Geochemistry of hydrothermal magnetite, biotite, chlorite and the host rocks in the Bagjata uranium deposit, Singhbhum IOCG province, India: Implications for alteration, physicochemical condition, and uranium fertility

Source and evolution of fluids in the Haidewula uranium deposit, Northwest China: evidence from elemental and isotopic compositions of pyrite

Contrasting uranium enrichment mechanisms and ore-forming fluid characteristics in the HLJ and DL uranium deposits, southern Songliao basin

The uranium metallogenic potential of the Dadongshan–Guidong granite belt in northern Guangdong, especially the Jiangwan area in the eastern Dadongshan pluton, remains unclear, which hinders the evaluation of exploration prospects in this area. In this study, we present new data on the mineralogy, U-Pb geochronology, trace element, and sulfur isotopic compositions of pitchblende and associated pyrite from the Jiangwan uranium deposit (JUD). The uranium ore is dominated by pitchblende, which commonly occurs as crustiform and fine veinlet-like aggregates. Part of the euhedral-to-subhedral pyrite grains are enclosed or partially replaced by pitchblende. LA-ICP-MS analyses of pitchblende yielded a Tera–Wasserburg lower intercept age of 60.2 ± 0.5 Ma (MSWD = 2.6, n = 16), indicating that uranium mineralization occurred during the Paleocene. Additionally, the pitchblende has ΣREE contents of 2489–4960 ppm and high U/Th ratios (>1000), indicating that the pitchblende has a hydrothermal origin, forming under moderate- to low-temperature conditions (T < 350 °C). HREE-enriched patterns suggest that carbonate complexing played an important role in uranium transport. Weak positive Ce anomalies in pitchblende, together with pervasive hematitization, indicate relatively oxidizing conditions for the ore-forming fluid. Pyrite has Co/Ni ratios of 1.03–4.53, indicating a hydrothermal origin. The δ34S values of pyrite, varying from −4.23‰ to −1.21‰, suggest that the sulfur source was unlikely to be derived solely from the granitic host rocks, but may have been influenced by mafic dike-related sulfur and hydrothermal fluid–rock interaction. Combined petrographic and geochemical evidence suggests that pyrite formed before pitchblende and likely acted as an important reductant during uranium precipitation. These results indicate that the JUD records a Paleocene hydrothermal uranium mineralization event, which corresponds to the age of the identified main mineralization period in the Xiazhuang ore field.

Abstract The Xiangshan volcanic basin in Jiangxi Province hosts China’s largest volcanic-related uranium deposit. The intermediate to felsic volcanic-intrusive complexes in the basin are the primary ore-bearing units and are central to studies of uranium mineralization. However, their formation mechanisms remain controversial. To address this, we integrate thermodynamic modeling with geochemical analyses of volcanic-intrusive complex samples to establish relationships between melt fraction, magma composition and bulk resistivity obtained from the electromagnetic imaging of the magma reservoir beneath Xiangshan basin. Our results demonstrate that the conductive feature of this magma chamber can be explained by saturated partial melt (~9 vol%) containing a volatile phase (~3 vol%) at 677°C. It suggested that the magma chamber is not a simple two-phase medium, as previous estimates, but rather a complex three-phase system comprising intermingled melt, crystals, and volatiles. Meanwhile, the volatile components are primarily attributed to mantle-derived CO₂ and F introduced during the evolution of the magmatic system, which indicate that the formation of Xiangshan felsic magma reservoirs likely involved contributions from mantle-derived materials. The identified volatiles in the magma system likely provide the direct carriers for the upward migration of uranium elements. Overall, this study provides novel geophysical constraints and petrogenetic evidence that help us understand the genesis of uranium-enriched volcanic-intrusive complexes and the trans-crustal migration of uranium elements in the Xiangshan uranium deposit.

The interlayer oxidation zone-type Mengqiguer uranium deposit in the southern Yili Basin is a typical sandstone-hosted uranium deposit in northwest China, and the lower member of the Jurassic Xishanyao Formation is its main ore-hosting stratum. However, mineralogical and geochemical responses to redox evolution in the deposit have not been systematically constrained. In this study, we carried out detailed petrographic observation, X-ray diffraction analysis, electron probe microanalysis, and whole-rock geochemical analyses on samples from the interlayer oxidation zone in the lower member of the Xishanyao Formation. Kaolinite and illite are the dominant clay minerals in the deposit, with higher contents in oxidation zones than in transition and unaltered zones, while the illite–smectite mixed-layer content shows the opposite trend. The main uranium minerals are uranium oxides and coffinite. U, S and organic carbon are enriched in the transition zone, while the Fe3+/Fe2+ ratio increases with the oxidation degree. Comprehensive analysis on clay minerals shows that the ore-forming fluids evolved from acidic oxidized meteoric fluids to weakly alkaline reduced fluids; the uranium was mainly derived from the leaching of uraniferous sandstone. The formation of the deposit is controlled by sedimentary facies, tectonic uplift, organic–inorganic fluid interaction and redox reaction. This study provides detailed mineralogical and geochemical evidence for the metallogenic mechanism of interlayer oxidation zone-type uranium deposits, and has important guiding significance for uranium prospecting in the Yili Basin.

Sandstone-hosted uranium deposits in the western Qaidam Basin are spatially associated with hydrocarbon-bearing structures, yet the specific roles of different sulfur sources in uranium mineralization remain poorly constrained. This study aims to distinguish the contributions of bacterial sulfate reduction and hydrocarbon-associated sulfate reduction to uranium precipitation by integrating detailed petrography, in situ trace element analyses, and sulfur isotope measurements of chalcopyrite from the Yuejin Ⅱ deposit. Chalcopyrite is restricted to high-grade uranium ores and occurs intergrown with uranium minerals, pyrite, baryte, and carbonate cements. Trace element patterns indicate that oxidizing brines acted as the main transport medium for both uranium and copper, as evidenced by positive correlations between U and brine-related elements (Ba, Sr, Na, K). Positive U-Th correlations with relatively constant Th/U ratios (0.027–0.225) reflect a combination of source composition, fluid transport capacity, and limited thorium remobilization in this near-source, hydrocarbon-rich environment. Correlations between U and high field strength elements (Sn, W) point to a highly evolved granitic origin, with Altyn granitoids likely supplying the copper. Sulfur isotopes show a clear bimodal distribution: one group exhibits heavy δ34S values (+6.9‰ to +18.5‰), while the other shows extremely light values (–36.0‰ to –44.6‰). The light group reflects bacterial sulfate reduction in shallow strata, supported by framboidal pyrite textures, whereas the heavy group corresponds to surface-derived sulfate reduced at hydrocarbon-associated redox fronts, rather than direct incorporation of deep H2S. The lack of intermediate δ34S values indicates that two discrete sulfur reduction mechanisms coexisted within the same deposit, refining genetic models for uranium mineralization in petroliferous basins and challenging frameworks that invoke a single dominant sulfur source.

While compressional tectonics has long been recognized as a significant factor in uranium mineralization, the role of extensional tectonics remains comparatively understudied. This investigation analyzes representative sandstone-hosted uranium provinces, including the Colorado Plateau (North America), the Agadez region (West Africa), the North China–Transbaikal region (Northeast Asia), and the Massif Central (Western Europe). Our systematic analysis reveals that extensional tectonics, building upon pre-existing rifting structures, amplify tectono-magmatic activity, which in turn exerts spatiotemporally control on uranium deposition and gives rise to diverse mineralization ages. Key structural elements within tectonic transition zones, such as uplifts, fault systems, and volcanism, play critical roles: uplifts and shallow-level faults govern the recharge and migration of supergene fluid, whereas deep-seated faults facilitate the transport of reductants (e.g., hydrocarbons) and magma. These deep pathways provide the essential thermal energy and additional components for uranium precipitation. Collectively, these processes collectively form high-relief transition zones that act as prime sites for uranium enrichment. In addition, multi-phase extensional events generate permeable conduits and thermal anomalies that are crucial for mobilizing and concentrating uranium from source rocks. This study provides an enhanced understanding of the genesis of sandstone-hosted uranium deposits and offers a theoretical framework for future exploration targeting.

Research on the relationship between electrical conductivity and uranium concentration in sandstone-hosted uranium in-situ leaching based on a CA-CNN-BiLSTM-LightGBM hybrid model.

The Mesozoic tectonomagmatic reactivation of the Aldan-Stanovoy Shield (ASS) is associated with formation of a regional-scale intratelluric-type alkaline fluid system, a material expression of which is low-temperature substantially potassium-feldspar metasomatites (gumbeites). The paper considers geological features of localization of the metasomatites, their compositional characteristics, and geochemical specialization. It is suggested that the intratelluric-type alkaline fluid system is genetically independent, and that it was involved in origination of the entire diversity of the Mesozoic igneous formations and their associated hydrothermal-metasomatic (including ore-bearing) ones. Evidence is presented for a self-realization of the intratelluric fluid system in form of the largest ore (gold, uranium) deposits in the ASS and of its daughter derivatives, the local-scale magmatic-type ore systems.

Tamusu, the only identified super-large sandstone-hosted uranium deposit in the Bayingobi Basin, provides an important natural laboratory for evaluating ore-controlling factors and genetic models of sandstone-type uranium mineralization. Based on core descriptions from more than 200 boreholes, log facies analysis and geochemical environmental proxies, this study constrains the sedimentary–mineralization architecture and key controlling factors of the deposit. Uranium orebodies are mainly hosted in the upper member of the Lower Cretaceous Bayingobi Formation (Sq2) within a gravity flow-dominated fan-delta–lacustrine system. Braided distributary channel sands on the fan-delta plain and subaqueous distributary channel sands on the delta front constitute the principal uranium reservoirs, controlling both the migration pathways and storage space for U-bearing fluids. Mineralization is jointly governed by fan-delta architecture, interlayer oxidation zonation and reducing agents. The interlayer oxidation zone displays a north-thick–south-thin geometry, and uranium orebodies are concentrated at redox transition positions, with grades of 0.01–0.33 wt%. The metallogenic evolution can be summarized in three stages: syndepositional uranium pre-enrichment, interlayer oxidation mineralization, and a late hydrothermal/diagenetic overprint that mainly modified reservoir properties, favored ore preservation, and did not contribute to the primary uranium budget. Accordingly, a genetic model of “fan-delta architecture + interlayer oxidation control + late overprint and preservation” is proposed to guide exploration in the Bayingobi Basin and analogous sandstone-type uranium systems.

The mineralogical composition, textural characteristics, and uranium occurrence of sandstone-hosted uranium ores significantly influence the leaching performance during in situ recovery. This study investigates ore samples from the Zhenyuan uranium deposit, China, utilizing SEM, EPMA, XRD, and XRF to characterize their texture and mineralogy. Combined with thin-section leaching tests, batch stirring experiments, and pressurized column leaching experiments, the leaching behavior of pitchblende, associated gangue minerals, and the whole rocks were evaluated. The results indicate that: Uranium mainly occurs as nano-spherical and film-like pitchblende distributed along the edges of detrital grains and Ti-oxides. Minor uranium is incorporated into Ti-oxides and dolomite lattices via isomorphic substitution or adsorbed by chlorite. Under CO2 + O2 leaching conditions, pitchblende was almost completely dissolved, while U-bearing Ti-oxides experienced slight corrosion. Dolomite underwent partial dissolution, providing bicarbonate ions and improving rock permeability. Pyrite dissolution was limited during the early stage of leaching. The high dolomite content, low clay abundance, favorable pore structure, and easily leachable pitchblende suggest that the Zhenyuan deposit is well suited for CO2 + O2 in situ recovery. Increasing CO2 pressure is recommended to enhance dolomite dissolution and improve uranium recovery efficiency.

Sandstone uranium deposits exhibit stratabound mineralization and strong vertical heterogeneity in geological space, which complicates the identification of uranium anomaly layers and their integration into deposit-scale 3D models using borehole datasets. In this paper, we propose a UAPC Fourier layer identification (UFLI) method for uranium anomaly layer identification. The method is based on multi-log feature construction, random forest-based estimation of a depth continuous uranium anomaly probability curve (UAPC), and improved Fourier vertical variation analysis. We used 19 boreholes arranged on four exploration lines (ZKA-ZKD) of the Daying uranium deposit in the northern Ordos Basin (north central China), for the validation. The proposed UFLI method identified 51 uranium anomaly layers at a 5 m sampling interval, forming discrete vertical clusters within the drilled successions. The results indicate that anomalies are overwhelmingly concentrated in the Middle Jurassic Zhiluo Formation, particularly within the lower Zhiluo member, with an anomaly-bearing depth range of approximately 550–745 m. Comparison with known mineralization records shows that both industrial and ordinary mineralization intervals are captured within the anomaly layers. Then, based on inter-borehole continuity of anomaly layers, we reconstructed five uranium orebodies (orebodies 1–5) and describe their distribution characteristics. The proposed method provides a technical means for subsurface visualization and exploration targeting in sandstone uranium systems.

Efficient uranium deposit exploration necessitates advanced predictive methodologies capable of effectively managing complex and imbalanced geoscientific big data. This paper introduces a novel prospectivity mapping framework that integrates geological, remote sensing, aeromagnetic, and geophysical datasets through advanced machine learning techniques optimized for severe data imbalance. Data from the Husab uranium mine, located in the Erongo region of Namibia within the central zone of the Damara orogenic belt, ~ 7 km south of the Rössing uranium mine and ~ 50 km east of Swakopmund, were standardized and spatially sampled, with clearly delineated mineralized and non-mineralized samples. Several machine learning models were evaluated, including balanced random forest, class-weighted LightGBM, class-weighted CatBoost, and a stacking ensemble method. The stacking ensemble exhibited superior performance, achieving an accuracy of 99.2%, balanced accuracy of 97.3%, recall of 95.0%, and F1 score of 95.3%. Notably, the class-weighted CatBoost and class-weighted LightGBM models demonstrated exceptional recall capabilities, with values reaching 97.5% and 97.3%, respectively, highlighting their strength in identifying mineralized samples. Evaluation using comprehensive metrics including receiver operating characteristic (ROC) and Precision–Recall (P–R) curves (ROC-AUC = 0.998, P–R-AUC = 0.989 for the stacking ensemble) confirmed the robustness of the proposed models. Moreover, model interpretability was addressed using the SHapley Additive exPlanations (SHAP) framework, a widely used model-agnostic explainable artificial intelligence technique that assigns each feature an importance value based on cooperative game theory, which quantitatively elucidated the contribution of each input feature to the prediction results. The SHAP analysis identified magnetic anomalies, lithology, and airborne radiometric anomalies (Th/K, Th, K, U) as major predictors of uranium mineralization occurrence, in agreement with established metallogenic mechanisms. The integration of multi-source geoscience data, advanced machine learning, and explainable artificial intelligence significantly enhances exploration efficiency and provides transparent, practical insights for identifying high-potential uranium targets.

The genesis of the Shaping carbonate-hosted uranium deposit, South China: Constraints from in situ calcite U-Pb dating and Sr isotopes

Genetic types, mineralization styles, and geodynamic drive of uranium deposits in the South China Block

Abstract The origin of both regolith-hosted rare earth elements (REE) and granite-related uranium deposits has been generally suggested to be associated with REE-U-bearing accessory minerals in granitic rocks. However, different mineralization styles are often associated with granites with specific geochemical and mineralogical fingerprints. Here, whole-rock geochemistry and mineralogy of the REE-fertile Zhaibei and U-fertile Aigao granites in southern Jiangxi Province were investigated to decode petrogenesis of granites and their genetic link with the REE and U mineralization. Zircon and monazite-(Ce) U-Pb dating indicates that the Aigao and Zhaibei granites were emplaced at the Triassic (∼231 Ma) and Jurassic (∼191 Ma), respectively. The Aigao granite belongs to low-Ca peraluminous L-type leucogranites with whole-rock 87Sr/86Sr ratios of 0.7059–0.7228 and ɛNd(t) values of −11.4 to −11.5, monazite-(Ce) ɛNd(t) values of −13.2 to −9.7, and Paleoproterozoic Nd model ages, suggesting that the granite was mainly derived from partial melting of ancient continental crust. In contrast, the Zhaibei granite is high in SiO2, (Na2O + K2O)/CaO, FeOT/MgO, and Zr + Nb + Ce + Y, but low in CaO, TiO2, and Sr and shows the affinity of A2-type granites. It has whole-rock 87Sr/86Sr ratios of 0.7016–0.7097 and ɛNd(t) values of −6.4 to −0.6 and monazite-(Ce) ɛNd(t) values of −6.7 to −5.5. These results indicate that the Zhaibei granite was generated by mixing between mantle-derived mafic magma and crustal-derived felsic magma. The Aigao granite, with low whole-rock Th/U and REE/U ratios, is characterized by the association of monazite-(Ce), Th-poor uraninite, and xenotime-(Y), and represents a favorable U source for uranium deposits. The Zhaibei granite exhibits higher REE + Y, Th, Zr, (REE + Y)/U, and Th/U and has primary REE-bearing minerals of monazite-(Ce), U-rich thorite, and zircon. Some magmatic phases have been transformed into the secondary forms (e.g., REE-fluorocarbonates) that are easier to be weathered during deuteric alteration, which sets the stage for regolith-hosted REE mineralization. This study suggests that uraninite-bearing, low-Ca peraluminous granites with U/(REE + Y) >∼0.2 should be considered as high-priority targets for exploration for U deposits, while high-Si (SiO2 >∼74 wt%), low-Ca (CaO <1 wt%) peraluminous granites with the LREE/(HREE + Y) ratio of <∼1.5 and high-Ca granites (CaO >1 wt%) with the LREE/(HREE + Y) ratio of >∼1.5 may have greater regolith-hosted HREE and LREE ore potential, respectively.

Background: Interindividual radiosensitivity is largely driven by genetic regulation of DNA damage recognition, repair, and cell-cycle control. TP53 and CDKN1A (p21) are key genomic markers associated with differential responses to ionizing radiation. Methods: This study investigated eight functional SNP markers across several key genes involved in DNA damage responses and cellular stress regulation, including TP53, CDKN1A/p21, APC, VEGF, XPD, and RAD51, in occupational groups exposed to chronic low-dose ionizing radiation at the Stepnogorsk Mining Chemical Combine and the Balkashinskoye uranium deposit. Genotyping was performed using PCR-based assays followed by restriction fragment length polymorphism (RFLP) analysis. Allele and genotype frequencies were compared between radiation-exposed workers and matched controls within Kazakh and Russian ethnic subgroups. Statistical differences were assessed using χ2 tests, and associations with radioresistance were interpreted based on established functional characteristics of each polymorphism. Results: Four SNPs showed significant allele and genotype frequency shifts in radiation-exposed populations. The TP53 intron 3 insertion allele, TP53 intron 6 A allele, TP53 Pro72 (C) allele, and p21 codon 31 A allele were consistently enriched among exposed individuals. The strongest deviations were observed in Russian workers from Stepnogorsk (p < 0.01). These alleles are functionally associated with enhanced DNA repair efficiency, modified apoptotic responses, and strengthened cell-cycle checkpoint regulation. Conclusions: Significant enrichment of radioresistance-associated TP53 and CDKN1A (p21) variants was observed in uranium industry workers chronically exposed to low-to-moderate ionizing radiation. The observed patterns support a polygenic model of adaptive responses and emphasize the importance of genetic background in determining individual radiosensitivity under occupational exposure conditions.

Genesis of ankerite and its relationship with uranium mineralization in the Hailijin uranium deposit, southern Songliao Basin, China

Optimization of CO2+O2 in-situ leaching parameters for sandstone-type uranium deposits under uncoupled charge blasting