U-Pb (SHRIMP-RG) age of zircon from rare-metal (Li, Cs)  pegmatites of the Okhmylk deposit of the Kolmozero-Voron’ya greenstone belt (northeast of the Fennoscandian shield)

Kudryashov, N. M.; Удоратина, О. В.; Kalinin, A. A.; Lyalina, L. М.; Selivanova, Ekaterina A.; Coble, Matthew A.

doi:10.31897/pmi.2022.41

Cited by 5 publications

(2 citation statements)

References 22 publications

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“…Minor and accessory minerals are spodumene (up to 5), polychrome tourmaline, lepidolite, pollucite, muscovite, columbite group minerals, lithiophilite and montebrasite. Recent U-Pb (SHRIMP-RG) geochronological dating of zircon from the Okhmylk pegmatite dyke yielded an age of 2607 ± 9 Ma [37]. We consider this age as the most reliable for the formation of the Li-Cs-Ta pegmatite deposits of the Kolmozero-Voronja belt.…”

Section: Geology Of the Kola Rare-metal Pegmatite Beltmentioning

confidence: 88%

Nb-Ta-Sn Oxides from Lithium-Beryllium-Tantalum Pegmatite Deposits of the Kolmozero–Voronja Belt, NW Russia: Implications for Tracing Ore-Forming Processes and Mineralization Signatures

Zozulya,

Morozova,

Kullerud

et al. 2023

Geosciences

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In this paper we present textural and compositional data for columbite group minerals (CGMs) and associated Nb-Ta-Sn oxides from lithium-beryllium-tantalum pegmatite deposits of the Kolmozero–Voronja belt, NW Russia, with the aim of deciphering these characteristics for minerals from deposits with different mineral signatures and lithium ore grade. Minerals from four deposits, including two of world-class (Kolmozero and Polmostundra), are examined. The main controlling factors for CGM compositional ranges are the diversity and rate of magmatic fractionation, hydrothermal overprint and mineral paragenesis, following the specific geochemical signature of the different pegmatite deposits. CGM from Kolmozero include several mineral species (columbite-(Fe), columbite-(Mn), tantalite-(Fe), and tantalite-(Mn)), showing large compositional variations, mainly controlled by Nb-Ta fractionation (Ta/(Ta + Nb) = 0.16–0.70; Mn/(Mn + Fe) = 0.45–0.63). Textural patterns are various (oscillatory, homogeneous, and patchy); spongy domains and overgrowing Ta-rich rims are also observed somewhere. This indicates the involvement of numerous magmatic and hydrothermal processes. The Polmostundra CGMs are represented by columbite-(Fe) with Ta/(Ta + Nb), ranging from 0.05 to 0.39; some crystals are homogenous, and others present normal, oscillatory, mottled and reverse-zoning patterns. The Okhmylk CGMs are irregular normal, patchy and homogeneous columbite-(Fe) and columbite-(Mn), with Ta/(Ta + Nb) = 0.09–0.24 and Mn/(Mn + Fe) = 0.29–0.92, indicating the suppressed magmatic fractionation and iron drop due to precipitation of Fe minerals. Columbite-(Fe) and columbite-(Mn) from the Be-Ta Shongui deposit are less evolved, with Ta/(Ta + Nb) = 0.07–0.23 and Mn/(Mn + Fe) = 0.31–0.55. The minerals are characterized by progressive normal, oscillatory, homogeneous and irregular reverse patterns. Associated pyrochlore minerals occur both as early magmatic (Kolmozero) and late hydrothermal (Polmostundra, Okhmylk). Cassiterite is found only in the Okhmylk dykes, and is apparently of hydrothermal origin. CGM from Li pegmatites have impurities of Ti (0.01–0.05 apfu) and W (up to 0.02 apfu), whereas CGM from Be pegmatites contains elevated Ti (up to 0.09 apfu). The mineral system analysis presented here is relevant for exploration.

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Section: Geology Of the Kola Rare-metal Pegmatite Beltmentioning

confidence: 88%

Nb-Ta-Sn Oxides from Lithium-Beryllium-Tantalum Pegmatite Deposits of the Kolmozero–Voronja Belt, NW Russia: Implications for Tracing Ore-Forming Processes and Mineralization Signatures

Zozulya,

Morozova,

Kullerud

et al. 2023

Geosciences

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“…The study of zircon trace elements, which has become possible with the arrival of high-precision microanalytical methods (SIMS, LA-ICP-MS, etc. ), provides more information on petrogenesis [4][5][6]. Therefore, it is important to obtain more evidence for zircon's isomorphic capacity for trace elements and zircon crystallization conditions when its impurity element concentrations are extremely high.…”

Section: Introductionmentioning

confidence: 99%

Th-Rich Zircon from a Pegmatite Vein Hosted in the Wiborg Rapakivi Granite Massif

Skublov,

Petrov,

Galankina

et al. 2023

Geosciences

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Zircon from a pegmatite vein hosted in the rapakivi granites occurring in the Gubanov Intrusion of the Wiborg Massif was shown by the EPMA method to contain an anomalously high Th of 18.3 wt% ThO2 (about 161,000 ppm Th). The SIMS method obtained a close value for thorium content—146,000 ppm. U increases to 6800 ppm. Zircon contains high values of other non-formula elements: Y (up to 51,500 ppm), Ti (up to 12,500 ppm), P (up to 9000 ppm), Nb (up to 3500 ppm), Ca (up to 2800 ppm) and Ba (up to 600 ppm). The average Hf value is 10,900 ppm. Total REE ranges from 25,500 to 49,400 ppm, and the average REE is 33,300 ppm. The REE patterns show poorly HREE fractionation over the LREE (LuN/LaN ratio average is 6.34) with well-marked negative Eu anomalies (Eu/Eu* averages 0.10) and slight positive Ce anomalies (Ce/Ce* averages 1.16). The formation of Th-rich zircon indicates that residual fluid-saturated pegmatite melt is saturated with Th and other trace elements (REE, Y, U, Ti and Nb).

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Geochemistry (TE, REE, Oxygen) of Zircon from Leucogranites of the Belokurikhinsky Massif, Gorny Altai, as Indicator of Formation Conditions

Levashova,

Mamykina,

Skublov

et al. 2023

Geochem. Int.

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The present contribution deals with the isotopic-geochemical study (by Electron Probe Microanalysis (EPMA) and Method of Secondary Ion Mass Spectroscopy (SIMS) of zircons from Belokurikhinsky massif leucogranites, which resulted in the determination of two morphological varieties of zircons (zonal and porous). Zonal zircons exhibit low content of trace elements, a “magmatic” type of REE distribution spectra, and geochemical indices consistent with those of magmatic zircons. Anomalously high REE (up to 38 800 ppm), Y (up to 50 700 ppm) and U (up to 24 700 ppm) contents, as well as elevated Hf, P, F, Cl, and water contents (up to 3.5 wt %) were found in porous zircons. They display gently flattened REE distribution spectra with no Ce-anomaly and the persistence of negative Eu-anomaly, as well as geochemical parameters that differ from typical zircons of magmatic origin. The obtained geochemical characteristics of porous zircons reflect the process of enrichment of the magmatic melt with rare and rare earth elements, and indicate a high fluid saturation of the melt. The δ18О determined value for porous zircons is in the range of 9.22 to 12.54‰, which significantly exceeds a mantle value and seems to be caused by influence of external fluids interacting with sedimentary rocks surrounding leucogranites. The detailed isotopic-geochemical study of zircon samples suggests that their crystallization from leucogranites of a third (final) phase in the evolution of the Belokurikhinsky massif took place from fluid-saturated melt with elevated incompatible element concentrations.

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U-Pb (SHRIMP-RG) age of zircon from rare-metal (Li, Cs) pegmatites of the Okhmylk deposit of the Kolmozero-Voron’ya greenstone belt (northeast of the Fennoscandian shield)

Cited by 5 publications

References 22 publications

Nb-Ta-Sn Oxides from Lithium-Beryllium-Tantalum Pegmatite Deposits of the Kolmozero–Voronja Belt, NW Russia: Implications for Tracing Ore-Forming Processes and Mineralization Signatures

Nb-Ta-Sn Oxides from Lithium-Beryllium-Tantalum Pegmatite Deposits of the Kolmozero–Voronja Belt, NW Russia: Implications for Tracing Ore-Forming Processes and Mineralization Signatures

Th-Rich Zircon from a Pegmatite Vein Hosted in the Wiborg Rapakivi Granite Massif

Geochemistry (TE, REE, Oxygen) of Zircon from Leucogranites of the Belokurikhinsky Massif, Gorny Altai, as Indicator of Formation Conditions

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