 2948.69 μg/L, respectively. When normalized to the North American Shale Composite (NASC), AMD samples exhibit enrichment patterns of MREEs (E_MREE = +0.17 to +0.28). The results of the SEM revealed that Fe had a direct negative impact on REEs (β = −0.25). Raman spectroscopic analysis confirmed the presence of sulfate minerals (coquimbite and melanterite) and Fe-bearing phases (hematite) in the sediments. TEM and SEM-EDS analysis detected the presence of Fe-containing minerals (e.g., jarosite and goesite) in the sediments, indicating that REEs migration in AMD is predominantly controlled by Fe-phase minerals. After the rapid mixing of AMD and KRW, the pH increased to above 5, and a sharp decrease in the concentration of REEs in the water was observed. SEM analyses revealed that Al had a direct positive effect on the concentration of REEs (β = 0.90), while the effect of Fe was not obvious. The detected Al-/Fe-phase minerals (e.g., coquimbite, jarosite) in sediments and the mineral saturation indices (SI) indicated the precipitation tendencies for both phases, with Al-phases being dominant. This suggests that Al-phase play a crucial role in the distribution and migration of REEs. Through processes such as adsorption and co-precipitation, REEs are transferred to the sediments, ultimately leading the mixed water to exhibit a trend of LREEs enrichment. The findings from this research will enhance our understanding of the geochemical dynamics of REEs within the distinctive environmental context of karst watersheds influenced by AMD.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"277 ","pages":"Article 107813"},"PeriodicalIF":3.4,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144213331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Traceability of hydrological cycle in a closed inland lake basin: Insights from triple isotopes (δ2H, δ18O, δ17O)","authors":"Xiaohui Ren ,&nbsp;Ruihong Yu ,&nbsp;Shen Qu ,&nbsp;Tingxi Liu ,&nbsp;Limin Duan ,&nbsp;Ruixiang Liu","doi":"10.1016/j.gexplo.2025.107817","DOIUrl":"10.1016/j.gexplo.2025.107817","url":null,"abstract":"<div><div>Water stable isotopes are powerful tools for tracing hydrological cycle in lake basins, especially the triple isotopes (δ²H, δ¹⁸O, and δ¹⁷O). However, the application of the triple isotopes has lagged because δ¹⁷O was long considered invariant, too difficult to measure, or redundant to δ¹⁸O. The spatio-temporal variations of the triple isotope compositions in different water bodies within closed inland lake basins and their indications for hydrological cycle are still poorly documented. This study investigated the water sources, evaporation, and surface water-groundwater interactions in the Daihai Lake basin (a typical closed inland lake basin in northern China), based on the δ²H, δ¹⁸O, δ¹⁷O, d-excess, and ¹⁷O-excess in groundwater, spring water, river water, and lake water during the dry and wet seasons. The stable isotopes in river water and lake water were more enriched, while those in groundwater and spring water were more depleted. The atmospheric precipitation controlled by the westerlies and the East Asian summer monsoon is the main recharge source of the water bodies, but they were affected by evaporation after receiving recharge and showed seasonal variations. Under the influence of hydrogeological conditions, groundwater in the area around Daihai Lake (groundwater discharge area) occurred greater evaporation in the wet season, while the lake water had a large evaporation in the dry season under the effect of climatic conditions. The evaporation to inflow ratio (E/I) of Daihai Lake was 0.68 and 1.53 during the dry season and wet season, respectively, which proves that evaporation dominated the water loss from the lake. Additionally, there are close surface water-groundwater interactions in the study area, especially lacustrine groundwater discharge. This study provides deeper and more comprehensive insights into the application of the triple isotopes in the hydrological cycle, and contributes to improving the understanding of regional hydrological processes and water transport patterns.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"277 ","pages":"Article 107817"},"PeriodicalIF":3.4,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144185665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New method to sequential thermal extract of fluid inclusion water associated with overprinted mineral deposits","authors":"Paula Montoya-Lopera ,&nbsp;Gilles Levresse ,&nbsp;Elisa Fitz-Díaz ,&nbsp;Edith Cienfuegos-Alvarado ,&nbsp;Francisco Otero-Trujano ,&nbsp;Pedro Morales-Puente","doi":"10.1016/j.gexplo.2025.107812","DOIUrl":"10.1016/j.gexplo.2025.107812","url":null,"abstract":"<div><div>The importance of fluid inclusions (FI) as a geological record of the fluid inventory of the earth's crust is current widely recognized. Less accepted, however, is their reliability in providing unequivocal information on the isotopic chemistry of the fluids. Such uncertainties are fully justified since the quantitative analysis of FI presents several technical issues. For example, the use of a small amount of water, typically &lt;30 μL, which could lead to errors. Also, it is unusual to find geological materials that contain only one FI generation. The study of multiple populations of inclusion offers an exciting insight into changes in fluid activity. The existence of multiple generations of FI complicates bulk sample analysis methods and led to data interpretation bias. To avoid these issues, we created a new method to identify multiple or particular hydrothermal events. We used data from a world-class silver‑gold multi-event (San Dimas District, Sierra Madre Occidental, Mexico) to describe this sequential thermal extraction method, that allows: (i) estimate decrepitation temperature range for multiple or particular FI generation, (ii) extract FI water for multiple or particular FI generations, and (iii) analyze δ¹⁸O and δ²H of trapped water from multiple generations. Our findings demonstrate that obtained δ¹⁸O and δ²H results of FI water of quartz crystals are reproducible and consistent with geological and geochemical contrasts on the different paragenetic events.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"277 ","pages":"Article 107812"},"PeriodicalIF":3.4,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discrimination of carbonatite and Mississippi Valley-type deposits by partial least squares-discriminant analysis of trace elements and Mg isotope compositions in dolomite","authors":"Daisuke Araoka ,&nbsp;Keita Itano ,&nbsp;George J. Simandl ,&nbsp;Suzanne Paradis ,&nbsp;Toshihiro Yoshimura","doi":"10.1016/j.gexplo.2025.107811","DOIUrl":"10.1016/j.gexplo.2025.107811","url":null,"abstract":"<div><div>Carbonatite-related rare earth element (REE), Nb, fluorite, and phosphate deposits and Mississippi Valley-type (MVT) deposits containing Zn, Pb, Ag, and Ge are increasingly important sources of critical metals and minerals. Geochemical classification of carbonatite-related and MVT deposits using chemical compositions of dolomite, the most common gangue mineral in such deposits, is potentially useful for tracing the deposit types and assisting in mineral exploration. Here, we studied variations in elemental contents (42 elements) and δ²⁶Mg of dolomite from deposits in the eastern Canadian Cordillera, where carbonatite-related and MVT deposits coexist, to examine its usefulness for geochemical discrimination.</div><div>Our dataset showed systematic differences between carbonatite and MVT deposits: dolomites from carbonatites were enriched in Fe, Ga, Sr, As, Ba, REEs, and Th and had high δ²⁶Mg values, whereas dolomites from MVT deposits were enriched in Zn and Pb, but there were obvious overlaps. We developed an accurate discrimination model by performing a partial least squares regression-discriminant analysis (PLS-DA) that considered all variables simultaneously. The results of PLS-DA showed that two components were sufficient for accurate classification of dolomites from the two deposit types in the study area in comparison with the results of principal component analysis and liner discriminant analysis (PCA-LDA). The δ²⁶Mg, Sr/Mg, Zn/Mg, Ba/Mg, and Pb/Mg yielded the highest variable importance on projection (VIP) scores, which is consistent with the geochemical parameters expected from previous studies on carbonatites and MVT deposits. Furthermore, we applied the developed discrimination model to a dataset of dolomite from other deposit (Rock Canyon Creek deposit) and unmineralized dolomite from the host rocks. The dolomites from the Rock Canyon Creek deposit were classified as carbonatite-related deposits, consistent with recent research, although their elemental signatures differ greatly from those of typical carbonatite-related deposits. The unmineralized dolomite plotted separately from the mineralized dolomite samples in the PLS-DA score plots. Our results suggest that PLS-DA score plots of dolomite chemistry are useful for classifying deposit types and probably applicable to exploration for critical metals and minerals associated with carbonatite-related and MVT deposits.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"278 ","pages":"Article 107811"},"PeriodicalIF":3.4,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144222811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}