Chemie Der Erde-Geochemistry最新文献

{"title":"Petrogenesis of post-collisional granites in the Arabian-Nubian Shield: The peraluminous A-type granites of the mounts Um-Sudaydat and Um-Erjaj plutons, South Eastern Desert, Egypt","authors":"Mohammed Z. El-Bialy ,&nbsp;Abdel-Aal Abdel-Karim ,&nbsp;Mokhles Azer","doi":"10.1016/j.chemer.2025.126346","DOIUrl":"10.1016/j.chemer.2025.126346","url":null,"abstract":"<div><div>The Younger Granite plutons of Gabal Um Erjaj (GUE) and Gabal Um Sudaydat (GUS) in the Eastern Desert of Egypt provide key insights into the geological history and crustal evolution of the Arabian-Nubian Shield (ANS). These granitic intrusions represent the final phase of magmatic activity in the region, cutting through older Neoproterozoic basement rocks. Both plutons exhibit sharp, non-reactive contacts with the surrounding rocks, with no evidence of thermal alteration. Based on modal analysis, these granites are primarily alkali feldspar granites and syenogranites. The GUS granites display more deformation features and inequigranular textures, suggesting a shallower level of intrusion compared to GUE. Electron microprobe analyses reveal significant compositional variations between the two plutons, particularly in feldspar and biotite chemistry. Geochemically, both granitoid suites exhibit peraluminous, ferroan A-type characteristics, with distinct geochemical signatures that differentiate them from other A-type granites. Geothermometric analyses indicate moderate to high crystallization temperatures for accessory minerals, suggesting a highly fractionated magmatic origin. Trace element distributions, including pronounced negative Nb, Ti, and Eu anomalies, coupled with high Y/Nb ratios (&gt;1.2), indicate a predominantly crustal-derived melt. The post-collisional geodynamic setting of these granitoids within the ANS aligns with lithospheric delamination and slab breakoff processes, contributing to the extensive crustal melting. The geotectonic discrimination diagrams support their classification as A₂-type granites, reinforcing their post-collisional evolution. These findings emphasize the significance of crustal processes in the formation of post-collisional A-type granites, contributing to a broader understanding of the crustal evolution within the ANS.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126346"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ediacaran and early-palaeozoic bimodal volcanism in the Ossa-Morena Zone, SW Iberian Massif: New clues for intraplate rifting shortly after the Cadomian Orogeny","authors":"P. Cachapuz ,&nbsp;M. Chichorro ,&nbsp;T. Bento dos Santos ,&nbsp;D.R. Carvalho ,&nbsp;U. Linnemann ,&nbsp;M. Zieger-Hofmann ,&nbsp;J. Zieger ,&nbsp;E. Dantas ,&nbsp;R.V. Santos ,&nbsp;P. Moita ,&nbsp;M. Beltrame ,&nbsp;A.R. Solá ,&nbsp;M. Díaz-Azpíroz ,&nbsp;C. Fernández","doi":"10.1016/j.chemer.2025.126351","DOIUrl":"10.1016/j.chemer.2025.126351","url":null,"abstract":"<div><div>This study focuses on bimodal meta-volcanic rocks present in the Iberian Massif, in the Évora-Aracena Metamorphic Belt of the Ossa-Morena Zone (OMZ), near the boundary with the South Portuguese Zone. New petrological, geochemical (whole-rock and Sr<img>Nd isotopes) and LA-ICP-MS U<img>Pb zircon geochronology data are presented to track the magmatic evolution of both felsic and mafic rocks and their respective geodynamic setting during the transition between the Cadomian Orogeny and subsequent Palaeozoic rifting events.</div><div>Our research shows that the Évora-Aracena Metamorphic Belt (EAMB) in the southwestern OMZ possesses a significant record of the transition between the Cadomian and Variscan cycles. U<img>Pb geochronological data confirm the existence of both felsic and mafic Ediacaran igneous rocks (546 and 556 Ma, respectively), a novelty in the region. The Cadomian-related felsic rocks show geochemical similarities to meta-felsic rocks formed during the initial phases of the Cambrian rifting event, namely very negative εNd values (−10.1 to −11.8), depleted HREE patterns and orogenic signatures. Such similarities imply that meta-felsic rocks formed in the earliest stages of the Cambrian Rift-to-Drift event resulted from a shallower melting.</div><div>Moreover, meta-felsic rocks formed in the early stages of the Cambrian rifting (525 Ma) present a significant amount of Ediacaran aged zircons, whereas the Cadomian-related counterparts display a few discordant Cambrian ages, likely a consequence of Pb-loss. This indicates that the convergent, subduction-related regime that prevailed during most of the Cryogenian-Ediacaran times along the boundaries of NW Gondwana was swiftly supplanted by a rift-dominated regime during the Cambrian, with no substantial gap between these two thermal events. Meanwhile, meta-felsic rocks formed during the Rift-to-Drift (525–480 Ma) event exhibit progressively higher εNd values (−5.0 to +3.0), HREE-enrichment, as well as anorogenic signatures, denoting an increasing contribution of mantle-derived melts. This increasing mantle contribution eventually led to the occurrence of bimodal magmatism in the Middle Cambrian Main Rift event. Such Cambrian mafic rocks, unlike the Ediacaran mafic rocks that present flat REE patterns and continental arc signatures, display varying degrees of LREE enrichment and N-MORB to <em>E</em>-MORB signatures.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126351"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Northwest Africa 4269: a metal-rich eucrite from the Algerian Sahara","authors":"Abdelmadjid Seddiki ,&nbsp;Bertrand Moine ,&nbsp;Jérôme Bascou ,&nbsp;Ratiba Kared ,&nbsp;Jean Yves Cottin ,&nbsp;Marguerite Godard ,&nbsp;François Faure ,&nbsp;Richard C. Greenwood ,&nbsp;Ian A. Franchi","doi":"10.1016/j.chemer.2025.126363","DOIUrl":"10.1016/j.chemer.2025.126363","url":null,"abstract":"<div><div>Northwest Africa (NWA) 4269 is an anomalous monomict eucrite that is characterized by a very high content of metallic iron (~ 3 %). It shows various textures (relict magmatic sub-ophitic, granulitic areas as coarse and fine-grained). NWA 4269 also shows petrographic evidence of secondary sub-solidus reheating events. Pyroxenes have homogeneous compositions and are iron-rich. NWA 4269 is metamorphosed type 5. It has a normal HED oxygen isotope composition. The chemical composition of NWA 4269 has characteristics similar to that of Nuevo-Laredo trend eucrites. Metal is extremely abundant in the fine-grained areas (~ 10 %). Metal also has a very low Ni content (Ni &lt; 0.1 %) that excludes a direct origin from a chondrite-like impactor. Origin of the pure-Fe groundmass metal remains enigmatic. The high metal content in NWA 4269 can be interpreted as having formed via the reduction of FeO and probably also by desulfidation of pre-existing troilite. Iron metal could have formed by deposition from a Fe-rich fluid that, probably after an event that triggered sudden reduction. NWA 4269 has normal HED oxygen isotope compositions and interpreted as belonging to the 4-Vesta asteroid.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126363"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phosphorus-induced REE enrichment and hydrothermal alteration in the Beldih fluorapatite-bearing rock, Purulia, West Bengal: Implications for REE mineralization","authors":"Reeya Ghosh ,&nbsp;Ashim Kumar Patel ,&nbsp;Manoj Kumar Ozha ,&nbsp;Sakthi Saravanan Chinnasamy","doi":"10.1016/j.chemer.2025.126352","DOIUrl":"10.1016/j.chemer.2025.126352","url":null,"abstract":"<div><div>Phoscorites (fluorapatite dominated rocks) from the Beldih carbonatite-alkaline complex of the South Purulia Shear Zone in eastern India were studied to investigate how the presence P in melt determines the fate of rare earth elements (REEs) enrichment in carbonatite during its magmatic and hydrothermal evolutionary stages through detailed petrographic and geochemical analyses. The study suggests that P-saturation at an early stage of magma evolution at Beldih facilitated early fluorapatite formation through fractional crystallization or exsolution of phosphorus-rich melt from the carbonatite counterpart led to phoscorite formation. The early fluorapatite fractionated almost all the REEs from melt, preventing direct REE crystallization.</div><div>Study of the associated calcite-bearing ultramafic silicate rocks, together with the phoscorites, revealed the occurrence of both magmatic (Fap1a and Fap1b) and hydrothermal or secondary (Fap2) varieties of fluorapatite with monazite, allanite, crandallite, and minor baddeleyite and betafite in the vicinity. The ΣREE₂O₃ contents in Fap1a &gt; Fap1b &gt; Fap2 with up to 1.50 wt% in Fap1a and Fap1b. They exhibit higher <em>Z</em>-contrast in BSE images than Fap2 alongside indications of hydrothermal dissolution-reprecipitation and REE redistribution manifested as intricate associations of secondary Fap2, crandallite, monazite, and allanite with both magmatic and hydrothermal variants of fluorapatite. The geochemical and textural evidence suggests that REE precipitation happened through two mutually compatible, low-mobility pathways (i.e., dissolution-reprecipitation and in-situ conversion) with only a few micrometers to essentially no REE mobilization. These pathways formed monazite in phoscorite and allanite in ultramafic rocks with Fe, Al, and Si after fluorapatite dissolution and fast REE immobilization by phosphorous at the reaction front. Aluminium-bearing fluid influx caused crandallite precipitation in phoscorite during fluorapatite dissolution. These findings demonstrate that the hydrothermal processes are only capable of localized REE redistribution rather than large-scale mobilization.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126352"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineralogical and geochemical significance of secondary burial-related barite and celestine: Evidence from Late Paleozoic evaporites in the Karawanke Mountains (Slovenia)","authors":"Aleš Šoster ,&nbsp;Matej Dolenec ,&nbsp;Luna Grum-Verdinek ,&nbsp;Janez Zavašnik","doi":"10.1016/j.chemer.2025.126354","DOIUrl":"10.1016/j.chemer.2025.126354","url":null,"abstract":"<div><div>The evaporites in the Karawanke Mountains (northwestern Slovenia) are hosted in a structurally complex lithological sequence, intercalated between Carboniferous-Permian and Permo-Triassic rocks. These evaporites are primarily composed of gypsum, with minor amounts of anhydrite, dolomite, and barite-celestine. Geochemically, the evaporites are characterized by elevated Sr (2000–2700 mg kg⁻¹) and low Ba (210–400 mg kg⁻¹) contents, reflecting the contrasting solubility behaviors of these elements in low-temperature syngenetic environments. Thermal dehydration, induced by peak burial temperatures ranging from 190 to 260 °C facilitated the transformation of gypsum to anhydrite. Subsequent cooling below the anhydrite stability threshold enabled gradual rehydration, accounting for the coexistence of both minerals. Thermal alteration also mobilized trace elements from the evaporites, which precipitated as secondary celestine and barite through dissolution-reprecipitation mechanisms, producing compositionally zoned fracture infills. The observed zoning, transitioning from Ba-rich to Sr-rich endmembers, likely reflects shifts in temperature, solubility and the chemical reactivity of evaporite-derived brine. Sulfur isotope analyses reveal δ³⁴S values of +11.8 to +13.7 ‰ for the evaporitic sulfates, showing minimal variation and only a small difference relative to coexisting sulfides. This small isotopic offset indicates nearly complete sulfate reduction under high-temperature conditions, consistent with thermal alteration inferred from burial temperatures. These geochemical and isotopic results put forward not only the thermal and diagenetic evolution of the Karawanke evaporites but also their broader significance as minor reservoirs of strontium, a critical element with growing industrial and technological importance.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126354"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Major and trace element geochemistry and Sr–Nd isotopic constraints on mafic volcanic rocks from the Ventura-Espiritu Santo Volcanic Field, San Luis Potosi, Mexico: Petrogenesis and tectonic implications of Cenozoic volcanism in the Basin and Range Province","authors":"Karla R. Hernández Martínez ,&nbsp;Sanjeet K. Verma ,&nbsp;Darío Torres-Sánchez ,&nbsp;Erik Emmanuel M. Torres ,&nbsp;José R. Torres Hernández ,&nbsp;Sonia A. Torres-Sánchez ,&nbsp;Hector Hernández-Mendoza ,&nbsp;Juan Antonio Moreno ,&nbsp;José Manuel Fuenlabrada ,&nbsp;Beatriz A. Rivera-Escoto","doi":"10.1016/j.chemer.2025.126355","DOIUrl":"10.1016/j.chemer.2025.126355","url":null,"abstract":"<div><div>The Ventura Espiritu Santo Volcanic Field (VESVF), located in the central part of the Mesa Central (MC), Mexico, is a monogenetic volcanic field dominated by Late Pleistocene mafic volcanism. It covers an area of approximately 100 km between the localities of Cúcamo and Santa Lucia and is emplaced on a basement composed of metamorphic rocks of the Sierra de Salinas and Triassic marine sequences that are tectonically overlain by the Guerrero Terrane. This study presents new petrographic observations, whole-rock major-and trace-element geochemistry, and Sr-Nd isotopic data for mafic rocks from the Cúcamo, El Rosario, and Santa Lucía areas to constrain the magmatic processes involved in the origin and evolution. Chondrite-normalized REE patterns display moderate enrichment in Light Rare Earth Elements (LREE) accompanied by slight depletion in Heavy Rare Earth Elements (HREE) and absence of an Eu anomaly. Primitive mantle-normalized diagrams show prominent positive anomalies in K, P, and Ti, together with negative anomalies in Pb. The absence of Nb-Ta troughs, together with multidimensional discrimination diagrams, could indicate an affinity to intraplate geochemical signature. Isotopic composition (⁸⁷Sr/⁸⁶Sr_i = [0.70307–0.70353, εNd = +5.8 to +6.3] suggests derivation from an enriched mantle source. The trace-element behavior, supported by geochemical modeling, further indicates that the mafic rocks were generated by low degree of partial melting of the enriched lherzolite upper lithospheric mantle source, pointing to a tectonic environment dominated by lithospheric extension and asthenospheric upwelling.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126355"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineral chemistry of porphyry indicator minerals in Kuh-e-Kapout Cu porphyry deposit, Kerman Cenozoic Magmatic Arc: Petrogenetic and exploration implications","authors":"Alireza Zarasvandi ,&nbsp;Nasim Haghighat Jou ,&nbsp;Nader Taghipour ,&nbsp;Mohsen Rezaei ,&nbsp;Johann Raith ,&nbsp;Mohammad Amiri Hoseini ,&nbsp;Ghazal Zarasvandi","doi":"10.1016/j.chemer.2025.126327","DOIUrl":"10.1016/j.chemer.2025.126327","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Kuh-e-Kapout porphyry copper deposit is located at the south end of the Kerman Cenozoic Magmatic Arc in the Jebal-Barez area. This article presents a first-time study on the evolution and origin of the magmatic-hydrothermal system associated with porphyry mineralization in this deposit. This deposit is affected by Jebal-Barez-type granitoids, which exhibit weak mineralization properties in PCDs. Using tools such as porphyry indicator minerals can help recognize the process that led to mineralization in this deposit. Based on electron probe micro-analyzer data from Biotite, plagioclase, and amphibole as indicator minerals, the physicochemical conditions of the hydrothermal-magmatic system associated with mineralization have been determined. This deposit is hosted in an arc-related, shallow calc-alkaline intrusive complex with a quartz diorite composition. In the study of drill cores, the central parts exhibit potassic alteration linked to copper sulfide mineralization veins, which includes potassium-rich phases of hydrothermal biotite and potassium feldspar that replace primary ferromagnesian minerals. This alteration transitions into a superimposed phyllic zone, characterized by increased sericitization of feldspars and mostly the presence of quartz±pyrite±Chalcopyrite veins. In the upper parts of the drill cores, advanced argillic alteration is indicated by fine-grained sulfides, sericite, and fluorite. Quartz diorite in the phyllic alteration zone intruded by an unmineralized microdiorite dike. Research on indicator minerals in quartz diorite and microdiorite, particularly in the potassic mineralizing zone in quartz diorite intrusion, provided insights into the physicochemical conditions of ore formation condition: biotites on the Fe/(Fe + Mg)-Al&lt;sup&gt;IV&lt;/sup&gt; diagram are plotted in the phlogopite field, indicating the Mg-biotite type, which is associated with I-type granitoid. These data show the mantle-crust mixture source for quartz diorite with mineralized properties. Biotite and calcic amphibole geochemistry exhibiting calc-alkaline affinity with subduction-related orogeny for the quartz diorite and microdiorite porphyries. Based on biotite and amphibole geochemistry, the oxygen fugacity of the magmatism is estimated to have a range of high (HM) to moderate (NNO) characteristics, respectively. The ratio of log &lt;em&gt;f&lt;/em&gt;(H&lt;sub&gt;2&lt;/sub&gt;O)&lt;em&gt;/f&lt;/em&gt;(HF) &gt; 1 and log &lt;em&gt;f(&lt;/em&gt;H&lt;sub&gt;2&lt;/sub&gt;O)&lt;em&gt;/ f&lt;/em&gt;(HCl) &gt; 1 based on biotite geochemistry indicates the mineralized fluid was relatively water-rich. Data points of Plagioclase from quartz diorite and microdiorite plotted on the Na&lt;sub&gt;2&lt;/sub&gt;O + K&lt;sub&gt;2&lt;/sub&gt;O + CaO (wt%)-SiO&lt;sub&gt;2&lt;/sub&gt; diagram, are between anorthite and albite. The excess Al in these data does not result from alteration and resulted from a magma with high PH&lt;sub&gt;2&lt;/sub&gt;O. Biotite chemistry indicates that mineralization in the quartz diorite magmatism occurred within a relatively closed system in the potas","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126327"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145100069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coupling hydrolyzed rice husk and ferric oxidation to enhance bio-oxidation of gold concentrate with high arsenic and sulfur","authors":"Shiqi Zhang ,&nbsp;Hongying Yang ,&nbsp;Linlin Tong ,&nbsp;Zhenan Jin ,&nbsp;Pengcheng Ma","doi":"10.1016/j.chemer.2025.126341","DOIUrl":"10.1016/j.chemer.2025.126341","url":null,"abstract":"<div><div>The bio-oxidation efficiency of refractory gold concentrate with high arsenic and sulfur is generally limited. In present study, the two-step ferric-biological process was employed to treat this gold concentrate, with an emphasis on investigating the impact of different organic nutrients on bio-oxidation performance. The results indicated that the addition of appropriate dosage of hydrolyzed rice husk (HRH, 1.2 g/L) combined with ferric oxidation significantly improved the bio-oxidation efficiency. The microbial growth rate and adsorption capacity were increase by 1.75 and 1 times, respectively. Specifically, it effectively facilitated the growth and adsorption of <em>Sulfobacillus</em> spp., while exhibiting no significant inhibitory effect on <em>Leptospirillum</em> spp. growth. Consequently, the homogeneity of the planktonic microbial community was improved. These effects resulted in a 0.06, 0.84, and 1.03 times increase in the oxidation efficiency of As, Fe, and S compared with one-step bio-oxidation, achieving extraction levels of 98.4 ± 0.2 %, 74.5 ± 0.1 %, and 60.4 ± 1.0 %, respectively. In consequence, the extraction levels of Au and Ag increased by 63.0 % and 51.3 %, respectively, reaching 93.7 ± 0.6 % and 91.6 ± 0.5 %. This study elucidated the enhancement mechanism of HRH on bio-oxidation and provided a theoretical basis for the efficient utilization of refractory gold ores and the application of lignocellulose in biohydrometallurgy.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126341"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical evolution of geothermal waters in Trans-Himalayas: Implications for critical mineral deposition","authors":"Archisman Dutta ,&nbsp;Parashar Mishra ,&nbsp;Abhijit Mukherjee ,&nbsp;Vivek P. Malviya ,&nbsp;Sanjeet Kumar Verma ,&nbsp;P.K. Singh ,&nbsp;Biswajit Ray","doi":"10.1016/j.chemer.2025.126348","DOIUrl":"10.1016/j.chemer.2025.126348","url":null,"abstract":"<div><div>The hydrothermal fluids of the Trans-Himalayan region host rich deposits of critical elements (e.g. Li, Cs, B, W, etc.), that forms critical energy minerals. We characterize geochemical evolution of hydrothermal waters in Trans-Himalayan region, delineating the origin and dissemination of critical energy minerals as epithermal deposits in the region. Thermal fluids exhibit enrichment in W with maximum value of 1603 μg/L and rare alkalis like Cs and Li, whose peak concentrations reach upto 6976 μg/L, and 6.8 mg/L, respectively. Similarly, soils/altered rocks are characterized by significant levels of Li (116–911 mg/kg), Cs (632.56–3317 mg/kg), Cu (181–343 mg/kg), Hg (11–2540 μg/kg), Sb (108.94–6602 mg/kg), BaSO₄ (27.49–71.13 %), S (37.3 %), and F (84–3848 mg/kg). This study identifies Li-bearing mica minerals in considerable concentrations, alongside epithermal minerals attributing to a paleo-high-temperature regime in the Himalayan geothermal field. A conceptual model has been developed to trace the origin of critical minerals in thermal fluids and spring deposits, suggesting that metals and metalloids degas from felsic magmatic melts, through less-denser geological vapours, primarily as vapour-soluble chloride and sulfide complexes, which mixes with genetically evolved secondary fluids undergoing gas-solution-rock interactions and gets enriched in liquid phase after steam segregation, mainly due to decompression boiling.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126348"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineral chemistry of the Gülkonak Fe-Skarn Deposit, Central Anatolia, Türkiye: Implications for ore genesis and mineralization process","authors":"Ayşe Orhan","doi":"10.1016/j.chemer.2025.126357","DOIUrl":"10.1016/j.chemer.2025.126357","url":null,"abstract":"<div><div>The newly discovered Gülkonak Fe-skarn deposit is located in Central Anatolia and lies at the contact zone between the late Cretaceous Behrekdağ granitoid and the late Permian Bozçaldağ marble. The Behrekdağ granitoid is quartz-monzonite – monzonite in composition and contains abundant MMEs of monzonite – monzodiorite composition. Whole-rock and mineral chemistry data suggest that the pluton was associated with subduction in a continental arc setting and derived from crust, mantle, and/or mixed sources. A couple of phases representing different physicochemical conditions in the continental crust for iron mineralization have been identified based on amphibole mineral chemistry. The first phase, which indicates the mixing of mafic-felsic magmas, exhibits relatively high pressure (132–203 MPa), depth (5.0–7.7 km), and temperature (804–871 °C), and moderate-high ƒO₂ (ΔNNO: −0.01 to +0.50) and H₂O content (3.5–4.9 wt%) in the melt. The second phase is the dissolution of Fe-rich liquid, characterized by decreasing pressure (44–45 MPa), depth (1.7 km), temperature (732–736 °C), and H₂O content (3.6–3.9 wt%) and increasing ƒO₂ (ΔNNO: +1.1 to +1.2) conditions.</div><div>Magnetites in Gülkonak Fe deposits occur as massive, irregular lenses and disseminated in the proximal and distal zones. Different types of magnetites were characterized by skarn-type deposit with Ca, Al, Ti, and V contents. Five main stages for skarn formation and mineralization were distinguished in the region: (1) Na-(Ca) alterations consisting mainly of albite (Ab₉₈) and actinolite; (2) prograde stage representing of early-andradite (Grs_0.0–28And_72–100) and diopside (Di_66–95Hed_4–31Joh_0–3) genetically related to mineralization and late-grossular-andradite (Grs_0.00–99.9And_0.1–99.6); (3) retrograde stage consisting of epidote (Ep_57–72Cli_28–43), magnetite, quartz, calcite, and less sulfide (pyrite, chalcopyrite) and chlorite (Mg-chlorite); (4, 5) quartz‑carbonate and supergene stage characterized by quartz, calcite, hematite, goethite, and less siderite, bornite, chalcocite, covellite and malachite.</div><div>These findings suggest that skarn and Fe mineralization are genetically related to the Behrekdağ granitoid. It is suggested that the sudden uplift of Fe-Mg-enriched melt into the shallow continental crust through magma-mixing processes may have promoted extensive dissolution of magmatic fluids. The metasomatic reaction of high-ƒO₂ and Fe³⁺-rich ore-forming fluids with carbonate rocks produced andradite and diopside. It can be stated that the primary mechanisms responsible for the precipitation of metals in Gülkonak skarn deposits are increased pH and decreased temperatures, resulting from the reaction of metals transported as metal chlorides with carbonate rocks.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126357"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}