Journal of Geochemical Exploration最新文献

{"title":"Radon contamination, risk evaluation, and their spatial distribution in groundwater of three selected northern districts","authors":"Said Muhammad ,&nbsp;Rizwan Ullah ,&nbsp;Sehrish Amin ,&nbsp;Ashfaq Ahmad","doi":"10.1016/j.gexplo.2024.107644","DOIUrl":"10.1016/j.gexplo.2024.107644","url":null,"abstract":"<div><div>Radon (²²²Rn) has a ubiquitous nature in the environment and can pose serious health threats to living beings. Groundwater is the primary source of drinking and domestic uses for &gt;3 million people in the area. The current study was conducted for investigation of groundwater for the ²²²Rn concentration and associated health risks. For that purpose, the groundwater was examined for ²²²Rn concentration using the RAD7 detector (Durridge Company, USA). Average concentrations of ²²²Rn were highest at 10.8 ± 3.6 Bq/L in the Lower Dir district and lowest at 6.39 ± 0.98 Bq/L in the Upper Dir. The average concentration of ²²²Rn was found below the threshold limit set by the US Environmental Protection Agency (USEPA) and the World Health Organization (WHO). However, the concentration in 30 % of sampling sites in the Lower Dir showed ²²²Rn concentrations higher than a recommended level of 11.1 Bq/L. This study evaluated the potential non-cancer risk and estimated lifetime cancer risk (ELCR) of various age groups via ²²²Rn consumption in groundwater. The results showed´s total annual mean exposure doses (EwTotal) values for infant of 43.7 ± 10.2, 25.2 ± 3.15, 27.0 ± 1.68 μSv/a, children 33.5 ± 7.80, 19.3 ± 2.42, 20.1 ± 1.29 μSv/a), and adults (32.3 ± 7.52, 18.6 ± 2.33, 20.0 ± 1.24 μSv/a) via groundwater intake in Lower Dir, Upper Dir, and Chitral districts, respectively. Infants showed higher vulnerability to health issues due to ²²²Rn contamination in groundwater. ²²²Rn concentrations showed a weak correlation with various studied physicochemical parameters in the groundwater.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107644"},"PeriodicalIF":3.4,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720926","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":"Rapid analysis of drill core data for detection of geological boundaries","authors":"Hamid Zekri ,&nbsp;David Cohen ,&nbsp;Neil Rutherford ,&nbsp;Chris Folkes ,&nbsp;Matilda Thomas","doi":"10.1016/j.gexplo.2024.107634","DOIUrl":"10.1016/j.gexplo.2024.107634","url":null,"abstract":"<div><div>Regolith geochemical and geophysical patterns related to underlying mineralisation may be difficult to detect in regions where the regolith is thick, transported or has developed complex layering during its mineralogical and geochemical evolution. Detection and accurate logging of geochemical and mineralogical interfaces and horizons within drill samples obtained from such regolith profiles, including the boundary between regolith and underlying bedrock can be critical for detection and interpretation of geochemical patterns. In turn, this assists in selecting zones for systematic sampling and the optimum combination of geochemical, mineralogical and geophysical analysis and data processing to enhance signals or patterns associated with mineralisation.</div><div>This study presents a multivariate data-driven approach to detecting boundaries within regolith and other profiles potentially incorporating near real-time, in-situ geochemical, mineralogical, and petrophysical data acquisition methods to aid decision-making during stratigraphic/exploration drilling campaigns. The approach is demonstrated using geochemical and mineralogical data from a drillhole at the McKinnons Au deposit in New South Wales (NSW), Australia. Embedding feature (variable) selection techniques to support vector machines and random forest approaches, followed by application of a wavelet tessellation technique encoded in Data Mosaic™ to the selected variables, delivered more detailed and refined identification of zonation and boundaries within the regolith compared with approaches using only visual core logging and geochemical assays. The method was subsequently applied to geochemical, petrophysical and spectral data acquired from two drillholes in the Delamerian Orogen of western NSW. Several subtle lithological boundaries were detected within the regolith and the interface between weathered profiles and basement rocks at different spatial scales. This included some zones displaying elevated Pb and Zn within the saprock part of the regolith profile. A critical zone above the saprock, highlighted by a high variance interval was also detected using the multivariate wavelet tessellation. This indicated shorter core sampling intervals may be needed to improve the likelihood of detecting mineralisation in this region. The methodology improves the identification of mineralised zones by enabling dynamic drilling adjustments through near real-time knowledge feedback, which also reduces costs and enhances field efficiency.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107634"},"PeriodicalIF":3.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Composition and geochemistry of recently formed secondary mineral parageneses from the Breiner mine, Maramureș, Romania","authors":"Anna Januszewska ,&nbsp;Rafał Siuda ,&nbsp;Łukasz Kruszewski","doi":"10.1016/j.gexplo.2024.107638","DOIUrl":"10.1016/j.gexplo.2024.107638","url":null,"abstract":"<div><div>The Maramureș region in Romania is renowned for its extensive mining history and rich polymetallic mineralization. This study focuses on the Breiner mine near Băiuț (~35 km east of Baia Mare), where historical Au-Ag-Pb-Cu-Zn exploitation took place. The weathering of ore minerals has led to the formation of rich assemblages of secondary minerals (SM). The dominant SM identified are melanterite, halotrichite group minerals, jarosite, goslarite, and schwertmannite. Their crystallization is significantly influenced by low pH, humidity, groundwater supply, temperature, microorganism activity, and saturation with the particular cations and SO₄²⁻. The availability of a variety of ions contributes to the formation of a diverse range of supergene phases, including Mg, Zn, and Al sulfates. Melanterite exhibits high enrichment in Zn (&gt;1 wt%) and, in certain instances, Cu (&gt;2800 ppm). Halotrichite group minerals demonstrate a notable capacity for retention of &gt;1 wt% Zn, 1700–3500 ppm As, and 1900–3500 ppm Mn. Arsenic, Pb, and Hg are mainly captured by jarosite (As &gt;1 wt%; Pb &gt;3300 ppm; Hg &gt;1 ppm) and schwertmannite (As &gt;1 wt%; Pb &gt;500 ppm; Hg &gt;9 ppm). Goslarite and rozenite exhibit enrichment in Ni (~1000 ppm) and Co (~700 ppm). Properties of mine waters within this site are characterized as low pH (pH 2.1–3.7) and extreme-metal concentration. Waters with the highest contamination levels are rich in As (&gt;1500 mg/l), Zn (&gt;9500 mg/l), Mn (&gt;1000 mg/l), Cu (&gt;350 mg/l), Cd (&gt;40 mg/l), and Ni (&gt;40 mg/l). Such high levels of dissolved contaminants are correlated with the presence of melanterite. The obtained values for toxic metals and semi-metals emphasize that these weathering zones pose a significant threat to the local environment.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107638"},"PeriodicalIF":3.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719980","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":"Origin of fluids in the Araró-Simirao geothermal system, Central Mexico","authors":"Isabel Pérez-Martínez ,&nbsp;Ruth Esther Villanueva-Estrada ,&nbsp;Claudio Inguaggiato ,&nbsp;Mario Alberto Hernández-Hernández ,&nbsp;Giovanni Sosa-Ceballos","doi":"10.1016/j.gexplo.2024.107637","DOIUrl":"10.1016/j.gexplo.2024.107637","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Araró-Simirao geothermal system is located in the eastern part of Cuitzeo Lake in Michoacán, Mexico. It is a liquid-dominated convective system featuring a high salinity, rapid discharge, and heat loss derived into a self-sealing process. The reservoir temperature is higher than 200 °C, associated with a fracture zone linked to the Araró-Simirao fault. Samples of thermal fluids (water and gases) were collected from springs, wells, a mud pool, and runoff water in the study area. The waters had temperatures ranging from 31 °C and 76 °C and near-neutral pH values. Three hydrogeochemical facies types were identified, Na&lt;sup&gt;+&lt;/sup&gt;- Cl&lt;sup&gt;−&lt;/sup&gt;, Ca&lt;sup&gt;2+&lt;/sup&gt;-Na&lt;sup&gt;+&lt;/sup&gt; - HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt;, and Na&lt;sup&gt;+&lt;/sup&gt; -HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt;, associated with deep thermal water, groundwater, and recently infiltrated water, respectively.&lt;/div&gt;&lt;div&gt;According to the stable isotopes systematics, a binary mixture of thermal water and groundwater was calculated at a proportion from 61 % to 80 % of the thermal component. In the mud pool sample, the chemical composition of bubbling gas is CO&lt;sub&gt;2&lt;/sub&gt;-dominated, with a mostly magmatic origin according to the Rc/Ra (5.19), CO&lt;sub&gt;2&lt;/sub&gt;/&lt;sup&gt;3&lt;/sup&gt;He (4.12 × 10&lt;sup&gt;9&lt;/sup&gt;) ratios, and the isotopic composition of δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;(CO2)&lt;/sub&gt; (−8 ‰). The gases dissolved in waters are characterized by higher N&lt;sub&gt;2&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt; concentrations compared to the other gases, representing possible mixing processes between an end-member enriched in CO&lt;sub&gt;2&lt;/sub&gt; and the chemical composition of air-saturated water. Regarding helium isotopes, the gases are the result of mixing origins between crustal, atmospheric, and mantellic helium, and 3 groups were identified: 1) high contribution of mantle helium ranging from 21 to 66 % up to (Mud pool, LS07 and LS07A) 2) high contribution of crustal helium (LSA-02, LSA-08A, Araró) ranging from 55 to 80 % and 3) high contribution of atmospheric helium of 84 % (LSA-08). The δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;(CO2)&lt;/sub&gt; results show a primary interaction with magmatic environments and a slightly sedimentary origin. The origin of CO&lt;sub&gt;2&lt;/sub&gt;, MORB-type, as well as other gases, may be similar to that in Los Azufres. However, these gases reach the surface through different vertical paths, resulting in varying fluid compositions. In the study area, the Araró-Simirao and Huigo faults would act as zones for these gas ascents from the degassing source (magma) at depth.&lt;/div&gt;&lt;div&gt;According to the estimates of the magma aging model, the age of the mud pool sample is estimated to be 2.7 × 10&lt;sup&gt;6&lt;/sup&gt; ± 1.2 × 10&lt;sup&gt;6&lt;/sup&gt; years, which is younger than the andesitic basement rocks. Additionally, there is evidence of a more recent &lt;sup&gt;3&lt;/sup&gt;He input in the sample. However, the Los Azufres geothermal system has a &lt;sup&gt;3&lt;/sup&gt;He input from rocks that are even younger (1.5 × 10&lt;sup&gt;5&lt;/sup&gt; years). This suggests that Los Azufres may have a more recent &lt;su","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107637"},"PeriodicalIF":3.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BWM-MARCOS: A new hybrid MCDM approach for mineral potential modelling","authors":"Bijan Roshanravan ,&nbsp;Oliver P. Kreuzer ,&nbsp;Amanda Buckingham","doi":"10.1016/j.gexplo.2024.107639","DOIUrl":"10.1016/j.gexplo.2024.107639","url":null,"abstract":"<div><div>Here we describe the application of a novel hybrid multi-criteria decision-making (MCDM) approach termed “Best-Worst-Method-Measurement of Alternatives and Ranking according to COmpromise Solution” (BWM-MARCOS) to mineral potential modelling (MPM). The newly proposed BWM-MARCOS technique combines two mathematical frameworks in which the BWM approach is utilised to weight decision criteria (i.e., predictor maps) whilst the MARCOS approach is applied to rank alternatives. A BWM-MARCOS model of orogenic gold mineral systems in the well-endowed Granites-Tanami Orogen (GTO) in Australia's Northern Territory was generated utilising the same study area and set of competent spatial proxies as previously developed and described by Roshanravan et al. (2020), facilitating the benchmarking of the new results against those obtained from previous models. We found the BWM-MARCOS approach to MPM performed better than any of the knowledge-driven (i.e., fuzzy inference system), continuous (i.e., data-driven index overlay, geometric average and fuzzy gamma) and data-driven (i.e., feed-forward deep neural network and ‘original’ random forest) mineral prospectivity models previously developed for the GTO by Roshanravan et al. (2020, 2023b). To further constrain the BWM-MARCOS outputs, the modeled gold potential zones were delimited utilising a concentration-area fractal approach. The areas covered by the prioritised 1st order (top priority) and 2nd order (high priority) targets represent significant reductions of the search space (i.e., &gt;303 times or two orders of magnitude, and &gt;93 times or one order of magnitude, respectively). Any order of magnitude, or greater, reduction of the search space, as achieved in this study, can be considered a hallmark of a well-performing, practically useful targeting approach.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107639"},"PeriodicalIF":3.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mapping geochemical anomalies using angle-based outlier detection approach","authors":"Shahed Shahrestani,&nbsp;Ioan Sanislav","doi":"10.1016/j.gexplo.2024.107635","DOIUrl":"10.1016/j.gexplo.2024.107635","url":null,"abstract":"<div><div>This study evaluates the effectiveness of the angle-based outlier detection (ABOD) method in identifying geochemical anomalies in the Ahar-Arasbaran Zone (AAZ) within the Alborz-Azerbaijan Magmatic Belt (AAMB), known for its diverse mineralization such as Cu-Mo porphyry deposits, epithermal base and precious metal veins, and Fe-Cu skarn deposits. ABOD and its fast approximation (FastABOD) were applied to datasets with 9 (Selective) and 32 (All) features. Results showed that with fewer variables, the performance difference between ABOD and FastABOD decreased, highlighting the impact of dimensionality on anomaly detection. Geochemical anomaly maps (ABOD_All, ABOD_Selective, FastABOD_All, FastABOD_Selective) were assessed for detecting known mineralization. ABOD_Selective demonstrated superior performance, effectively placing 76 % of skarn and 70 % of porphyry mineral occurrences into the highest anomaly class, despite its overall performance being approximately 61 %.</div><div>Additionally, ABOD was compared with independent component analysis (ICA), focusing on IC2 and IC5. ICA effectively highlighted unique geochemical patterns, with IC2 excelling in identifying Cu-enriched zones and ABOD effectively delineating both Au- and Cu-bearing zones. ABOD was also compared with local outlier detection methods LOF, kNN, and iNNE. LOF showed distinct anomaly distributions due to its local density approach, while kNN, iNNE, and FastABOD produced similar maps based on distance, isolation, and angle-distance. ROC analysis revealed no significant performance difference, though FastABOD showed slight superiority, particularly with mineralized samples as validation points. Moreover, applying principal component analysis (PCA) as feature selection method enhanced the performance of the FastABOD method in delineating geochemical anomalies related to hydrothermal mineralization. Finally, random forest regression identified key elements such as Sb, Au, As, and Cu as significant in distinguishing geochemical signals from various mineralization types.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107635"},"PeriodicalIF":3.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A hydrogeochemical and isotopic approach for assessing the origin, recharge and mixing process of geothermal water in the Yinchuan Basin","authors":"Yiwen Zhu ,&nbsp;Qingchun Yang ,&nbsp;Xinzhu Chang ,&nbsp;Weijun Hao ,&nbsp;Yuxue Ma ,&nbsp;Jordi Delgado Martín","doi":"10.1016/j.gexplo.2024.107636","DOIUrl":"10.1016/j.gexplo.2024.107636","url":null,"abstract":"<div><div>The hydrogeochemistry of geothermal fluids is fundamental to reveal the genesis, recharge mechanism and circulation pattern of geothermal water. However, the origin and hydrogeochemical process of geothermal water in deep aquifer system still remain unclear. In this study, 17 water samples were analyzed to study the origin, recharge and mixing process of geothermal water in the Yinchuan basin by using a hydrogeochemical and isotopic approach. The results showed that the concentrations of major ions (SO₄²⁻, Na⁺, Cl⁻, TDS, Ca²⁺, K⁺, Mg²⁺ and NH₄⁺) and trace elements (Li, F⁻, Br⁻, I⁻, Sr and Mn) in geothermal water are significantly greater than those in shallow water, hot spring and cold spring in the study area. The hydrochemical type of geothermal water is dominated by Cl·SO₄-Na, which is mainly influenced by dissolution of halides, chlorides and sulfates under strong fluid-rock interactions. The isotope analysis demonstrated that the atmospheric precipitation in the Helan Mountain area is the major recharge source of geothermal water, the recharge elevation is 1118 m–1133 m, and the deep geothermal water is formed by a mixing process of ancient precipitation and modern precipitation. The silica-enthalpy mixing model suggested that the reservoir temperature of deep geothermal fluid is between 110 °C and 175 °C, and the mixing ratio of cold water is about 54 % to 92 %. The present study sheds some light on the genesis, recharge mechanism and hydrogeochemical evolution of geothermal water in deep aquifers, which are vital for sustainable exploitation and utilization of geothermal resources.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107636"},"PeriodicalIF":3.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719866","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":"Metal nanoparticles in soil: Indicators of concealed mineral deposits","authors":"Bimin Zhang ,&nbsp;Yuexin Lu ,&nbsp;Xueqiu Wang ,&nbsp;Jian Zhou ,&nbsp;Hongwei Li","doi":"10.1016/j.gexplo.2024.107633","DOIUrl":"10.1016/j.gexplo.2024.107633","url":null,"abstract":"<div><div>Nanogeology represents a cutting-edge scientific discipline characterized by its multi-disciplinary nature. This study provides an overview of the characteristics and behaviors of metal-bearing nanoparticles in soils above different ore deposits in China. It discusses the proposed origins, migration, and precipitation of these nanoparticles, as well as their applications in mineral exploration. Additionally, this study highlights the challenges and prospects of metal-bearing nanoparticles used in the mineral exploration.</div><div>Metal-bearing nanoparticles, which contain varying proportions of ore-related elements (e.g., Au, Ag, Cu, Pb and Zn) are rarely found in natural settings unrelated to ore bodies or mineral extraction. Due to the compositional similarity between metal-bearing nanoparticles in soil and likely link to concealed ore bodies, these nanoparticles can be effectively sampled in the soil, to understand the properties of the deeper concealed mineralization. Therefore, metal-bearing nanoparticles can serve as effective indicators of buried deposits. These nanoparticles may migrate from deep ore bodies to the surface through multi-process relay mechanisms, including geogas flow, atmospheric pressure pumps, electrochemical processes, and plant transpiration. They accumulate in fine-grained soil fractions with larger surface areas and adsorptive potential, such as clay minerals and organic matter, making fine-grained soil an important sink for metal-bearing nanoparticles. By separating fine-grained soil, the intensity of geochemical anomalies can be increased, thereby enhancing the accuracy of mineral exploration. Current research predominantly provides qualitative descriptions of nanoparticle characteristics, lacking quantitative analysis methods. Future efforts should focus on using high-resolution technologies such as Nano Scale Secondary Ion Mass Spectrometry (NanoSIMS), Atom Probe Tomography (APT), Focused Ion Beam Scanning Electron Microscopy (FIB-SEM), and synchrotron radiation to conduct detailed studies on the isotopic composition, internal structure, and elemental coupling relationships of nanoparticles. This approach will allow for better tracing of their origins and realize their potential in mineral exploration.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107633"},"PeriodicalIF":3.4,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720927","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":"Genetic link between concealed granite and tin mineralization in the Yuling tin deposit, Nanling Range, South China: Constraints from zircon and cassiterite U-Pb dating, geochemistry, and Lu-Hf isotopes","authors":"Yong-Kang Chen ,&nbsp;Pei Ni ,&nbsp;Jun-Yi Pan ,&nbsp;Yi-Ming Xu ,&nbsp;Qi-Zhi Yang ,&nbsp;Jian-Ming Cui ,&nbsp;Wen-Sheng Li ,&nbsp;Guan-Jian Fang","doi":"10.1016/j.gexplo.2024.107627","DOIUrl":"10.1016/j.gexplo.2024.107627","url":null,"abstract":"<div><div>The Nanling Range in South China is a world-renowned tin (Sn)-tungsten (W) metallogenic belt. The Yuling deposit is a representative Sn deposit newly discovered in the Nanling Range in recent years. The mineralization of Sn and accompanied Pb-Zn(-Sb) is controlled by faults and hosted in shallow metamorphic sandstone of the Cambrian, with concealed granitic intrusion in the deep. Here, we report for the first time precise in-situ U-Pb dating of zircon and cassiterite, petrogeochemistry, zircon trace element and Hf isotope data from the Yuling Sn deposit to clarify the genetic link between Sn mineralization and the concealed biotite granite. The U-Pb ages of the concealed granite and Sn mineralization are 155.1 ± 0.7 Ma and 154.4 ± 1.4 Ma, respectively, indicating that Sn mineralization occurred simultaneously with Late Jurassic granitic magmatism. Combined with the geological observation that Sn mineralization developed locally near the roof of concealed granite, further attests to the close genetic link between the Yuling Sn deposit and the deep-seated concealed granite. The zircon ε_Hf(t) values range from −5.14 to −1.37 (mean = −2.87), and the two-stage Hf mode ages (T_DM2) range from 1.29 to 1.52 Ga (mean = 1.38 Ga), indicating that the source rocks of the Yuling granite primarily originated from the remelting of ancient crustal rocks in the Mesoproterozoic of South China, with the involvement of some juvenile mantle-derived components. The Yuling granite exhibits high content of SiO₂, K₂O, K₂O + Na₂O, low content of MgO, CaO, Ba, Sr, Ni, Cr, relatively flat REE patterns and significant negative Eu anomalies. Petrographic and whole-rock geochemical data show that the Yuling granite has an A₂-type granite affinity and formed in an intraplate extensional setting of intense crust-mantle interaction similar to that of numerous A₂-type granites associated with Sn-W mineralization during the early Yanshanian in the Nanling Range. It may be related to the extension and thinning of the continental lithosphere and asthenosphere upwelling induced by northwestward subduction of the paleo-Pacific plate. Moreover, the factors controlling the Sn mineralization potential of granitic magma were evaluated using zircon trace elements and petrogeochemical data. These findings indicate that the Yuling granite crystallized from higher temperature, lower water content, F-rich, and highly-fractionated reduced granitic magma. Such granitic magma is conducive to generating Sn-rich fluids and has high Sn mineralization potential.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107627"},"PeriodicalIF":3.4,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719983","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":"Differentiating Triassic W–Sn ore-bearing and ore-free plutons in the Xitian Ore Field (South China) using apatite geochemistry","authors":"Xiaojun Hu ,&nbsp;Huan Li ,&nbsp;Thomas J. Algeo ,&nbsp;Biao Liu ,&nbsp;Fan Kang ,&nbsp;Yiming Xie ,&nbsp;Dapeng Zhu","doi":"10.1016/j.gexplo.2024.107628","DOIUrl":"10.1016/j.gexplo.2024.107628","url":null,"abstract":"<div><div>Though the metallogenic process of the Xitian W–Sn deposit has been established, the key factors distinguishing Triassic W–Sn ore-bearing granites from ore-free granites remain uncertain, leaving an important gap in understanding the controls on Triassic W–Sn mineralization. In this study, we present a comprehensive investigation of apatite from the Triassic Longshang W–Sn ore-bearing and Goudalan ore-free granites, to trace the nature of parental magma and to provide constraints on the processes related to Triassic W–Sn mineralization in Xitian Ore Field (South China). Apatites from ore-bearing (AOB) granites and apatites from ore-free (AOF) granites exhibit distinct Cathodoluminescence (CL) images: AOB samples feature darker cores and brighter rims, with concentric oscillatory growth zoning in the rim sections, whereas AOF samples exhibit chaotic textures in CL images. The U–Pb age dating of AOB and AOF yield a lower intercept age of 227.3 ± 4.3 Ma (1σ, MSWD = 3.9) and 227.1 ± 7.8 Ma (1σ, MSWD = 2.4) on the Tera-Wasserburg diagrams, respectively. The similar ε_Nd(t) values (−10.91 to −9.82 for AOB; −10.42 to −8.77 for AOF) (expressed as deviation in parts per 10,000 from CHUR composition), relatively low Cl contents (&lt;0.05 wt%), and high F (~3 wt%) of studied apatites, suggest that W–Sn ore-bearing and ore-free granitic magmas were both generated by melting of old continental crust. The texture and high concentration of REE + Y and Th in AOB could be assumed as the result of fluid exsolution. The chaotic texture, broad variation in ¹⁴⁷Sm/¹⁴⁴Nd ratios, may imply that AOF might have experienced metasomatic modification. Lower Eu/Eu* value together with higher Ce/Ce* value in AOB suggests a more reduced environment for W–Sn ore-bearing granites. Lower Sr, Mg content, and higher Y contents suggest that W–Sn ore-bearing granites have a higher degree of fractionation than ore-free granites. We propose that the mobilization and transport ability of W and Sn by hydrothermal fluids play an important role in the enrichment of W and Sn, and redox state of magma and the degree of magma differentiation determine the final enrichment level of tungsten and tin.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"268 ","pages":"Article 107628"},"PeriodicalIF":3.4,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664303","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}