Mineral Ages Research Articles

U-Pb Geochronology of Fersmite: Potential Time Constraints on Magnesite Formation, Sparry Dolomitisation, and MVT Pb-Zn Mineralisation in SE British Columbia, Canada

Fersmite ([Ca,Ce,Na][Nb,Ta,Ti]2[O,OH,F]6) from the Mount Brussilof magnesite deposit, British Columbia, Canada occurs as accessory brittle, black, submetallic to vitreous lustre, acicular to platy crystals up to 2 cm long, developed in sparry dolomite, which lines cavities in sparry magnesite. Fersmite also occurs as smaller crystals (<3 mm) enclosed by dolomite, where it is commonly fractured or broken, formed during the final stage of dolomite crystallisation. Electron microprobe (WDS) major element data indicate that the grains confirmed to be fersmite by X-ray diffraction contain >50% Nb and are atypically Ta-poor. Fersmite contains significant U and Th (up to 4700 ppm and 6 wt.%, respectively) and therefore is a viable mineral for U-Pb geochronology. A series of laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) spot analyses and maps were collected on fersmite grains. Although the fersmite grains have considerable common Pb and have experienced Pb loss, the U-Pb spot data suggest growth or pervasive resetting at ca. 190 Ma. Some 40Ar/39Ar ages (two of four samples) are consistent with the ~190 Ma U-Pb date. Electron microprobe and LA-ICP-MS mapping indicate that the fersmite is middle to heavy rare earth element-rich. The ~190 Ma fersmite age estimate provides an approximate upper time constraint on the age of sparry magnesite mineralisation, sparry dolomitisation, and, indirectly, on the formation of MVT deposits in the Kicking Horse Rim area and possibly elsewhere in southeastern British Columbia.

New 40Ar/39Ar mineral ages of Archaean to early Proterozoic rocks in northern Sweden and implications for the 1.8–1.5 Ga tectonothermal history of northernmost Fennoscandia

Abstract The bedrock in northernmost Sweden comprises Archaean (2.8–2.65 Ga) and Karelian (2.4–1.96 Ga) rocks and a volumetrically dominant population of magmatic rocks which formed during the Svecofennian (1.9–1.8 Ga) stage. New Ar–Ar (hornblende and muscovite) and U–Pb (zircon and monazite) isotopic results from representative lithologies are used to shed further light on the geological evolution. With respect to the Ar–Ar isotopic system, somewhat variable dates (hornblende) are interpreted as cooling ages that indicate different uplift histories, following a 1.8 Ga metamorphic peak, at different sides of the Karesuando-Arjeplog deformation zone. Other post-1.7 Ga 40Ar/39Ar ages are suggested to reflect either a neocrystallisation (muscovite) or an event leading to isotopic resetting (hornblende). It is suggested that post-1.76 Ga crustal processes have influenced the Ar–Ar mineral systems during three relatively short-lived (a few tens of million years) stages; peaking at ~ 1.73 Ga, ~ 1.63 Ga and ~ 1.55 Ga. Tentatively, the timing of these stages is coupled with far-field effects that elsewhere are associated with the alkali-rich granitic magmatism forming part of the Transscandinavian Igneous Belt (the 1.73 Ga event) and Rapakivi massifs (the 1.63 and 1.56 Ga events). It is proposed that the N-S to NW–SE orientation of these vast, regional granitic complexes matches that of major deformation zones in northernmost Fennoscandia and that locally initiated hydrothermal fluids followed weakness zones in the crust and ultimately led to element mobilisation, new mineral growth and isotopic over-printing preferentially affecting shear- and ore zones. Graphical abstract

Enhancing the affinity of Pb(II) to the metastable ferrihydrite with the presence of gallic acid and anoxia condition.

Naturally widespread ferrihydrite is unstable and often coexists with complex ions, such as the heavy metal ion Pb(II). Ferrihydrite could fix Pb(II) by precipitation and hydroxyl adsorption, but release Pb(II) with mineral aging. Gallic acid plays an important role in influencing the geochemical behavior of ferrihydrite-Pb, and anoxia is one of the factors influencing the transformation of mineral. This study investigated the effects of Gallic acid and anoxia on the migration and distribution of Pb(II) in ferrihydrite-Pb co-precipitates. XRD, FT-IR, SEM, XPS were employed to explore the internal interactions. The results showed that Gallic acid could promote Pb(II) to enter the mineral and inhibit the release of Pb(II). The fixation of Pb(II) could be achieved under anoxia by passivating ferrihydrite. Gallic acid could formed ferrihydrite-gallic acid-Pb ternary complexes with ferrihydrite-Pb co-precipitates, which improved the affinity of ferrihydrite to Pb(II) and promoted the ability of ferrihydrite to fix Pb(II). The anoxia allowed the Fe(II) produced by reductive dissolution of ferrihydrite to be retained for longer time, thus catalyzed the production of goethite from ferrihydrite and passivating ferrihydrite to inhibit the aging of ferrihydrite. In addition, acid environments caused most of Pb(II) to be released into solution through competition with hydrogen ions. Pb(II) in alkaline environment led to Pb(II) immobilization by entering the interior of mineral. The findings of this study provide references for better understanding the environmental behavior of Pb(II) during ferrihydrite transformation.

Mineralization age and magmatic origin of the Pujue Cu-polymetallic deposit in the western Gangdese belt: Implication for regional exploration

Mineralization age and magmatic origin of the Pujue Cu-polymetallic deposit in the western Gangdese belt: Implication for regional exploration

Сomposition, evolution and age of NB-REE mineralization in carbonatite complexes in the ural fold belt: New insight into metallogenesis

Сomposition, evolution and age of NB-REE mineralization in carbonatite complexes in the ural fold belt: New insight into metallogenesis

Metallogenic Evolution Related to Mantle Delamination Under Northern Tunisia

Mineralization processes in the Tell-Atlas of North Africa coincided with magmatism, extension, and lithospheric rejuvenation during the middle to late Miocene. This review examines the lead isotope compositions and Pb-Pb age dating of ore deposits in the region to elucidate the sources and timing of mineralization events. The data reveal a predominantly radiogenic signature in the ores, indicating that the primary component is from a crustal source, with a contribution from the mantle. Pb-Pb age dating suggests the ranges of mineralization ages, with late Miocene events being particularly significant, coinciding with proposed sub-continental mantle delamination following subduction of the African lithosphere. In this context, polymetallic mineralizations formed related to felsic magmatism, hydrothermalism driven by extensional faults, resulting in the formation of Mississippi Valley-Type, and Sedimentary exhalative deposits within associated semi-grabens and diapirism. The correlation between orogenic extensional collapse, magmatism, and mineralization underscores the importance of understanding the specific geological context of ore formation. The detachment of subducted slabs and subsequent influx of hot asthenosphere play pivotal roles in creating conducive conditions for mineralization. This study sheds light on the intricate interplay between tectonic mechanisms, mantle-crust interactions, and mineralization events in the Tell-Atlas, offering insights for further exploration in the region.

Problems of dating the Au-Pd mineralization of the Chudnoye deposit (the Subpolar Urals)

The ages values of the minerals that make up the ores of the Chudnoe deposit, established using isotope geochronology methods, do not allow us to correctly estimate the time of formation of Au-Pd mineralization due to the lack of reliable signs of their syngeneticity with gold. Based on linking isotope-geochronological data with the history of the geological development of the Subpolar Urals and the entire complex of endogenous and exogenous processes which determined the features of its geological structure and minerageny, the Early Paleozoic age of mineralization is substantiated. The similar age of the metarhyolites hosting the mineralization suggests not only a spatial, but also a paragenetic relations between ore mineralization and felsic volcanites. When studying the mineral composition and structural and textural features of ores, it is necessary to take into account the imposition of post-ore processes, especially the most powerful metamorphism manifested in the Subpolar Urals, the peak of which occurred in the Upper Paleozoic (~250 Ma).

Age and sources of low-sulfide gold-quartz mineralization of the Karalon gold ore field (North Transbaikalia, Russia): results of isotope-geochemical (Rb-Sr and Pb-Pb) studies

The article presents the results of studying the Rb–Sr isotope system of ore-bearing granitoids, apogranite metasomatites and hydrothermalites of the Verkhnekaralonskoye gold deposit, as well as the Pb-Pb isotope system in galena of the gold-quartz low-sulfide mineralization of the Karalonskoye gold ore field. Three groups of ore objects with different Pb isotopic compositions of galena associated with varying contributions from mantle and ancient crustal sources have been identified. The isotope characteristics of Pb in galena of the Verkhnekaralonskoe deposit indicate its genetic relationship with ore-bearing juvenile granites, whose age of ~ 600 Ma may be close to the age of the earliest stage in the formation of gold–quartz mineralization. The ancient crustal source is common for the leading gold deposits of Northern Transbaikalia and is characterized by the parameters of the continental crust of the Siberian craton at a time of 500–600 Ma. The rearrangement of the Rb–Sr system in the studied rocks and minerals of the Verkhnekaralonskoe deposit and the redistribution of Pb isotopes in galena of the Vodorazdelnaya ore zone of the Karalonskoe ore field at the turn of 290–250 Ma have been established. Isotope data show that in the geological history of the Verkhnekaralonskoe deposit and the Karalonskoe ore field, the formation of gold mineralization had a long multi-stage character and was accompanied by the regeneration of primary ore concentrations.

Petrogenesis and Metallogenic Significance of the Demingding Mo-Cu Porphyry Deposit in the Gangdese Belt, Xizang: Insights from U-Pb and Re-Os Geochronology and Geochemistry

The 1500 km-long Gangdese magmatic belt is a crucial region for copper polymetallic mineralization, offering valuable insights into collisional porphyry copper systems. This study focuses on the Demingding deposit, a newly identified occurrence of molybdenum–copper (Mo-Cu) mineralization within the eastern segment of the belt. While the mineralization age, magmatic characteristics, and tectonic context are still under investigation, we examine the deposit’s petrology, zircon U-Pb geochronology, whole-rock chemistry, and Re-Os isotopic data. The Demingding deposit exhibits a typical alteration zoning, transitioning from an inner potassic zone to an outer propylitic zone, which is significantly overprinted by phyllic alteration closely associated with Mo and Cu mineralization. Zircon U-Pb dating of the ore-forming monzogranite porphyries reveals crystallization ages ranging from 21 to 19 Ma, which is indistinguishable within error from the mean Re-Os age of 21.3 ± 0.4 Ma for Mo veins and veinlets hosted by these porphyries. This alignment suggests a late Miocene magmatic event characterized by Mo-dominated mineralization, coinciding with the continuous thickening of the continental crust during the collision of the Indian and Asian continents. The ore-forming porphyries range in composition from granodiorite to monzogranite and are classified as high-K calc-alkaline with adakite-like features, primarily resulting from the partial melting of subduction-modified thickened mafic lower crust. Notably, the ore-forming porphyries exhibit higher fO2 and H2O levels than barren porphyries in this area during crustal thickening, highlighting the significant contributions of hydrous and oxidized fluids from their source to the Mo-Cu mineralization process. Regional data indicate that the Gangdese porphyry metallogenic belt experienced concentrated Cu-Mo mineralization between 17 and 13 Ma. The formation of Mo-dominated deposits such as Demingding and Tangbula in the eastern segment of the belt, with slightly older ages around 20 Ma, underscores the presence of a significant porphyry Mo metallogenic event during this critical post-collision mineralization period.

Geology and geochronology of the Xingfengshan deposit, Jiangnan orogenic belt, South China: Implication for intrusion-related Au–W mineralization

The Xingfengshan is a slate-hosted Au–W deposit in the central part of the Jiangnan orogenic belt, South China. It comprises stratiform skarns and sheeted quartz veins, and both two types of mineralization have W and Au metal association. In this study, systematic geological investigation, together with TESCAN Integrated Mineral Analyzer (TIMA), and biotite 40Ar/39Ar analyses were performed to determine the geological features and mineralization age. Formation of skarn stage (Stage 1) is represented by three substages: (I) prograde skarn, (II) retrograde skarn, and (III) quartz–sulfide. Scheelite and minor native gold formed during substage II and III, respectively. TIMA results confirm the coexistence of skarn minerals such as garnet, pyroxene, actinolite, and biotite, and scheelite. Sheeted Au–W quartz veins (Stage 2) crosscutting skarns contain auriferous arsenopyrite, scheelite, pyrrhotite, quartz, and display coexistence of Au (arsenopyrite), W (scheelite), and biotite. Post-ore barren quartz veins (Stage 3) are mainly composed of quartz, muscovite and tourmaline. 40Ar/39Ar dating results of biotite from retrograde skarn and sheeted veins constraining the formation ages are 215.0 ± 1.7 Ma and 211.9 ± 1.7 to 209.8 ± 2.1 Ma, respectively. These ages are broadly contemporaneous with the surrounding granitoid intrusion (218.7 ± 1.5 to 204.5 ± 2.8 Ma). It is likely that mineralizing fluids responsible for Au–W mineralization are of magmatic in origin. Considering the temporal and spatial association of the widespread Late Triassic magmatism and Au–W mineralization in the central Jiangnan orogenic belt, an intrusion-related Au system could be established for genesis of the Xingfengshan Au–W deposit.

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.

Genetic relationship between W mineralization and granitic intrusion in Nanling Region, South China: Constraints from zircon and cassiterite u-pb age from new drill holes in Shangping deposit

The Nanling metallogenic belt is known for the widely development of typical quartz vein type W deposit. These quartz veins that contain wolframite are frequently located in close proximity to granitic intrusions. The genetic relationship between tungsten mineralization and the associated granitic rocks is still a subject of controversy. The Shangping deposit stands out as a historically significant W deposit with a quartz vein type in the region of Nanling. However, the specific time that W mineralization occurred remains enigmatic. Granitic intrusions are absent from the mine and only granite porphyry dike is exposed, so the link between tungsten mineralization and magmatic activity remains unclear. Fortunately, in recent years, a concealed granite intrusive has been exposed in drill holes in the southeastern of the Shangping W deposit. To comprehensively address the connection between granitic magma activity and W mineralization, it is vital to make up a relative deficiency of geochronological information on granite and ore mineral. Here, in order to get the first direct age constraints on the origin of the Shangping W deposit, we use a combination of different techniques, incorporating the Hf isotope geochemistry of zirconium and cassiterite U-Pb assessment using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Based on these robust data, we tentatively evaluated the connection between W mineralization and granitic intrusion.For the granite porphyry, the majority of representative U-Pb zircon assays establish a206Pb/238U age of 150.2 ± 0.5 Ma. An inferred emplacement age of ca. 151 Ma for the concealed granite in Kengweiwo is supported by a U-Pb isochron age from zircon. Combined with Hf isotopic characterization, it illuminates the mineralization potential of the Kengweiwo concealed granite. Cassiterite grains from hydrothermal quartz vein are subhedral to anhedral and have a lower intercept 206Pb/238U age of 153.9 ± 1.0 Ma. For the Shangping W deposit, all of these new geochronological dates provide well-constrained mineralization ages of 150–154 Ma. The dates of the concealed granite in the Kengweiwo area and the tungsten mineralization in the Shangping area are extremely concordant, indicating that they occurred roughly concurrently. The vein type tungsten mineralization in Shangping deposit may has a genetic link with crystallization of uncovered granite present at depth, which requires further investigation. These results emphasize the significance and potential of concealed granitic intrusion to host disseminated W mineralization in the deep part of Shangping deposit.

Cathodoluminescence textures and trace elements in quartz: Constraints on Ag mineralization in adularia–sericite epithermal systems

Cathodoluminescence textures and trace elements in quartz: Constraints on Ag mineralization in adularia–sericite epithermal systems

3D geometry of the Dugald River Shear Zone, Mount Isa Inlier, Australia

The Dugald River Shear Zone is a structurally complex, anastomosing shear zone that hosts high-grade Zn mineralisation within the Dugald River Slate. The Dugald River Zn–Pb–Ag mine is situated within the Mount Isa Inlier, Australia and developed through two phases of mineralisation with high-grade Zn mineralisation intimately associated with the development of the brittle–ductile Dugald River Shear Zone. The first phase of mineralisation occurred during the regionally extensive, D2 ductile fold and axial planar cleavage forming event and resulted in the development of a sulfide horizon. This horizon was a preferential site for strain partitioning during early D4 ductile deformation, which resulted in transposition-related concentration and thickening of a sulfide horizon marking the second phase of mineralisation. The Dugald River Shear Zone developed during D4 wherein strain rate incompatibilities between a ductile-deforming sulfide horizon and the brittle-deforming Dugald River Slate resulted in the development of a Riedel shear zone. A high-resolution 3D model of the shear zone was constructed from robust drilling and mapping datasets in which releasing and restraining bends highlight the thickening and thinning of ore lenses, respectively. The 3D model with detailed structural analysis and observations allows for predictive modelling of dilational zones within throughgoing Y-shears, which are prospective sites for remobilisation of high-grade Zn sulfides as the ore body developed coevally with progressive shearing.

Pyrite in-situ S–Fe isotope constraints on the ore-forming sources and mineralization processes of gold and polymetallic deposits in the Liaodong Peninsula, North China Craton

Plenty of gold and polymetallic deposits are widespread in the eastern part of the North China Craton. They are associated with mafic to felsic dikes and hosted by Precambrian basement or Mesozoic granitoids. However, the sources of gold and other metals in the ore-forming fluids remain controversial. Here we present in-situ S and Fe isotopes and trace element contents of pyrites from various gold and Pb–Zn–(Ag) deposits in the Liaodong Peninsula, China. Pyrites from quartz vein-type gold deposit hosted by Mesozoic granites in the Wulong deposit have relatively homogeneous magmatic-like S isotopes (δ34S values of 0.9 ‰ to 2.5 ‰) and Co/Ni ratios, indicating derivation of sulfur and, by inference, of ore fluids/materials most likely from Mesozoic magmas. In contrast, pyrites from gold and Pb–Zn–(Ag) deposits in the Qingchengzi orefield hosted by Precambrian basement have high and variable δ34S values (9.7 ‰ to 12.7 ‰ for the Wandigou altered rock-type gold deposit and 4.7 ‰ to 8.5 ‰ for the Xiquegou Pb–Zn deposit and the Zhenzigou Pb–Zn–Ag deposit), identical to those of host rocks, indicating the important contributions of gold and other metals from wall rocks to the ore deposits. Pyrites from the various deposits have variable δ56Fe values of 0.08 ‰ to 0.63 ‰ for the Pb–Zn–Ag deposit, –0.58 ‰ to 1.23 ‰ for the altered rock-type gold deposit, and –0.68 ‰ to 0.77 ‰ for the quartz vein-type gold deposit, indicating distinct mineralization processes. Rapid precipitation of pyrites (with negative δ56Fe values) in the alteration rock and subsequent deposition of pyrites (with positive δ56Fe values) from the residual fluids in an Fe-open hydrothermal system during intensive ore-forming fluid-wall rock interaction account for the Pb–Zn–Ag mineralization, while weak fluid-rock interaction and pyrites precipitation from a Fe-closed hydrothermal system contribute to gold mineralization. Our observations provide a robust S–Fe isotope evidence for the contribution of various sources and metallogenic processes for distinct gold and polymetallic deposits.

Robust Timing Constraints for Granitic Magmatism and Hydrothermal Mineralization in the Tieshanlong W‐Sn Ore Field, Eastern Nanling Range, South China

AbstractThe Tieshanlong ore field is an important part of the Nanling Range, which is famous worldwide for its W‐Sn mineralization. Notably, the mineralization age of the Tieshanlong ore field is not well constrained, and our field investigation reveals that granitic emplacement occurred at different stages. However, previous studies have not distinguished these multiple stages of magmatism. The Tieshanlong granite complex is closely related to the Huangsha quartz vein‐type W‐Sn deposit and Tongling skarn‐type Cu‐W‐Sn deposit in this field. Through field investigations and isotopic age analyses, this work studies the relationship between multistage magmatic activity and mineralization in the Tieshanlong ore field. LA‐ICP‐MS zircon U‐Pb isotope analyses revealed that the first‐ and second‐staged granites formed at 154.2 ± 0.6 Ma (MSDW = 1.4) and 151.2 ± 0.4 Ma (MSDW = 1.5), with zircon εHf(t) values ranging from ‐13.1 to ‐10.5 and from ‐14.7 to ‐11.1, respectively. These data suggest that the Tieshanlong granite complex was derived from the partial melting of ancient crustal material. LA‐ICP‐MS U‐Pb dating of wolframite and cassiterite reveals that W‐Sn mineralization occurred at 160–150 Ma, which agrees well with the U‐Pb dating results of the second‐staged granite within analytical errors. The magmatic activity in this ore field can be divided into three stages: 175–154 Ma, 154–150 Ma and 150–145 Ma. The quartz vein‐ and skarn‐type W‐Sn mineralization is closely related to second‐staged fine‐grained two‐mica granite, and formed earlier than skarn‐type Cu‐ mineralization. This study establishes a metallogenic model for the Tieshanlong ore field, and this model has important practical significance for identifying concealed W‐Sn(‐Cu) deposits around other granitic complexes in the Nanling Range.

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.

The Xilaokou carbonate-sulfide vein type gold deposit: A distinct mineralization in the giant Jiaodong gold province, North China

The Xilaokou gold deposit with ca. 50 t of gold reserve @ 2.7 g/t represents a novel type (carbonate-sulfide vein type) of gold mineralization within the Jiaodong gold province. However, its mineralization age and metallogenic mechanism remain poorly constrained, hindering a comprehensive understanding of the ore-forming processes in the Jiaodong gold province. In this study, we employ syn-ore stage hydrothermal monazite in situ U-Pb geochronology to determine the ore-forming age of the Xilaokou gold deposit. Additionally, we conduct in situ LA-(MC)-ICP-MS elemental mapping and sulfur isotope analysis in ore-related pyrite to unravel the sulfur source(s) and provide new insights into the ore-forming processes of the Xilaokou gold deposit. Our findings reveal the following key points: (1) U-Pb dating of hydrothermal monazite in Au-bearing pyrite yields an ore-forming age of119.9 ± 3.0 Ma. This age is consistent with the mineralization ages (around 120 ± 5 Ma) of other gold deposits in the region, including Liaoshang-, Jiaojia-, and Linglong-type deposits. (2) Gold in pyrite primarily occurs as micro-grains (5–20 μm) within pyrite fissures associated with sphalerite and galena. (3) Elemental mapping and sulfur isotope analysis indicate that major Au mineralization is linked to elevated concentrations of As, Sb, and Tl, along with heavy sulfur isotope values (δ34S∼24.7 ‰). (4) Early-stage Au mineralization is characterized by enrichment of As, Cu, and Bi, with normal sulfur isotopic composition (δ34S∼8 ‰). We propose that the carbonate-sulfide vein type gold deposits represented by the Liaoshang and Xilaokou gold deposits in the Jiaodong gold province are genetically linked to quartz-sulfide vein and disseminated type deposits. The major ore-forming stage involved the addition of S and Au from a metamorphic massif at slightly lower temperatures. These findings highlight a new exploration direction within the North China Craton. In summary, the Xilaokou gold deposit provides valuable insights into gold mineralization processes in Jiaodong, emphasizing the importance of considering diverse deposit types and their genetic relationships in the region.

Paleozoic stage formation of the alkaline rocks massif Bogdo, Arctic Siberia (by <SUP>40</SUP>Ar/<SUP>39</SUP>Ar dating)

The age of potassium-bearing minerals from high-K nepheline syenites, libeneritized and carbonatized nepheline syenites, as well as pseudoleucite syenites of the Bogdo alkaline massif (Arctic Siberia) was determined by the 40Ar/39Ar method. As a result of generalization and analysis of the 40Ar/39Ar dating data, on the summary thermochronological diagram for minerals from the rocks of the Tomtor massif, the Udachnaya-Vostochnaya kimberlite pipe, and alkaline rocks of the Bogdo massif, the polychronicity of the formation of alkaline complexes of the Tomtor type at the Paleozoic stage was revealed. Based on isotopic data, a complex, three-stage history of the formation of the rocks of the Bogdo massif is reconstructed, with the manifestation of the Late Devonian-Early Carboniferous stage – the most productive for rare-metal-rare-earth mineralization. The Devonian period of the formation of the Tomtor and Bogdo massifs is associated with the impact of the Vilyui plume on the eastern edge of the Siberian craton. A close age interval is fixed during the formation of the rocks of the Kola alkaline province.

The Yanshanian Uranium Mineralization Age and Its Geological Significance in the Dashigou Carbonatite-Type Mo-REE-U Deposit, East Qinling Orogen, China

The Dashigou deposit is one of the most representative carbonatite-type Mo-REE deposits in the East Qinling metallogenic belt of China, with a molybdenum resource of more than 180 kt and a rare earth resource of 37.8 kt. Recent exploration has revealed a considerable scale of uranium mineralization within this deposit. Therefore, this study conducted detailed mineralogical and EPMA U-Th-Pb chemical dating on the uranium mineralization in the Dashigou deposit. The results indicate that the U-ore body in the Dashigou deposit mainly consists in carbonatite veins, and principally as anhedral, mesh-like uraninite. The mineral assemblage is characterized by uraninite + rutile + bastnasite + parisite or brannerite. The uraninite displays geochemical compositions of high Y and Ce and low Si, Ti, and Mg. The EPMA U-Th-Pb chemical dating is 144 ± 3.1 Ma, representing the Yanshanian uranium mineralization age in the region. The newly discovered uranium mineralization age indicates that the deposit experienced a uranium remobilization event during the Cretaceous and was formed in an intracontinental orogenic and extensional environment post-collision orogeny.