Chemie Der Erde-Geochemistry最新文献

{"title":"Emplacement impacts of post-collisional Batuga granite, south Eastern Desert of Egypt: Formation of garnetiferous calc-silicate rocks and gold re-distribution in arc-related gabbros","authors":"Adel A. Surour , Mohamed A. El-Sobky , Ahmed A. Madani , Hesham Mokhtar","doi":"10.1016/j.chemer.2026.126395","DOIUrl":"10.1016/j.chemer.2026.126395","url":null,"abstract":"<div><div>At Wadi Kalalat area in the south Eastern Desert of Egypt, felsic magmatism represented by the Batuga granite is a late Neoproterozoic post-collisional granite intrusion. The present work integrates field and laboratory techniques to reveal the effects or impacts of this granite emplacement on the country rocks, particularly the formation of garnetiferous calc-silicate rocks and re-distribution of gold in fresh arc-related gabbro. Mineral chemistry and the FTIR, Raman, UV–Vis spectra indicate a grossular-andradite composition of garnet in the garnetiferous calc-silicate rock, which forms in a narrow thermal aureole superimposed island arc impure metacarbonate adjacent to the Batuga pluton. Garnet associates wollastonite (Wo<sub>92</sub><sub>–</sub><sub>99</sub>) and diopside (Wo<sub>47</sub><sub>–</sub><sub>51</sub>, En<sub>36</sub><sub>–</sub><sub>43</sub> and Fs<sub>8</sub><sub>–</sub><sub>16</sub>). It is believed that within the aureole, these minerals crystallize at a near-equilibrium condition in a Ca-Mg-Si-rich environment with minimal Al activity induced by hot fluids that are expelled from the Batuga granite to form garnet-bearing calc-silicate rocks. In the whole-rock of the investigated calc-silicates, both Al<sub>2</sub>O₃ and ΣNa<sub>2</sub>O + K<sub>2</sub>O, which indicate a strong depletion in aluminosilicate and alkali-bearing minerals. All samples of calc-silicate are scapolite-free, and therefore the Batuga granite pluton is a shallow intrusion emplaced at temperature lower than 550–600 °C. Due to the emplacement of the pluton, gold is also re-distributed and concentrated from 0.9 g/t in olivine gabbro without effect of thermal metamorphism to up to 16 g/t in a narrow melanocratic thermal aureole made up of hornfelsic olivine gabbro. Gold is also enriched in the alteration zones (up to 2.17 g/t) adjacent to some quartz veins with Au content not exceeding 0.17 g/t. The UV–Vis-NIR spectra of garnet shows Fe<sup>3+</sup> charge-transfer bands (182–361 nm), which is a confirmation of an andradite-grossular solid solution end-member. It is believed that garnet is developed under oxidizing conditions when Fe<sup>3+</sup> prevails due to impacts of metasomatism and thermal metamorphism. A strong Raman shift at 753 cm<sup>−1</sup> and a relatively weaker shift at 911 cm<sup>−1</sup> is another confirmation of solid solution along the andradite (Ca<sub>3</sub>Fe<sub>2</sub>Si<sub>3</sub>O<sub>12</sub>) and grossular (Ca<sub>3</sub>Al<sub>2</sub>Si<sub>3</sub>O<sub>12</sub>) compositional range. The ASD FeldSpec is a powerful remote sensing technique to separate between metamorphosed and fresh gabbroic lithologies. The metagabbro has reflectance features that are related to the vibrational process of Mg-O-H and Al-OH due to chloritization and uralitization of magmatic pyroxene, and also because of Ca-plagioclase sericitization upon regional metamorphism of the island arc association. On the other hand, in the fresh arc-related ","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126395"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147395775","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 composition, trace element geochemistry and metallogenic processes of the early Cambrian black rock series-hosted Xiajiadian gold‑vanadium deposit, southern Qinling, China","authors":"Bei Li,&nbsp;Laimin Zhu,&nbsp;Xiao Xiong,&nbsp;Lele Ding,&nbsp;Yuanbo Ma,&nbsp;Shenghao Li,&nbsp;Yang Jiang","doi":"10.1016/j.chemer.2025.126362","DOIUrl":"10.1016/j.chemer.2025.126362","url":null,"abstract":"<div><div>Black rock series are significant in economic geology as they harbor abunbant mineral resources and are often spatially associated with several types of ore deposits. The Xiajiadian deposit is a large-scale, unique Au<img>V co-product system within these series, yet its mineralogy and detailed metallogenic mechanisms remain poorly constrained. This study employs an integrated approach, including scanning electron microscopy (SEM), X-ray diffraction (XRD), electron probe micro-analysis (EMPA), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), to systematically determine the mineral composition, trace element geochemistry, and occurrence modes of Au and V.</div><div>The black rock series exhibit a complex mineral assemblage, comprising not only quartz, feldspar, carbonates, and clays but also key ore-related minerals such as barite, roscoelite, anatase, and goethite. Geochemical data reveal significant enrichment of Au, V, Ba, P, and Mo,compared to the upper continental crust. Furthermore, we propose a two-stage metallogenic model: first, a sedimentary/diagenesis and metallogenic stage during which hydrothermal-seawater-microbial interactions led to V enrichment to industrial grades and pre-concentration of Au; subsequently, a tectonic-hydrothermal reformation stage during which pre-enriched Au was remobilized and precipitated to form economic orebodies. Vanadium occurs primarily as V³⁺ in anatase and roscoelite, and in an adsorbed state on goethite and clay minerals. Gold exists predominantly as “invisible gold”, mainly in the form of adsorbed gold (on goethite, illite, kaolinite, and organic matter) and structurally bound Au⁺, with a minor component of nanoparticulate Au⁰. Rare earth element and yttrium (REE + Y) systematics indicate that the ore-forming materials were sourced primarily from the black rock series, which formed in a redox-stratified basin through the mixing of seawater, hydrothermal fluids, and microbial interactions. This two-stage genetic model elucidates the coupled enrichment and differential mobilization of Au and V, providing critical insights for regional exploration.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126362"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145685746","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, geochemical, spectroscopic, and color-making elements investigation of agate and chalcedony mineralization; case study: Kasrab district, east Iran","authors":"Mohammadreza Hosseinzadeh ,&nbsp;Ali Asadi ,&nbsp;Vartan Simmonds ,&nbsp;Matthew I. Leybourne","doi":"10.1016/j.chemer.2025.126381","DOIUrl":"10.1016/j.chemer.2025.126381","url":null,"abstract":"<div><div>The agate and chalcedony mineralization in the Kasrab area displays a wide spectrum of colors, including black, purple, green, blue, lily (lavender), moss, red, lemon, and white, reflecting variations in trace elements and formation conditions. These minerals occur mainly in veins and veinlets cutting through carbonate rocks, as well as in open-space fillings within fresh and hydrothermally altered andesites. Moganite, a quartz polymorph, occurs both in vesicles and as microcrystalline overgrowths, indicating its role in the complex silica precipitation processes. Altered volcanic rocks show elevated concentrations of Al₂O₃, Fe₂O₃, Na₂O, K₂O, P₂O₅, and TiO₂, whereas fresh host rocks are richer in CaO and MgO, reflecting element mobilization during acidic hydrothermal alteration. Geochemical analyses reveal enrichment of LILEs (relative to primitive mantle-normalized values) and LREEs (relative to chondrite-normalized REE values) in both agates samples and host rocks, with agates showing slight LREE depletion, HREE enrichment (except Tm), and anomalies of Nb (negative) and Cs, U, Pb (positive), but negligible Eu anomaly. Petrographic study identified two main fluid inclusion types—vapor-rich (VL) and liquid-rich (LV)—with microthermometry indicating salinities up to 4.65 wt% NaCl equivalent and homogenization temperatures of 97–124 °C, consistent with low-salinity, low-temperature hydrothermal formation. Fluorescence spectroscopy revealed emission peaks of quartz, Cr³⁺, and Ca-bearing minerals (aragonite, calcite, diopside), while FT-IR confirmed hydroxyl groups, molecular water, and hydrated silica phases (opal-A, opal-C, opal-T). UV–Vis spectroscopy identified Fe³⁺ and Ni²⁺ transitions associated with hematite and goethite, contributing to coloration. Physical measurements show translucent agates have higher refractive indices and specific gravity than transparent ones, reflecting subtle differences in microstructure and impurity content.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126381"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884251","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":"A review of the distinctive spatial and temporal compositions of basalt sequences associated with slow-spreading zones influenced by mantle plumes and their petrogenetic implications","authors":"David A. Wood","doi":"10.1016/j.chemer.2026.126392","DOIUrl":"10.1016/j.chemer.2026.126392","url":null,"abstract":"<div><div>Systematic and substantial temporal and local spatial variations in trace element and radiogenic isotope ratios are reviewed in basalts sequences from East Greenland, Iceland, Faeroe Islands, Rockall Trough, Hebridean Islands and the Mohns Ridge. These variations are indicative of local scale mantle heterogeneities relating to mantle plume influences in these zones of incipient rifting and slow-spreading extensional tectonics. The magnitude and range of key elemental and isotopic variations are reviewed and found to be similar in each region. To effectively characterize the compositional variations, two relevant reference compositions are employed: worldwide averages for mid-ocean ridge basalt (N-MORB) and intraplate basalt (WLD). Profiles of regional average trace element concentrations and Pb-isotopes normalized to the WLD reference also reveal characteristic patterns. Some basalt series from East Greenland, Faeroe Islands, Rockall Trough and the Hebridean Islands have been affected by crustal contamination. However, the trace element ratios and normalized profiles are still able to reveal mantle heterogeneities influencing those lava sequences. Based on the regional comparisons in spatial and temporal variations, dominated by fertile compositions in the earlier stages and more refractory compositions in the later stages, a conceptual petrogenetic model is developed and illustrated. This incorporates pulsed-plume diapirism and sequential, incremental upper mantle dynamic partial melting forming distinctive magma pulses, Asthenosphere outflow and magma mixing in an interconnected network of lower crustal, sill-like magma chambers are additional features of the model. This review reveals that in slow-spreading or incipient-rifting, extensional regions, where mantle plumes are laterally constrained for longer periods than at fast spreading ridges, a distinctive compositional evolution occurs in the basalt sequences generated.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126392"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146173643","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":"Unravelling the origin of A-type granites in an extensional arc setting: Insights from the Permian El Fierro pluton, Colangüil batholith (Frontal Cordillera, Argentina)","authors":"Juan A. Moreno ,&nbsp;Gilmara Santos da Cruz ,&nbsp;Juan A. Dahlquist ,&nbsp;Matías M. Morales Cámera ,&nbsp;Priscila S. Zandomeni ,&nbsp;Gabriela A. Gonzalez-Liedtke ,&nbsp;Miguel A.S. Basei ,&nbsp;Sanjeet K. Verma","doi":"10.1016/j.chemer.2026.126388","DOIUrl":"10.1016/j.chemer.2026.126388","url":null,"abstract":"<div><div>The El Fierro pluton represents one of the late-stage plutons of the Choiyoi Magmatic Province in the Colangüil batholith (Frontal Cordillera, Argentina). New U‑Pb zircon dating yields a crystallisation age of 262 ± 2 Ma, with zircon antecrysts (∼273 Ma) indicating prolonged magmatic activity that overlaps with the early-stage Choiyoi I-type magmatism (ca. 270–290 Ma). This pluton is ferroan, alkali-calcic to calc-alkalic, and essentially weakly peraluminous (av. 1.05 ± 0.06), exhibiting high Ga/Al ratios, elevated HFSE concentrations (Ce + Zr + Nb + Y; av. 310 ± 147 ppm; range: 150–584 ppm), extreme F enrichment (6101–31,442 ppm) and relatively high zircon-saturation (775 ± 45 °C) and apatite-saturation temperatures (887 ± 78 °C), consistent with an A-type affinity. Isotope data (εHf_t = −7.0 to +1.25; εNd_i ≈ −3), together with geochemical compositions, reflect a hybrid crustal source involving metasedimentary components likely metasomatized by mantle fluids. Accordingly, we interpret the El Fierro pluton as the product of crustal melting during lithospheric thinning and slab retreat, marking the onset of incipient rifting in southwestern Gondwana. This study highlights that A-type granites can be generated in extensional regimes within arc settings.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126388"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022427","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":"Petrogenesis of Paleoproterozoic mafic magmatic rocks from Garhwal Lesser Himalayan Sequence: Implications for Precambrian crustal recycling and geodynamic evolution of proto-northern Indian continental margin","authors":"Ashutosh Pandey ,&nbsp;H.K. Sachan ,&nbsp;Digvijay K. Dubey","doi":"10.1016/j.chemer.2026.126387","DOIUrl":"10.1016/j.chemer.2026.126387","url":null,"abstract":"<div><div>The Precambrian geodynamic evolution of the proto-northern Indian continental margin remains elusive. Mafic magmatic rocks from the Lesser Himalayan Sequence, representing the northern extremity of the Indian Shield, provide key constraints on this evolution. This study presents new mineralogical and whole-rock geochemical data from mafic rocks in the Rudraprayag-Karnaprayag sector of the Garhwal Lesser Himalayan region, aiming to elucidate their genesis and geodynamic significance. The whole-rock geochemistry of the studied rocks exhibits enrichment in large-ion lithophile elements and depletion in high-field strength elements, with elevated Ba/Nb, Th/Yb, and La/Sm ratios, indicative of subduction-related metasomatism of the mantle source. The most primitive samples (with MgO &gt; 7.5 wt%) exhibit major element systematics consistent with melts derived from a pyroxene-dominated mantle source, possibly produced by interaction between peridotite and siliceous melt. Estimated melting temperatures (1198–1385 °C) exclude the possibility of involvement of anomalously hot mantle plumes in the origin of these rocks and point towards a passive continental rifting setting. These observations suggest that the Paleoproterozoic mafic magmatic rocks of the Lesser Himalayan Sequence possibly originated in a continental back-arc extensional setting linked to an Andean-type active continental margin along the proto-northern Indian cratonic block. Our results support the evidence for an Andean-type active continental margin along the proto-northern Indian continental margin during the assembly of the Columbia supercontinent in the Paleoproterozoic.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126387"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977864","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":"Geochemistry and mineralogy of neoproterozoic exotic minerals-bearing post-collisional A-type granites of Jebel Qutn intrusion, Arabian shield, Saudi Arabia","authors":"Bassam A. Abuamarah ,&nbsp;Kirsten Drüppel ,&nbsp;Mokhles K. Azer","doi":"10.1016/j.chemer.2026.126385","DOIUrl":"10.1016/j.chemer.2026.126385","url":null,"abstract":"<div><div>The Jabal Qutn intrusion (JQI) is a Late Ediacaran post-collisional granitic intrusion in the northeastern part of the Arabian Shield, the western extension of the Neoproterozoic Arabian-Nubian Shield (ANS). The study area is dominated by Neoproterozoic rocks including sedimentary units of the Murdama group, granodiorites, and A-type granites. The latter form a ring complex that consists of an inner core of alkali feldspar granite and an incomplete outer zone of syenogranite with gradational contacts between them. The Qutn granites are mainly composed of feldspars, micas and quartz and contain a large variety of accessory phases including zircon, allanite, thorite, topaz, titanite, waimirite-(Y), bastnäsite, Nb-Ta oxides (columbite, qitianlingite and nioboaeschynite), wolframite, pyrochroite, apatite, and gold alloys (Au contents of 60–80 wt%). Rare mineral species such as qitianlingite and nioboaeschynite-(Y) are recorded for the first time in the whole ANS. In case of waimirite-(Y) the study area represents the third reported occurrence in the world. The granites are highly evolved (SiO₂ = 72.69–76.65 wt%), and exhibit almost identical chondrite-normalized rare-earth elements patterns with slight enrichment in LREE compared to HREE [(La/Lu)_<em>n</em> = 1.24–2.92] and prominent negative Eu anomalies (Eu/Eu* = 0.04–0.13)<em>.</em> They show geochemical characteristics of anorogenic granites and continuous compositional trends for both major and trace elements, indicating a common source, i.e. partial melting of juvenile crust, followed by extensive fractional crystallization of feldspars, apatite, and Fe-Ti oxides associated with minor crustal contamination. The granites were emplaced at shallow depths (&lt; 6 km) with their estimated crystallization temperatures ranging between ca. 780 and 850 °C. The late formation of F-rich minerals (topaz, fluorite, waimirite-(Y)) implies a F-rich composition of the parental magma with strong late-magmatic F- and REE-enrichment. Textural characteristics provide evidence for a strong metasomatic alteration in the late-magmatic stage that mainly occurred in the apical and marginal parts of the alkali feldspar granite, with the hydrothermal solutions being concentrated in the upper part of the magma chamber before complete crystallization of granitic magma</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126385"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022428","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":"New geochemical and geochronological findings from the Mesozoic ophiolites and marine rock sequences in the Tauride ribbon continent (southern Turkiye) and implications for the evolution of the Inner - Tauride and Pindos (Greece) seaways within the Mesozoic Neotethys","authors":"Ender Sarifakioglu ,&nbsp;Alican Ozturk ,&nbsp;Yıldırım Dilek ,&nbsp;Bilgehan Yabgu Horasan ,&nbsp;Tamara Bayanova ,&nbsp;Mustafa Sevin ,&nbsp;Muhammed Çoban ,&nbsp;Dmitry Elizarov","doi":"10.1016/j.chemer.2025.126356","DOIUrl":"10.1016/j.chemer.2025.126356","url":null,"abstract":"<div><div>Ophiolites exposed in the Konya region of south-central Anatolia play an important role in understanding the distribution of Neotethyan suture zones and paleogeography in the eastern Mediterranean region. The Dipsizgöl ophiolites consist mainly of upper mantle peridotites, rare ultramafic cumulates, and microgabbro – diabase dykes that locally crosscut the peridotites. Basaltic rocks of the Dipsizgöl ophiolite and the Huğlu Unit display P-MORB composition affected by subduction-affected melts. The Huğlu Unit developed in a continental back-arc setting within the Tauride ribbon continent during the Middle-Late Triassic through Cretaceous. The Dipsizgöl ophiolite is geochemically similar to the ophiolites derived from the Pindos back-arc basin, which opened between the Dinaride–Hellenide microcontinent and the Pelagonia Platform to the west during the Late Triassic. A diabase dyke from the Dipsizgöl ophiolite revealed a Rb–Sr whole-rock isochron age of 183 ± 69 Ma. Although we take into account the possibility of errors arising from processes within the system or external factors, this data indicates that the oceanic basin existed between the Lower Triassic to the latest Lower Cretaceous. This intra-continental back-arc basin was likely part of the Southern Inner-Tauride Ocean (SITO), which constituted the eastern equivalent of the Mesozoic Pindos ocean farther west. The Hatip-Çağırbağı, Yükselen, Yunak, Çeşmelisebil and Altınekin ophiolites in the Anatolides exhibit geochemical characteristics of back-arc to fore-arc environments, and represent the remnants of the Mesozoic Northern Inner-Tauride Ocean (NITO). The U<img>Pb zircon dating of a shoshonitic mafic dyke that crosscuts the Altinekin ophiolitic mélange revealed a 70–85 Ma crystallization age, which is interpreted as the timing of the development of an immature volcanic arc. With the opening of the Neotethys in the late Permian, the Apulian microcontinent, which comprised the Dinaride–Hellenide–Tauride carbonate platforms, broke away from the Gondwana continent and drifted northwards. The Pindos basin was a separate seaway in Neotethys and opened within the Apulian microcontinent in the early? Triassic and closed in the Late Cretaceous–Early Paleocene.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126356"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145685747","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":"Large-scale REE mineralization linked to intensive evolution of carbonatitic-alkaline magmas to brine-melts: Insights from Sr-Nd-Ba isotopes","authors":"Xiao-Chun Li ,&nbsp;Geng-Xin Deng ,&nbsp;Xiao-Yun Nan ,&nbsp;Xue-Yin Yuan ,&nbsp;Hong-Rui Fan ,&nbsp;Fang Huang","doi":"10.1016/j.chemer.2026.126390","DOIUrl":"10.1016/j.chemer.2026.126390","url":null,"abstract":"<div><div>Most global rare earth element (REE) deposits are generated by liquids derived from carbonatitic-alkaline magmas. However, the nature of REE mineralizing liquids and how they were related to the carbonatite systems remain enigmatic. In this study, we present new Sr-Nd-Ba isotope data for a REE-rich, syenite‑carbonatite complex at Dong Pao, Vietnam to trace the generation process of the ore-forming liquid. The complex records early-stage K-feldspar crystallization to form syenite<strong>,</strong> followed by late-stage calcite crystallization forming carbonatite. The hydrothermal REE ores show identical initial Sr isotope ratios (0.7075 to 0.7083) and εNd(t) values (−4.6 to −7.5) with syenite and carbonatite (⁸⁷Sr/⁸⁶Sr_i: 0.7072–0.7079; εNd(t): −6.5 to −5.6), indicating a common source of these rocks. Importantly, the Dong Pao syenite, carbonatite, and REE ores show distinct variations in Ba isotope compositions, with the latter two rock domains having higher Ba isotope values (δ^138/134Ba: 0.03‰ to 0.12‰) than syenite (δ^138/134Ba: −0.03‰ to 0.03‰). This isotope signature <strong>is</strong> interpreted to result from extensive fractional crystallization of K-feldspar, which preferentially incorporates light Ba isotopes<strong>,</strong> thereby enriching the residual melts and fluids in heavy Ba isotopes. This provides strong evidence for the generation of ore-forming liquids through intensive magmatic evolution. The common occurrence of high-salinity melt-fluid inclusions in REE ores further support the involvement of chemically evolved, alkali- and volatile-rich liquids during mineralization. Because REE are incompatible in common rock-forming minerals<strong>,</strong> continuous and intensive melt-fluid evolution can significantly enhance the potential for REE ore formation. Collectively, these findings highlight the important role of chemically evolved, high-salinity liquids in REE mineralization, and demonstrates the utility of Ba isotopes as a novel tracer for ore-forming process in th<strong>e</strong> carbonatite-alkaline systems.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126390"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077410","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":"Characterization of geothermal water-rock interaction processes and transport patterns using geochemical methods","authors":"Zhang Hanxiong ,&nbsp;Wang Guiling ,&nbsp;Zhang Wei ,&nbsp;Wang Mengmeng","doi":"10.1016/j.chemer.2026.126389","DOIUrl":"10.1016/j.chemer.2026.126389","url":null,"abstract":"<div><div>Geothermal resources are green renewable economic energy, and the efficient development and utilization of geothermal resources has become an important research direction of common concern for all countries in the world. Knowledge of the transport processes, circulation patterns, water-rock reactions, and geochemical change processes of geothermal water is an important prerequisite for the efficient development and utilization of geothermal resources. To elucidate the mechanisms of water-rock interaction and the circulation pathways of geothermal fluids, the Rongcheng geothermal field in Xiong'an New Area, China, was selected as the study area. An integrated approach combining hydrochemical analysis, stable isotope techniques, and hydrochemical inverse modeling was employed to systematically characterize the hydrogeochemical evolution of the groundwater systems. Hydrochemical analysis reveals that geothermal fluids are predominantly of the Na-Cl type, with total dissolved solids (TDS) exceeding 1000 mg/L, significantly higher than the Ca-HCO₃ type shallow groundwater. Isotopic data (δ¹⁸O and δ²H) confirm origin for all water types is atmospheric precipitation, with geothermal fluids exhibiting a distinct “δ¹⁸O shift” and lower deuterium excess values, reflecting intensive water-rock interactions under high-temperature conditions. Results of water rock equilibrium state show that the water samples of the study area are partially equilibrated and immature. Saturation index (SI) calculations further demonstrate that chalcedony and quartz are closer to being saturated in the hydrologic reactions of the water compared with other minerals. Driven by distinct circulation pathways, carbonate geothermal water exhibit greater circulation depths and higher reservoir temperatures compared to those in sandstone reservoirs. Three circulation patterns (directions 1, 2, and 3) are proposed based on a combination of clustering analysis, water-rock interactions, inverse simulation of the water circulation paths, and a more refined conceptual model of the water circulation in typical profiles. It is concluded that direction 3 is a deep carbonate geothermal reservoir cycle and that the carbonate geothermal water exhibits more reduction and stronger water-rock reactions because the temperature and pressure of the environment are higher than those for directions 1 and 2. The results of geothermal water genesis patterns and circulation paths and scientific theoretical support for in-depth study of geothermal resources.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126389"},"PeriodicalIF":2.9,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022429","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}