Journal of Geochemical Exploration最新文献

{"title":"Hydrothermal geochemical signatures in zircon as a pathfinder for IOCG mineralization: An example from the Carajás Mineral Province (Brazil)","authors":"Maurício L. Borba ,&nbsp;Colombo C. Tassinari ,&nbsp;Fernando M. Matos ,&nbsp;John M. Hanchar ,&nbsp;Fernando Tornos ,&nbsp;Sergio Huhn ,&nbsp;Kei Sato","doi":"10.1016/j.gexplo.2025.107934","DOIUrl":"10.1016/j.gexplo.2025.107934","url":null,"abstract":"<div><div>Zircon from hydrothermally altered host rocks of Archean iron oxide‑copper‑gold (IOCG) deposits in the Carajás Mineral Province (CMP), Brazil, display distinct U, Th, and rare earth element (REE) compositions when compared to zircon from typical unaltered igneous rocks. Uranium-Pb geochronology of zircon from the Furnas and Paulo Afonso deposits reveals a complex, multi-episodic, evolution of deposit formation, characterized by: (1) ∼2.75 Ga zircon grains from wall rocks that exhibit typical magmatic features and lack evidence of metasomatic alteration (e.g., sieve texture, elevated U, and LREE enrichment); (2) ∼2.55 Ga zircon from the same rocks showing metasomatic textures and compositions; and (3) ∼1.9 Ga zircon crystals from host rocks displaying magmatic Chondrite-normalized REE patterns but with significant U enrichment. Both the Furnas and Paulo Afonso deposits contain at least three zircon populations; recording Archean and Proterozoic magmatic-tectonic and metasomatic events. Hydrothermal zircon of ∼2.55 Ga occurs regionally in CMP rocks; commonly associated with major IOCG deposits and aligned with the regional-scale Cinzento Shear Zone (CSZ). These zircon crystals are interpreted as having crystallized from, or altered by, chemically similar hydrothermal fluids during <em>syn</em>-tectonic hydrothermal activity, rather than through direct magmatic crystallization. Their complex geochronological record, trace element compositions, and internal zoning and structures, reflect overprinting by hydrothermal fluids associated with IOCG mineralization. We propose that these hydrothermal zircon populations may serve as pathfinder indicators of <em>syn</em>-mineralization hydrothermal activity, and thus represent valuable exploration vectors for IOCG systems in similar polycyclic terranes elsewhere. In addition, the newly introduced Sm/Sm* parameter (derived from zircon REE systematics) emerges as a promising geochemical tool for mineral exploration. By quantifying subtle LREE flattening associated with hydrothermal modification, Sm/Sm* is a promising parameter for distinguishing ore-related from barren zircon populations and reinforces the potential of zircon geochemistry as a practical proxy in IOCG-style systems.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"281 ","pages":"Article 107934"},"PeriodicalIF":3.3,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617341","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":"In Situ RbSr dating of hydrothermal sericite constrains Paleocene-Eocene PbZn mineralization in eastern Gangdese to India-Asia collisional tectonics","authors":"Zezhang Yu ,&nbsp;Xin Chen ,&nbsp;Xiaoyi Wang ,&nbsp;Yu Liu ,&nbsp;Dongrui Zhang ,&nbsp;Xiaojia Jiang ,&nbsp;Nan Chao ,&nbsp;Youye Zheng ,&nbsp;Shunbao Gao","doi":"10.1016/j.gexplo.2025.107932","DOIUrl":"10.1016/j.gexplo.2025.107932","url":null,"abstract":"<div><div>Dating Pb<img>Zn polymetallic deposits is challenging due to low-temperature hydrothermal formation and common detachment from obvious magmatic sources, which often limits the availability of datable minerals. A prime example of this issue is observed in the eastern Gangdese metallogenic belt of Xizang, a globally significant province characterized by skarn-style and hydrothermal vein-type Pb<img>Zn polymetallic systems. Despite their economic importance, the absolute timing of mineralization in these deposits remains contentious, with competing hypotheses invoking Paleozoic submarine exhalative sedimentation, Cenozoic magmatic-hydrothermal activity, or multistage metallogenic pulses linked to episodic tectonic events. To address this, we integrate in situ Rb<img>Sr dating of micas with U<img>Pb zircon/monazite geochronology and geochemistry for the Bagaladong and Mengya'a deposits. At Bagaladong, magmatic zircon/monazite from altered granite yields a crystallization age of 130 ± 3 Ma, while muscovite gives an alteration/cooling age of 110 ± 2 Ma. Critically, hydrothermal sericite from mineralization veins yields ages of 55.8 ± 2.4 Ma (skarn-type mineralization) and 49.0 ± 0.3 Ma (vein-type mineralization), revealing a significant temporal gap from the associated magmatism. For the Mengya'a deposit, hydrothermal sericite (coeval with galena-sphalerite) yields an age of 53.0 ± 4.0 Ma, which is consistent with prior <em>Re</em><img>Os and garnet U<img>Pb data from the region. These results definitively refute Paleozoic or Mesozoic origins, instead establishing Paleocene-Eocene mineralization linked to concealed intrusions. The timing precisely coincides with the ∼55–45 Ma phase magmatic peak in the Gangdese batholith, suggesting a genetic association with Neo-Tethyan slab rollback during the India-Asia collision. This investigation highlights the analytical potential of in situ Rb<img>Sr dating for hydrothermal sericite, representing a methodological advancement particularly applicable to low-temperature metallogenic systems where conventional datable minerals are absent but sericitic alteration is pervasive.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"281 ","pages":"Article 107932"},"PeriodicalIF":3.3,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145594701","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":"Physicochemical controls on Mo mineralisation of the Caosiyao porphyry deposit, northern North China Block","authors":"Jialu Song ,&nbsp;Fan Yang ,&nbsp;Zhenyu Qin ,&nbsp;Leon Bagas ,&nbsp;Yingjie Li ,&nbsp;Xiaoyu Ge ,&nbsp;Likun Yang","doi":"10.1016/j.gexplo.2025.107931","DOIUrl":"10.1016/j.gexplo.2025.107931","url":null,"abstract":"<div><div>Physicochemical conditions play a key role in magmatic differentiation, fluid exsolution and migration, and the enrichment of ore-forming elements in porphyry deposits. Biotite is a critical indicator mineral that has been used to constrain physicochemical conditions and trace the hydrothermal evolution of mineralisation. The Caosiyao deposit, a super-large porphyry Mo deposit located at the northern margin of the North China Block, has been primarily studied in terms of its metallogenic age and genetic evolution. However, the physicochemical conditions during magmatic and hydrothermal evolution remain poorly understood. This study analysed major and trace elements of hydrothermal biotite from the mineralised granite porphyry to better constrain the physicochemical conditions, hydrothermal evolution, and Mo mineralisation at Caosiyao. Hydrothermal biotite geochemical data reveals crystallisation temperatures ranging from 174 to 462 °C, high oxygen fugacity, and elevated F fugacity (IV(F) = 0.87–1.33; IV(Cl) = −4.63 to −3.74; IV(F/Cl) = 4.83–5.77). During the formation of deposit, the mixing of late hydrothermal fluids with meteoric water promoted the generation and transport of stable Cl⁻ and Mo⁶⁺ complexes under favorable physicochemical conditions, resulting in significant Mo enrichment. The formation of the Caosiyao Mo deposit can be divided into three main stages: (1) The mineralisation process initiated with the generation of high-K, high-<em>f</em>O₂ granitic magmas derived from lower crustal melting, triggered by an enriched mantle source. Magmatic differentiation concentrated Mo in the residual melt, whereas fluid exsolution facilitated the migration of Mo-rich fluids along fractures, accompanied by widespread K-alteration. (2) Subsequent fluid–rock interaction led to the decomposition of Mo complexes and the precipitation of ore minerals in structurally weak zones. (3) In the late stage, the mixing of hydrothermal fluids with meteoric water and the release of sulfide altered the physicochemical conditions of the hydrothermal system, further enhancing Mo deposition. This study provides new insights into the common mineralisation processes observed in similar Mo deposits worldwide and offers significant implications for prospecting.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107931"},"PeriodicalIF":3.3,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145568418","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 prospecting significance of the Xiaodonggou granites in the eastern Central Asian Orogenic Belt: Evidence from geochronology, geochemistry, and Hf isotope characteristics","authors":"Lele Qiu ,&nbsp;Peiwen Chen ,&nbsp;Renchang Mi ,&nbsp;Zhujun Liu ,&nbsp;Yong Fu ,&nbsp;Qingdong Zeng","doi":"10.1016/j.gexplo.2025.107928","DOIUrl":"10.1016/j.gexplo.2025.107928","url":null,"abstract":"<div><div>The Xiaodonggou granites are located in the southwestern part of the Xilamulun Mo Metallogenic Belt, within the eastern Central Asian Orogenic Belt. They are characterized by significant Mo mineralization and minor Pb<img>Zn enrichment. The pluton mainly consists of fine-grained granite (FG), coarse-grained granite (CG), granite porphyry (GP), and diorite. However, the genetic relationships among these lithologies and their tectonic implications remain unclear. To address this, we conducted an integrated geochemical, geochronological, and isotopic study to investigate the origin of the Xiaodonggou granites. Zircon U<img>Pb dating identifies two distinct magmatic events: Cretaceous granites (FG: 141.0 ± 0.86 Ma; CG: 140.9 ± 0.86 Ma; GP: 137.7 ± 0.75 Ma), formed during the lithospheric thinning of the North China Craton, and Permian diorite (273.3 ± 1.8 Ma), which was emplaced earlier than the Cretaceous granitic magmatism. The granites belong to the high-K calc-alkaline series and are characterized by high SiO₂ and low P₂O₅ contents. They show enrichments in Rb, Th, U, and Pb, and depletions in Nb, Ta, Ti, and P, with low Zr/Hf and high Rb/Sr ratios, suggesting strong fractional crystallization. The occurrence of amphibole and magnetite, combined with A/CNK values &lt;1.1, indicates I-type granite characteristics. Most granites display εHf(t) values ranging from −1.0 to +3.34 and <em>T</em>_DM2(Hf) ages of 979–1261 Ma, indicating that their primary magmas were largely derived from the juvenile lower crust. The ore-forming granites are characterized by increased oxygen fugacity (ΔFMQ = +2.84) and a high capacity for transporting ore-forming elements. The FG and CG were emplaced first, followed by the GP, which carried the majority of ore-forming materials and ultimately formed the Mo mineralization. Owing to the lower crystallization temperatures of Pb and Zn in the hydrothermal system, these elements migrated distally along the early-emplaced diorite dikes, leading to Pb<img>Zn mineralization. Based on the Early Cretaceous magmatic-metallogenic age, the Xiaodonggou porphyry system is interpreted to have originated from partial melting of the juvenile lower crust in an extensional setting driven by the rollback of the Paleo-Pacific Plate.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107928"},"PeriodicalIF":3.3,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145568419","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":"Bauxite exploration in Odisha using advanced hyperspectral remote sensing and analytical techniques","authors":"Susovan Layek ,&nbsp;Ashim Sattar ,&nbsp;Deep Raj Das ,&nbsp;A. Abhinav ,&nbsp;Richa Upadhyay Sharma ,&nbsp;T.K. Biswal","doi":"10.1016/j.gexplo.2025.107930","DOIUrl":"10.1016/j.gexplo.2025.107930","url":null,"abstract":"<div><div>Bauxite, being the primary source of aluminium, is essential for industries such as aerospace, construction, and packaging. The study reports the first regional-scale potential bauxite exploration zones in Odisha, India covering two entire districts-Koraput and Rayagada. PRISMA hyperspectral data of SWIR wavelength range between 1.55 μm and 2.3 μm is exploited, due to its sensitivity to Al-OH absorption in bauxite. Spectral response curves are compared to lab spectroscopy of field samples from the bauxite zones of Marwaiguda village in Koraput district. The study is supplemented by petrographic, geochemical (XRD and XRF), and geomorphological assessments showing its distribution on flat-topped hills with ooides and pisoides microstructures, and Al₂O₃ wt% ranging between 43 % and 50 %. The average RMSE in reflectance between lab spectra vs. USGS and lab spectra vs. PRISMA is 0.16 and 0.18, respectively, whereas the cosine similarity is 0.99 and 0.90, respectively, which defines a well correlation between the spectra. The results show that the bauxite is distributed linearly along the NE-SW direction traversing the Koraput and Rayagada districts. The hyperspectral-based potential zones is validated by creating an inventory of existing bauxite mines and zones in advanced stages of initial exploration. The results show a strong correspondence between the identified zones and existing bauxite mines. The new potential bauxite exploration zones in the study can support future bauxite exploration in Odisha. The results will aid stakeholders such as the Odisha Mining Corporation, NALCO, Vedanta, Hindalco, and other government agencies in cost-effective bauxite exploration.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107930"},"PeriodicalIF":3.3,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145516469","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":"Hydrochemical insights into lithium enrichment mechanisms in Southern Tibet's geothermal systems","authors":"Jiexiang Li ,&nbsp;Hankun Li ,&nbsp;Chuanxia Ruan ,&nbsp;Gideon Sagoe ,&nbsp;Guanghui Tian ,&nbsp;Shen Wang ,&nbsp;Wenjing Lin","doi":"10.1016/j.gexplo.2025.107929","DOIUrl":"10.1016/j.gexplo.2025.107929","url":null,"abstract":"<div><div>Some geothermal systems in Southern Tibet stand out for their exceptionally high lithium (Li) compared to other geothermal regions in Himalayan geothermal belt, yet the Li sources and enrichment processes remain underexplored. To fill this gap, hydrogeochemical data of 156 geothermal water samples from Chabu, Kawu, Laduogang, Mangre, Yangbajain, Targejia and Yangyi geothermal systems in Southern Tibet and of 23 geothermal water samples from Tengchong, Kangding and Litang in the Hengduan Mountains District (as a reference) were retrieved from the literature to investigate the occurrence and hydrogeochemical processes of Li. Using thresholds of 4 % molar proportion of sulfate (SO₄²⁻) in the anions and 10 mg/L Li concentration in the geothermal waters, the geothermal systems chosen in this study are categorized into four types. In the “Low-SO₄, High-Li” geothermal systems, such as Kawu, Yangbajain and Laduogang, the majority of the geothermal waters have high Li concentrations due to significant magmatic water input with limited Li enrichment from the surrounding rocks. The Laduogang geothermal waters exhibit unusually high Li concentrations, reflecting the combined effect of magmatic water mixing and intense concentration processes. Contrastingly, in the “High-SO₄, Low-Li” geothermal systems, including Chabu, Mangre, and Targejia, the geothermal waters have relatively low Li concentrations. These fluids likely originate from deep geothermal reservoirs, with minimal influence of water-rock interaction in the reservoirs and along the flow paths. They likely mix with a smaller proportion of magmatic water and traverse a longer flow path after leaving the reservoirs. During the ascent, S²⁻ oxidation elevates the levels of SO₄²⁻ and other solutes like magnesium. In the “High-SO₄, High-Li” geothermal system (i.e, Yangyi), the presence of high-Li geothermal waters may be attributed to water-rock reaction interactions rather than being solely due to the input of deep magmatic waters. All geothermal systems in HMD are classified as “Low-SO₄, Low-Li”, suggesting a different Li enrichment mechanism compared to Southern Tibet.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107929"},"PeriodicalIF":3.3,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145516468","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 GIS-based intelligent system for geochemical sampling: From fieldwork to data management","authors":"Zhou Yining ,&nbsp;Chang Chan ,&nbsp;Ma Jianguo ,&nbsp;Gao Yanfang ,&nbsp;Tian Mi ,&nbsp;Liu Qingqing ,&nbsp;Wang Xueqiu ,&nbsp;Sun Binbin ,&nbsp;Wang Jing","doi":"10.1016/j.gexplo.2025.107925","DOIUrl":"10.1016/j.gexplo.2025.107925","url":null,"abstract":"<div><div>In traditional geochemical field surveys, particularly in areas with large sample volumes and harsh environmental conditions, the cumbersome transportation of sampling tools and the labor-intensive process of data organization often compromise the quality and accuracy of the survey. The computerization and automation of geochemical field sampling are not only an essential response to contemporary demands but also an inevitable trend driven by advancements in methods and technologies. In this study, we integrate mobile GIS, database technologies, and other tools to streamline the geochemical field sampling. A geochemical field sampling software has been developed on the ArcGIS and Android platforms, incorporating functionalities such as task assignment, field work, and quality control. The system facilitates the computerization and automation of the entire geochemical survey process, simplifying field sampling, reducing the time required for fieldwork, enhancing the efficiency of data processing, improving the quality and accuracy of field data, and advancing the digitalization of geochemical field surveys.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107925"},"PeriodicalIF":3.3,"publicationDate":"2025-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466343","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":"Geochemical characteristics and uranium occurrence state of carbonaceous-siliceous slates and their geological significance for uranium mineralization: A case study from the Tichong black shale-type uranium deposit","authors":"Fan Zhang ,&nbsp;Jianying Wang ,&nbsp;Yangquan Jiao ,&nbsp;Shiping Yang ,&nbsp;Liqun Wu ,&nbsp;Hui Rong ,&nbsp;Qunzong Luobu","doi":"10.1016/j.gexplo.2025.107927","DOIUrl":"10.1016/j.gexplo.2025.107927","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Black shale-type uranium deposits make important contributions to uranium resources. However, there is controversy over the enrichment mechanism of uranium in black shale. In the Tichong black shale-type uranium deposit from Hubei province, carbonaceous-siliceous slates are the dominant enrichment agent for uranium enrichment. The geochemical compositions and uranium mineralogy of carbonaceous-siliceous slates were investigated by using rock pyrolysis analyzer, X-ray diffractometer (i.e., XRD), inductively coupled plasma mass spectrometry (i.e., ICP-MS), sequential chemical extraction (i.e., SCE) and scanning electron microscope-energy dispersive X-ray spectroscopy (i.e., SEM-EDS). The results show that total organic carbon (TOC) of carbonaceous-siliceous slates is about 4.00 %, and inorganic minerals are composed of quartz, clay mineral, albite and pyrite. Uranium contents of carbonaceous-siliceous slates are from 39 ppm to 174 ppm, element U bears positive relationships with elements V, Ni, Mo, Cu, Zn, and Pb, indicating that uranium enrichment might be related to hydrothermal fluid. Uranium occurrence states are composed of scattered adsorption state (accounting for 52.39 %) and uranium minerals, including that coffinite and (REE-bearing) pitchblende are the primary uranium minerals. Uranium minerals mostly occur around organic matter (OM), intergranular pores of pyrites, kaolinite, corrosion of quartz, monazite, sericite and limonite. Moreover, element U also closely coexists with elements Ni, Zn, REY, Cu, and V by using SEM-EDS. Pyrites coexisting with uranium minerals are unevenly altered by xenotime. Moreover, element U is closely associated with elements Rb and C, implying that uranium might originate from magmatism, and OM might play roles in uranium enrichment. It is also supported by the positive relations among U and TOC, S1 (liquid hydrocarbons), and S2 (thermally cracked hydrocarbons). OM is at the stage of overmaturity with vitrinite reflectance from 3.56 % to 4.27 %, and the maximum rock pyrolysis temperature S2 of about 480 °C. It could produce low molecular organic compounds, which is beneficial for uranium reduction. Besides, sphalerite, chrysocolla, chalcocite, and (Y-) monazite also display that hydrothermal fluid exists. The REY distributions of the carbonaceous-siliceous slates are similar to the Mufushan rock formation rather than the Dahushan rock formation, suggesting the uranium source might be from the Mufushan rock formation. Hence, it is referred that uranium enrichment is comprehensively affected by multiple factors. Under certain geological conditions, uranium from the marine sedimentary environment is pre-enriched in the Lower Cambrian Niutitang Formation (∈&lt;sub&gt;1&lt;/sub&gt;&lt;em&gt;n&lt;/em&gt;), and is adsorbed and precipitated by pyrite and organic matter (i.e., OM). Then, the fracture zones develop, especially the Taoshugang fault by the influences of Indosinian and Yanshanian tectonic movements. The uranium-bearing","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107927"},"PeriodicalIF":3.3,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466342","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":"Age and mineralization mechanisms of the Babanqiao tin polymetallic deposit in the Dupangling area, Nanling region, South China","authors":"Chunlan Meng ,&nbsp;Lingan Bai ,&nbsp;Shouyu Zhou ,&nbsp;Yu Dai ,&nbsp;Chongjin Pang ,&nbsp;Zuohai Feng ,&nbsp;Xijun Liu ,&nbsp;Chunyan Zhou ,&nbsp;Jiao Yang","doi":"10.1016/j.gexplo.2025.107926","DOIUrl":"10.1016/j.gexplo.2025.107926","url":null,"abstract":"<div><div>The Nanling region in South China contains widespread granites of variable ages. Large-scale W and Sn mineralization were closely associated with Yanshan granites, but the mineralization related to granites of other ages has been little studied. Understanding the metallogenic significance of Indosinian granites is crucial for refining exploration models, as recent discoveries suggest they may have played a greater role than previously recognized. The weighted mean zircon U<img>Pb age of the biotite granite from the eastern part of the Dupangling pluton is 224.7 ± 4.8 Ma, while the cassiterite U<img>Pb age from the Babanqiao Sn-polymetallic deposit is 223.6 ± 4.0 Ma. These results indicate that the Babanqiao deposit formed contemporaneously with late Indosinian granitic magmatism, suggesting that the deposit was likely associated with granitic activity during the late Indosinian period. Fluid inclusion data reveal the initial ore-forming fluids were part of a NaCl–H₂O system with high to moderate temperatures and salinities, which contained CH₄ ± N₂. Homogenization temperatures ranged from 182.1 °C to 381.5 °C in the early mineralization stage and decreased to 145.4 °C to 279.8 °C in the main mineralization stage, with corresponding salinities of 13.62–25.15 wt% NaCl equiv. and 7.45–19.76 wt% NaCl equiv., respectively. These values indicate that ore deposition occurred under reducing conditions, with a progressive decrease in temperature and salinity as meteoric water mixed with the magmatic fluids. δ¹⁸O and δD values show that the ore-forming fluids were magmatic waters that gradually transitioned to meteoric waters. This progressive dilution likely influenced metal transport. Integrated analysis indicates that during the Indosinian period, Sn-bearing magmatic–hydrothermal fluids migrated into closely spaced microfractures and joints, where localized boiling may have occurred, producing limited precipitation. The fluids then ascended along these structures and mixed with infiltrating meteoric water, destabilizing Sn<img>Cl complexes and precipitating Sn in fault zones to form quartz-vein–type Sn ore. Thus, fluid mixing was the primary mineralization mechanism at Babanqiao. These findings also highlight the exploration potential of Indosinian granites in South China as hosts of previously unrecognized W<img>Sn systems.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107926"},"PeriodicalIF":3.3,"publicationDate":"2025-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466345","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, enrichment mechanisms and geomedical assessment of fluoridated groundwater in some parts of the largest semi-arid sedimentary basin in Ghana","authors":"Emmanuel Daanoba Sunkari ,&nbsp;Onesimus D. Zeon ,&nbsp;Asare Asante-Annor ,&nbsp;Samuel Nunoo ,&nbsp;Abayneh Ataro Ambushe","doi":"10.1016/j.gexplo.2025.107924","DOIUrl":"10.1016/j.gexplo.2025.107924","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This study investigated the hydrogeochemistry, spatial distribution, health risks, and underlying mechanisms of elevated fluoride (F&lt;sup&gt;−&lt;/sup&gt;) concentrations in groundwater across communities situated within the Voltaian Supergroup of the semi-arid Volta Basin in Ghana. This was achieved through a medical geology framework that integrates hydrogeochemistry, GIS-based spatial analysis, geochemical modelling, unsupervised machine learning, petrography, PXRD analysis, Monte Carlo Simulation, Sobol sensitivity analysis, probabilistic health risk assessment, and community-based health surveillance to investigate the geogenic sources, spatial distribution, and health implications of F&lt;sup&gt;−&lt;/sup&gt; in groundwater. Thirty-one borehole water samples were collected from Mion District, Karaga District, and Gushegu Municipality in the Northern Region of Ghana. Petrographic and PXRD analyses identified minerals such as quartz, albite, biotite, zeolite, illite, and opaque minerals in the reservoir rocks. Lithological evaluation of boreholes confirmed the reservoir rocks at depth. These minerals dissolve in groundwater, enriching it with various ions. The major cations in groundwater were found in the order: Mg&lt;sup&gt;2+&lt;/sup&gt; &gt; Ca&lt;sup&gt;2+&lt;/sup&gt; &gt; K&lt;sup&gt;+&lt;/sup&gt; &gt; Na&lt;sup&gt;+&lt;/sup&gt;, and the major anions in the order: HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; &gt; SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2−&lt;/sup&gt; &gt; Cl&lt;sup&gt;−&lt;/sup&gt;. The groundwater is alkaline, with Mg&lt;sup&gt;2+&lt;/sup&gt; − HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;−&lt;/sup&gt; as the common water type. Fluoride concentrations ranged from 0.23 to 19.5 mg/L, with an average of 4.71 mg/L, exceeding the World Health Organization's guideline value of 1.5 mg/L in about 87 % of the boreholes around the northeastern fringe of the study area. The high F&lt;sup&gt;−&lt;/sup&gt; levels are primarily due to natural sources and are influenced by water-rock interaction, weathering, ion exchange, and mineral dissolution and precipitation. Health risks associated with fluoridated drinking water were assessed using the US Environmental Protection Agency Model, Monte Carlo Simulation, and Sobol sensitivity analysis revealing non-carcinogenic risks such as dental and skeletal fluorosis, particularly affecting children, followed by adults, teenagers, and infants. Sobol sensitivity analysis reveals that body weight is the primary driver of the non-carcinogenic risk variability across the population, followed by water consumption and F&lt;sup&gt;−&lt;/sup&gt; concentration. However, age-specific patterns show that for infants and children, F&lt;sup&gt;−&lt;/sup&gt; levels and body weight are key contributors, while in teenagers and adults, F&lt;sup&gt;−&lt;/sup&gt; concentration alone dominates risk variability. Community-based health surveillance confirmed these findings. Due to the high F&lt;sup&gt;−&lt;/sup&gt; levels, the people now use polluted surface water for drinking and domestic purposes, leading to severe gastrointestinal infections. Therefore, urgent attention is needed by the stakeholders to curb the threat of ground","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107924"},"PeriodicalIF":3.3,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145416288","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}