Journal of Geochemical Exploration最新文献

{"title":"CNN inversion model considering texture features and its application to soil selenium content","authors":"Gong Cheng ,&nbsp;Xingwang Zhou ,&nbsp;Yuanyuan Tang ,&nbsp;Jin Chen ,&nbsp;Wenrui Yang ,&nbsp;Liangliang Dai ,&nbsp;Jia Liao ,&nbsp;Lingyi Liao","doi":"10.1016/j.gexplo.2025.107909","DOIUrl":"10.1016/j.gexplo.2025.107909","url":null,"abstract":"<div><div>Soil remote sensing geochemistry typically involves constructing inversion models by correlating geochemical data from samples with spectral data from remote sensing image pixels to infer soil element concentrations. However, the accuracy of modeling using only the emissivity of image element is low. Therefore, this paper incorporates texture information from the images as a modeling factor and constructs a Convolutional Neural Networks (CNN) inversion model that considers texture features, exploring the impact of texture features on the modeling process. Taking selenium (Se) as an example, the study first conducts a correlation analysis between the pretreatment remote sensing data and the soil sample chemical data to select the spectral bands with strong correlations. Then, based on these selected bands, the study uses a 17 × 17 grid of pixels surrounding the sample points as the input and the selenium content at the sample points as the output to construct the CNN inversion model. Finally, the inversion effect of CNN model is compared with Multiple Linear Regression (MLR), Support Vector Machines (SVM), Random Forests (RF) and Backpropagation Neural Networks (BPNN) models conducted by spectral feature alone or a combination of spectral and texture features. This comparison highlights the role of texture features in quantitative remote sensing modeling and the advantages of the CNN inversion model. The results show that compared to the best-performing model based on spectral features alone, SVM (with a test set R² = 0.286), the best model based on spectral and texture features, BPNN (with a test set R² = 0.377), improved the inversion accuracy by nearly 0.1. The CNN model achieved a test set R² of 0.504, significantly outperforming the other models. In conclusion, incorporating texture information into quantitative remote sensing modeling can effectively improve inversion accuracy, and the CNN model demonstrates a clear advantage in soil element inversion.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107909"},"PeriodicalIF":3.3,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155535","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":"Textural and geochemical constraints on the formation of the magmatic Fe–Ti oxide deposit at Boreum Island, South Korea","authors":"Ji-Hyun Lee ,&nbsp;Eui-Jun Kim ,&nbsp;Seok-Jun Yang ,&nbsp;Heonkyong Im ,&nbsp;Dongbok Shin","doi":"10.1016/j.gexplo.2025.107908","DOIUrl":"10.1016/j.gexplo.2025.107908","url":null,"abstract":"<div><div>This paper investigates the complex magmatic processes of the Boreum magmatic Fe–Ti oxide deposit through comprehensive field observation, petrography, and geochemistry. Located in the marginal zone of the Gyeonggi Massif, central-western Korean Peninsula, this deposit represents one of South Korea's most important Fe–Ti oxide provinces, providing an ideal natural laboratory for understanding ore formation mechanisms. The sill-like Boreum ultramafic rocks (30 m wide, 300 m long) intrude Paleoproterozoic Boreumdo schist and comprise three distinct phases: actinolite-, diopside-, and olivine-dominant. Cross-cut relationships indicate formation through multiple melt injections rather than single-melt fractionation processes. Iron–Ti oxide mineralization concentrates unevenly in the highly fractured olivine-dominant phase as sill-dyke networks. Magnetite and ilmenite are dominant, with subordinate pleonaste and perovskite (restricted to diopside-dominant phase). Magnetite shows complex exsolution textures indicating subsolidus re-equilibration during slow cooling. It is significantly enriched in compatible elements (Cr: 25,622–140,526 ppm; Ti: 18,160–87,919 ppm; V: 2421–18,433 ppm), plotting within magmatic Fe–Ti, V deposit compositional fields. Mineral chemistry reveals high-temperature magnetite crystallization (T_Mg-Mag = 885–607 °C, T_Ilm-Mag = 754–594 °C) under low oxygen fugacity conditions (ΔFMQ −2.60 to +0.69). Magnetite exhibits restricted δ⁵⁶Fe (+0.12 to +0.40 ‰) and δ¹⁸O (−0.75 to +2.89 ‰) values, consistent with magmatic origin. Fe–Ti oxide mineralization resulted from high-temperature magmatic melt migration into already solidified ultramafic rocks, not in situ crystallization or crystal settling. These findings provide new insights into magmatic processes forming Fe–Ti oxide deposits in mafic–ultramafic intrusions.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107908"},"PeriodicalIF":3.3,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155534","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":"Relationship between provenance-deposition lobes and uranium mineralization: A case study from the northern Songliao basin","authors":"Yang Liu ,&nbsp;Kun Huang ,&nbsp;Hui Rong ,&nbsp;Tao Sun ,&nbsp;Yongpeng Yin","doi":"10.1016/j.gexplo.2025.107907","DOIUrl":"10.1016/j.gexplo.2025.107907","url":null,"abstract":"<div><div>The uranium mineralization in the Sifangtai Formation of the northern Songliao Basin is widely distributed, and the complex origins of its uranium reservoir sand bodies pose significant constraints on uranium deposit prediction and exploration. The uranium mineralization in the Sifangtai Formation of the northern Songliao Basin is extensively distributed, with the complex origins of its uranium reservoir sand bodies posing severe constraints on uranium deposit prediction and exploration. This paper employs comprehensive research methods, including sandstone geochemistry, heavy mineral analysis, and detrital zircon U<img>Pb geochronology, to accurately trace the provenance of uranium reservoir sand bodies in the Sifangtai Formation of the northern Songliao Basin. The research results indicate that the average content of quartz, feldspar, and rock debris in the sandstone of the Sifangtai Formation is 42 %, 37 %, and 21 %, and the CIA is from 61.81 to 72.81 with an average of 68.56. The apatite-tourmaline index of heavy minerals (ATi) in the sandstone of the Sifangtai Formation are mostly greater than 50, the Garnet-Zircon index of heavy minerals (ZGi) is mostly less than 50, and the stable coefficient of heavy minerals (ZTR) ranges from 9.63 % to 35.78 %. The main peak value of detrital zircon is concentrated in the Jurassic-Permian, with ages ranging from 165 to 294 Ma, and the secondary peak is concentrated in the Cretaceous, with ages ranging from 92 to 148 Ma. This study indicates that the uranium reservoirs of the Sifangtai Formation are greywacke and feldspathic sandstone, with the parent rock originating from the upper crust and being the Permian-Jurassic and Early Cretaceous medium acidic magmatic rocks formed in the active continental margin. The western provenance of the Sifangtai Formation is provided by the Daxing'an Moutains, the northern provenance is supplied by the Xiaoxing'an Moutains, and the eastern provenance is offered by the Zhangguangcai Mountains. The source-to-sink system of the Sifangtai Formation has led to the formation of three provenance-deposition lobes in the west, north and east of the northern Songliao Basin, which control the development of the uranium reservoirs. The three provenance-deposition lobes show different uranium mineralization potential, in which the western provenance-deposition lobe has the highest metallogenic potential.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107907"},"PeriodicalIF":3.3,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119050","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":"GEMAS: Novel continental-scale patterns revealed in the spatial distribution of Cr in European agricultural soil – A systematic method validation","authors":"Attila Petrik ,&nbsp;Gyozo Jordan ,&nbsp;Ahmed Abdelaal ,&nbsp;Alecos Demetriades ,&nbsp;Benedetto De Vivo ,&nbsp;Stefano Albanese ,&nbsp;Martiya Sadeghi ,&nbsp;The GEMAS Project Team","doi":"10.1016/j.gexplo.2025.107906","DOIUrl":"10.1016/j.gexplo.2025.107906","url":null,"abstract":"<div><div>Following the Ni-focused experimental investigation, it was clear that a critical advancement in digital image analysis of geochemical data sets required the validation of the procedures used with another element. Chromium was selected because its geochemical behaviour closely mirrors that of Ni in both lithological context and surface processes. Our current study, conducted with rigorous methodological precision, aims to assess a novel geospatial technique capable of capturing spatially variable continental-scale element distribution patterns. To reduce localised anomalies, we applied a moving average filter to the TIN-based interpolated Cr data set. The processed grid was then subjected to digital image analysis, which highlighted several continental-scale spatial orientations — NE-SW, E-W, and NW-SE — that closely resemble those found in the Ni study. Notably, prominent NE-SW and ENE-WSW linear Cr structures were identified, aligning with the known structural imprints of the Variscan and Alpine orogenic belts. Elevated Cr variable concentrations mainly occur in the Balkans and Alpine regions, consistent with exposures of mafic to ultramafic lithologies. A striking east-west trending Cr feature, with lower concentrations northwards, was also observed within the terminal zone of the last major glaciation, aligning with Cr-depleted glaciofluvial deposits. Chromium anomalies with a NW-SE trend also occur in regions such as Fennoscandia, Hellenic Republic, northern Italy, and the Pyrenees, aligning with those for Ni. Beyond confirming the efficacy of image analysis techniques in uncovering and describing new geochemical spatial patterns, this research also reinforces the approach by showing a pronounced continental-scale spatial correspondence between Cr and Ni distributions.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107906"},"PeriodicalIF":3.3,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096903","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":"Contributions from source enrichment and late hydrothermal activity to the formation of the No. 782 REE-Nb-Zr deposit, NE China","authors":"Zeen Han ,&nbsp;Guozhan Xu ,&nbsp;Mingqian Wu ,&nbsp;Deyou Sun ,&nbsp;Xiaohui Zeng ,&nbsp;Bizheng Yang ,&nbsp;Xingmin Zhang ,&nbsp;Weipeng Liu ,&nbsp;Changzhou Deng","doi":"10.1016/j.gexplo.2025.107904","DOIUrl":"10.1016/j.gexplo.2025.107904","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Granite-type rare metal and rare earth element deposits (GRMEDs) have garnered significant attention from both academia and industry owing to their strategic importance in supplying critical metal resources. Nevertheless, the critical factors controlling the formation of GRMEDs remain empirically ambiguous. In the No. 782 REE-Nb-Zr deposit, NE China, three distinct periods of granites have been recognized: pre-mineralization monzogranite, &lt;em&gt;syn&lt;/em&gt;-mineralization granitic complex comprising biotite granite-muscovitized granite-albitized granite, and post-mineralization syenogranite. Systematic petro-genetic investigations of these intrusive phases provide crucial insights into element super-enrichment mechanisms inherent to GRMEDs systems. Zircon U&lt;img&gt;Pb geochronological constraints reveal successive emplacement ages of 488 ± 4 Ma for monzogranite, 458 ± 4 Ma for the mineralized complex, and 451 ± 4 Ma for syenogranite. These granites exhibit diagnostic A-type affinities manifested by elevated Zr + Ce + Nb + Y concentrations (330–544 ppm), enhanced 10,000 × Ga/Al ratios (2.93–3.40), and pronounced negative Eu anomalies (Eu/Eu* = 0.15–0.29), consistent with magmatic rocks formed under extensional tectonics. Zircon grains from the monzogranite, biotite granite and syenogranite show positive &lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Hf&lt;/sub&gt;(t) values of 4.2 ± 0.93 ‰ (1σ, &lt;em&gt;n&lt;/em&gt; = 19), 3.6 ± 0.63 ‰ (1σ, &lt;em&gt;n&lt;/em&gt; = 10) and 5.4 ± 0.82 ‰ (1σ, n = 10), respectively, coupled with elevated &lt;em&gt;δ&lt;/em&gt;&lt;sup&gt;18&lt;/sup&gt;O values of 7.72 ± 0.80 ‰ (1σ, &lt;em&gt;n&lt;/em&gt; = 15), 7.45 ± 1.23 ‰ (1σ, n = 10) and 7.06 ± 0.74 ‰ (1σ, &lt;em&gt;n&lt;/em&gt; = 20), respectively, indicative of derivation from juvenile lower crustal sources. Our geochemical data reveal distinct variations in ore-forming elements: the monzogranite shows significant depletion, contrasting with pronounced enrichment in the biotite granite and syenogranite. This result suggests that the monzogranite was likely derived from a crustal source depleted in ore-forming elements, while the enrichment of ore-forming elements in the granitic complex and syenogranite may be attributed to the incorporation of fluorine-rich volatile components from mantle sources. Furthermore, the granitic complex displays distinct HREE and HFSE distribution patterns, where biotite granite shows moderate HREE-Nb enrichment, albitized granite demonstrates significant enrichment (∑REE up to 2850 ppm), while muscovitized granite exhibits relative depletion. This differential distribution implies that element remobilization during muscovitization and subsequent precipitation through albitization constituted the dominant mechanism for rare earth super-enrichment. We therefore propose that the formation of GRMEDs requires two essential and interdependent conditions: (1) the generation of fertile magma through lower crustal metasomatism by mantle-derived volatiles, and (2) subsequent metal extraction and reconcentration via hydrothermal activity during the l","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107904"},"PeriodicalIF":3.3,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096902","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":"Magmatic controls and chronology of tin mineralization in the Mengsong Deposit, Southern Lincang Batholith, SW China","authors":"Jiale Wang ,&nbsp;Xiaobo Si ,&nbsp;Mingjun Zheng ,&nbsp;Huanchao Xu ,&nbsp;Xiang Sun","doi":"10.1016/j.gexplo.2025.107902","DOIUrl":"10.1016/j.gexplo.2025.107902","url":null,"abstract":"<div><div>The Triassic Lincang granite batholith in southwestern Yunnan, China, hosts numerous granite-related tin deposits. This study investigates the Mengsong tin deposit, located in the southern part of the Lincang batholith, by integrating zircon U<img>Pb geochronology, Hf isotopic analysis, and trace element geochemistry. Zircon from the Mengsong deposit reveals crystallization ages of 225.5 ± 0.9 Ma (MSWD = 2.3, <em>n</em> = 20) for the muscovite granite and 224.7 ± 0.9 Ma (MSWD = 1.9, <em>n</em> = 25) for the two-mica granite. This indicates that the Mengsong granites was formed during the Triassic period. Zircon trace element signatures indicate that the Mengsong granites are highly fractionated and crystallized from magmas with low oxygen fugacity (ΔFMQ). Negative zircon ε_Hf(t) values (−14.3 to −1.5) indicate derivation from an ancient crustal source. We propose that reduced magmas were fundamental prerequisite for tin enrichment. This factor, in conjunction with highly magmatic differentiation of crustal melts generated during post-collisional extension after the Paleo-Tethys closure, created the ideal conditions for Sn mineralization. These results highlight the genetic relationship between tin mineralization and synchronous granitic magmatism in the Mengsong deposit and provide valuable insights for future exploration targeting Triassic tin systems in southwestern Yunnan.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107902"},"PeriodicalIF":3.3,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of FeP coupling on arsenic species in sediments during the ice-bound period of lakes in cold regions","authors":"Wenjing Shi ,&nbsp;Xinya Zhao ,&nbsp;Yizhe Liu ,&nbsp;Haoran Xu ,&nbsp;Changwei Lü ,&nbsp;Weiping Li","doi":"10.1016/j.gexplo.2025.107903","DOIUrl":"10.1016/j.gexplo.2025.107903","url":null,"abstract":"<div><div>The redox behavior of iron (Fe) significantly impacts the biogeochemical cycle of arsenic (As), with iron minerals serving as major reservoirs for phosphate (P). The cycle of As inherently associates with its species. However, the effect of Fe<img>P coupling on As species in lake sediments remain largely unknown, especially during the ice-bound period. The novelty of this study is to explore the effect of Fe<img>P coupling on As speciation during an ice-bound period using PLS-SEM model based on As、Fe and P species as well as environmental factors monitoring in sediments. Our findings revealed that Fe<img>P coupling accounts for 95.7 % of As speciation variability, playing a pivotal role in As transformation and partitioning, particularly in labile As pool that contained adsorbed As, moderately labile As pool that closely related to iron species, and pyrite-coprecipitated As. The significant influence of Fe<img>P coupling on the reductive transformation and re-distribution of amorphous and crystalline iron oxides, which in turn affects As adsorption-desorption processes. This interaction subsequently influences the speciation of Fe and P, as well as the release and ecotoxicity of As. Notably, exchangeable phosphorus, iron-bound P fraction and organic P fraction (OP) were identified as the primary P species mediating the effects of Fe<img>P coupling on As speciation. Interesting, OP also play the major role in the effect of Fe<img>P coupling on As species, potentially releasing As adsorbed on crystalline Fe hydroxides during organic matter mineralization. Results emphasize the importance of Fe(hydro)oxides and P in controlling As partitioning, with iron (hydro)oxides being particularly critical in P behavior and its interaction with As. This work provides insights into the cycling of As and the enrichment of P and As in sediment-water systems, providing a reference for environmental monitoring and remediation in sedimentary environments facing dual risks of As pollution and eutrophication.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107903"},"PeriodicalIF":3.3,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046587","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":"Trends of Cu and Co contaminated sediment dispersal along the Kafue River, the Zambian Copperbelt","authors":"Ondřej Bábek ,&nbsp;Ondra Sracek ,&nbsp;Vojtěch Ettler ,&nbsp;Jaroslav Kapusta ,&nbsp;Bohdan Kříbek ,&nbsp;Martin Mihaljevič ,&nbsp;Imasiku Nyambe ,&nbsp;Vít Penížek ,&nbsp;Aleš Vaněk ,&nbsp;Gabriel Ziwa","doi":"10.1016/j.gexplo.2025.107900","DOIUrl":"10.1016/j.gexplo.2025.107900","url":null,"abstract":"<div><div>Rivers are important pathways for metal(loid) contamination in mining areas. The Kafue River flows through the Zambian Copperbelt with nearly a hundred-year history of Cu and Co mining. Nine cores down to 2.5 m deep were drilled in fluvial sediments along a 750-km long river section and analysed for grain size, elemental composition, and mineralogy using extraction tests and scanning electron microscopy with an aim to investigate the spatial and temporal contamination patterns. The silty and fine- to coarse grained sandy sediments were deposited in natural levees, semi-abandoned meanders, and channel bars. They are heavily polluted by Cu reaching ore grade (up to 1.9 %) and Co, with UCC-based enrichment factors (EF) as high as 704 and 60, respectively, which is more than an order of magnitude higher than the most severely impacted large European rivers, and slightly polluted by Pb, As, U and other elements. The main carriers of Cu are malachite, pseudomalachite, secondary Fe oxyhydroxides (ferrihydrite, goethite), sulphides, and Cu-bearing grains of kaolinite, chlorite, and mica. This Cu contamination is traceable (EF up to 13) in sediments 750 km downstream of the Kafue River inflow to the Copperbelt. The contaminated sediments are ~100 cm to ~220 cm thick and their average sediment accumulation rates ~12 to ~27 mm/yr indicating that the contaminated suspended particulate matter can be rapidly deposited along the river, representing a potential environmental hazard. Arsenic and Pb can be scavenged to Fe oxyhydroxides and accumulate in capillary fringe above groundwater level during early diagenesis.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107900"},"PeriodicalIF":3.3,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096901","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 genesis of the carbonate-hosted Tuokesai Pb–Zn deposit, West Tianshan, NW China: Synsedimentary strata-bound mineralization and hydrothermal remobilization","authors":"Shunda Li ,&nbsp;Wenjiao Xiao ,&nbsp;Chuan Chen ,&nbsp;Miao Sang ,&nbsp;Qigui Mao ,&nbsp;Lingling Gao ,&nbsp;Fang Xia ,&nbsp;Wei Wang ,&nbsp;Xiaofei Du","doi":"10.1016/j.gexplo.2025.107891","DOIUrl":"10.1016/j.gexplo.2025.107891","url":null,"abstract":"<div><div>The Tuokesai Pb–Zn deposit is located in the eastern section of the West Tianshan Orogen within Precambrian carbonate rocks. However, the genesis of the ore, including sedimentary exhalative and sedimentary-metamorphic types, remains controversial owing to varying interpretations of strata-bound and vein-type mineralization. In this study, we aimed to construct an innovative genesis model, focusing on two mineralization types, by analyzing fluid evolution, material sources, and trace element distributions. Three mineralization stages were identified, each with specific pyrite generation. Stage I pyrite–sphalerite–galena bands (Py-1 and Py-2) represent strata-bound mineralization. Stage II sphalerite–pyrite–quartz veins (Py-3) and Stage III pyrite–quartz–calcite veins (Py-4) represent vein-type mineralization. Fluid inclusion microthermometric and H–O isotopic analyses revealed that Stage I fluids are characterized by low temperatures (132–171 °C) and moderate salinities (11.8–17.3 wt% NaCl eqv.), and are derived from modified seawater. Conversely, fluids in Stages II–III are associated with moderate temperatures (165–267 °C) and variable salinities (2.1–35.3 wt% NaCl eqv.), being derived from a mixture of magmatic and meteoric water. The in situ S isotopic composition suggests that Py-1 and Py-2 (δ³⁴S = 9.46–12.20 ‰) originated from the thermochemical reduction of marine sulfate, whereas Py-3 and Py-4 (δ³⁴S = 0.85–3.85 ‰) originated from magmatic components. LA–ICP–MS analysis of trace elements in pyrite, combined with machine learning classification methods, indicated that Py-1 and Py-2 have a synsedimentary origin whereas Py-3 and Py-4 have a magmatic-hydrothermal origin. Overall, our findings support a novel multistage genesis model for the Tuokesai Pb–Zn deposit, suggesting that Neoproterozoic syngenetic strata-bound mineralization was overprinted by Late Paleozoic vein-type hydrothermal remobilization. This model highlights the importance of incorporating diverse geological events into our understanding of the ore-forming process to facilitate the exploration of carbonate-hosted Pb–Zn deposits within the West Tianshan Orogen.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"280 ","pages":"Article 107891"},"PeriodicalIF":3.3,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046585","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 review of Australian carbonatites and associated REE-Nb mineralisation","authors":"Ross Chandler ,&nbsp;Ignacio González-Álverez ,&nbsp;John Mavrogenes ,&nbsp;Luke Blais","doi":"10.1016/j.gexplo.2025.107870","DOIUrl":"10.1016/j.gexplo.2025.107870","url":null,"abstract":"<div><div>Australia has 16 known carbonatites, and two other occurrences of REE mineralisation interpreted as carbonatite-related. These are all located within Precambrian crust, and host known resources of c. 7.2 Mt. of rare earth oxides (containing c. 1.73 Mt. of Nd₂O₃ and Pr₆O₁₁), and c. 2.7 Mt. of Nb₂O₅.</div><div>Australia's carbonatites range from Neoarchean to Jurassic, and display extreme diversity in geological characteristics, ranging from large, multiphase intrusive complexes dominated by either carbonatite (e.g. Gifford Creek and Mt. Weld, Western Australia) or silicate rocks (e.g. Cummins Range and Cundeelee, Western Australia), to single phase and small volume carbonatite dykes (e.g. Yungal dykes, Western Australia). Studied occurrences show similarly diverse radiogenic isotopic signatures (Rb/Sr and Sm/Nd), indicating derivation from a variety of mantle sources ranging from HIMU through to EM1.</div><div>Significant rare earth element (REE) and niobium (Nb) mineralisation occurs in both fresh and weathered carbonatites throughout Australia, with markedly different mineralogical and grade characteristics. While weathering history and preservation are crucial to the formation of supergene enrichments in REE and Nb, analysis of whole-rock geochemical data for different carbonatite types from the Mt. Weld and Gifford Creek complexes suggest primary magmatic composition plays the strongest determinant in the magnitude of grade increase, with siderite-dominated carbonatites having less potential for supergene upgrade than dolomite, ankerite and calcite-dominated examples.</div><div>The distinct geophysical signatures of Australia's known carbonatites have aided exploration efforts leading to early discoveries of deposits within highly magnetic complexes such as Mt. Weld and Cummins Range. Recent discoveries of geophysically subtle complexes (e.g. Gifford Creek complex, West Arunta) suggests both alternative geophysical techniques and a comprehensive structural understanding are crucial to discovery.</div><div>Explorers should focus on areas of known carbonatite magmatism, with a particular focus on developing an understanding of the regional structures that can facilitate carbonatite intrusion. On a local scale, the selection of relevant carbonatite geophysical and exploration signatures leveraging previous local discoveries should be prioritised. The small number of known carbonatites in Australia compared to the other continents abundances indicates further carbonatites and associated mineralisation may be discovered with increased exploration.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"279 ","pages":"Article 107870"},"PeriodicalIF":3.3,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996910","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}