Journal of Geochemical Exploration最新文献

{"title":"Mineralized-anomaly identification based on potential-enhanced positive-unlabeled bagging: A case study from Guangxi gold ore province","authors":"Guodong Zhu ,&nbsp;Lin Yang ,&nbsp;Yunyun Niu ,&nbsp;Qingfei Wang","doi":"10.1016/j.gexplo.2025.107772","DOIUrl":"10.1016/j.gexplo.2025.107772","url":null,"abstract":"<div><div>Stream sediment geochemistry data has emerged as a valuable tool for identifying potential mineral deposits. However, there is a severe imbalance in the distribution of known (positive) and unknown (negative) mineralization samples in these data. To address this challenge, this study proposes a potential-enhanced positive-unlabeled bagging (PEPUB) algorithm, which takes into account the potential contribution of target mineral deposits in unsampled areas. Furthermore, the PSO algorithm is employed to optimize the model's hyperparameters and enhance its performance. To validate the proposed method, we conducted tests in the Guangxi Zhuang Autonomous Region, situated on the southwestern edge of the South China Block. The results indicate that the PEPUB-based method demonstrates superior performance in predicting potential gold deposits, with an F1 score of 0.928 and a precision rate of 90.6 %. Additionally, the obtained mineralization anomaly maps show a high level of agreement between the predicted mineralization points and the known mineralization points. This model not only facilitates the identification of potential target mineral deposits and improves exploration efficiency but also offers valuable insights into the application of semi-supervised learning in mineral exploration.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"275 ","pages":"Article 107772"},"PeriodicalIF":3.4,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143816960","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":"Trace elements in pyrite from AuAg epithermal deposits of Kamchatka, Russia: Comparison with geochemical features of mineral systems","authors":"Nadezhda Tolstykh ,&nbsp;Nikolay Bortnikov ,&nbsp;Irina Zhukova ,&nbsp;Aleksandr Stepanov ,&nbsp;Galina Palyanova ,&nbsp;Maria Shapovalova ,&nbsp;Kuidong Zhao","doi":"10.1016/j.gexplo.2025.107774","DOIUrl":"10.1016/j.gexplo.2025.107774","url":null,"abstract":"<div><div>Trace elements in pyrite from adularia-sericite (LS type) deposits (Aginskoe, Baranyevskoe, Rodnikovoe, and Kumroch) and acid-sulfate (HS type) deposits (Maletoyvayam) of Au<img>Ag epithermal systems in Kamchatka, Russia, were analyzed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In most of the studied deposits, the concentration of Au in pyrite did not exceed 10 ppm. The Au/Ag ratio in pyrites from most deposits is less than 1, except for the Aginskoe deposit, in which pyrite is notably enriched in Au (up to 120 ppm), similar to the Au-rich ores of this deposit with an Au/Ag ratio &gt;1. The concentration of copper (Cu) in pyrite reaches 10,000 ppm in both deposit types. However, Cu is positively correlated with Ag only in the adularia-sericite type deposits (Kumroch, Rodnikovoe, and Aginskoe), aligning with the presence of Ag-containing sulfosalts in these deposits. The neutral and alkaline conditions in the adularia-sericite deposits contribute to an enrichment of the ore-forming system in As, which is significantly concentrated in pyrite (up to 10,000 ppm). Moderate concentrations of Te (up to 100 ppm) were found in pyrite from deposits where tellurides are typically present, with the exception of the Te-depleted pyrite (&lt;10 ppm) from the Rodnikovoe deposit, where telluride minerals were absent. In contrast, the acidic conditions at the Maletoyvayam deposit led to the enrichment of the ore system in Se, Te, and Sb, facilitating the incorporation of these elements into pyrite (up to 10,000 ppm Se, and 1000 ppm each for Te and Sb), as well as the formation of minerals containing these elements. Lead and zinc are moderately present in the pyrite from all deposits, while galena and sphalerite are commonly found only in the Kumroch deposit; their presence may be limited by structural factors. The trace elements found in pyrite, either as solid solutions or nanoclusters, play an important role in the formation of ore assemblages in all studied epithermal Au<img>Ag deposits in Kamchatka. The geochemical specialization of ore-forming systems is the main factor controlling these processes, while physical and chemical conditions of ore deposition also significantly influence the enrichment of these trace elements in pyrite.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"275 ","pages":"Article 107774"},"PeriodicalIF":3.4,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834248","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":"Geoenvironmental characterization of abandoned copper tailings pond combining electrical resistivity imaging (ERI) and geochemical methods (Tongling, China)","authors":"Qifeng Yin ,&nbsp;Shengjun Ni ,&nbsp;Yimin Xia","doi":"10.1016/j.gexplo.2025.107775","DOIUrl":"10.1016/j.gexplo.2025.107775","url":null,"abstract":"<div><div>Metallic mining tailings ponds are a kind of land resource which should be rehabilitated and utilized urgently but are also a crucial environmental concern due to the accumulation and emission of toxic elements. The abandoned Shuimuchong tailings pond, from the exploitation of Shizishan copper mine district at Tongling City, China, has been exposed to aeolian and water agents for almost 34 years (1990–2024) generating a huge volume of waste composed of sulfide minerals, especially in the surface layer, which eroded and dispersed further afield. In this paper, we demonstrated a successful combined approach of geophysics and geochemistry to explore geoenvironmental characterization of such deposits, including their geometry and the potential risk evaluation. Super-high density electrical resistivity imaging (ERI) surveys were carried out for characterizing the inner structure of this tailings pond, determining both the general geometry of the oxide layer and the stability of the tailings. The analysis of resistivity profiles makes it possible to visualize a low resistivity layer associated with the oxidized iron covering and provide the potential pathways of heavy metal along fractures with high resistivity. Besides, in order to investigate the variation of heavy metal concentration and soil physicochemical parameters in depth, especially associated with the oxidized iron covering, 9 solid samples were collected under the ERI lines from topsoil to subsoil at an interval of 10 cm and the surrounding soil samples were collected along the tailings dam downward to the farmland in 2 parallel lines. Furthermore, mineralogical and geochemical characterization techniques (XRD, XRF and ICP-MS) were carried out to determine the possible occurrence of heavy metals that could entail ecosystem and human risks and the assessment of heavy metal pollution. In conclusion, the permanent application of geophysical and geochemical techniques should be recommended in order to minimize the environmental impact of the tailings on the areas affected, and also to provide scientific basis for environmental restoration.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"275 ","pages":"Article 107775"},"PeriodicalIF":3.4,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143828618","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":"Gas geochemical characteristics and heat source mechanisms of a fault-controlled geothermal system: A case study from the western Wugongshan area, South China","authors":"Luyao Wang ,&nbsp;Kai Liu ,&nbsp;Li Wan ,&nbsp;Wuhui Jia ,&nbsp;Shouchuan Zhang ,&nbsp;Haoming Tang ,&nbsp;Gaoyang Bu ,&nbsp;Xinrui Yue","doi":"10.1016/j.gexplo.2025.107768","DOIUrl":"10.1016/j.gexplo.2025.107768","url":null,"abstract":"<div><div>Geothermal systems controlled by active fault zones represent a critical component of sustainable energy exploration, yet their fluid genesis and heat source mechanisms remain poorly constrained in complex tectonic settings. This study investigates the chemical composition and isotopic data of dissolved gases from multiple water bodies in the western Wugongshan area to elucidate the sources of hydrothermal volatiles, reservoir temperature, lithospheric thermal structure, and heat source mechanisms. Our findings reveal a distinctive gas assemblage dominated by N₂ (74.51–90.83 vol%), with subordinate O₂ (3.58–18.19 vol%) and CO₂ (1.17–5.93 vol%). Helium isotopic signatures (0.08–0.16 Ra) indicate a primary crustal radiogenic origin (97.79–99.21 %), while δ¹³C_CO2values (−11.9 ‰ to −21.9 ‰ VPDB) and δ¹³C_CH4 values (−49.8 ‰ to −74.8 ‰ VPDB) suggest that CO₂ predominantly originates from crustal organic sources and CH₄ is primarily generated through thermogenic and microbiological processes. The application of IMG and CO₂-CH₄ gas isotope geothermometers indicates that the temperature of the deep gas source varies between 100.2 °C and 197.3 °C, which is marginally above the temperature range of the geothermal water reservoir, recorded at 120.3 °C to 137.1 °C. Furthermore, integrated analysis of ³He/⁴He, borehole temperature measurements, and rock thermophysical properties indicate that the lithospheric thermal structure of the study area is classified as “hot crust-cold mantle,” with a crust-mantle heat flow ratio ranging from 1.36 to 1.56. Finally, the heat source mechanism of the fault-controlled geothermal system in the western Wugongshan area was presented: (1) thermal accumulation of blanket-shaped heat flow conduction and Moho surface thinning diffluence; (2) radioactive decay heat from crustal concentrated layers; and (3) convective heat from deep faults. This study provides a new perspective on the heat source mechanisms of fault-controlled geothermal systems and serves as an important reference for the exploration and utilization of geothermal resources with similar origins.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"274 ","pages":"Article 107768"},"PeriodicalIF":3.4,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143777550","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":"A first national nickel petrogeochemical map of China: Methodology and implications","authors":"Dongsheng Liu ,&nbsp;Yuanyuan Chen ,&nbsp;Gareth G. Roberts ,&nbsp;Qinghua Chi ,&nbsp;Xueqiu Wang ,&nbsp;Zhijuan Guo ,&nbsp;Lanshi Nie ,&nbsp;Yuntao Song","doi":"10.1016/j.gexplo.2025.107770","DOIUrl":"10.1016/j.gexplo.2025.107770","url":null,"abstract":"<div><div>Large-scale petrogeochemical maps are invaluable tools in Earth system science and applied geochemistry. Their creation often requires extensive sampling and careful consideration of how representative a sample's composition is of local chemistry, making them relatively rare. By integrating geochemical data from 39951 rock samples and employing advanced mapping techniques, this study presents the first petrogeochemical map of nickel across China. Sampling across China provides novel insights into spatial variability at large scales and geological controls of nickel within exposed crust. A close relationship between nickel concentration and lithology is observed. Nickel concentration tends to be relatively low in regions dominated by granites, carbonates (<span><math><mi>Ni</mi><mo>≲</mo></math></span>14.5 μg/g), arenaceous, argillaceous, and intermediate rock (<span><math><mi>Ni</mi><mo>≲</mo></math></span>34.8 μg/g), and highest in regions dominated by basic and ultrabasic rocks and their eroded products (<span><math><mi>Ni</mi><mo>≳</mo></math></span>34.8 μg/g). Concentrations of nickel measured in exposed crust and nearby sediments are highly correlated. Additionally, nickel concentrations are shown to vary systematically between tectonic units. For instance, large-scale geological processes such as continent collision, plume activity, and plate subduction, which generated widespread ophite belt sutures, basaltic igneous provinces, and granitic igneous provinces, have significant influence on nickel concentration. The mapping approach used in this study can be extended to incorporate other elements in future research.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"275 ","pages":"Article 107770"},"PeriodicalIF":3.4,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768261","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":"Rhenium in molybdenite from Mo (-Cu) deposits in northeastern China","authors":"Jianlin Zhang ,&nbsp;Qihai Shu","doi":"10.1016/j.gexplo.2025.107769","DOIUrl":"10.1016/j.gexplo.2025.107769","url":null,"abstract":"<div><div>Rhenium (Re) is a strategic metal that has wide applications in the field of aerospace, materials science, chemistry, and medicine, and plays an indispensable role in the manufacturing of aircraft engines. It mostly occurs in and is extracted from molybdenite from porphyry deposits. Northeastern China is one of the most Mo-rich regions in the world and contains &gt;90 Mo deposits with a total tonnage of &gt;10 Mt. Mo metal. Previous studies have been mainly focusing on the Mo mineralization, but little is known about the associated Re resources and their enrichment mechanisms. In this study, 73 Mo (-Cu) deposits from NE China with available <em>Re</em>-Os dating ages and molybdenite Re contents have been compiled, with the aims of exploring the factors controlling the Re variations in these different deposits and evaluating their Re recovery potentials. The results show that the majority of the <em>Re</em>-bearing deposits in NE China have Mesozoic ages (i.e., &lt;250 Ma), with only three forming in the Paleozoic. Five of the deposits (i.e., Wunugetu, Chalukou, Duobaoshan, Diyanqin'amu and Daheishan) contain Re reaching large sizes (&gt;50 t Re), and 13 have medium sizes (5–50 t Re). A total of &gt;700 t Re metal has been estimated to be included in these Mo (-Cu) deposits. Generally, the Re contents in molybdenite decrease from porphyry Cu-Mo (100–400 ppm), through porphyry Mo-Cu (20–70 ppm), to porphyry Mo (8–30 ppm) deposits. Skarn and greisen-type deposits are less common in NE China, and the former has molybdenite Re contents ranging mainly from 1 to 30 ppm, while the latter contains Re contents between 5 and 10 ppm. Geochronologically, the older, Paleozoic deposits contain higher-Re molybdenite, while the low-Re molybdenite is more abundant in these younger deposits with Early Cretaceous ages. In the porphyry Cu-Mo deposits, the average molybdenite Re content shows a negative correlation with the Mo grade, demonstrating higher-Re molybdenite in lower Mo grade systems. But this relationship is not observed in the Mo-dominated deposits. The causative intrusions with higher whole-rock ε_Nd(t) and zircon ε_Hf(t) values are generally related to higher molybdenite Re contents, indicating more mantle or juvenile crust contributions to the Re enrichment. In an individual deposit, the <em>Re</em>-rich molybdenite commonly occurs in veins with sericite alteration, likely due to the favorable precipitation of Re at lower fluid temperature and pH conditions. This study reveals that the variations in molybdenite Re contents in NE China are controlled by a combined effect of several factors, including the deposit types and ages, magmas sources, Mo grades, and deposition conditions.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"275 ","pages":"Article 107769"},"PeriodicalIF":3.4,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776446","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":"Multistage ore-forming processes in the genesis of the fluorite-baryte Merguechoum ore deposit (Moroccan eastern Meseta) in relation to Pangea rifting","authors":"Larbi Rddad ,&nbsp;Mohammed Cherai ,&nbsp;Benjamin F. Walter ,&nbsp;Fouad Talbi","doi":"10.1016/j.gexplo.2025.107766","DOIUrl":"10.1016/j.gexplo.2025.107766","url":null,"abstract":"<div><div>This study investigates the origin of the hydrothermal fluorite-baryte veins at Merguechoum, hosted in Late Hercynian granite beneath the Paleozoic-Triassic unconformity in the Moroccan eastern Meseta. The ore comprises two stages: fluorite 1and baryte 1 precipitated from a hot (156 C°–180 °C), moderate- to- high salinity fluid (13.5 to 39.4 wt% NaCl+CaCl₂), followed by the deposition of fluorite 2 and baryte 2 from a cooler (100 °C–135 °C), lower salinity fluid (22.2–25.4 wt% NaCl). Crush-leach data and rare earth element signatures indicates that the ore-forming fluids were initially evaporated seawater, which infiltrated the Paleozoic basement via NNE-NE trending faults and fractures during the Permian-Triassic rifting and evolved into F- and Ba-rich brines through fluid-rock interactions.</div><div>During the Triassic-Jurassic extension, a high geothermal gradient triggered localized convection, circulating basement-derived metalliferous fluids toward shallower zones along reactivated faults and fractures. The mixing of these basement-derived fluids with less saline, calcium- and sulfate-rich fluids stored in open spaces causing the deposition of fluorite and baryte. This study highlights the role of rift-related convection and fault-controlled fluid pathways in ore genesis, offering insights for exploring similar unconformity-related ore deposits in extensional settings.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"275 ","pages":"Article 107766"},"PeriodicalIF":3.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143791735","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":"Zircon UPb geochronology and geochemistry of ore-bearing rhyolites in the Fuxingtun Ag–Pb–Zn deposit, Great Xing'an Range, NE China: Constraints on petrogenesis and tectonic setting","authors":"Shanming Zhang ,&nbsp;Xiangguo Guo ,&nbsp;Haijun Li ,&nbsp;Genhou Wang ,&nbsp;Lixin Fan ,&nbsp;Erhong Hu ,&nbsp;Fukang Fang ,&nbsp;Junyi Zi ,&nbsp;Minghao Wang","doi":"10.1016/j.gexplo.2025.107765","DOIUrl":"10.1016/j.gexplo.2025.107765","url":null,"abstract":"<div><div>The Fuxingtun Ag–Pb–Zn deposit, located in the Right Front Banner of Horqin, Inner Mongolia, is a superlarge Ag–Pb–Zn deposit discovered in 2019 in the southern-central Great Xing'an Range. In this work, LA–ICP–MS zircon U<img>Pb, petrogeochemical and zircon Hf isotope data were obtained from ore-bearing rhyolites in the Manketouebo Formation in the Fuxingtun mining area. The zircon U<img>Pb ages of the eight rhyolite samples range from 140.1 Ma to 133 Ma, corresponding to the Early Cretaceous. The geochemical characteristics reveal that the rhyolites belong to the high-k calc-alkaline peraluminous series and are characterized by high silicon, alkali and aluminum contents and low iron, magnesium and calcium contents. The total amount of rare earth elements (REEs) is low, and the light and heavy REEs exhibit a certain degree of fractionation, with a moderate negative Eu anomaly. The enrichment of Rb, Th, U, K, Zr, and Hf and the depletion of Ba, Sr, P, Ti, Nb, and Ta correspond to the geochemical characteristics of I-type rhyolites. The source of the rhyolitic magma may have been the remelting of Paleozoic juvenile crust in a postcollisional extensional geotectonic environment.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"275 ","pages":"Article 107765"},"PeriodicalIF":3.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768260","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":"Isotopic study (UPb, SmNd, and PbPb) of rocks and auriferous mineralizations from the Volta Grande do Xingu deposits, Bacajá Domain, Amazonian craton","authors":"Moacir José Buenano Macambira ,&nbsp;Stephane Amireault","doi":"10.1016/j.gexplo.2025.107767","DOIUrl":"10.1016/j.gexplo.2025.107767","url":null,"abstract":"<div><div>The Três Palmeiras volcano-sedimentary sequence in the northern Bacajá Domain, southeastern of the Amazonian craton, hosts gold occurrences and deposits, classified as orogenic type. In the Volta Grande do Xingu area, samples of outcrops and drill holes allowed us to identify three main lithological units: (1) a sequence of mafic metavolcanic rocks, represented by metabasalt, mafic schist and restricted metagabbro bodies; (2) a sequence of intermediate metavolcanic rocks, represented by porphyritic meta-andesite and metavolcanoclastic rocks; both sequences are cut by (3) quartz-diorite and granodiorite bodies, correlated with the Oca Granodiorite, previously dated at 2160 ± 3 Ma. Gold mineralization occurs as microinclusions in pyrite, chalcopyrite and/or quartz. Dating results indicate that meta-andesite and metavolcanoclastic rocks are, respectively, 2417 ± 4 Ma and 2410 ± 7 Ma by Pb-evaporation in zircon method, whereas the metavolcanoclastic rock was dated at 2415 ± 50 Ma by the U<img>Pb (LA-ICP-MS) zircon method, age corroborated by a Sm<img>Nd whole-rock isochron of metabasalt and meta-andesite samples at 2465 ± 17 Ma. These ages denote the presence of Siderian volcanic rocks, predating those previously recorded in the Bacajá Domain (2359 ± 2 Ma). Pyrite (leachates) hosted in meta-andesite and quartz-diorite was dated at 2353 ± 43 Ma and 2146 ± 19 Ma, respectively, according to Pb-isotopic data, whereas gold particles yielded ages between 2.40 and 2.18 Ga by Pb-evaporation. The ages for pyrite and gold particles contained in dioritic suite samples imply at least two generations of pyrite, suggesting the mineralization likely relates to the Rhyacian granitogenesis recorded in the Bacajá Domain. Pb whole-rock isotopic analyses of meta-andesite and metabasalt samples indicate an age of 2403 ± 92 Ma, with high MSWD and error, but consistent with ages obtained by other methods for this sequence. The Nd-T_DM of 2.49 to 2.39 Ga and εNd_(t) (+2.03 to +3.63) indicate essentially a juvenile mantle origin for the metavolcanic rocks. The integration of field, mineralogical, isotopic, and geochronological data suggest that the mineralization event was most likely connected to metamorphic-deformational processes and granitoid intrusion associated with the Transamazonian cycle, complemented by inherited components from the Três Palmeiras sequence.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"274 ","pages":"Article 107767"},"PeriodicalIF":3.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747792","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":"Vanadium and other critical elements in North Gondwana Silurian black shales: The SE Sardinia (Italy) case","authors":"Maria Boni ,&nbsp;Nicola Mondillo ,&nbsp;Licia Santoro ,&nbsp;Giuseppina Balassone","doi":"10.1016/j.gexplo.2025.107760","DOIUrl":"10.1016/j.gexplo.2025.107760","url":null,"abstract":"<div><div>Vanadium currently represents a critical metal for the global economy, due to its increasing application in low CO₂-emission technologies such as vanadium redox flow batteries. Black shale-hosted deposits cover about 80 % of the potential global V resources, although only &lt;2 % of them is economic. During Silurian, significant black shale successions were deposited under strong anoxic conditions in the North Gondwana. This study aims at investigating the deportment of V in association with other trace elements in Silurian black shales of SE Sardinia (Italy), for understanding the nature of the depositional environment and the metallogenetic potential of these rocks at regional scale. Sardinian black shales have variable V amounts, ranging from hundreds to thousands ppm and organic carbon contents from 0.7 to 10.1 wt%. These values, together with observed Th/U, Ni/Co, V/Cr ratios indicate that the initial sedimentary environment was clearly anoxic. The positive correlation between V and total organic carbon indicates that organic matter retains most of V. Local V concentrations in rutile and illite may derive from metal remobilization during diagenesis and low-grade metamorphism. Compared to other coeval Silurian successions of North Gondwana, Sardinian black shales have anomalous values of Sb, Ba, Se, Mo, As, V, and Ag, this suggesting that, in the frame of a peculiar sedimentary process occurred in a similar way at the global scale, distinct controls existed in the various basins.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"275 ","pages":"Article 107760"},"PeriodicalIF":3.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916843","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}