Chemie Der Erde-Geochemistry最新文献

{"title":"Chemistry and He isotope systematics of olivine as tracers of source in mantle xenoliths from Harrat Hutaymah and Harrat Kishb Cenozoic lava fields, Western Saudi Arabia","authors":"Ahmed Hasan Ahmed ,&nbsp;Abdel-Kader M. Moghazi ,&nbsp;Finlay M. Stuart ,&nbsp;Shehta Abdallah ,&nbsp;Moustafa Hashad ,&nbsp;Kamal A. Ali","doi":"10.1016/j.chemer.2025.126342","DOIUrl":"10.1016/j.chemer.2025.126342","url":null,"abstract":"<div><div>Mantle xenoliths from the Cenozoic volcanic fields of Harrat Hutaymah and Harrat Kishb, located in the western part of the Arabian Shield, consist of proto-granular lherzolite, harzburgite, and to a lesser extent dunite and wehrlite. The olivine displays variations in Mn, Ni, and Ca contents relative to the forsterite (Fo) content that is similar to that of residual mantle olivine, which crystallized after being exposed to low to intermediate degrees of melt derived from mantle peridotite. The elemental ratios of Ca-Fe-Ni-Mg-Mn in the olivine further indicate a contribution from peridotite. Pressure-temperature calculations and previous geochemical studies indicate that the peridotite xenoliths were entrained from below the crust-mantle boundary (~35 km in the mantle lithosphere) under the Arabian Shield. Olivine ³He/⁴He ratios range from 6.1 to 8.5 R_a, which overlap the range of &lt;7 to 9 R_a recently reported for off-craton-derived subcontinental lithospheric mantle (SCLM) xenoliths and is consistent with mantle beneath the region. This tends to rule out the overprinting of the SCLM by fluids/melts derived from the deep upwelling mantle sampled by the Afar plume. However, the influence of deep mantle fluid may be cryptic and warrants further exploration because the He content of the Afar mantle plume is unknown.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126342"},"PeriodicalIF":2.9,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269661","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 U-Pb geochronology of the Neoproterozoic aluminous A-type granite in the south-western Tanzania: Implications to the Tonian geodynamic evolution of Southern Africa","authors":"Emmanuel O. Kazimoto ,&nbsp;Charles H. Kasanzu ,&nbsp;Ernest Mulaya ,&nbsp;Remigius Gama ,&nbsp;Rachid Benaouda","doi":"10.1016/j.chemer.2025.126339","DOIUrl":"10.1016/j.chemer.2025.126339","url":null,"abstract":"<div><div>This study presents new insights on the Litembo granite, a 30 km wide pluton located south of the Ubendian Belt in the southern Tanzania, East Africa. Whole-rock geochemistry, U-Pb zircon geochronology, and the Rb-Sr isotope system were used to determine its geochemical composition, age, and origin, contributing to regional geological and geodynamic context. The granite is metaluminous to peraluminous, ferroan, and calc-alkalic with high concentrations of Sr, Rb, Ba, High Field Strength Elements (HFSE; e.g., Zr, Y, Nb, and Ta), and high Ga/Al ratios. The total Rare Earth Element (REE) concentrations of the granite range from 335 to 693 ppm, showing fractionated REE patterns in the chondrite-normalized spider diagram ((La/Yb)_CN = 9.40–15.41) and a negative Eu anomaly (Eu/Eu*; mean = 0.87). Primitive mantle-normalized spidegrams reveal negative patterns for Ti, Sr, P, Y, and Cs, along with enrichment in Large Ion Lithophile Elements (LILE; e.g. Rb and Ba). Geochemical features of the rock are akin to anorogenic (A-type) granites, implying formation of Litembo granite from a deep source melt, involving plagioclase, garnet, and amphibole and/or complex differentiation processes, under extensional tectonics. An initial ⁸⁷Sr/⁸⁶Sr ratio (∼0.7113) suggests evolved crustal origins, with a Rb–Sr imprecise age of about 658 ± 20 Ma. Laser ablation ICP-MS U-Pb zircon dating yields crystallisation ages of 737.1 ± 2.9 Ma and 730.1 ± 3.0 Ma, indicating emplacement between 730 and 740 Ma, followed thermal diffusion of Rb and Sr in the rock at about 660 Ma. These ages and compositional features align with the Tonian intraplate (alkaline and carbonatite magmatism) in southern Africa and support for a thermal event linked to Rodinia's breakup, preceding development of the Mozambique Belt.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126339"},"PeriodicalIF":2.9,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269663","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":"2025-09-23","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":"A new framework for exploration targeting: Integrating multifractal geochemical analysis, structural controls and fuzzy C-means unsupervised clustering","authors":"Reza Ghezelbash ,&nbsp;Abbas Maghsoudi ,&nbsp;Mehrdad Daviran","doi":"10.1016/j.chemer.2025.126340","DOIUrl":"10.1016/j.chemer.2025.126340","url":null,"abstract":"<div><div>In mineral exploration, detecting weak geochemical anomalies in covered areas remains a significant challenge due to overlapping backgrounds and anisotropic mineralization controls, particularly in tectonically complex regions like the Takhte-Soleyman district, northwest Iran, part of the Urumieh-Dokhtar magmatic arc (UDMA). This study addresses these issues by introducing a novel framework that enhances exploration targeting for gold (Au) and lead‑zinc (Pb<img>Zn) deposits. The methodology integrates multifractal geochemical anomaly separation, including multifractal inverse distance weighting (MIDW), spectrum-area (S-A) and local singularity mapping (LSM) models, alongside distance-distribution analysis (DDA) and fuzzy c-means (FCM) clustering, to account for structural and geochemical complexities. Factor analysis identifies key elemental associations—Au with As and Sb, and Pb<img>Zn with Ag and Cd—while DDA delineates northwest (NW) and northeast (NE) trending faults as critical controls, with approximately 85 % of Au and 77 % of Pb<img>Zn deposits located within 1 km of these faults. The framework refines prospectivity models by optimizing FCM clustering with the <em>V</em>_<em>XB</em> index, targeting high-potential zones. Results demonstrate FCM-based LSM's superior anomaly detection, achieving area under curve (AUC) values of 94.8 % for Au and 88.08 % for Pb<img>Zn, with strong spatial correlations to known deposits, offering a practical tool for exploration in challenging environments. This approach advances mineral prospectivity mapping (MPM) by overcoming limitations of traditional methods, with potential applications to other metallogenic provinces.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126340"},"PeriodicalIF":2.9,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145160181","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":"Analysis of clustering methods for geochemical anomaly identification through weighted sample catchment basins","authors":"Maryam Shirjang ,&nbsp;Abbas Maghsoudi ,&nbsp;Reza Ghezelbash","doi":"10.1016/j.chemer.2025.126337","DOIUrl":"10.1016/j.chemer.2025.126337","url":null,"abstract":"<div><div>The cruciality of geochemical exploration in discovering new mineral deposits demands the use of high-performance computational techniques to recognize geochemical anomaly patterns associated with mineralization. High dimensionality and complexity of geochemical datasets lead to use of brand-new methods including machine learning tools to get more efficient and accurate outcome. In this regard, advanced clustering methods have gained significant popularity over the years in the field of mineral exploration. This study presents an integrated mineral exploration approach using multiple clustering algorithms to identify Cu mineralization potential in the Kariz-Now district, Razavi Khorasan, northeastern Iran. The methodology uses faults within the study area to weight the catchment basins and brings grade characteristics of role-playing elements along with fault weights to highlight the potential areas. Three clustering techniques including K-Means (KM), Fuzzy C-Means (FCM), and DBSCAN were applied to the variables attached to their corresponding sample catchment basins to predict potential areas. The results were validated by success rate curves of the selected methods and the area under curve was calculated. The results reveal that DBSCAN has higher area under curve (AUC) than KM and FCM. Furthermore, there is a strong correlation between predicted anomalies and Paleogene volcanic and sedimentary rocks, particularly in areas with high fault density.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126337"},"PeriodicalIF":2.9,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269664","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":"2025-09-04","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":"Neotethyan Jurassic supra-subduction ophiolitic complex with Triassic subducted sole: Mineral chemistry, sole P–T estimates, and U/Pb geochronology of an intra-oceanic domain (Central Dinarides, Bosnia and Herzegovina)","authors":"Marián Putiš ,&nbsp;Ondrej Nemec ,&nbsp;Samir Ustalić ,&nbsp;Dražen Balen ,&nbsp;Jiří Sláma ,&nbsp;Elvir Babajić ,&nbsp;Ján Soták ,&nbsp;Peter Ružička ,&nbsp;Sergii Kurylo ,&nbsp;Petar Katanić","doi":"10.1016/j.chemer.2025.126263","DOIUrl":"10.1016/j.chemer.2025.126263","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The ophiolitic blocks in the Cretaceous mélanges of the Central Dinaridic Ozren and Borja–Mahnjača massifs revealed two different evolutionary periods of the Neotethys Ocean: (1) A pre-subduction Middle Triassic to Early Jurassic spreading, and (2) Late Early Jurassic (Toarcian) intra-oceanic subduction and the formation of late Early to Middle Jurassic supra-subduction ophiolitic complex. The goal of this paper is to report the rebuilding of the upper oceanic plate mid-ocean ridge (MOR) abyssal to supra-subduction zone (SSZ) ophiolites. This process is indicated by an increase of Cr# in spinel (Spl) from ~0.1 to 0.6, exceptionally to 0.75 in peridotite, the Mg# decrease in orthopyroxene1 (Opx1) from ~89–91.5 in abyssal to ~86–88 in SSZ types of peridotites, as well as with overall Al and Ti decrease in pyroxene1. However, refertilization was rarely detected in newly formed Cpx, Opx, and Spl (2, 3) generations. A relatively thin, amphibole (Amp)-rich gabbro-dolerite layer of this Jurassic Ozren–Borja–Mahnjača ophiolitic complex may have formed in a nascent fore-arc, slow-spreading ridge. Remnants of Middle Triassic oceanic crust was dated at 242 ± 1 Ma from a relic zircon population in a trondhjemite (remelted plagiogranitic) dyke of the sole eclogite by LA–ICP–MS U–Pb method, whereas its main zircon population of 176 ± 2 Ma constrains the metamorphic-anatectic recrystallization age of the dyke in eclogite. Another trondhjemitic dyke gave a magmatic crystallization zircon age of 216 ± 6 Ma with rare inherited Middle Triassic (240–230 Ma) zircon. The clinopyroxene (Cpx)–garnet (Grt)–rutile (Rt) eclogites indicate the intra-oceanic subduction of the Triassic oceanic crust to about 50 km, which was estimated from Perple_X modelling of 1.5–1.6 GPa and 860–870 °C. However, a sole skarn achieved 950 °C at 0.5 GPa. Metamorphic zircon of a sole eclogite yielded 173 ± 2 Ma (D1 subduction event at ~180–175 Ma). Partial melting of the subducted slab and the mantle wedge initiated the transition of MOR to SSZ type ophiolites. The late Early Jurassic lower oceanic crust was dated on a gabbro (178 ± 1 Ma, zircon) and plagiogranite (177 ± 1 Ma, zircon). The Spl lherzolite, harzburgite, and dunite are crosscut by early Middle Jurassic Cpx–plagioclase (Pl) and Amp–Cpx–Pl gabbro, gabbro-pegmatite, leuco-gabbro (174 ± 1 Ma, zircon), and dolerite (174 ± 5 Ma, apatite) dykes, all suggesting an advanced evolutional stage and a shallower level of ophiolites due to extension and the deeper mantle melting in the SSZ setting. Inferred slab roll-back enhanced the sole exhumation (D2) between ~175–171 Ma followed by obduction of the upper plate, hot mantle rocks over the exhuming sole (the zircon age of 171 ± 0.5 Ma at D3 ~171–168 Ma from the sole Grt–pargasite–ilmenite skarn). The outboard-directed compression led to the formation of the rear fore-arc basin upper oceanic crust basalt–radiolarite section (~170–164 Ma) sited on the upper plate lower oceanic crust. ","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126263"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060177","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":"Hydrothermal carbonate chimney event from yin’ e basin: Mineralogy, geochemistry, and mode of evolution","authors":"Tianxin He ,&nbsp;Rong Liu ,&nbsp;Qianghao Liu ,&nbsp;Hongliang Dang ,&nbsp;Xu Wang","doi":"10.1016/j.chemer.2025.126266","DOIUrl":"10.1016/j.chemer.2025.126266","url":null,"abstract":"<div><div><span><span>Hydrothermal chimney, one of Earth's most mysterious geological events, is crucial for understanding Earth's systems and the history of life. Fine-scale studies of these events help us better understand geological processes, though their transient and complex nature presents significant challenges. Through TIMA, LA-ICP-MS in-situ elemental testing, and Sr and S isotope testing, a relatively complete picture of a carbonate chimney event in the upper section of the Bayingebi Formation in the Yin'e Basin was revealed with high precision. This event was divided into four distinct stages: the prehydrothermal eruption stage, the initial hydrothermal eruption stage, the strong hydrothermal eruption stage and the sustained hydrothermal overflow stage. The pre-hydrothermal eruption stage (Area I) indicates dominant terrigenous sedimentation in a low-energy hydrodynamic environment, with coarse-crystalline </span>calcite enriched in Mn and depleted in K, Na, and Sr and featuring high </span>⁸⁷Sr/⁸⁶Sr values. Subsequently, a transient hydrothermal eruption initiated the deposits in Area II, marked by the appearance of thin-plate calcite and dolomite. During the strong hydrothermal eruption stage (Area III), radial pyrite intersected with calcite, and extensive dolomite precipitation occurred. The ⁸⁷Sr/⁸⁶Sr ratio and the δ³⁴S_V-CDT<span><span> value observed may have been a result of the activities of sulfate-reducing bacteria (SRB). In the sustained hydrothermal overflow stage, the eruption intensity decreased, leading to the formation of abundant microcrystalline carbonates in Area IV. Results show regular changes in hydrothermal mineral combinations, eruption modes, material composition, depositional environments, etc., in each stage of the carbonate chimney event, which can provide important information for global lacustrine </span>hydrothermal activity research.</span></div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126266"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060178","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":"Сomposition, evolution and age of Nb-REE mineralization in carbonatite complexes in the Ural Fold Belt: New insight into metallogenesis","authors":"I.L. Nedosekova ,&nbsp;B.V. Belyatsky ,&nbsp;S.V. Pribavkin ,&nbsp;V.А. Bulatov","doi":"10.1016/j.chemer.2025.126246","DOIUrl":"10.1016/j.chemer.2025.126246","url":null,"abstract":"&lt;div&gt;&lt;div&gt;&lt;span&gt;&lt;span&gt;The Ilmeno-Vishnevogorsk (IVC) and Buldym carbonatite complexes of the Southern Urals are deformed linear-type carbonatite complexes that underwent &lt;/span&gt;tectonic evolution&lt;span&gt;&lt;span&gt;&lt;span&gt; as a result of accretion-collision processes and the Hercynian collision orogeny. The deposits of niobium and &lt;/span&gt;rare earth elements are associated with the Ural carbonatite complexes. Nb-REE ore mineralization is represented by the pyrochlore supergroup minerals, aeschynite and &lt;/span&gt;monazite&lt;span&gt;. Their compositional evolution and connection with various phases of alkaline magmatism, pegmatite and carbonatite formation, and late postmagmatic (carbothermal) processes were studied. To determine the age and duration of the ore-forming stages, U&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;img&gt;Pb dating of minerals pyrochlore supergroup phases and monazite was carried out. The pyrochlore-group minerals of the Ural carbonatite complexes are represented by calciopyrochlore, rarely natropyrochlore, and kenopyrochlore. Pyrochlore &lt;em&gt;I&lt;/em&gt;, rich in U-(Ta), crystallizes in the earliest magmatic phases of the IVC, in the miaskites and carbonatites I of the Central Alkaline Band. In contrast, Ta-(U)-bearing pyrochlore &lt;em&gt;II&lt;/em&gt;&lt;span&gt; is formed in the later magmatic phases, in the taxitic miaskites and miaskite-pegmatites, and is present in explosive carbonatite breccias and carbonatites II of the Vishnevogorsk massif. Both varieties of pyrochlore have magmatic characteristics – oscillatory zoning, absence of vacancies in the A-site, and low Nb/Ta &lt;80. Pyrochlore &lt;/span&gt;&lt;em&gt;III&lt;/em&gt; and Sr-REE-containing pyrochlore &lt;em&gt;IV&lt;/em&gt;&lt;span&gt; – with high Nb/Ta &gt;300 and fluorine (4–5 wt%), are formed from fluid-saturated F-containing carbonate systems&lt;span&gt; in carbonatites II of the IVC miaskite intrusions and fenite halos, as well as in carbonatites III and fenites of the Buldym complex. REE minerals – aeschynite-(Ce) and monazite-(Ce) formed in the carbothermalites of the Buldym complex and in fenite halos of miaskite massifs. The morphological features and evolution of the pyrochlore composition indicate the polygenic nature of the ore process, the late low-temperature stage of which is associated not only with Nb but also with REE mineralization (aeschynite, monazite).&lt;/span&gt;&lt;/span&gt;&lt;/div&gt;&lt;div&gt;&lt;span&gt;The results of U-Pb-dating of the pyrochlore- and monazite-group minerals make it possible to distinguish two stages of ore formation in the studied carbonatite complexes of the Southern Urals. The early stage is recorded by U-(Ta)-rich pyrochlore in carbonatites I, the Potanino deposit (378 ± 5 Ma), and can be correlated with the primary crystallization of the IVС alkaline rocks and carbonatites at the rifting stage (D&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;) of the forming continental margins. Whereas, the late stage is dated at ∼255–230 Ma yielded for pyrochlores &lt;/span&gt;&lt;em&gt;II-IV&lt;/em&gt; of the Vishnevogorsk deposit – in taxitic miaskites, syenite- and miaskite-pegmatites, as well a","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126246"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060249","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, fluid inclusion, and stable isotope constraints on the genesis of Keban PbZn skarn deposit, southeast Anatolia","authors":"Ece Kırat ,&nbsp;Halim Mutlu","doi":"10.1016/j.chemer.2025.126326","DOIUrl":"10.1016/j.chemer.2025.126326","url":null,"abstract":"<div><div>The Keban Pb<img>Zn deposit is located in the Elazığ district, southeastern Turkey and hosted by the Permo-Triassic/Permo-Carboniferous Keban Metamorphics and the Late Cretaceous-Paleocene Keban Magmatics. Mineralization develops as disseminated, veins and massive types of ore within alkali syenite porphyry, sericite-chlorite banded calc-schist and dolomitic limestone.</div><div>Three paragenetic stages of skarn formation and ore deposition are recognized in the Keban Pb<img>Zn deposit: prograde (stage I), retrograde-sulfide (stage II), and supergene (stage III). The endoskarn forming a narrow zone is composed of grossular (Grt 1), Fe-rich grossular (Grt 2) and andradite (Grt 3) with diopside and plagioclase. The exoskarn comprises grossular (Grt 4), pyroxene and vesuvianite. Ore minerals include galena, sphalerite, chalcopyrite, magnetite, hematite, molybdenite, and pyrite accompanied in small quantities by pyrrhotite, arsenopyrite, manganese oxides, native gold, and sulfosalts. Mineral chemistry of garnets suggests that Grt 1 precipitated under a low water/rock (W/R) ratio and relatively reduced conditions. Grt 2 with strong oscillatory zoning and Grt 3 with high Fe³⁺ contents were formed under infiltration metasomatism with high W/R ratios. When the water–rock intereaction was decreased, Grt 4 and vesuvianite were affected by Al-bearing residual metasomatic fluids that are derived from calc-schist under reduced conditions.</div><div>Depletion of δ¹³C and δ¹⁸O in skarn calcites is largely controlled by hydrothermal fluid infiltration and meteoric water influx. Microthermometric measurements support that magmatic fluids comprising the stage I (473 to 572 °C; 11.9 wt% NaCl eq.) were sequentially mixed with meteoric waters of stage II (230 to 524 °C; 0.8.-6.6 wt% NaCl eq). Based on FI trapping pressures and depths of the boiling system, the mineralization developed after boiling during the retrograde stage in a shallow environment characterized by low to moderate temperatures and low salinities, within the pressure and depth range of ∼100–500 bar and &lt; 1.5 km, respectively. δ³⁴S values of sulfide minerals are between −8.5 and + 2.1 ‰ indicating that ore-forming fluids and metals originated principally from a magmatic-hydrothermal source. High Fe, Mn and Ga contents of sphalerites might point to deposition at low to moderate temperature conditions and trace element concentrations imply that mineralization took place at distal part of the skarn system.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126326"},"PeriodicalIF":2.9,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912510","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}