Pub Date : 2025-10-20DOI: 10.1016/j.gexplo.2025.107923
Hui Rong , Jun Zhou , Yu Zhou , Yuchen Zhang , Min Liu , Kaiyu Chang
The Changjihe Group in the northwestern Santanghu Basin can serve as a typical case for studying the uranium metallogenic regularity in arid red beds. The uranium reservoirs of the Changjihe Group comprise of red sandstone, yellow sandstone, gray mineralized sandstone, and primary gray sandstone. The red sandstone is characterized by the predominance of hematite, hydromica, and rhodochrosite, and the hematite predominantly occurs in colloidal and framboidal forms. The yellow sandstone primarily contains hematite and anatase, and the anatase is found within dissolved titanite pores and fractures. The gray mineralized sandstone is distinguished by the presence of pyrite, anatase, uranium-bearing minerals, and kaolinite. The pyrite frequently exhibits framboidal, colloidal, and euhedral granular textures, while the anatase occurs within dissolved titanite pores and fractures, often adsorbing uranium internally. The primary gray sandstone is dominated by pyrite and chlorite, and the pyrite chiefly appears as euhedral granules within biotite cleavage fissures. Uranium accumulation is fundamentally governed by redox interfaces (macro-scale) and precursor mineral reactivity (micro-scale). The redox transition zone hosts peak uranium mobility, with anomalies concentrated at advancing oxidation fronts. At the grain scale, uranium mineralization requires antecedent anatasization of titanite, wherein neoformed anatase provides a carrier for uranium enrichment. The Hanshuiquan uranium system exemplifies a tripartite control involving sedimentary architecture, epigenetic alteration, and basement unconformities. Titanite-to-anatase transformation in the mineralized sandstones emerges as a mineralization driver and indicator. These findings provide novel insights that fundamentally advance our understanding of metallogenic mechanisms and distribution patterns in sandstone-hosted uranium deposits.
{"title":"Metallogenic constraints of sandstone-hosted uranium deposits in arid red beds: A case study from the northwestern Santanghu Basin","authors":"Hui Rong , Jun Zhou , Yu Zhou , Yuchen Zhang , Min Liu , Kaiyu Chang","doi":"10.1016/j.gexplo.2025.107923","DOIUrl":"10.1016/j.gexplo.2025.107923","url":null,"abstract":"<div><div>The Changjihe Group in the northwestern Santanghu Basin can serve as a typical case for studying the uranium metallogenic regularity in arid red beds. The uranium reservoirs of the Changjihe Group comprise of red sandstone, yellow sandstone, gray mineralized sandstone, and primary gray sandstone. The red sandstone is characterized by the predominance of hematite, hydromica, and rhodochrosite, and the hematite predominantly occurs in colloidal and framboidal forms. The yellow sandstone primarily contains hematite and anatase, and the anatase is found within dissolved titanite pores and fractures. The gray mineralized sandstone is distinguished by the presence of pyrite, anatase, uranium-bearing minerals, and kaolinite. The pyrite frequently exhibits framboidal, colloidal, and euhedral granular textures, while the anatase occurs within dissolved titanite pores and fractures, often adsorbing uranium internally. The primary gray sandstone is dominated by pyrite and chlorite, and the pyrite chiefly appears as euhedral granules within biotite cleavage fissures. Uranium accumulation is fundamentally governed by redox interfaces (macro-scale) and precursor mineral reactivity (micro-scale). The redox transition zone hosts peak uranium mobility, with anomalies concentrated at advancing oxidation fronts. At the grain scale, uranium mineralization requires antecedent anatasization of titanite, wherein neoformed anatase provides a carrier for uranium enrichment. The Hanshuiquan uranium system exemplifies a tripartite control involving sedimentary architecture, epigenetic alteration, and basement unconformities. Titanite-to-anatase transformation in the mineralized sandstones emerges as a mineralization driver and indicator. These findings provide novel insights that fundamentally advance our understanding of metallogenic mechanisms and distribution patterns in sandstone-hosted uranium deposits.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107923"},"PeriodicalIF":3.3,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145362973","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}
Pub Date : 2025-10-17DOI: 10.1016/j.gexplo.2025.107922
Reneé González-Guzmán , Alejandro Rodríguez-Trejo , Sara Solís-Valdez , Luis Alejandro Elizondo-Pacheco , Zayre I. González-Acevedo , Héctor Enrique Ibarra-Ortega
Power plants and oil refineries emit a variety of harmful pollutants that pose a significant health risk to the surrounding population. Therefore, it is important to understand the source of pollution to develop indicators for effective environmental management and control the risk of exposure. Lanthanum (La) is a chemical element normally enriched in atmospheric aerosols from oil-burning residues that can be used as pollution tracer but their role as a proxy is rarely documented. This study evaluates the La enrichment in topsoils from the major industrial emission hotspot in the northern part of the Mexico City megalopolis. Twenty-seven topsoil samples and three rocks were collected. Initial characterization of the soils included the evaluation of its physical and chemical properties, such as granulometry, pHH2O (6.83–8.33), pHKCl (6.80–7.80), organic carbon (0.58–12.02 %), cation exchange capacity (17.40–80.23 cmolc/kg), and magnetic susceptibility (36.25–153.61 10−8 m3 kg−1). Soils ranged from sandy loam to silty clay. Elements analyzed by ICP-MS included potentially toxic elements (PTEs: V, Cr, Co, Cu, Ni, Zn, As, Mo, Sn, Sb, Pb), lanthanides (La → Lu), and geogenic elements (Al, Ti, Rb, Zr, Ba, Hf, Th). Both natural and anthropogenic sources influenced the geochemistry of soils in the study area. Based on statistical analyses and ternary diagrams, the enrichment of VNi is associated with atmospheric residues derived from heavy oil combustion. Magnetic susceptibility data, which are dominated by residual ferromagnetic minerals, correlate with V, Ni, Mo, and La. PAAS-normalized REE patterns mainly reflect local volcanic rock sources, but positive anomalies of La (La/La* > 1) in several samples are related to anthropogenic inputs from the industrial complex. Comparisons between La enrichment and other geochemical and geophysical pollution proxies, combined with spatial interpolation maps, indicate that La/La* is a suitable tracer to monitor soil pollution through the deposition of oil combustion residues on a local scale.
{"title":"Lanthanum anomaly as monitor of the burning of fossil fuels pollution in surface soil surrounding the industrial complex in Tula (Mexico City megalopolis)","authors":"Reneé González-Guzmán , Alejandro Rodríguez-Trejo , Sara Solís-Valdez , Luis Alejandro Elizondo-Pacheco , Zayre I. González-Acevedo , Héctor Enrique Ibarra-Ortega","doi":"10.1016/j.gexplo.2025.107922","DOIUrl":"10.1016/j.gexplo.2025.107922","url":null,"abstract":"<div><div>Power plants and oil refineries emit a variety of harmful pollutants that pose a significant health risk to the surrounding population. Therefore, it is important to understand the source of pollution to develop indicators for effective environmental management and control the risk of exposure. Lanthanum (La) is a chemical element normally enriched in atmospheric aerosols from oil-burning residues that can be used as pollution tracer but their role as a proxy is rarely documented. This study evaluates the La enrichment in topsoils from the major industrial emission hotspot in the northern part of the Mexico City megalopolis. Twenty-seven topsoil samples and three rocks were collected. Initial characterization of the soils included the evaluation of its physical and chemical properties, such as granulometry, pH<sub>H2O</sub> (6.83–8.33), pH<sub>KCl</sub> (6.80–7.80), organic carbon (0.58–12.02 %), cation exchange capacity (17.40–80.23 cmolc/kg), and magnetic susceptibility (36.25–153.61 10<sup>−8</sup> m<sup>3</sup> kg<sup>−1</sup>). Soils ranged from sandy loam to silty clay. Elements analyzed by ICP-MS included potentially toxic elements (PTEs: V, Cr, Co, Cu, Ni, Zn, As, Mo, Sn, Sb, Pb), lanthanides (La → Lu), and geogenic elements (Al, Ti, Rb, Zr, Ba, Hf, Th). Both natural and anthropogenic sources influenced the geochemistry of soils in the study area. Based on statistical analyses and ternary diagrams, the enrichment of V<img>Ni is associated with atmospheric residues derived from heavy oil combustion. Magnetic susceptibility data, which are dominated by residual ferromagnetic minerals, correlate with V, Ni, Mo, and La. PAAS-normalized REE patterns mainly reflect local volcanic rock sources, but positive anomalies of La (La/La* > 1) in several samples are related to anthropogenic inputs from the industrial complex. Comparisons between La enrichment and other geochemical and geophysical pollution proxies, combined with spatial interpolation maps, indicate that La/La* is a suitable tracer to monitor soil pollution through the deposition of oil combustion residues on a local scale.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107922"},"PeriodicalIF":3.3,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145362220","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}
Pub Date : 2025-10-16DOI: 10.1016/j.gexplo.2025.107921
Ming-Ji Zhang , Jia-Yong Pan , Yang Xu , Mostafa Fayek , Zhan-Shi Zhang , De-Hui Zhang , Cheng-Biao Leng
Tourmaline is a reliable recorder of magmatic-hydrothermal evolution and ore mineralization. Numerous investigations on tourmaline from magmatic rocks and ore deposits have been conducted, while the links between tourmaline and granite-related uranium (U) mineralization systems remain poorly understood. This paper presents data of in-situ major and trace elemental compositions of tourmaline in the U-bearing and U-barren granitic plutons from the Xiazhuang U orefield by EPMA and LA-ICP-MS. Four types of tourmalines are identified by occurrences: (1) disseminated tourmaline (D-T) in the U-barren Luxi pluton; (2) interstitial tourmaline (I-T) in the U-bearing Maofeng pluton; (3) segregational tourmaline (S-T) in the U-bearing Xiazhuang pluton and (4) tourmaline veins (V-T) (including samples from the Zhushanxia U deposit (VZ-T), the Xiwang U deposit (VX-T) and the Luxi pluton (VL-T)). Tourmaline grains from the U deposits all display “cracked” appearance under the microscope, whereas those from the U-barren area remain intact. All the tourmalines are rich in Al (>6 apfu), and belong to the alkali group and schorl endmember, falling into field 2 in the total Al-Fe-Mg ternary diagram. Petrographic and chemical composition data suggest that the D-T was primary magmatic in origin and formed in a late stage from the fractionated magma; the I-T and the S-T crystallized during the magmatic-hydrothermal transition; the V-T formed in magmatic hydrothermal fluids that may have been interacted with country rocks. The negative correlation of Fe and Mg from the D-T to the V-T demonstrates the MgFe−1 exchange vector, suggesting constant reduced crystallization environments from magmatic to hydrothermal fluids. Concentrations of V, Sr, Sc, Nb, Ta, and Mg/(Mg + Fe) ratios in tourmaline exhibit marked differences between the D-T and the V-T, and are considered as efficient discriminators for the magmatic and hydrothermal tourmaline. The gradually elevated contents of Sr and Mg/(Mg + Fe) ratios from the D-T, I-T to the S-T perfectly monitors fluid evolution from magmatic to magmatic-hydrothermal transition. The VZ-T and the VX-T from the U deposits show pronounced higher concentrations of Pb (>10 ± 2 ppm) and lower Sn/Pb ratios (<10 ± 1). The high anomaly of Pb in the hydrothermal tourmaline from the U-rich granites reflects accumulations of Pb in the magmatic hydrothermal fluids possibly through radioactive decay of U from the fertile granitic melts. The unique “cracked” appearance of the tourmaline in the U deposits is attributed to the alkaline hydrothermal alteration associated with U remobilization, which in turn may provide another sign for U-bearing fluid activity and the process of U enrichment at Xiazhuang. The “cracked” texture and Pb contents of tourmaline can serve as powerful and cost-effective vectoring tools for uranium exploration in similar granite-related systems globally.
{"title":"Petrography and chemical composition of tourmaline from the Xiazhuang uranium orefield, South China: Implications for magmatic-hydrothermal evolution and uranium exploration","authors":"Ming-Ji Zhang , Jia-Yong Pan , Yang Xu , Mostafa Fayek , Zhan-Shi Zhang , De-Hui Zhang , Cheng-Biao Leng","doi":"10.1016/j.gexplo.2025.107921","DOIUrl":"10.1016/j.gexplo.2025.107921","url":null,"abstract":"<div><div>Tourmaline is a reliable recorder of magmatic-hydrothermal evolution and ore mineralization. Numerous investigations on tourmaline from magmatic rocks and ore deposits have been conducted, while the links between tourmaline and granite-related uranium (U) mineralization systems remain poorly understood. This paper presents data of <em>in</em>-<em>situ</em> major and trace elemental compositions of tourmaline in the U-bearing and U-barren granitic plutons from the Xiazhuang U orefield by EPMA and LA-ICP-MS. Four types of tourmalines are identified by occurrences: (1) disseminated tourmaline (D-T) in the U-barren Luxi pluton; (2) interstitial tourmaline (I-T) in the U-bearing Maofeng pluton; (3) segregational tourmaline (S-T) in the U-bearing Xiazhuang pluton and (4) tourmaline veins (V-T) (including samples from the Zhushanxia U deposit (VZ-T), the Xiwang U deposit (VX-T) and the Luxi pluton (VL-T)). Tourmaline grains from the U deposits all display “cracked” appearance under the microscope, whereas those from the U-barren area remain intact. All the tourmalines are rich in Al (>6 apfu), and belong to the alkali group and schorl endmember, falling into field 2 in the total Al-Fe-Mg ternary diagram. Petrographic and chemical composition data suggest that the D-T was primary magmatic in origin and formed in a late stage from the fractionated magma; the I-T and the S-T crystallized during the magmatic-hydrothermal transition; the V-T formed in magmatic hydrothermal fluids that may have been interacted with country rocks. The negative correlation of Fe and Mg from the D-T to the V-T demonstrates the MgFe<sub>−</sub><sub>1</sub> exchange vector, suggesting constant reduced crystallization environments from magmatic to hydrothermal fluids. Concentrations of V, Sr, Sc, Nb, Ta, and Mg/(Mg + Fe) ratios in tourmaline exhibit marked differences between the D-T and the V-T, and are considered as efficient discriminators for the magmatic and hydrothermal tourmaline. The gradually elevated contents of Sr and Mg/(Mg + Fe) ratios from the D-T, I-T to the S-T perfectly monitors fluid evolution from magmatic to magmatic-hydrothermal transition. The VZ-T and the VX-T from the U deposits show pronounced higher concentrations of Pb (>10 ± 2 ppm) and lower Sn/Pb ratios (<10 ± 1). The high anomaly of Pb in the hydrothermal tourmaline from the U-rich granites reflects accumulations of Pb in the magmatic hydrothermal fluids possibly through radioactive decay of U from the fertile granitic melts. The unique “cracked” appearance of the tourmaline in the U deposits is attributed to the alkaline hydrothermal alteration associated with U remobilization, which in turn may provide another sign for U-bearing fluid activity and the process of U enrichment at Xiazhuang. The “cracked” texture and Pb contents of tourmaline can serve as powerful and cost-effective vectoring tools for uranium exploration in similar granite-related systems globally.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107921"},"PeriodicalIF":3.3,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145362311","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}
Pub Date : 2025-10-12DOI: 10.1016/j.gexplo.2025.107920
Tiziano Boschetti , Adedapo N. Awolayo
Lithium-rich formation brines from sedimentary basins are emerging as key unconventional resources in response to the growing global demand for lithium. This study integrates geochemical data from diverse settings, including the Smackover and Edwards Formations (Gulf Coast, USA), the Alberta Basin (Canada), and Salsomaggiore (Northern Apennine, Italy), to investigate the role of diagenetic processes and clay mineral equilibria on lithium mobility and retention. A new thermodynamic dataset was developed for lithium-bearing clay minerals and jadarite, allowing the construction of activity diagrams, calculation of saturation indices, and modeling. Activity diagrams indicate progressive brine evolution from kaolinite to montmorillonite, and toward Mg-rich saponite/chlorite assemblages, consistent with advanced diagenetic stages and lithium uptake into octahedral sites. The transition from equilibrium with smectites to chlorite-like phases reflects increasing temperature and prolonged water-rock interactions. A hyperalkaline paleo-fluid in equilibrium with jadarite and associated phases was also modeled, indicating that lithium concentrations in the Jadar Basin may have reached levels comparable to those currently observed in the Salar de Atacama. These findings underscore the dual role of clay minerals as buffers and potential sources for lithium in sedimentary systems, providing new insights for exploration and geochemical modeling of lithium-rich formation brines.
{"title":"Constraining lithium-clay equilibria in sedimentary environments using a new thermodynamic dataset","authors":"Tiziano Boschetti , Adedapo N. Awolayo","doi":"10.1016/j.gexplo.2025.107920","DOIUrl":"10.1016/j.gexplo.2025.107920","url":null,"abstract":"<div><div>Lithium-rich formation brines from sedimentary basins are emerging as key unconventional resources in response to the growing global demand for lithium. This study integrates geochemical data from diverse settings, including the Smackover and Edwards Formations (Gulf Coast, USA), the Alberta Basin (Canada), and Salsomaggiore (Northern Apennine, Italy), to investigate the role of diagenetic processes and clay mineral equilibria on lithium mobility and retention. A new thermodynamic dataset was developed for lithium-bearing clay minerals and jadarite, allowing the construction of activity diagrams, calculation of saturation indices, and modeling. Activity diagrams indicate progressive brine evolution from kaolinite to montmorillonite, and toward Mg-rich saponite/chlorite assemblages, consistent with advanced diagenetic stages and lithium uptake into octahedral sites. The transition from equilibrium with smectites to chlorite-like phases reflects increasing temperature and prolonged water-rock interactions. A hyperalkaline paleo-fluid in equilibrium with jadarite and associated phases was also modeled, indicating that lithium concentrations in the Jadar Basin may have reached levels comparable to those currently observed in the Salar de Atacama. These findings underscore the dual role of clay minerals as buffers and potential sources for lithium in sedimentary systems, providing new insights for exploration and geochemical modeling of lithium-rich formation brines.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107920"},"PeriodicalIF":3.3,"publicationDate":"2025-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324859","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}
Phosphorites constitute a potential non-traditional source of rare earth elements (REE), although their resource viability is still being evaluated globally. This study presents the first documentation of REE-enriched sediment-hosted phosphorites from India, and evaluates the processes driving REE mobilization, enrichment and accumulation. The Ediacaran phosphatic beds from the Owk Shale Formation, Kurnool Group of the Cuddapah basin, interbedded with shales and tuffs, were analysed using optical and SEM imaging, whole rock geochemical, in-situ fluorapatite (EPMA, LA-ICP-MS) and Raman spectroscopic analyses. Two apatite phases were identified: primary authigenic (Ap-1), fluorine-poor variety and secondary/reprecipitated REE-enriched fluorapatite (Ap-2). Whole-rock REE + Y concentrations reach up to 1075 ppm, with characteristic middle REE (MREE) enriched patterns, also recorded in fluorapatite, interpreted as a result of diagenetic uptake from sediment porewaters. A strong correlation between REE + Y and redox tracer, Mn indicates initial MREE scavenging by Mn-(oxy)hydroxides and organic matter, followed by MREE release during Mn-reductive dissolution. While diagenesis enhanced REE enrichment, post-diagenetic hydrothermal reworking associated with igneous intrusions diluted REE concentrations through the formation of abundant FeMg chlorite (chamosite) and REE and P redistribution within the interbedded shales. Sequence stratigraphic analysis suggests that these pristine phosphorites were deposited during marine regression, without subsequent reworking, preventing the formation of high grade phosphorite deposit, emphasizing the role of sea-level changes in controlling phosphogenesis, formation of a phosphorite giant and thus, REE enrichment. A temporal analysis of global phosphorites further reveals that progressive seawater influence, modulated by biogeochemical recycling and episodic weathering, together controlled the REE enrichment patterns in phosphorites through Earth's history.
{"title":"Critical mineral potential of Indian phosphorites: Evidence of REE enrichment in Ediacaran sediments from the Cuddapah Basin","authors":"Gangula Harshitha , Ignacio González-Álvarez , Chakravadhanula Manikyamba , Joëlle D'Andres , Jayant Kumar Yadav , Mrinal Kanti Mukherjee","doi":"10.1016/j.gexplo.2025.107918","DOIUrl":"10.1016/j.gexplo.2025.107918","url":null,"abstract":"<div><div>Phosphorites constitute a potential non-traditional source of rare earth elements (REE), although their resource viability is still being evaluated globally. This study presents the first documentation of REE-enriched sediment-hosted phosphorites from India, and evaluates the processes driving REE mobilization, enrichment and accumulation. The Ediacaran phosphatic beds from the Owk Shale Formation, Kurnool Group of the Cuddapah basin, interbedded with shales and tuffs, were analysed using optical and SEM imaging, whole rock geochemical, in-situ fluorapatite (EPMA, LA-ICP-MS) and Raman spectroscopic analyses. Two apatite phases were identified: primary authigenic (Ap-1), fluorine-poor variety and secondary/reprecipitated REE-enriched fluorapatite (Ap-2). Whole-rock REE + Y concentrations reach up to 1075 ppm, with characteristic middle REE (MREE) enriched patterns, also recorded in fluorapatite, interpreted as a result of diagenetic uptake from sediment porewaters. A strong correlation between REE + Y and redox tracer, Mn indicates initial MREE scavenging by Mn-(oxy)hydroxides and organic matter, followed by MREE release during Mn-reductive dissolution. While diagenesis enhanced REE enrichment, post-diagenetic hydrothermal reworking associated with igneous intrusions diluted REE concentrations through the formation of abundant Fe<img>Mg chlorite (chamosite) and REE and P redistribution within the interbedded shales. Sequence stratigraphic analysis suggests that these pristine phosphorites were deposited during marine regression, without subsequent reworking, preventing the formation of high grade phosphorite deposit, emphasizing the role of sea-level changes in controlling phosphogenesis, formation of a phosphorite giant and thus, REE enrichment. A temporal analysis of global phosphorites further reveals that progressive seawater influence, modulated by biogeochemical recycling and episodic weathering, together controlled the REE enrichment patterns in phosphorites through Earth's history.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107918"},"PeriodicalIF":3.3,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267259","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}
<div><div>Metamorphosed sedimentary exhalative (SEDEX) deposits contain higher concentrations of sulfosalts and rare metals within their remobilized zones. As sulfides (e.g., pyrite and sphalerite) incorporate a wide range of trace elements during <em>syn</em>-sedimentary Pb<img>Zn mineralization, their recrystallization during metamorphism may play a crucial role in metal enrichments in the remobilized zones of SEDEX deposits. To explore this, we analyzed pyrite and sphalerite from different ore stages (syngenetic, <em>syn</em>-metamorphic, and post-metamorphic) of two major SEDEX deposits (Rajpura-Dariba and Rampura-Agucha) of Aravalli-Delhi Fold Belt (ADFB), northwestern India. We further applied supervised machine learning (ML) algorithms (XGBoost, LightGBM, Random Forest and Extra Tree) on sulfide compositions from the ADFB and global “world class” SEDEX deposits to assess if ML models could efficiently classify sulfides formed at distinct stages of ore genesis and thus constrain trace element re-distribution. This exercise allowed us to investigate the role of sulfide recrystallization in trace element enrichments within SEDEX deposits.</div><div>Ore textures suggest that sulfides in the SEDEX deposits of ADFB have broadly formed in three distinct episodes; during, 1) syngenetic (<em>syn</em>-sedimentary to diagenetic) ore mineralization, 2) metamorphic recrystallization, and 3) retrograde cooling of sulfide melts produced at peak metamorphism. The syngenetic to diagenetic pyrite and sphalerite can be distinguished by their higher Pb, Ag, Sb and Tl contents. Pyrite and sphalerite formed during metamorphic recrystallization of early formed sulfides are characterized by higher concentrations of structure bound elements (As, Co and Ni in pyrite and Hg, Cd, Mn and Ga in sphalerite). Our study reveals that the tested ML algorithms (XGBoost, LightGBM, Random Forest and Extra Tree) can effectively identify sulfides (pyrite and sphalerite) of distinct origin, with significant accuracy (93–96 %), thus, providing new insights on the applicability of ML methods to study ore genesis. Similarly, syngenetic sulfides (Py-S and Sph<img>S) from global SEDEX deposits are also characterized by higher concentrations of low melting point chalcophile elements (LMCEs: Pb, Ag, Sb and Tl) and lower concentrations of structure bound trace elements (As, and Ni in pyrite; Mn, Ga and Ge in sphalerite) compared to metamorphic recrystallized sulfides (Py-M and Sph-M). The expulsion of metals (Pb, Ag, Sb and Tl) during metamorphic sulfide recrystallization, as observed in the ADFB and global SEDEX deposits, suggests that the redistribution of trace elements from sulfides during metamorphism plays a critical role in the enrichment of rare metals (Ag, Sb and Tl) in remobilized zones of SEDEX deposits. This is consistent with the textural observation that remobilized zones contain abundant sulfosalts of Ag, Sb and Tl in these deposits.</div><div>Our study further highlights
{"title":"Metamorphogenic compositional changes in sulfides and their role in metal enrichment in SEDEX deposits: Insights from machine learning algorithms","authors":"Niraj Bhuyan , Pranjit Hazarika , Rissnalin Syiemlieh , Eeshankur Saikia","doi":"10.1016/j.gexplo.2025.107915","DOIUrl":"10.1016/j.gexplo.2025.107915","url":null,"abstract":"<div><div>Metamorphosed sedimentary exhalative (SEDEX) deposits contain higher concentrations of sulfosalts and rare metals within their remobilized zones. As sulfides (e.g., pyrite and sphalerite) incorporate a wide range of trace elements during <em>syn</em>-sedimentary Pb<img>Zn mineralization, their recrystallization during metamorphism may play a crucial role in metal enrichments in the remobilized zones of SEDEX deposits. To explore this, we analyzed pyrite and sphalerite from different ore stages (syngenetic, <em>syn</em>-metamorphic, and post-metamorphic) of two major SEDEX deposits (Rajpura-Dariba and Rampura-Agucha) of Aravalli-Delhi Fold Belt (ADFB), northwestern India. We further applied supervised machine learning (ML) algorithms (XGBoost, LightGBM, Random Forest and Extra Tree) on sulfide compositions from the ADFB and global “world class” SEDEX deposits to assess if ML models could efficiently classify sulfides formed at distinct stages of ore genesis and thus constrain trace element re-distribution. This exercise allowed us to investigate the role of sulfide recrystallization in trace element enrichments within SEDEX deposits.</div><div>Ore textures suggest that sulfides in the SEDEX deposits of ADFB have broadly formed in three distinct episodes; during, 1) syngenetic (<em>syn</em>-sedimentary to diagenetic) ore mineralization, 2) metamorphic recrystallization, and 3) retrograde cooling of sulfide melts produced at peak metamorphism. The syngenetic to diagenetic pyrite and sphalerite can be distinguished by their higher Pb, Ag, Sb and Tl contents. Pyrite and sphalerite formed during metamorphic recrystallization of early formed sulfides are characterized by higher concentrations of structure bound elements (As, Co and Ni in pyrite and Hg, Cd, Mn and Ga in sphalerite). Our study reveals that the tested ML algorithms (XGBoost, LightGBM, Random Forest and Extra Tree) can effectively identify sulfides (pyrite and sphalerite) of distinct origin, with significant accuracy (93–96 %), thus, providing new insights on the applicability of ML methods to study ore genesis. Similarly, syngenetic sulfides (Py-S and Sph<img>S) from global SEDEX deposits are also characterized by higher concentrations of low melting point chalcophile elements (LMCEs: Pb, Ag, Sb and Tl) and lower concentrations of structure bound trace elements (As, and Ni in pyrite; Mn, Ga and Ge in sphalerite) compared to metamorphic recrystallized sulfides (Py-M and Sph-M). The expulsion of metals (Pb, Ag, Sb and Tl) during metamorphic sulfide recrystallization, as observed in the ADFB and global SEDEX deposits, suggests that the redistribution of trace elements from sulfides during metamorphism plays a critical role in the enrichment of rare metals (Ag, Sb and Tl) in remobilized zones of SEDEX deposits. This is consistent with the textural observation that remobilized zones contain abundant sulfosalts of Ag, Sb and Tl in these deposits.</div><div>Our study further highlights ","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107915"},"PeriodicalIF":3.3,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324552","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}
Trace element analysis of plant tissues can aid mineral exploration for sediment hosted Cu-Co deposits in the Zambian Copperbelt (ZCB). This study was conducted at the Mitumba prospect, an area in the ZCB known to have copper minerals but no historical mining activities, to identify native plant species and their tissues that are most indicative of mineralized zones. Field inventory and ecological analysis identified 22 native plant species from 12 different families, of which Fabaceae (36.4%) was dominant. At species level and based on the coating index, we identified several predominant species, among them, Haumaniastrum katangense (Lamiaceae), Aframomum angustifolium (Zingiberaceae), Brachystegia boehmii (Fabaceae), and Diplorynchus condilocarpon (Apocynaceae). Sampling was undertaken of soils and plant organs above the known mineralized zone and at control points outside of the mineralized area. Most species translocated Cu from the roots to the aboveground biomass as indicated by translocation factors (TF) 1 but only three species, namely, Haumaniastrum katangense, Aframomum angustifolium and Diplorynchus condilocarpon can both translocate and bioconcentrate (BCF 1) bioavailable Cu from the rhizosphere, making them ideal candidates for phytogeochemical exploration. Only Haumaniastrum katangense and Aframomum angustifolium accumulated Co. Plant roots and leaves demonstrate significant Cu anomalism and show a wider population of anomalous values compared to the soils. Statistical and machine learning techniques both indicate significant relationships between soil Cu concentration and the content of Cu in plant roots and leaves highlighting soil pH, organic matter and clay content as the major physicochemical variables influencing metal bioavailability in soil-plant systems.
{"title":"Native plant species screening for phytogeochemical exploration in the Zambian Copperbelt","authors":"Pumulo Mukube , Stephen Syampungani , Lerato Machogo-Phao , Murray Hitzman","doi":"10.1016/j.gexplo.2025.107914","DOIUrl":"10.1016/j.gexplo.2025.107914","url":null,"abstract":"<div><div>Trace element analysis of plant tissues can aid mineral exploration for sediment hosted Cu-Co deposits in the Zambian Copperbelt (ZCB). This study was conducted at the Mitumba prospect, an area in the ZCB known to have copper minerals but no historical mining activities, to identify native plant species and their tissues that are most indicative of mineralized zones. Field inventory and ecological analysis identified 22 native plant species from 12 different families, of which Fabaceae (36.4%) was dominant. At species level and based on the coating index, we identified several predominant species, among them, <em>Haumaniastrum katangense</em> (Lamiaceae), <em>Aframomum angustifolium</em> (Zingiberaceae), <em>Brachystegia boehmii</em> (Fabaceae), and <em>Diplorynchus condilocarpon</em> (Apocynaceae). Sampling was undertaken of soils and plant organs above the known mineralized zone and at control points outside of the mineralized area. Most species translocated Cu from the roots to the aboveground biomass as indicated by translocation factors (TF) <span><math><mo>></mo></math></span> 1 but only three species, namely, <em>Haumaniastrum katangense</em>, <em>Aframomum angustifolium</em> and <em>Diplorynchus condilocarpon</em> can both translocate and bioconcentrate (BCF <span><math><mo>></mo></math></span> 1) bioavailable Cu from the rhizosphere, making them ideal candidates for phytogeochemical exploration. Only <em>Haumaniastrum katangense</em> and <em>Aframomum angustifolium</em> accumulated Co. Plant roots and leaves demonstrate significant Cu anomalism and show a wider population of anomalous values compared to the soils. Statistical and machine learning techniques both indicate significant relationships between soil Cu concentration and the content of Cu in plant roots and leaves highlighting soil pH, organic matter and clay content as the major physicochemical variables influencing metal bioavailability in soil-plant systems.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107914"},"PeriodicalIF":3.3,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267257","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}
Pub Date : 2025-10-08DOI: 10.1016/j.gexplo.2025.107916
Yong Yin , Heng-Feng Zhang , Zhuang Duan , Bing-Fei Yu , Heng Luo , Yan-Gang Fu , David R. Lentz , Tao Luo , Ke-Yu Ren , Zhe Ren , Hao Hu
The Hongjianbingshan (HJBS) W–Li–(Be) deposit in the Beishan Mineralization Belt of the Central Asian Orogenic Belt has significant potential for rare-metal mineralization and exhibits a close genetic relationship with extremely fractionated granites. Previous geochronological studies have established that the host granites (321.2 ± 2.7 to 306.3 ± 2.3 Ma) were formed during the Carboniferous. However, muscovite 40Ar/39Ar ages from greisen-type ores are ~216 Ma. Therefore, the precise age of the ore-forming and ore-related granites in the HJBS deposit remains uncertain. We present a comprehensive geochronological investigation of the primary ore minerals in the HJBS deposit. By integrating these results with zircon and monazite ages from the host rocks, we reassess the temporal framework of the magmatism and mineralization associated with this deposit. Our analysis indicates that both the magmatic and mineralization processes (232 ± 38 Ma) occurred during the Indosinian orogeny, in contrast to prior assumptions linking these events to Carboniferous magmatism. The mineralization history of the HJBS deposit closely resembles that of other rare-metal deposits across the Tianshan–Altay–Songpan–Ganzi–West Kunlun regions in western China. These deposits occur along the Paleo-Tethyan tectonic belt and formed during the closure of the Paleo-Tethys Ocean. This suggests that the HJBS deposit in the Beishan Mineralization Belt formed during the same tectonic events as other rare-metal deposits associated with extremely fractionated granites in western China. The closure of the Paleo-Asian and the Paleo-Tethys oceans, along with subsequent tectonic changes, led to significant magmatism and large-scale rare-metal mineralization in western China. Our study underscores the substantial impact of large-scale rare-metal mineralization events during the Indosinian orogeny on the Beishan Mineralization Belt, as exemplified by the HJBS deposit. These findings provide new insights into the geological evolution and mineralization processes in the Beishan area, revealing substantial potential for rare-metal mineralization. Furthermore, they establish a foundation for future exploration and exploitation of rare-metal deposits in the Beishan region.
{"title":"The Hongjianbingshan W–Li–(Be) deposit in the Beishan Orogenic Belt is not related to carboniferous magmatic–hydrothermal events: Insights from multi-mineral U-Pb and zinnwaldite Rb-Sr geochronology","authors":"Yong Yin , Heng-Feng Zhang , Zhuang Duan , Bing-Fei Yu , Heng Luo , Yan-Gang Fu , David R. Lentz , Tao Luo , Ke-Yu Ren , Zhe Ren , Hao Hu","doi":"10.1016/j.gexplo.2025.107916","DOIUrl":"10.1016/j.gexplo.2025.107916","url":null,"abstract":"<div><div>The Hongjianbingshan (HJBS) W–Li–(Be) deposit in the Beishan Mineralization Belt of the Central Asian Orogenic Belt has significant potential for rare-metal mineralization and exhibits a close genetic relationship with extremely fractionated granites. Previous geochronological studies have established that the host granites (321.2 ± 2.7 to 306.3 ± 2.3 Ma) were formed during the Carboniferous. However, muscovite <sup>40</sup>Ar/<sup>39</sup>Ar ages from greisen-type ores are ~216 Ma. Therefore, the precise age of the ore-forming and ore-related granites in the HJBS deposit remains uncertain. We present a comprehensive geochronological investigation of the primary ore minerals in the HJBS deposit. By integrating these results with zircon and monazite ages from the host rocks, we reassess the temporal framework of the magmatism and mineralization associated with this deposit. Our analysis indicates that both the magmatic and mineralization processes (232 ± 38 Ma) occurred during the Indosinian orogeny, in contrast to prior assumptions linking these events to Carboniferous magmatism. The mineralization history of the HJBS deposit closely resembles that of other rare-metal deposits across the Tianshan–Altay–Songpan–Ganzi–West Kunlun regions in western China. These deposits occur along the Paleo-Tethyan tectonic belt and formed during the closure of the Paleo-Tethys Ocean. This suggests that the HJBS deposit in the Beishan Mineralization Belt formed during the same tectonic events as other rare-metal deposits associated with extremely fractionated granites in western China. The closure of the Paleo-Asian and the Paleo-Tethys oceans, along with subsequent tectonic changes, led to significant magmatism and large-scale rare-metal mineralization in western China. Our study underscores the substantial impact of large-scale rare-metal mineralization events during the Indosinian orogeny on the Beishan Mineralization Belt, as exemplified by the HJBS deposit. These findings provide new insights into the geological evolution and mineralization processes in the Beishan area, revealing substantial potential for rare-metal mineralization. Furthermore, they establish a foundation for future exploration and exploitation of rare-metal deposits in the Beishan region.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107916"},"PeriodicalIF":3.3,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324551","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}
Pub Date : 2025-10-08DOI: 10.1016/j.gexplo.2025.107911
Pedro Acosta-Góngora , Malin Andersson , Terje Bjerkgård , William A. Morris , Tobias Kurz , Madeline Lee , Marie-Andre Dumais , Aziz Nasuti , Mikis van Boeckel , Johannes Jakob , Ana Carolina R. Miranda , Aidian Crilly , Ying Wang , Behnam Sadeghi
This study presents a multivariate framework for geochemical data processing and anomaly detection to support mineral exploration in the Hattfjelldal area, Norway. The workflow integrates data levelling, multivariate analysis, and spatial evaluation to improve the detection and interpretation of geochemical anomalies associated with volcanogenic massive sulfide (VMS) mineralization. Soil geochemical and magnetic susceptibility data were log-transformed and subsequently levelled using Z-score normalization by soil type and lithology. Both linear (principal component analysis, PCA) and non-linear algorithms (hierarchical clustering, isolation forest, and angle-based outlier detection) were applied to construct anomaly detection vectors. Hierarchical clustering proved particularly effective in defining element assemblages that refine anomaly detection, including associations of Type 1 (Ag, Mo, S, Sb, Bi, Pb); Type 2 A (Fe, Zn, Co, Mn) and Type 2B (Fe, Zn, Co, Mn, As, Cu). These groupings provide a robust geochemical and geological context within established VMS zoning models.
Magnetic susceptibility, although less reliable as a stand-alone exploration vector, enhances interpretation when integrated with geochemical anomalies. Fractal analysis applied to both, geochemical vectors and magnetic susceptibility data effectively distinguished background from anomalous values, delineating areas of potential economic interest. Spatial Feature Embeddings (SFE), derived from clustering radiometric, topographic, and spectral datasets, further improved the spatial characterization of anomalies. When combined with airborne magnetics, SFE enabled the refinement and prioritization of specific targets within broad anomaly zones.
Overall, this framework demonstrates the value of integrating statistical, geochemical, and geophysical methods within their spatial context, providing a transferable approach for exploration programs in Arctic environments.
{"title":"Soil anomaly mapping in the Hattfjelldal area, Norway: Reconciling soil geochemical and geophysical properties within their spatial context","authors":"Pedro Acosta-Góngora , Malin Andersson , Terje Bjerkgård , William A. Morris , Tobias Kurz , Madeline Lee , Marie-Andre Dumais , Aziz Nasuti , Mikis van Boeckel , Johannes Jakob , Ana Carolina R. Miranda , Aidian Crilly , Ying Wang , Behnam Sadeghi","doi":"10.1016/j.gexplo.2025.107911","DOIUrl":"10.1016/j.gexplo.2025.107911","url":null,"abstract":"<div><div>This study presents a multivariate framework for geochemical data processing and anomaly detection to support mineral exploration in the Hattfjelldal area, Norway. The workflow integrates data levelling, multivariate analysis, and spatial evaluation to improve the detection and interpretation of geochemical anomalies associated with volcanogenic massive sulfide (VMS) mineralization. Soil geochemical and magnetic susceptibility data were log-transformed and subsequently levelled using <em>Z</em>-score normalization by soil type and lithology. Both linear (principal component analysis, PCA) and non-linear algorithms (hierarchical clustering, isolation forest, and angle-based outlier detection) were applied to construct anomaly detection vectors. Hierarchical clustering proved particularly effective in defining element assemblages that refine anomaly detection, including associations of Type 1 (Ag, Mo, S, Sb, Bi, Pb); Type 2 A (Fe, Zn, Co, Mn) and Type 2B (Fe, Zn, Co, Mn, As, Cu). These groupings provide a robust geochemical and geological context within established VMS zoning models.</div><div>Magnetic susceptibility, although less reliable as a stand-alone exploration vector, enhances interpretation when integrated with geochemical anomalies. Fractal analysis applied to both, geochemical vectors and magnetic susceptibility data effectively distinguished background from anomalous values, delineating areas of potential economic interest. Spatial Feature Embeddings (SFE), derived from clustering radiometric, topographic, and spectral datasets, further improved the spatial characterization of anomalies. When combined with airborne magnetics, SFE enabled the refinement and prioritization of specific targets within broad anomaly zones.</div><div>Overall, this framework demonstrates the value of integrating statistical, geochemical, and geophysical methods within their spatial context, providing a transferable approach for exploration programs in Arctic environments.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107911"},"PeriodicalIF":3.3,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145362309","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}
Pub Date : 2025-10-08DOI: 10.1016/j.gexplo.2025.107917
Ha Hyun Park , Jung Hun Seo , Bum Han Lee , Chul-Ho Heo , Marcel Guillong
Several SnLi prospects in the Uljin area, which is in the eastern part of South Korea, including Dongseok, Yuchang, Buguk, Chomak, Hyundong, and Boam, contain sub-economic cassiterite and Li-bearing silicate minerals such as lepidolite and spodumene, and phosphate mineral such as amblygonite, along with accessory Nb-Ta-bearing minerals. Among these, Dongseok and Yuchang are Sn-dominant, Buguk, Hyundong, and Chomak exhibit mixed SnLi mineralization, while Boam (Western, Main, Eastern) is Li-rich. The SnLi mineralization is associated with a series of hydrothermal alterations, particularly greisenization and albitization. Two stages of greisenization have been identified, with albite alteration occurring between them. Cassiterite (± NbTa minerals) precipitated during early greisenization (Greisen I), whereas spodumene crystallized as a primary mineral in subsequent pegmatite intrusion, lepidolite and amblygonite formed during late-stage greisenization (Greisen II). SEM-CL analysis distinguishes two types of cassiterite: CL-brighter, oscillatory-zoned type I (commonly found in Dongseok) and CL-darker, massive type II (dominant in Yuchang, Buguk, and Chomak).
Muscovite ArAr dating constrains the timing of greisenization, placing Greisen I (cassiterite formation) at 168–174 Ma and Greisen II (lepidolite formation) at ~166 Ma. These overlapping ages suggest that the SnLi mineralization was derived from a fractionating magmatic batholith. Fluid inclusions in cassiterite and quartz contain CO2, CH4, and N2, with CH4/CO2 ratios indicating a reducing environment during early cassiterite precipitation. A positive correlation between homogenization temperatures and salinities in the fluid inclusions suggests the mixing of magmatic and meteoric fluids during cassiterite and lepidolite precipitation. The transition from Sn to Li mineralization was driven by progressive oxidation and cooling, as reflected in CO2/CH4 ratios and cassiterite chemistry. Higher-temperature (>300 °C), lower-salinity fluids (>8 wt% NaCl eq.) formed cassiterite during Greisen I, while later, somewhat cooler (>250 °C), more saline fluids (>10 wt% NaCl eq.) facilitated lepidolite precipitation during Greisen II. This magmatic-hydrothermal evolution, potentially controlled by batholith-scale magma fractionation, resulted in these sequential Sn and Li mineralization in the Uljin area.
{"title":"Magma fractionation and the magmatic-meteoric fluids mixing drive the sequential deposition of cassiterite to lepidolite in the Uljin prospects, South Korea","authors":"Ha Hyun Park , Jung Hun Seo , Bum Han Lee , Chul-Ho Heo , Marcel Guillong","doi":"10.1016/j.gexplo.2025.107917","DOIUrl":"10.1016/j.gexplo.2025.107917","url":null,"abstract":"<div><div>Several Sn<img>Li prospects in the Uljin area, which is in the eastern part of South Korea, including Dongseok, Yuchang, Buguk, Chomak, Hyundong, and Boam, contain sub-economic cassiterite and Li-bearing silicate minerals such as lepidolite and spodumene, and phosphate mineral such as amblygonite, along with accessory Nb-Ta-bearing minerals. Among these, Dongseok and Yuchang are Sn-dominant, Buguk, Hyundong, and Chomak exhibit mixed Sn<img>Li mineralization, while Boam (Western, Main, Eastern) is Li-rich. The Sn<img>Li mineralization is associated with a series of hydrothermal alterations, particularly greisenization and albitization. Two stages of greisenization have been identified, with albite alteration occurring between them. Cassiterite (± Nb<img>Ta minerals) precipitated during early greisenization (Greisen I), whereas spodumene crystallized as a primary mineral in subsequent pegmatite intrusion, lepidolite and amblygonite formed during late-stage greisenization (Greisen II). SEM-CL analysis distinguishes two types of cassiterite: CL-brighter, oscillatory-zoned type I (commonly found in Dongseok) and CL-darker, massive type II (dominant in Yuchang, Buguk, and Chomak).</div><div>Muscovite Ar<img>Ar dating constrains the timing of greisenization, placing Greisen I (cassiterite formation) at 168–174 Ma and Greisen II (lepidolite formation) at ~166 Ma. These overlapping ages suggest that the Sn<img>Li mineralization was derived from a fractionating magmatic batholith. Fluid inclusions in cassiterite and quartz contain CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>, with CH<sub>4</sub>/CO<sub>2</sub> ratios indicating a reducing environment during early cassiterite precipitation. A positive correlation between homogenization temperatures and salinities in the fluid inclusions suggests the mixing of magmatic and meteoric fluids during cassiterite and lepidolite precipitation. The transition from Sn to Li mineralization was driven by progressive oxidation and cooling, as reflected in CO<sub>2</sub>/CH<sub>4</sub> ratios and cassiterite chemistry. Higher-temperature (>300 °C), lower-salinity fluids (>8 wt% NaCl eq.) formed cassiterite during Greisen I, while later, somewhat cooler (>250 °C), more saline fluids (>10 wt% NaCl eq.) facilitated lepidolite precipitation during Greisen II. This magmatic-hydrothermal evolution, potentially controlled by batholith-scale magma fractionation, resulted in these sequential Sn and Li mineralization in the Uljin area.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107917"},"PeriodicalIF":3.3,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267258","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}
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