Journal of Geochemical Exploration最新文献

{"title":"Trace element and sulfur isotope constraints on the Genesis of Sb-(Au) deposits in Southern China: Insights from the Longkou deposit","authors":"Junwei Xu ,&nbsp;Xiangfa Song ,&nbsp;Degao Zhai ,&nbsp;Linyan Kang ,&nbsp;Xianghua Liu ,&nbsp;Kui Jiang ,&nbsp;Yulin Chen","doi":"10.1016/j.gexplo.2025.107892","DOIUrl":"10.1016/j.gexplo.2025.107892","url":null,"abstract":"<div><div>The Xiangzhong Metallogenic Province (XZMP) in southern China hosts the region's most extensive Sb-polymetallic mineralization system, comprising two principal deposit types: Sb-only and Sb–Au–(W). To investigate their genetic distinctions, we conducted in-situ LA-ICP-MS and sulfur isotope analyses on stibnite from the Longkou Sb<img>Au deposit in the Shaoyang Basin, and integrated these results with published data from the Xikuangshan, Daocaowan, Woxi, and Banxi deposits. Multivariate statistical analyses (PCA and PLS-DA) of stibnite trace elements reveal systematic geochemical differences between the two deposit types. Sb<img>Au deposits (e.g., Longkou, Woxi, Banxi) are enriched in Cu and Pb, whereas Sb-only deposits (e.g., Xikuangshan, Daocaowan) show elevated Hg and lower Cu<img>Pb concentrations. These patterns suggest that, while Sb in both deposit types was likely derived from Proterozoic basement rocks, metals such as Au, Cu, and Pb in Sb<img>Au deposits originated from deep magmatic-hydrothermal fluids. In contrast, ore-forming fluids in Sb-only systems were dominated by shallow-crustal or metamorphic sources, with limited magmatic input. The δ³⁴S values of stibnite are relatively uniform across most deposits, further supporting a shared sulfur source linked to basement lithologies. Trace element and sulfur isotope data point to two distinct mineralization mechanisms: in Sb<img>Au systems, magmatic-hydrothermal fluids transported metals from depth and leached Sb and S from basement rocks, while in Sb-only systems, magmatic activity primarily acted as a heat source, promoting the circulation of meteoric and metamorphic fluids that leached Sb and S from the basement. These findings provide a geochemical framework for distinguishing Sb deposit types and offer new insights into the metallogenic processes of Sb–(Au) systems in South China.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107892"},"PeriodicalIF":3.3,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation mechanism of high arsenic geothermal water in Gonghe basin, Northwest China","authors":"Zhen Wang ,&nbsp;Yongge Li ,&nbsp;Chuanxia Ruan ,&nbsp;Fu Wang ,&nbsp;Wenjing Lin ,&nbsp;Yu Yang ,&nbsp;Narsimha Adimalla","doi":"10.1016/j.gexplo.2025.107890","DOIUrl":"10.1016/j.gexplo.2025.107890","url":null,"abstract":"<div><div>The occurrence of high arsenic (As) concentrations in groundwater within overlying aquifers, influenced by deep geothermal activities, has been reported globally. However, its genetic mechanisms remain inadequately understood. In this study, forty-one water samples were collected to analyze the major and trace chemical compositions of water, along with isotopic signatures (δ¹⁸O, δD, δ¹³C, δ¹⁴C, δ³²S_SO4). Results show that As concentrations in NGW (with an average 452 μg/L) are significantly higher than in QGW (with an average 36.0 μg/L). Additionally, hydrochemical type of QGW gradually evolves from Na-HCO₃ to Na-SO₄ and Na-Cl·SO₄ along the flow path. The δ¹⁸O and δD isotopic results suggest that local atmospheric precipitation is the primary source of QGW, while glacial meltwater or high altitude atmospheric precipitation serves as the main source of NGW. The high temperature environment contributes to an oxygen drift in the δ¹⁸O of NGW. Results of δ¹³C indicate that the main sources of inorganic carbon in geothermal water are likely from the dissolution of carbonates and decomposition of organic matter. According to δ¹⁴C data, the average apparent age of QGW is 18.8 ka, with relatively older ages found in the south and southeastern parts of the study area, whereas NGW has an average age of 29.1 ka. The continuous upwelling of deep geothermal energy raises the temperature of hot storage aquifer, promoting the release and migration of As. Additionally, silicate weathering and microbial sulfate reduction play significant roles in As enrichment in both QGW and NGW. Furthermore, As desorption from QGW and NGW is another factor contributing to the elevated As levels in the investigated region.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107890"},"PeriodicalIF":3.3,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144989841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry and economic evaluation of REE + Y potential in the fine-grained matrix of sedimentary phosphorites from the Tebessa region, eastern Algeria","authors":"Riadh Aouachria ,&nbsp;Rabah Kechiched ,&nbsp;Roberto Buccione ,&nbsp;Giovanni Mongelli ,&nbsp;Ouafi Ameur-Zaimeche ,&nbsp;Olivier Bruguier ,&nbsp;László Kocsis ,&nbsp;Rabah Laouar","doi":"10.1016/j.gexplo.2025.107889","DOIUrl":"10.1016/j.gexplo.2025.107889","url":null,"abstract":"<div><div>The Algerian phosphorites, deposited during the Paleocene-Eocene, are part of the Tethyan phosphogenesis along the southern paleo-Tethys margin. Located primarily in the Tebessa region, these deposits hold reserves exceeding 2 billion metric tons. Recent interest has grown due to their enrichment in rare earth elements plus yttrium (REY). While previous studies have examined whole-rock and grain-size fractions, the fine-grained matrix (&lt;45 μm) remains poorly explored. This study provides the first mineralogical and geochemical characterization of this fraction to assess its economic potential and paleoenvironmental significance. Twenty-two fine-fraction samples from four Tebessa localities were separated using humid grain-size classification. Mineralogical analysis was supported by X-Ray Powder Diffraction (XRD), whereas geochemical analyses were carried out using inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS).</div><div>The XRD results show that the phosphorite fine-grained matrix is composed of calcite, dolomite, carbonate fluorapatite, glauconite, quartz, chlorite, and gypsum. Notably, glauconite occurs in higher amounts in southern deposits (Kef Essenoun), suggesting intensified glauconitization process. Geochemically, the fine fraction contains an average of 12.48 wt% P₂O₅, with REY concentrations ranging from 55 to 863 ppm. REY contents increase southward, with REEs ranging between 68 and 678 ppm (avg. 416 ± 198 ppm) and Y varies from 9 to 187 ppm (avg. 125 ± 56 ppm). The higher REY content is partly linked to glauconite phase abundance. Normalized REY contents indicate seawater-like patterns in the northern deposits, whereas the southern deposits show middle REE (MREE) enrichment patterns. High (La/Yb)_N ratios in the glauconite-rich samples suggest early-diagenetic adsorption under slow sedimentation rate and sub-reduced conditions. An enhanced glauconitization process occurred in the southern basin at the Paleocene–Eocene boundary, which is marked by global thermal event. These findings suggest that the fine-grained matrix, typically considered as waste during the treatment of raw phosphorites, holds economic potential due to its high REY content, presenting a promising resource for future exploitation.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107889"},"PeriodicalIF":3.3,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large-scale polymetallic mineralization driven by long-lived magmatic-hydrothermal activity and subducted sediment influx: A case study from Toyoha, NE Japan","authors":"Mizuki Ishida ,&nbsp;Yuki Hieda ,&nbsp;Shuhei Araki ,&nbsp;Koichiro Fujinaga ,&nbsp;Toru Shimizu ,&nbsp;Masaharu Tanimizu ,&nbsp;Cindy Broderick ,&nbsp;Hitomi Nakamura ,&nbsp;Hikaru Iwamori ,&nbsp;Shiki Machida ,&nbsp;Shigekazu Yoneda ,&nbsp;Kentaro Nakamura ,&nbsp;Yasuhiro Kato","doi":"10.1016/j.gexplo.2025.107887","DOIUrl":"10.1016/j.gexplo.2025.107887","url":null,"abstract":"<div><div>Although there is increasing recognition that long-lived magmatic-hydrothermal systems are essential components of large-scale mineralization, relatively little is known about the source processes that enable such activity, especially in areas of average crustal thickness. To address this issue, we investigated the sources of ore-forming elements and drivers of prolonged ore-forming activity (&gt;1 million years) in the Toyoha polymetallic intermediate-sulfidation deposit, located at the northern end of the Northeast Japan Arc. We have presented Pb isotopic evidence that in the southeastern part of the deposit, where the hydrothermal activity lasted substantially longer (&gt;1 million years) than the nearby (&lt;10 km) volcanic activities, sulfide minerals from the ore had a specific metal source in addition to the wall rocks and the magmas observable as nearby extrusive rocks. The additional source was likely latent intrusions similar to the isotopically enriched volcanic rocks ~20 km southeast of the deposit, which incorporated abundant components from the subducting sediment. Based on regional geological, geochemical (major, trace elements and Sr-Nd-Pb isotopes) and geochronological data, we propose that seamount subduction induced the extra sediment input into the mantle wedge, which generated additional magma batches and helped to sustain magmatic-hydrothermal activity in the study area. The large tonnage, particularly of Pb, Zn, Ag, and In, in Toyoha was likely a result of the productive source, which enabled long-lived magmatic-hydrothermal activity, and an effective structure for the transport and trapping of ore-forming materials.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107887"},"PeriodicalIF":3.3,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145027313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Bujinhei Pb-Zn deposit in the southern Great Xing'an Range, China: An example of the reduced hydrothermal vein type Pb-Zn mineralization system","authors":"Cheng-yang Wang ,&nbsp;Yun-sheng Ren ,&nbsp;Yi-cun Wang ,&nbsp;Zhen-jun Sun ,&nbsp;Li-juan Fu","doi":"10.1016/j.gexplo.2025.107888","DOIUrl":"10.1016/j.gexplo.2025.107888","url":null,"abstract":"<div><div>The Bujinhei deposit, a representative vein-type Pb-Zn mineralization, is situated on the western slope of the southern Great Xing'an Range (SGXR). The ore bodies of Bujinhei are primarily hosted within Permian sedimentary rocks and structurally controlled by nearly EW-trending faults. Three types of fluid inclusions (FIs), including gas-liquid two-phase inclusions (Type-1), CH₄ (±CO₂)-rich inclusions (Type-2), and pure CH₄-CO₂ inclusions (Type-3) can be recognized in hydrothermal veins. Laser Raman spectral analysis further confirmed that the gas phase of these fluid inclusions contained large amounts of CH₄. Petrographic analysis, microthermometry, and laser Raman spectroscopy of fluid inclusions suggest that the ore-forming fluids comprise a NaCl-H₂O-CH₄ ± CO₂ system, characterized by moderate temperatures and low salinity. Oxygen and hydrogen isotope data for quartz and carbonate from the ore-bearing veins fell between the fields of typical magmatic and meteoric water (δ¹⁸O_fluid = 4.0 ‰–7.2 ‰, δD_fluid = −123.1 ‰ to −112.7 ‰). The extremely low δD_fluid values of Bujinhei fluids could be due to water-rock reactions between ore fluids and carbonaceous strata. The δ¹³C _PDB value of the CH₄ in fluid inclusions ranged from −31.8 ‰ to −27.9 ‰, also suggesting the hydrolysis of organic matter in the sedimentary was involved in the mineralizing fluids. Sulfides from the Bujinhei show restricted δ³⁴S_CDT values of −3.2 to −0.7 ‰, without the diagnostic signature of sedimentary sulfur. These sulfides have ²⁰⁶Pb/²⁰⁴Pb = 18.200–18.285, ²⁰⁷Pb/²⁰⁴Pb = 15.519–15.623, and ²⁰⁸Pb/²⁰⁴Pb = 38.020–38.364, overlapping with most of the hydrothermal vein type deposits, which were sourced primarily from deep-seated magma. Genetically, the Bujinhei Pb-Zn deposit shows characteristics of a typical reduced hydrothermal system, which may be originally magmatic-related and dramatically influenced by carbonaceous-reducing rocks. The investigation results presented in this paper provide compelling evidence that carbonaceous wall rocks exert a substantial influence on the formation of reducing conditions in lead‑zinc ore-forming hydrothermal systems in the southern Great Xing'an Range.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"279 ","pages":"Article 107888"},"PeriodicalIF":3.3,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144916564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineral system modeling of Lithium-Cesium-Tantalum (LCT)-type pegmatites: Regional-scale exploration targeting and uncertainty analysis in the Sanandaj-Sirjan zone, Western Iran","authors":"Majid Keykhay-Hosseinpoor ,&nbsp;Alok Porwal ,&nbsp;R. Kalimuthu ,&nbsp;Shanta Panja","doi":"10.1016/j.gexplo.2025.107885","DOIUrl":"10.1016/j.gexplo.2025.107885","url":null,"abstract":"<div><div>Granitic pegmatites, particularly lithium‑cesium‑tantalum (LCT) types, are vital sources of rare metals crucial for modern technologies, including sustainability, energy storage, and green energy applications. Exploring and targeting LCT pegmatites are essential to meet the increasing demand for critical metals like lithium in green technologies. Mineral prospectivity modeling provides a systematic approach to identifying these deposits, especially in regions such as western Iran, where the Sanandaj-Sirjan Zone (SaSZ) is the potential host of LCT pegmatites. This study aims to model the prospectivity of LCT pegmatites in the SaSZ, with three primary objectives: (i) to construct a mineral systems framework that defines the critical processes controlling the genesis of LCT pegmatites and their mappable proxies, (ii) to identify high-priority exploration targets using knowledge-driven approaches, and (iii) address uncertainties stemming from limited data availability (epistemic) and from the integration of multiple models (systemic) to improve exploration reliability. To achieve these objectives, three well-known knowledge-based algorithms—fuzzy inference systems, continuous fuzzy gamma, and geometric average—were employed using publicly available geo-exploration datasets to generate prospectivity models based on the mineral systems approach. These were subsequently combined into a final predictive model using a majority voting (MV) ensemble technique. A confidence index (CI) was incorporated to quantify and mitigate uncertainties associated with the multi-algorithm approaches, delineating low-risk, high-confidence zones for future exploration. The results show high prospectivity zones (~2 % of the study area) in the northern and southern parts of the SaSZ, particularly near the Alvand complexes, predominantly located farther from their host plutons and within metamorphic aureoles. This study highlights the efficacy of integrating mineral systems frameworks with geospatial modeling to optimize exploration strategies. Future research should prioritize acquiring high-resolution geophysical and geochemical data and conducting systematic ground-truthing to validate and refine these targets, ensuring economic feasibility and resource-efficient exploration.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"279 ","pages":"Article 107885"},"PeriodicalIF":3.3,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144896090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical stability and environmental characterization of alkali-activated mine tailings generated using a MgCO3/MgO industrial residue","authors":"Antonio J. Diosdado-Aragón ,&nbsp;José Miguel Dávila ,&nbsp;Manuel A. Caraballo","doi":"10.1016/j.gexplo.2025.107886","DOIUrl":"10.1016/j.gexplo.2025.107886","url":null,"abstract":"<div><div>Mining tailings are commonly combined with ordinary Portland cement (OPC) and water to form a paste used for mine gallery backfilling (MGBF). Although OPC remains the most frequent choice, alternative alkaline reagents such as Mg(OH)₂ are being investigated due to several limitations: its high cost, a significant carbon footprint associated with its production, and limited long-term durability, especially because of its vulnerability to sulfate attack. This study examines how the use of a MgCO₃/MgO industrial residue affects the environmental behavior of alkali-activated pastes in a wide range of mine tailings (MTs), considering the results obtained from different tests: ABA test, leaching test according to UNE 12457-4 and uniaxial compressive strength (UCS) tests. Various paste formulations were generated using different MgCO₃/MgO concentrations and six very different types of MTs spanning a wide range mineralogical, chemical and acid potential characteristic. As a main conclusion, all alkali-activated pastes, when compared with the original MTs, showed a very important improvement of their environmental behavior, marked by a consistent reduction of their acid generation potential, a water quality improvement of their leachates and their new consideration of inert wastes according to the European regulation for waste acceptance at landfills. While dynamic long-term leaching experiments and reactive transport geochemical models are advisable to better understand the behavior of these type of mine residues under real conditions and in the long term (decades to centuries); the present study shows how the combined application of ABA and UNE 12457-4 tests can offers a reliable initial environmental characterization of alkali-activated mine pastes.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107886"},"PeriodicalIF":3.3,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144989840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metallogenic process of the metasedimentary rock-hosted HREE deposit at Guangshui (Hubei Province, Central China)","authors":"Cheng-Lai Deng ,&nbsp;Shao-Yong Jiang ,&nbsp;Xue-Wen Yuan ,&nbsp;Hui-Min Su ,&nbsp;Wei Wang","doi":"10.1016/j.gexplo.2025.107880","DOIUrl":"10.1016/j.gexplo.2025.107880","url":null,"abstract":"<div><div>Guangshui (Hubei Province, Central China) is an exceptional heavy rare earth element (HREE) deposit that occurred within a series of metasedimentary rock (e.g. leptynite). This study integrates detailed petrography with in situ U-Pb geochronology, Nd isotope systematics, and mineral chemistry of the principal REE phases—gadolinite, fergusonite, monazite and xenotime—to reconstruct the timing, sources and mechanisms of mineralization. Two generations of each mineral are recognized on the basis of crystal habit and paragenesis: Gad-I/II, Fgs-I/II, Mnz-I/II, Xtm-I/II. U-Pb dating of Mnz-I yields an age of 239 ± 13 Ma, while Xtm-I records 210 ± 6 Ma. These ages coincide with prograde and retrograde stages of Triassic high-grade metamorphism in the Dabie orogen, underscoring a direct link between regional metamorphism and HREE mobilization. Petrological observations indicate that the Mnz-I marks the crystallization of the earliest HREE assemblage (Fgs-I + Gad-I), whereas Xtm-I brackets the final stage of HREE mineralization. Geochemical variations between the two mineral generations are evident. Mnz-I and Mnz-II exhibit low Th contents, consistent with a hydrothermal origin. Mnz-II is spatially associated with Xtm-II, and its pronounced HREE enrichment coincides with HREE depletion from Xtm-I to Xtm-II, suggesting that Xtm-II formed via alteration of Xtm-I. Positive Ce anomalies in Fgs-I and Gad-I suggest crystallization under oxidizing conditions. Combined with petrological evidence and geochemical variation, the composition of Gad-II may have affected by coeval hydrothermal zircon crystallization. For Fgs-II, hydrothermal alteration likely facilitated substitution of LREE and Ca for HREE and Y at the A-site. Nd isotope compositions of Mnz-I (ε_Nd(t) = −5.1 to −5.6; T_DM2 = 1.38–1.43 Ga) and Mnz-II (ε_Nd(t) = −4.8 to −5.8; T_DM2 = 1.38–1.45 Ga) indicate a crustal source for the ore-forming materials, most likely derived from Mesoproterozoic rocks. Regionally, the phosphorus-rich Huangmailing Formation and Triassic metamorphism played critical roles in HREE enrichment. Overall, the Guangshui deposit exemplifies HREE mineralization controlled by metamorphism and fluid–rock interaction during continental collision, firmly tying its metallogenesis to the Triassic evolution of the Dabie orogen.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"279 ","pages":"Article 107880"},"PeriodicalIF":3.3,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ore-forming process and fluid development at Nanpo Au deposit, Luang Prabang-Loei Belt (NW Laos): Evidence from H-O-S-Pb isotopes and inclusions","authors":"Wei Wang ,&nbsp;Hui Li ,&nbsp;Jie Gan ,&nbsp;Fuhao Xiong ,&nbsp;Yu Gan ,&nbsp;Bin Wang ,&nbsp;Junqing Mu ,&nbsp;Huan Liu","doi":"10.1016/j.gexplo.2025.107883","DOIUrl":"10.1016/j.gexplo.2025.107883","url":null,"abstract":"<div><div>The Luang Prabang-Loei tectonic belt, as a significant polymetallic metallogenic belt within the Southeast Asian Tethys tectonic domain, hosts numerous gold deposits. However, the current understanding of the genetic types and mineralization processes of these gold deposits remains insufficient, which restricts the advancement of regional metallogenic theories. This study focuses on the newly discovered large-scale Nanpo gold deposit in this metallogenic belt. By systematically conducting analyses of ore deposit geological characteristics, fluid inclusion testing, and H-O-S-Pb isotope analyses, it aims to reveal the sources of ore-forming materials, clarify the properties and evolutionary patterns of ore-forming fluids, and further elucidate the genetic mechanism and the process of mineralization of the deposit. The orebodies of the Nanpo gold deposit typically have lenticular, stratoid, and veined shapes, which are clearly controlled by ductile shear zones. The ores are mainly of two types: quartz vein type and altered rock type. Based on the interpenetrating relationship of veins and the symbiotic assembly of minerals, the metallogenic process of the Nanpo gold deposit can be divided into three stages: (I) quartz-sericite-gold-poor pyrite stage, (II) quartz-polymetallic sulphide stage, and (III) quartz-carbonate mineral stage. With the help of studies on fluid inclusion petrography, microscopic thermometry and laser Raman spectroscopy, it can be found that there are three main types of fluid inclusions in the deposit, namely, NaCl-H₂O, NaCl-CO₂-H₂O and pure CO₂. In general terms, they are part of a NaCl - H₂O - CO₂ ± CH₄ ± N₂ low-temperature to intermediate-temperature/low-salinity fluid system. Using the isotopes S-Pb can be seen, the ore - forming materials come to a large extent from the homogenized lower crust - upper mantle. The H - O isotopes suggest that the ore - forming fluids were of metamorphic water which had an affinity to meteoric waters in the later stage. These evidences suggest that the Nanpo gold deposit is a typical orogenic gold deposit, and its formation is closely associated with the collisional orogeny in Indo - China block after the Paleo — Tethys closed. This study provides a theoretical foundation for the advancement of regional metallogenic theories and offers guidance for regional mineral exploration.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"279 ","pages":"Article 107883"},"PeriodicalIF":3.3,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144907090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genesis and magmatic-hydrothermal evolution of the Silurian Pingtan W deposit, Nanling Range, South China: Constraints from scheelite and apatite geochemistry and geochronology","authors":"Hongfei Di ,&nbsp;Yong-Jun Shao ,&nbsp;David Chew ,&nbsp;Jian-Feng Chen ,&nbsp;Wen-Jie Fang ,&nbsp;Yi-Qu Xiong","doi":"10.1016/j.gexplo.2025.107884","DOIUrl":"10.1016/j.gexplo.2025.107884","url":null,"abstract":"<div><div>A cluster of Silurian W mineralization events have been reported in South China but the ore-forming processes remain not well-constrained, impeding a comprehensive understanding of deposit genesis and hindering the deployment of further exploration programs. In this study, we examine the newly discovered Silurian Pingtan W deposit as a case study. We undertook a comprehensive study of microtextures and geochemistry on scheelite and apatite, and U–Pb geochronology on apatite to determine the timing of W mineralization as well as the origin and evolution of the ore-forming fluids. Based on BSE and CL images, we identify two types of scheelite (Sch) and apatite (Ap): Sch A (A1 and A2) and Ap I in the altered granite-scheelite stage, and Sch B (B1 and B2) and Ap II in the quartz-scheelite stage. The Mo contents and Eu/Eu* ratios of multi-stage scheelite suggest a decrease in fluid <em>f</em>O₂ from the early to late stages within each mineralization phase. The Eu/Eu* ratios of multi-stage apatite indicate an increase in fluid <em>f</em>O₂ from the altered granite-scheelite stage to the quartz-scheelite stage. The Y/Ho ratios of these phases of apatite and scheelite growth imply that the initial fluids originated from the host porphyritic biotite monzogranite, and early-stage apatite crystallization led to the depletion of Y and Ho in scheelite. A support vector machine biplot shows that Ap I is magmatic in origin, while Ap II is hydrothermal in origin. The hydrothermal Ap II yields a U–Pb age of 433.7 ± 9.7 Ma (2σ, MSWD = 1.9), aligning with the emplacement ages (431–430 Ma) of the porphyritic biotite monzogranite. These data imply that the Pingtan W deposit represents a typical altered-granite type W deposit genetically linked to its host Silurian porphyritic biotite monzogranite. In addition, the estimated F and Cl contents in melt and fluid based on their contents in apatite indicate that the volatile-rich altered porphyritic biotite monzogranite has great W mineralization potential. Considering previous studies on the Silurian W mineralization, we propose that the Silurian may represent another significant period for W mineralization in South China, with contemporaneous highly evolved and volatile-rich granites serving as a new exploration target for W deposits.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"279 ","pages":"Article 107884"},"PeriodicalIF":3.3,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}