Chemie Der Erde-Geochemistry最新文献

{"title":"Petrogenesis of the Niancaowan mafic-ultramafic intrusion: Decoding magmatic evolution in the cuNi Metallogenic Province of the Bayan obo rift zone","authors":"Linna LI ,&nbsp;Jiangang JIAO ,&nbsp;Yunfei MA","doi":"10.1016/j.chemer.2025.126359","DOIUrl":"10.1016/j.chemer.2025.126359","url":null,"abstract":"<div><div>The Niancaowan mafic-ultramafic intrusion is located within the Bayan Obo Rift Zone of central Inner Mongolia. Systematic genetic investigations were conducted in this study to clarify the genetic relationship between the Niancaowan mafic-ultramafic intrusion and known Cu<img>Ni deposits within the rift zone, as well as to assess the comparability of their mineralization potential. Through integrated petrographic observations, high-precision geochronological dating, whole-rock geochemical analyses, and zircon Hf isotope tracing, the research specifically focused on elucidating the magmatic source characteristics, rock-forming timing, and magmatic evolutionary processes of the intrusion. The Niancaowan mafic-ultramafic intrusion is predominantly composed of hornblende gabbro and gabbro-diabase. LA-ICP-MS zircon U<img>Pb dating reveals that the hornblende gabbro crystallized during the Early Permian (273.2 ± 3.5 Ma), which demonstrates temporal synchronicity with the emplacement ages of other mafic-ultramafic intrusions within the central-western Inner Mongolia rift system. Geochemical tracers further disclose significant zircon Hf isotopic heterogeneity, indicating that the parental magma was derived from partial melting of a lithospheric mantle source and underwent contamination by lower crustal materials during its ascent. Comparative analysis indicates that the zircon Hf isotopic compositions of the Niancaowan intrusion (ε_Hf(t) = −17.0 to +1.4) are similar to those of typical regional intrusions such as the Wulantaolegai and Huanghuatan intrusions, revealing that crustal contamination was prevalent during the emplacement of mafic-ultramafic magmatic systems within the Bayan Obo Rift Zone. The incorporation of such crust-derived components may be controlled by the melting or assimilation processes of ancient basement rocks in the extensional setting of the rift zone. The petrological characteristics and quantitative modeling results indicate that the Niancaowan intrusion experienced relatively weak crustal contamination (4 %–8 %). If sulfide mineralization were to occur in this intrusion, it would primarily depend on deep-seated magmatic differentiation. Comparative studies between the Niancaowan intrusion and other intrusive bodies within the Bayan Obo Rift Zone reveal that the mineral exploration potential of mafic-ultramafic intrusions in the Bayan Obo Rift Zone should not be overlooked. Particular attention should be given to highly contaminated mafic-ultramafic intrusion clusters within the rift zone and multi-stage tectonic-magmatic convergence nodes.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126359"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617852","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":"Shear-deformation related Li-Rb-Cs mineralization: The case study from mineral chemistry and 40Ar39Ar ages of phlogopite in the Gaoligong Shear Zone, eastern Tibetan","authors":"Xuanchi Deng ,&nbsp;Xiaofeng Li ,&nbsp;Yiting Zhu ,&nbsp;Heng Xu ,&nbsp;Yong Yu","doi":"10.1016/j.chemer.2025.126365","DOIUrl":"10.1016/j.chemer.2025.126365","url":null,"abstract":"<div><div>Li-Rb-Cs rare metal mineralization is closely linked to highly fractionated granites. However, the origin of Li-Rb-Cs rare metal mineralization during the shear-deformation remains unclear. The Gaoligong Shear Zone (GSZ) is situated along the eastern margin of Tibetan in southwestern China. It is a dextral strike-slip shear zone formed by the northward movement of the India Plate to relative to the Eurasia Plate during Oligocene-Miocene. Bulk mineral composition, together with EMPA and LA-ICP-MS data, reveal that Li-Rb-Cs-rich phlogopite occurs in Carboniferous metamorphic rocks of the GSZ. This phlogopite is enriched in F (4.29–5.06 wt%), Li (1281–1849 ppm), Rb (2550–3242 ppm), and Cs (386–1575 ppm), but depleted in Be (&lt;1 ppm). In contrast, scapolite (marialite) intergrown with the Li-Rb-Cs-rich phlogopites is enriched in Be (31.31–91.34 ppm), and Ga (38.92–48.83 ppm), but poor in Li (1.86–18.71 ppm). Two phlogopite samples yield ⁴⁰Ar<img>³⁹Ar plateau ages of 15.64 ± 0.36 Ma, and 14.44 ± 0.23 Ma, indicating Miocene formation. These ages coincide with major shearing and regional metamorphism in the Gaoligong area. This suggests the formation of Li-Rb-Cs-rich phlogopite may have been related to intense shearing and intracrustal melting. Magma-derived metasomatic hydrothermal fluids may have contributed to the formation of the Li-Rb-Cs-rich phlogopite and the Be-rich scapolite. The study suggests that the Li-Rb-Cs rare metal mineralization can form during the shear deformation and that F-rich phlogopite is a promising indicator for rare-metal exploration in the shear deformation zone.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"86 1","pages":"Article 126365"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145658899","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}

{"title":"Fluid evolution and ore genesis of the Amensif ZnCu (Pb-Ag-Au) distal skarn deposit (western High Atlas, Morocco): Constraints from fluid inclusions, crush-leach analysis, REY geochemistry, and Pb isotopes","authors":"Larbi Rddad ,&nbsp;Abdessamad Jinari ,&nbsp;Benjamin F. Walter ,&nbsp;Mohsin Raza ,&nbsp;Rachid Benaouda ,&nbsp;El Mostafa Mouguina","doi":"10.1016/j.chemer.2025.126353","DOIUrl":"10.1016/j.chemer.2025.126353","url":null,"abstract":"<div><div>This study investigates the genesis of hydrothermal mineralization at the Amensif Zn<img>Cu (Pb-Ag-Au) ore deposit, hosted within Cambrian carbonates. Three stages of mineralization are identified, beginning with a pre-ore phase characterized by early pyrite precipitation from high-temperature (395–426 °C), highly saline (53.0–59.3 wt% NaCl + CaCl₂) magmatic-hydrothermal fluids under reducing conditions, consistent with a negative Eu anomaly in the Rare Earth Elements and Yttrium (REY) data. Stage I is marked by homogenization temperatures (340–395 °C) and moderate salinities (23.3–24.4 wt% NaCl + CaCl₂), indicating mixing of magmatic and cooler meteoric fluids. Stage II involves cooler (225–260 °C), less saline (17.6–20.4 wt% NaCl + CaCl₂) fluids, indicating dilution with meteoric waters. Principal Component Analysis (PCA) of crush-leach data indicates the involvement of both brine and vapor phases in metal transport and mineralization.</div><div>Lead isotopic and REY data point to a common metal source derived from both mantle and crustal reservoirs, with isotopic uniformity indicating thorough Pb mixing. This aligns with a conceptual metallogenic model in which deep-seated ENE-WSW faults enable magma ascent during post-collision collapse, whereas reactivated NE-SW and NW-SE faults provide pathways for metal-rich magmatic-hydrothermal fluids exsolved from a Permian granitic magma. Fluid mixing and fluid-rock interaction processes facilitated ore deposition in the Cambrian carbonates. These findings provide new insights into the structural and geochemical factors controlling ore genesis at the Amensif deposit and similar magmatic-hydrothermal skarn systems associated with the Hercynian/Variscan orogeny.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126353"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617954","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":"2025-12-01","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":"Late Mesoarchean crustal reworking/recycling and magma underplating process: Insights from the petrogenesis of 3.0–2.9 Ga potassic granitoids in the Anshan area, North China Craton","authors":"Yufei Xuan ,&nbsp;Jin Liu ,&nbsp;Zhenghong Liu ,&nbsp;Wang Ding ,&nbsp;Liqiang Liu","doi":"10.1016/j.chemer.2025.126361","DOIUrl":"10.1016/j.chemer.2025.126361","url":null,"abstract":"<div><div>The evolution and differentiation of early continental crust remain a fundamental research frontier, with potassic granitoids providing critical insights into these processes. This study investigates the petrogenesis and tectonic setting of Late Mesoarchean (3.0–2.9 Ga) potassic granitoids in the Anshan area of the North China Craton (NCC) through comprehensive geochronological, geochemical, and zircon Hf-O isotopic analyses. Zircon U-Pb dating reveals the studied Late Mesoarchean potassic granitoids include <em>ca.</em> 2.95 Ga Tiejiashan biotite monzogranitic-quartz monzonitic gneisses and <em>ca.</em> 3.0 Ga Donganshan monzogranitic gneisses.</div><div>The Tiejiashan potassic granitoids exhibit high SiO₂ (68.47–75.28 wt%), K₂O (4.32–4.93 wt%) contents, K₂O/Na₂O (1.19–1.53) ratios, low Mg# (23–25) values and strongly negative Eu anomalies (δEu = 0.19–0.31), with metaluminous and ferroan affinities, classifying them as A-type granites. Magmatic zircons yield δ¹⁸O values of+4.66 ‰–+6.10 ‰ and ε_Hf(<em>t</em>) values of −10.61 to −6.34, with T_DM² ages of 4.43–3.99 Ga. The geochemical and Hf-O isotope characteristics suggest that Tiejiashan potassic granitoids originated from partial melting of Eo-Paleoarchean TTGs (3.8–3.3 Ga) under shallow crustal conditions. In contrast, the Donganshan monzogranitic gneisses display higher SiO₂ (75.69–76.14 wt%) and peraluminous signatures, with pronounced LREE-HREE fractionation, moderately negative Eu anomalies (δEu = 0.69–0.80) and unradiogenic Hf isotopes (<em>i.e.</em>, ε_Hf(<em>t</em>) values = −0.85–+1.87, T_DM² age = 3.63–3.39 Ga), indicating Donganshan monzogranitic gneisses originated from partial melting of short-residence TTGs with garnet and amphibole residues. The emplacement of these potassic granitoids records a crustal recycling process, while primary magmatic fabrics (<em>i.e.</em> L ≫ S, L = S) in the <em>ca.</em> 2.95 Ga Tiejiashan pluton suggest high-temperature plastic flow linked to magma underplating. These findings highlight a Late Mesoarchean crustal reworking/recycling process of NCC, driven by the remelting of ancient crust due to magma underplating associated with mantle upwelling in an extensional setting.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126361"},"PeriodicalIF":2.9,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617853","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}