Source Of Uranium Research Articles

Unraveling the genetic type and metallogenetic mechanism of the oldest uranium deposit associated with granitoid, South China: A comprehensive analysis of whole-rock geochemistry, and elemental and U-Pb isotopic signatures of uranium minerals

The Daliang deposit in the Motianling area of South China is unique for its synchronous uranium mineralization with regional metamorphism. To elucidate its genetic mechanism, whole-rock geochemistry from the Daliang deposit was undertaken, along with analyses of the chemical and isotopic signatures of minerals. The Motianling granitoids exhibit strongly peraluminous S-type affinities with low Th/U ratios, representing a uranium source for mineralization. Altered mineralogical and geochemical signatures of altered and ore samples indicate a multi-stage history after granitic emplacement: (1) Late magmatic-hydrothermal alteration characterized by greisenization, K-feldspathization, and propylitization; and (2) brittle-ductile deformation with uranium mineralization. Notably, ore-stage alteration mineral contains chlorite + quartz + sericite, which is consistent with the mineral assemblage of low-greenschist facies metamorphism. EMPA and LA-ICPMS dating on pitchblende yielded ages of 378 and 380 Ma, coinciding with the timing of regional ductile deformation. The pitchblende exhibits weak fractionation between LREEs and HREEs and negative Eu anomalies, mirroring characteristics observed in syn-metamorphic uranium deposits. Therefore, we suggest that uranium mineralization within the Daliang was related to crustal metamorphism, and the Daliang deposit belongs to syn-metamorphic deposit. Fluids likely have been liberated from the acidic brines-bearing Sibao Group that underwent low-greenschist facies metamorphism. Paleozoic intracontinental orogeny in South China resulted in brittle-ductile deformation in the Motianling pluton. These zones provided favorable pathways for the migration of ore-forming fluids and subsequent uranium mineralization. Late Devonian retro-metamorphism facilitated the percolation of oxidizing metamorphic fluids into the Motianling granitoids, circulating along the pre-existing brittle-ductile zones. This study presents the first evidence for syn-metamorphic uranium deposits within the granite of South China. This finding suggests potentially distinct mineralization mechanisms compared to traditional granite-related uranium deposits in the region, warranting further investigation.

Evaluation of uranium migration during the maturation of hydrocarbon source rocks.

The source of uranium is an important research topic related to the exploration of sandstone-type uranium deposits, and potential uranium sources in deep basins are often overlooked. Black organic-rich shale is a common uranium-bearing rock in deep sedimentary basins. However, relatively few studies have investigated the migration of uranium during hydrocarbon generation in and release from uranium-rich shale. In this study, the uranium-rich shale in the Chang 7 member of the Yanchang Formation of the Upper Triassic in the Ordos Basin was selected to investigate the migration of uranium and other trace elements during the thermal maturation of uranium-rich shale via a semiopen pyrolysis simulation system. The gas and liquid products as well as the solid residue were thoroughly analysed by means of multiple instruments. The results showed that uranium significantly migrated before hydrocarbon generation (Ro < 0.61%), with a leaching rate between 12.1% and 18.8%. The leaching rate of uranium during the hydrocarbon generation stage (0.63% < Ro < 1.35%) was relatively low, ranging from 0 to 7.2%. Cu, Pb, Zn, Mo, and other trace elements also migrated considerably during the early stage of thermal evolution, with leaching rates ranging from 2.9 ~ 11.6%. The yield of low-molecular-weight organic acids (LOAs) was the highest in the early stage of thermal maturity, and the LOA yield exhibited a good correlation with the leaching rates of Cu, Pb, Zn, Co, Mo, etc. The generation of LOAs from source rocks was conducive to the leaching and migration of trace elements. Moreover, according to a statistical analysis of published geochemical data, the total organic carbon (TOC) content, uranium content, and U/TOC ratio in shale decreased significantly with increasing burial depth, indicating that uranium migrated significantly upon kerogen hydrocarbon generation during thermal evolution. Therefore, uranium-rich shale is an important deep uranium source in sedimentary basins.

Uranium in groundwaters of North Kazakhstan

Relevance. The need to dentify the characteristics of the distribution of radioactive elements in the groundwater of Northern Kazakhstan. Aim. Generalization of available data on the geochemistry of groundwater and uranium and radon distribution in them using the example of the northern regions of the Republic of Kazakhstan. Methods. Generalization of long-term hydrogeochemical research and compilation of an electronic data bank on the territory of Northern Kazakhstan. A laboratory study of the chemical composition of groundwater was carried out at the Research Laboratory of Hydrogeochemistry of the School of Natural Resources Engineering of Tomsk Polytechnic University. Measurements of 222Rn contents in waters were carried out using the Alfarad Plus complex in the Laboratory of Hydrogeology of Sedimentary Basins of Siberia, Institute of Geology and Geography, Siberian Branch, Russian Academy of Sciences. Results. The groundwater of aquifers of different ages, distributed in the territory of Northern Kazakhstan (North Kazakhstan uranium province), was studied. Two geochemical sets of groundwater were identified. The first is characterized by the dominance of HCO3– and Mg2+ in the water composition, and the second by Cl– and Na+. A change in composition and an increase in the value of total mineralization from 0,1 to 49 g/dm3, in the direction from north to south, indicate the development of continental salinization. In natural waters of the first group, uranium content varies from 0.065 to 16000 μg/dm3 and radon activity from 4 to 3885 Bq/dm3. For sodium chloride waters of the second set, concentrations can reach 32500 μg/dm3, and radon activity is 6–59 Bq/dm3, since the emanating reservoir (granitoids) is located to the north – at a distance of 80–100 km. Naturally, granitoid massifs of the studied region are sources of uranium. Their drainage by the river network leads to its removal and concentration on geochemical barriers in the groundwater of the Neogene-Quaternary aquifer. This distribution of radioactive elements is associated with the high migration ability of uranium in solution in the form of uranyl ion in oxidizing geochemical conditions.

Unraveling the metallogenic mechanisms of uranium-rich ore bodies: Insights from Xinqiaoxi’s pitchblende geochronology and pyrite geochemistry

Granite-related uranium deposits are essential for the global uranium supply, with the uranium-rich ore bodies within these deposits being crucial to their value. However, the sources of uranium, fluid characteristics, and metallogenic mechanisms within these uranium-rich ore bodies remain unclear. In this study, we analyzed pitchblende and pyrite from the Xinqiaoxi uranium deposit to determine uranium age and clarify the mineralization of uranium-rich ore bodies. The pitchblende samples provided a U-Pb age of 58.5 ± 3 Ma (MSWD = 3.4), closely aligns with the mineralization ages in other uranium deposits within the Xiazhuang uranium ore-field. This consistency suggests a significant uranium mineralization event in South China during this period. The vein-like and concentric structure of the pitchblende, coupled with its enrichment in U, Sr, As, W, and Mo but depletion in Th, Pb, and REEs, indicates a strong association with hydrothermal activity. Moreover, its REE pattern closely resembles that of the host rock (Xiazhuang and Maofeng granites), suggesting the latter as a crucial uranium source. Pyrite and pitchblende are coeval, yet pyrite was formed slightly earlier than pitchblende. Pyrite exhibits depletion in Co and Ni but enrichment in As, along with high Co/Ni ratios ranging from 1.68 to 12.2, indicative of a medium- to low temperature hydrothermal genesis. Furthermore, the positive cerium (Ce) anomaly observed in pyrite may indicate elevated oxygen fugacity in the fluids during precipitation. The δ34S values of pyrite (−10.42 ‰ to −15.26 ‰, averaging −13.44 ‰) are consistent with those of the host rock (Xiazhuang and Maofeng granites), indicating a primary sulfur source from the host rock. Additionally, pyrite may serve as a reductant, facilitating the formation of uranium ore. Our proposed genetic model suggests that CO2-rich oxidizing fluids facilitate uranium leaching from host rocks, resulting in the formation of a uranium-enriched fluid that migrates along faults, where U6+ undergoes reduction to U4+ within secondary fracture zones, facilitated by reductants such as pyrite.

Multimethod characterization of geogenic sources of fluoride, arsenic, and uranium in Mexican groundwater

Geogenic groundwater F, As and U affect drinking-water availability and safety, with up to 60% of groundwater sources in some regions contaminated by more than recommended concentrations. As a result, an estimated 300–500 million people are at risk of severe health impacts and premature mortality. In the regions of Chihuahua, Zacatecas and Salinas, San Luis Potosí, Mexico (Sierra Madre Occidental), concentrations of fluoride (F), arsenic (As) and uranium (U) have been detected in groundwater above national and international drinking water standards. These elevated concentrations have been associated mainly with geogenic sources in volcanic rocks and basin fill sediments. However, the specific host phases and processes that release these toxic elements into groundwater have never been identified.In a new multi-method approach that combines classical approaches of hydrochemistry, petrography, and geochemistry, with more advanced techniques such as Raman spectroscopy (RS), scanning electron microscopy (SEM), electron microprobe (EMP) and laser ablation LA-ICP-MS, this research proposes an innovative methodology for the characterization and identification of F, As and U bearing phases in volcanic rocks and sediments, as well as some of the processes favoring the mobilization of these elements to groundwater. Groundwater chemical composition allowed the identification of 3 groundwater flow systems: a) local flows, hosted in basin-fill sediments with average temperatures of 21.7 °C, and low As (≈6.2 μg L−1), F (≈0.5 mg L−1) and U (≈1.1 μg L−1) concentrations; b) intermediate flows, characterized by average temperatures of 24.5 °C, and intermediate concentrations of As (≈17.7 μg L−1), F (≈1.1 mg L−1) and U (≈4.2 μg L−1); c) regional flows, circulating mainly through rhyolites and ignimbrites, temperatures that can reach up to 36.6 °C, and higher concentrations of As (≈36.5 μg L−1), F (≈2.6 mg L−1) and U (≈7.4 μg L−1). The presence and distribution of As, F and U in groundwater are associated with the local, intermediate and regional Tóthian flow systems proposed. Through microanalytical analyses, it was possible to identify F-rich minerals like fluorapatite (≈2.3 wt%), biotite (≈1.8 wt%) and fluorite (≈37 wt%). Glassy matrix rich in As (≈0.83–163 μg g−1), U (0.15–11.7 μg g−1) and F (200–1600 μg g−1) was mainly found in rhyolites and ignimbrites from the Tertiary volcanic outcrops of the tectonostratigraphic province of the Sierra Madre Occidental, and basin-fill sediments derived from these rocks. Based on the present study, the groundwater As, F, and U anomalies in the different study zones are associated with ignimbrites and rhyolites considered as their primary source, where processes like weathering, dissolution and devitrification, are directly linked to variations in the concentrations of these elements.This multi-method approach proposes a new efficient way to identify geogenic sources associated with F, As and U in groundwater, especially in regions where groundwater is the main source of supply. The outcome of this research can explain the possible reason behind the high concentrations of F, As and U in a number of regional groundwater flow systems which are well documented cases in volcanic regions of the world and Mexico. The results obtained through the analysis of water-rock interaction in this research can be applied to other semi-arid regions with geogenically impacted aquifers, due to the geological and climatic similarity with numerous volcano-sedimentary basins around the world.

The genesis of intersection-type uranium deposits in south China: Insights from zircon and pitchblende U-Pb geochronology and pyrite sulfur isotopes of the Egongtang uranium deposit, southern Jiangxi

Intersection-type uranium deposits refer to the uranium deposits that are located at the intersection of mafic dykes and silicified faults and are an important type of granite-related uranium deposits in South China. However, the genesis of these deposits still remain poorly understood. The Egongtang uranium deposit is a typical intersection-type uranium deposit in the Huangsha uranium ore district (southern Jiangxi) that bears a number of NWW-trending mafic dykes, thus providing an excellent opportunity to study the genesis of intersection-type uranium deposits. In this study, the mineralization age and genesis of this deposit were constrained using in situ zircon and pitchblende U-Pb geochronology, whole-rock geochemistry, and pyrite sulfur isotope data. The zircon U-Pb dating constrains the crystallization ages of 240.4 ± 1.3 Ma and 160.7 ± 1.6 Ma for granites in the Huangsha ore district. The samples (including altered and unaltered) of the granites are characterized by variable whole-rock U contents of 5.8–14.1 ppm and Th/U ratios of 2.4–7.7, which favor the crystallization of uraninite in the granites and suggest U leaching from the granites during alteration. In situ U-Pb dating on pitchblende from the Egongtang uranium deposit yielded a lower intercept age of 89.8 ± 1.1 Ma, indicating that the uranium mineralization took place at the Late Cretaceous. Pyrite associated with pitchblende has δ34S values ranging from 1.6‰ to 3.8‰, suggesting a magmatic source. This study indicates that granites in this area might have represented the source of uranium for the Egongtang deposit, and that the uranium mineralization was probably related to the Late Cretaceous crustal extension in South China.

Uranium mobility and enrichment during hydrocarbon generation and accumulation processes: A review

Black shale serve as a new uranium sources and provide reducing agents for uranium deposits through hydrocarbon generation. However, the systematically interplay between the black shale and the formation of uranium deposits is not obscure. This paper provides a comprehensive summary and critical assessment of the depositional control factors of uranium in black shales, the extent of uranium migration during hydrocarbon generation, the enrichment of uranium in oil/gas reservoirs, and the relationship between crude oil-natural gas leakage and uranium. The study show that U-riched constituents within black shale persist through mechanisms of adsorption, reduction, complexation, and absorption within matrices rich in phosphates, iron, carbonate minerals, and organic matter. The U in black shale originates from continental weathering, volcanic eruptions, and seabed hydrothermal activities. The average U concentration in black shale is determined by the U content in atmosphere, while its relative content is controlled by the degree of anoxia during the geological historical periods.. Black shale prior to the Late Neoproterozoic period exhibits minimal migration with hydrocarbon substances, whereas black shale post the Late Neoproterozoic period demonstrates migration, with a migration rate ranging approximately between 55 and 75 %. However, the migrated uranium does not accumulate in (ancient) reservoirs. The correlation between hydrocarbon substances and sandstone-type uranium deposit is attributed to the oxygen uptake by hydrocarbons or the thermochemical sulfate reduction (TSR). The study has fundamental significance for further understand the interaction mechanisms between uranium and hydrocarbon substances.

Enhancing mechanical and radiation shielding properties of concrete with lead monoxide and granodiorite: Individual and synergistic effects at micro and nano particle scales

AbstractThis study investigates the individual and combined effects of micro and nano lead monoxide (PbO) and granodiorite (GD) on concrete's mechanical and radiation shielding properties. Both materials were partially substituted for cement at varying ratios. Additionally, mixtures with optimal radiation shielding performance were prepared to explore the synergy of combining them. The mentioned materials are used for the first time in an extensive study at the nano scale to investigate their impact on concrete's mechanical properties, microstructure, and gamma radiation attenuation. Two gamma ray sources of uranium (U238) and cesium (Cs137) were used measure the radiation attenuation coefficients for all designed concrete mixes. A simple methodology was followed to assess the concrete shields efficiency via utilizing portable handheld gamma‐ray spectrometer that offers two reading modes. Results indicated that increasing the ratio of PbO is directly proportional to the concrete ability to attenuate radiation, where the optimal individual replacement ratios were recorded at 5% for micro and nano particle sizes. At this ratio, the linear attenuation coefficient (μ) values were improved by 39.57% and 24.78% for the nano and micro PbO, respectively. Additionally, the optimal ratio for improving mechanical properties was at 3% and 2% for nano and micro PbO, while the higher ratios showed a decline in mechanical properties especially at 5% micro PbO with 7.02% reduction in the compressive strength value. Regarding GD powder, the optimal replacement ratios for improving concrete radiation shielding were consistent with those enhancing its mechanical properties at 4% and 7% in both nano and micro scales, respectively. The combined mixes further enhanced the overall concrete performance, especially its radiation shielding ability. Compared to the control mix, the compressive strength, tensile strength, and μ were increased by 25.7%, 16.2%, and 44.7% at the optimal mixture of 5% nano PbO + 4% nano GD.

Hydrothermal Uranium Mineralization in the Tuyukan Ore Field (Northern Transbaikalia): Time of Precipitation of the Pitchblende and Age of the Uranium Source

Hydrothermal Uranium Mineralization in the Tuyukan Ore Field (Northern Transbaikalia): Time of Precipitation of the Pitchblende and Age of the Uranium Source

Geochemical and detrital zircon U[sbnd]Pb geochronology of the qigequan formation in the yuejin 2 area: Implications for tectonics and uranium sources

The Yuejin 2 mining area lies within the Mangya region, situated on the northwestern periphery of the Qaidam Basin. Recently discovered, it harbors a medium-sized uranium deposit within the basin. Nonetheless, investigations into the sedimentary provenance and paleoclimate of the Neogene Qigequan Formation in this locale have been sparse. This study delves into a meticulous examination of petrogeochemical attributes and the detrital zircon UPb geochronology of sandstones from the Qigequan Formation within the mining area, aiming to discern their origins and tectonic context. By scrutinizing the trace and rare earth element signatures of the rocks, we discern that the lower strata of the Qigequan Formation primarily originate from felsic sedimentary sources, indicative of a continental island arc tectonic. Detrital zircon ages from the Qigequan Formation manifest primarily in three distinct periods: 169–292 Ma, 327–505 Ma, and > 670 Ma, corresponding with geological ages documented in the Altyn Tagh and East Kunlun Mountains orogenic belts. Predominantly, the Altyn Tagh orogenic belt and the Qimantag Mountains in the eastern Kunlun Mountains serve as the principal source of the Qigequan Formation. The chemical weathering index (CIA*) is 70.54, suggesting a moderate level of chemical weathering within the source region. Additionally, the angular morphology of the detrital zircon implies proximity between the source area and the basin. During the late sedimentary epoch of the Qigequan Formation, rapid uplift of the Altyn Tagh led to a notable rise in temperature within the Yuejin 2 area, transitioning from a reducing to an oxidizing environment. Surface water enriched with uranium and eroded source rocks gradually infiltrated the sand bodies of the lower Qigequan Formation. Interaction with reducing agents facilitated the enrichment and formation of ore. Paleoclimatic shifts instigated the oxidation–reduction sequence necessary for uranium mineralization. Favorable conditions, characterized by oxygen-rich paleo-water, facilitated the activation, migration, and re-enrichment of uranium. Moreover, the Himalayan movement acted as a driving force and a pivotal factor in creating the conducive conditions imperative for large-scale uranium mineralization in the area.

Sedimentary Environment, Tectonic Setting, and Uranium Mineralization Implications of the Yimin Formation, Kelulun Depression, Hailar Basin, China

The sandstone-type uranium deposit of the Kelulun Depression is the first industrially valuable uranium deposit discovered in the Hailar Basin. This study performed a systematic examination of 17 sandstone samples from the Yimin Formation in the Kelulun Depression based on various analytical techniques. The findings of the current study were synthesized with previous research to investigate the impact of the redox conditions and the tectonic background of the source area, as well as the paleoclimatic evolution of the Yimin Formation on uranium mineralization. The elemental Mo, U/Th, V/Cr, Ni/Co, and V/(V + Ni) ratios indicate that the paleowater was in an oxygen-rich environment during the deposition of the Yimin Formation. Additionally, the C-value, Sr/Cu, Al2O3/MgO, and Rb/Sr ratios indicate that the Yimin Formation was formed in a paleoclimate characterized by arid-to-semi-arid conditions. The geochemical characteristics of the observed elements indicated that the sediment source of the Yimin Formation was mainly felsic rocks from the upper continental crust, the weathering of the rock was weak, and the tectonic background was a passive continental margin. Coffinite is distributed in the form of cementation and stellates within or around pyrite crystals, and uranium-titanium oxide is mostly distributed in an irregular granular distribution in the biotite cleavage fractures of the study area. In summary, the findings of this study reveal that the tectonic settings, provenance, uranium source, paleoclimate, and oxygen-rich paleowater of the Yimin Formation have important geological significance for the large-scale uranium mineralization of the Kelulun Depression.

Identification of the Sedimentary Sources and Origin of Uranium for Zhiluo Formation of the Tarangaole U Deposit, Northeastern Ordos Basin

The large-sized Tarangaole uranium deposit and its neighboring Daying and Nalinggou deposits, located in the northeastern margin of the Ordos Basin, constitutes a major uranium resource base in northern China. In order to further clarify the sedimentary material source, uranium source and regional sediment–tectonic setting of the uranium-fed clastic rocks (i.e., Zhiluo Formation(J2z)) in the district, this paper carried out whole-rock geochemistry, heavy minerals composition and in situ U-Pb dating of detrital zircons for sandstones from the lower section of the Zhiluo Formation. The results have shown that the average chemical differentiation index (CIA) for the host rocks is 73.16 and the chemical weathering degree is moderate. Heavy minerals are mainly composed of ilmenite, garnet, chlorpyrite, zircon, pyrite, apatite, hematite, etc. The U-Pb dating of detrital zircon generally indicates three age peaks, i.e., 260~Ma, 1850~Ma and 2450~Ma, respectively. In conclusion, the source rocks may have been formed at active continental margins, e.g., in a continental margin arc environment. The sedimentary materials mainly come from khondalite series, TTGs, granulite, and mafic–ultramafic intrusive rocks distributed among the Daqing–Ula Mountains and adjacent areas, etc. The Late Paleozoic U-rich intermediate and acidic magmatic rocks spreading over the eastern part of the Ula–Daqing and Wolf mountains have provided the main uranium sources for the formation of major U deposits in the northern Ordos Basin.

Genesis of gray sandstone within the red beds in HLJ-DL uranium deposit, southwest Songliao Basin and its relationship with uranium mineralization

The search for uranium deposits in the red beds is currently a hotspot in China's sandstone-type uranium exploration efforts. The typical occurrence of uranium deposits is within gray sandstone layers amidst the red beds, where the distribution of these gray sand bodies dictates the presence of uranium deposits. Hence, delving into the genesis of gray sandstone within the red beds proves beneficial for both uranium exploration and unraveling the ore-forming mechanisms. However, there is currently significant controversy surrounding the genesis of gray sandstone in the red beds. This paper focuses on the typical uranium deposit in the red beds—the HLJ-DL uranium deposit in the southwestern part of the Songliao Basin. It investigates the genesis of gray sandstone within uranium-bearing rock series and its relationship with uranium mineralization. The lithology of representative drill cores, including the red sandstone for comparative study, is methodically examined, along with their elemental geochemistry as well as carbon and oxygen isotope characteristics. The petrological characteristics suggest that both the gray and red sandstone share similar compositions of clastic particles, indicating minimal influence of the source rock on the sandstone color. The gray sandstone displays comparable TOC content (averaging around 0.05 %) and δ18OPDB values (averaging around −16 ‰) to the red sandstone. However, it exhibits relatively higher δ13CPDB values (averaging −0.26 ‰), whereas the average δ13CPDB value for the red beds is −1.61 ‰. The data indicate that the gray sandstone is less affected by hydrothermal or hydrocarbon fluids. Compared to the red sandstone, which has relatively higher Cu/Al values (averaging 1.09) and Fe3+/Fe2+ ratios (averaging 3.37), the gray sandstone exhibits low Cu/Al values (averaging 0.44) and a low Fe3+/Fe2+ ratio (averaging 0.36), suggesting its formation in a relatively reducing environment. The reducing conditions necessary for the formation of gray sandstone may stem from the climate becoming relatively warm and humid, irrespective of whether it originates from the original sedimentary environment or is induced by the reducing pore water discharged from dark mudstones. The chemical weathering index of fine-grained sediments indicates that, the gray sandstones were commonly configured in relatively humid-warm climate with fairly low dissolved oxygen content in the bottom water. Additionally, the deposition of the uranium-bearing rock series experienced alternating climatic changes, rather than consistently being in a humid-warm climate. This resulted in the sand bodies with low TOC content, insufficient reducing potential, and uranium mineralization primarily occurring in the interior of the basin. Organic matter has a relatively weak control over uranium mineralization, whereas uranium mineralization shows a certain correlation with iron reduction. The ore-forming fluid was uranium-rich oxygenated atmospheric water. Dark-colored mudstones, formed under humid-warm climatic condition, contain relatively high TOC contents (avg. 0.43 %) and exhibit a strong reducing capacity. The reducing pore water in dark-colored mudstones excreted into the adjacent sandstones under compaction during the early diagenesis, is able to serve as a vital reducing agent in later-stage uranium mineralization. Additionally, certain dark-colored mudstones with high uranium content (up to 944 ppm) undergo significant uranium pre-enrichment, providing a partial uranium source for uranium mineralization.

Ultrapotassic plutons as a source of uranium of vein-type U-deposits (Moldanubian Zone, Bohemian Massif): insights from SIMS uraninite U–Pb dating and trace element geochemistry

The Bohemian Massif hosts significant hydrothermal U-deposits associated with shear zones in the high-grade metamorphic basement. But there is a lack of evidence of a genetic link between mineralization and U-fertile igneous rocks. This contribution provides constraints on the major U source of the vein-type U-deposits, the timing of ore formation and the metallogenetic model. The anomalous trace element signatures of the low-temperature hydrothermal deposits (high Zr, Y, Nb, Ti, ∑REE) and their close spatial relation with ultrapotassic rocks of the durbachite series point to a HFSE and REE enriched source rock. The durbachites have high U content (13.4–21.5 ppm) mainly stored in magmatic uraninite and other refractory minerals (e.g., thorite, zircon, allanite) that became metamict over a time interval sufficient to release U from their crystal structure, as suggested by the time gap between emplacement of the durbachites (EMP uraninite U–Pb age ~ 338 Ma) and hydrothermal activity (SIMS uranium ore U–Pb age ~ 270 Ma). Airborne radiometric data show highly variable Th/U ratios (1.5–6.0), likely reflecting a combination between (1) crystallization of magmatic uraninite, (2) hydrothermal alteration, and (3) leaching and mobilization of U along NW–SE-trending fault zones, manifested by elevated Th/U values in the radiometric map. The presence of rare magmatic uraninite in durbachites suggests almost complete uraninite dissolution; EMP imaging coupled with LA-ICP-MS analyses of refractory accessory phases revealed extensive mobilization of U together with HFSE and REE, providing direct evidence for metal leaching via fluid-driven alteration of radiation-damaged U-rich minerals. The large-scale HFSE and REE mobilization, demonstrated by the unusual trace element signatures of the U-deposits, was likely caused by low-temperature (270–300 °C), highly alkaline aqueous solutions containing F-, P-, and K-dominated complexing ligands. The first SIMS U–Pb age of 270.8 ± 7.5 Ma obtained so far for U-mineralization from the Bohemian Massif revealed a main Permian U mineralizing event, related to crustal extension, exhumation of the crystalline basement, and basin formation, as recorded by U–Pb apatite dates (280–290 Ma) and AFT thermal history models of the durbachites. The Permo-Carboniferous sedimentary cover probably represented a source of oxidized basinal brines infiltrating the basement-hosted durbachite plutons and triggering massive metal leaching. The interaction between basin-derived brines and durbachites resulted in significant modification of the chemical composition of the hydrothermal system (K and F release during biotite chloritization, P liberation through monazite alteration), leading to the formation of ore-bearing fluids responsible for the metallogenesis of the basement-hosted unconformity-related U-deposits in shear zones in the Bohemian Massif.

Tracking of uranium and thorium natural distribution in the chemical fractions of the Nile Valley and the Red Sea phosphorites, Egypt

The present study aims to elucidate the possible sources of uranium and thorium content in the Campanian–Maastrichtian phosphorites from the Duwi Formation in the Nile Valley and Red Sea by conducting facies analysis and sequential leaching method. Nile Valley samples were collected from the El-Sibaiya East area, while those of the Red Sea were collected from two locations: Hamadat and Zug El Bahar. The petrographic investigation revealed that the Sibaiya East phosphorites exhibit peloidal bioclastic phospharenite–phospharudite microfacies, while Hamadat and Zug El Bahar phosphorites display peloidal bioclastic phosphalutite and silicified peloidal bioclastic phospharenite microfacies, respectively. Besides, U–Th bearing accessory minerals, such as zircon and monazite occur in Sibaiya East phosphorites. Thorium is present in Zug El Bahar phosphorites as minute accumulations associating apatite and quartz. Moreover, uranium is found with vanadium and iron as fine patches in the Sibaiya East phosphorite, and as small disseminations associated with Ca and Si in the Hamadat phosphorite. The X-ray diffraction shows that the investigated phosphorites are essentially built up of hydroxyl apatite Ca5(PO4)3(OH) and quartz SiO2. To accurately evaluate the bioavailability and mobility of uranium and thorium in the investigated phosphorites, it was necessary to identify the overall concentration and the various chemical forms of these elements by a five-step sequential leaching technique. The results indicate that Th and U are more abundant in the Red Sea phosphorites than in the Nile Valley phosphorites. Furthermore, Th is not bio-available and it is mostly found in the residue as Th-bearing minerals. Uranium, unlike Th is bio-available and fractionates among all fractions, indicating that U accumulation is the result of various diagenetic processes.

Bentonites as Natural Sources of Thorium and Uranium

Bentonites are natural reservoirs of various elements and are of interest because they are sources of thorium and uranium, which are transition elements that provide nuclear energy. The objective of this work was to study the plausible association(s) of these elements with other transition elements of interest. The contents of 18 transition elements (cerium, cobalt, chromium, copper, iron, hafnium, lanthanum, manganese, molybdenum, neodymium niobium, nickel, tantalum, thorium, uranium, vanadium, yttrium, zinc, and zirconium) in 38 bentonites determined experimentally by X-ray fluorescence spectroscopy (XRF) were analyzed. The contents of the elements were plotted in (x,y) graphs and then fitted to polynomial functions (orders 1 through 6). According to the coefficient of determination (r2: 0.5 ≤ r2 strong, 0.3 ≤ r2 ≤ 0.5 medium, and r2 ≤ 0.3 weak), the contents of thorium, uranium, niobium, and nickel related strongly, thus the presence of niobium and nickel served to predict the presence of detectable concentrations of thorium and uranium. The equations showing higher r2 values were 1. {Th} = 1e-6{Nb}5 − 3e-4{Nb}4 + 1.9e-2{Nb}3 − 5.4e-1{Nb}2 + 7.3{Nb} − 6.3, r2 = 0.53. 2. {Th} = −3e-8{Nb}6 + 9e-6{Nb}5 − 1e-3{Nb}4 + 4.7e-2{Nb}3 − 1.1{Nb}2 + 11.5{Nb} − 16, r2 = 0.54. 3. {Th} = 5e-6{Ni}4 − 1.5e-3{Ni}3 − 1.5e-1{Ni}2 − 5.8{Ni} + 9e+1, r2 = 0.49. 4. {Th} = −7e-8{Ni}5 + 3e-5{Ni}4 − 5.1e-3{Ni}3 + 3.4e-1{Ni}2 − 9.5{Nb} + 1e+2, r2 = 0.56. 5. {Th} = 2e-9{Ni}6 − 8e-7{Ni}5 + 2e-4{Ni}4 − 1.5e-2{Ni}3 − 7e-1{Ni}2 − 1e+1{Ni} + 1e+1, r2 = 0.60. 6. {Th} = −1e-4{U}5 + 1.3e-2{U}4 − 4.3e-1{U}3 + 5.7e-1{U}2 − 2e+1{U} + 5e+1, r2 = 0.54. 7. {Th} = 6e-6{U}6 − 9e-4{U}5 + 4.5e-2{U}4 − 1.1{U}3 + 1e+1{U}2 − 5e+1{U} + 1e+2, r2 = 0.64. 8. {U} = 8e-6{Nb}4 − 1.2e-3{Nb}3 + 4.8e-2{Nb}2 − 4.3e-1{Nb} + 6.8, r2 = 0.48. 9. {U} = 2e-7{Nb}5 − 4e-5{Nb}4 + 2.8e-3{Nb}3 − 7.6e-2{Nb}2 + 1.1{Nb} + 1.9, r2 = 0.5. 10. {U} = 1e-8{Nb}6 − 3e-6{Nb}5 + 2e-4{Nb}4 − 8e-3{Nb}3 + 1.3e-1{Nb}2 − 5.4e-1{Nb} + 5.4, r2 = 0.51. 11. {U} = 1.8e-1{Th} + 2.6, r2 = 0.49; {U} = 1.7e-3{Th}2 − 2.9e-2{Th} + 6.3, r2 = 0.60. 12. {U} = 2e-5{Th}3 − 1.7e-3{Th}2 + 1.4e-1{Th} + 4.5, r2 = 0.58; {U} = −5e-7{Th}4 + 2e-4{Th}3 − 1.5e-2{Th}2 + 5.5e-1{Th} + 1.5, r2 = 0.6. 13. {U} = −7e-9{Th}5 + 2e-6{Th}4 − 1e-4{Th}3 − 3e-4{Th}2 + 2.7e-1{Th} + 2.9, r2 = 0.6. 14. {U} = 2e-9{Th}6 − 8e-7{Th}5 + 1e-4{Th}4 − 8.1e-3{Th}3 − 2.4e-1{Th}2 + 15, r2 = 0.65. This study provided a joint experimental and theoretical approach to optimize the recovery of thorium and uranium and to save invaluable onsite and off-site natural resources and work time. The findings might expand on other studies reporting the quantification of transition metals on bentonite matrices. For instance, the concentrations of nickel reported in studies using bench techniques could serve as the basis to calculate the contents of thorium.

The Study of Radioactive Contaminations within the Production Processes of Metal Titanium for Low-Background Experiments.

Ultra-low-radioactivity titanium alloys are promising materials for the manufacture of low-background detectors which are being developed for experiments in astroparticle physics and neutrino astrophysics. Structural titanium is manufactured on an industrial scale from titanium sponge. The ultra-low-background titanium sponge can be produced on an industrial scale with a contamination level of less than 1 mBq/kg of uranium and thorium isotopes. The pathways of contaminants during the industrial production of structural titanium were analyzed. The measurements were carried out using two methods: inductively coupled plasma mass spectroscopy (ICP-MS) and gamma spectroscopy using high-purity germanium detectors (HPGes). It was shown that the level of contamination with radioactive impurities does not increase during the remelting of titanium sponge and mechanical processing. We examined titanium alloy samples obtained at different stages of titanium production, namely an electrode compaction, a vacuum arc remelting with a consumable electrode, and a cold rolling of titanium sheets. We found out that all doped samples that were studied would be a source of uranium and thorium contamination in the final titanium alloys. It has been established that the only product allowed obtaining ultra-low-background titanium was the commercial VT1-00 alloy, which is manufactured without master alloys addition. The master alloys in the titanium production process were found cause U/Th contamination.

Modeling evaluation of the impact of residual source material on remedial time frame at a former uranium mill site

Groundwater contamination at legacy uranium processing sites is an ongoing global challenge. Plumes at many uranium-contaminated sites are more persistent than originally predicted by groundwater modeling. Previous investigations of uranium plume persistence identified residual and secondary sources that contribute to plume longevity, but there is a remaining need to revise forecasted cleanup times using information about these ongoing sources. The purpose of this study is to investigate the quantitative impact of residual vadose zone sources of uranium on groundwater remediation time frame. This objective was approached by applying numerical uranium transport simulations and uncertainty analysis to a former uranium mill site in the southwestern United States. Information from recent site investigations provided details about the distribution and release characteristics of uranium accumulations in the vadose zone. The residual uranium characteristics were incorporated as decaying source terms in the transport model. A stochastic approach using an iterative ensemble smoother was applied for history matching, and the transport model was used to assess the impact of multiple remedial alternatives on forecasted time frame. The forecasted time frame to achieve the groundwater remediation goal for uranium by monitored natural attenuation is on the order of thousands of years, and treatment of the dissolved plume does not reduce the projected time frame. The large proportion of residual uranium mass remaining in the vadose zone and the gradual leaching rate due to the site's semiarid climate create a long-lived source that can sustain a dissolved plume for thousands of years despite an estimated 99% mass removal achieved during mill tailings disposal. Residual uranium in vadose zone sediments beneath former tailings impoundments could present comparable uranium plume persistence and remediation challenges at other legacy uranium mill sites in semiarid climates. Other remaining uranium-impacted sites are similarly complex, and forecasted remedial time frames are needed to effectively achieve compliance, manage risk, assess the benefits of additional treatment, manage and project costs, and support beneficial site reuse.

Development of Process Flow Sheet for Recovering Strategic Mineral Monazite from a Lean-Grade Bramhagiri Coastal Placer Deposit, Odisha, India

The present investigation deals with the development of a process flow sheet for recovering strategic mineral monazite concentrate from a lean-grade offshore placer deposit of the Bramhagiri coast along the southeast coast of Odisha, India.In the present study, both dry and wet processes are investigated to improve the recovery and purity of monazite. The results of the pre-concentration studies reveal that by using multi-stage spiral concentrators, the Total Heavy Minerals [THM] have been upgraded to 97.8% with a monazite content of 0.33% from a feed sample containing 4.72% total heavy minerals and 0.01% monazite content. The beneficiation studies revealed that the feed was initially subjected to a high-tension separator, and the non-conducting fraction of the high-tension roll was further subjected to magnetic separation. The magnetic product was again subjected to a flotation process followed by cleaning of the flotation product using a magnetic separator. This magnetic product contains 98.89% monazite with 84% recovery and 0.28% yield from a spiral product containing 0.33% monazite and qualifies for extracting rare earths. It is worth recovering monazite mineral from even lean-grade deposits, as it is a source of uranium, thorium, and rare earth elements and is very high in demand for humankind due to technological advancements. In view of this, monazite recovery is not to be considered for the economic profitability of the process but for strategic requirements.

The Early Cretaceous hydrothermal sedimentation and its influence on sandstone-type uranium mineralization in the Xinniwusu Sag, Bayingobi Basin, NW China

The presence of Early Cretaceous hydrothermal sedimentation was initially observed in the Xinniwusu Sag, Eastern Bayingobi Basin, NW China. To gain deeper insights into the features of hydrothermal sedimentation in this region and its relationship with uranium mineralization, we conducted an analysis encompassing petrography, geochemistry, the electron microprobe, and low-temperature thermochronology of the hydrothermal sedimentary rocks. Petrographic analysis revealed that the predominant hydrothermal sedimentary rocks in the upper member of the Bayingobi Formation within the Xinniwusu Sag encompass dolomitic limestone and sinter, followed by clastic rocks mixing with hydrothermal sedimentation. Major and trace element analyses emphasized the enrichment of elements including Ca, Mg, P, U, REEs, Sr, Y, Mo, Sb, Cd, and Pb in the hydrothermal sedimentary rocks. Notably, a prominent positive correlation was identified between U and P, REEs, Sr, and Y. Electron microprobe analyses illuminated that uranium primarily exists within fluorapatite in the form of adsorption or isomorphism. Isotopic analyses, δ13CV-PDB and δ18OV-PDB, of carbonate cements in clastic rocks and limestone yielded values ranging from −3 to 2.1 ‰ and − 17 to −6.9 ‰, respectively. These findings suggest that the carbon in the hydrothermal fluids predominantly originates from marine strata, with some potential contribution from the mantle. The paleotemperatures based on the O isotope data range from 67 °C to 78 °C, with an average of 71 °C, implying that the hydrothermal sedimentation corresponds to the continental low temperature white smoker type. Furthermore, apatite fission-tracks of grayish-white gritstone within the upper member of the Bayingobi Formation were completely annealed at 116 ± 7 Ma, partially annealed at 112 ± 4 Ma, also indicating that there was a hydrothermal sedimentary environment for a long time. The hydrothermal sedimentation predominantly influenced the uranium preconcentration in the upper member of the Bayingobi Formation. The uranium source in the hydrothermal fluids is likely linked to the Mesoproterozoic Zhaertai Group within the southern basement of the basin. This revelation offers valuable insights into the distribution of uranium deposits and mineralization points in the Bayingobi Basin, primarily concentrated in the southern sector. Consequently, these areas characterized by well-developed faults connecting the basement and the Lower Cretaceous Formation in the south of Bayingobi Basin are favorable areas for uranium mineralization. This study bears immense significance in enhancing our understanding of the uranium metallogenic mechanisms in the Bayingobi Basin and hydrothermal sedimentation mineralization widely distributed in the world.