Uranium oxidation states in allanite, fergusonite and monazite of pegmatites from Finland

Ervanne, Heini

doi:10.1127/0028-3649/2004/2004-0289

Cited by 19 publications

(6 citation statements)

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“…In general, laboratory investigations of dolomite growth have been conducted under constant supersaturation (4,36). However, in natural environments, the supersaturation of fluids around dolomite can be dynamic and fluctuating (37)(38)(39)(40)(41)(42).…”

Section: Dolomite Growth Under Fluctuating Supersaturationmentioning

confidence: 99%

Dissolution enables dolomite crystal growth near ambient conditions

Kim,

Kimura,

Puchala

et al. 2023

Science

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Crystals grow in supersaturated solutions. A mysterious counterexample is dolomite CaMg(CO 3 ) 2 , a geologically abundant sedimentary mineral that does not readily grow at ambient conditions, not even under highly supersaturated solutions. Using atomistic simulations, we show that dolomite initially precipitates a cation-disordered surface, where high surface strains inhibit further crystal growth. However, mild undersaturation will preferentially dissolve these disordered regions, enabling increased order upon reprecipitation. Our simulations predict that frequent cycling of a solution between supersaturation and undersaturation can accelerate dolomite growth by up to seven orders of magnitude. We validated our theory with in situ liquid cell transmission electron microscopy, directly observing bulk dolomite growth after pulses of dissolution. This mechanism explains why modern dolomite is primarily found in natural environments with pH or salinity fluctuations. More generally, it reveals that the growth and ripening of defect-free crystals can be facilitated by deliberate periods of mild dissolution.

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Section: Dolomite Growth Under Fluctuating Supersaturationmentioning

confidence: 99%

Dissolution enables dolomite crystal growth near ambient conditions

Kim,

Kimura,

Puchala

et al. 2023

Science

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“…] may contain significant quantities of U and Th, and thus it is commonly metamict [16][17][18]. It is measured by SEM that contains 40.24% Nb, 22.17% Fe, 15.24% Y, 2.66% Ta, 10.29% Ti, 2.79% Al, 2.86% Si, and 2.07% Ca (Fig.…”

Section: Fergusonite [(Yer) (Nbtati)o4mentioning

confidence: 99%

Radioelements Potentiality Around Gabel Nugrus Area, South Eastern Desert, Egypt: Geological and Mineralogical Implications

Salem

saleh

Kamar

et al. 2022

Arab Journal of Nuclear Sciences and Applications

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The present study spotlights on the geological, petrographical, mineralogical and radiometric prospecting, which control the distribution of radioactive elements within the granitic rocks of Gabel Nugrus. The study area is composed of ultramafic rocks, ophiolitic metagabbros, biotite hornblende gneisses and granitic rocks. The granitic rocks are represented by monzogranite, syenogranite and garnetiferous muscovite granite. The minerals (uranophane, uranothorite, fergusonite, zircon, monazite, xenotime, allanite, sphalerite, gold, arsenopyrite and pyrite) were identified by Scanning Electron Microscope (SEM) and back-scattered electron imaging system. In monzogranite, the average eU and eTh contents in both north and south of Gabel Nugrus are 9.25ppm, 5.4ppm, 31.41ppm, 19.29ppm respectively. In the syenogranite, the average eU, eTh contents are 10.22ppm and 24.45ppm respectively. In the garnetiferous muscovite granite, the average eU and eTh contents are 7.82ppm and 13.33ppm respectively. The radioactive anomaly in the study area is confined to the fractures cutting through the garnetiferous muscovite granite at the northern part of Gabel Magal El Harami area. The average of eU, eTh and eUm contents within fractures are187.87ppm, 109.57ppm, 156.57, this reflects a strong addition of uranium from the surrounding rocks. While the radioelements have been dissolved from the surrounding rocks (different types of granites) by meteoric and/or surface water through joints and fissures and finally, it deposited/trapped along the fractures of garnetiferous muscovite granites (absorbed by iron oxides) and less impermeable mica lenses due to the change in the physicochemical conditions, Eh and Ph in the given medium.

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“…Additionally, natural U deposits (natural analogue sites) and U-rich rock formations have been important research topics of radionuclide migration in Finland. In these geochemical studies, determination of U and Th concentrations, oxidation states of U, as well as sample age determination via U and Th isotope ratios, have been utilized as research methods [36][37][38][39]. The majority of ingested uranium in Finland, and possibly following health effects from uranium exposure, is due to consumption of drinking water containing substantial amounts of 238 U and its daughters.…”

Section: Uranium Isotopesmentioning

confidence: 99%

Transfer of Natural Radionuclides in Terrestrial Food Chains—A Review of Investigations in Finland

Salminen‐Paatero

Paatero

2021

IJERPH

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Transfer of natural radionuclides 210Pb, 210Po, 238U, and 228,230,232Th in subarctic food chains has been studied in Finland since the 1960s. The unique food chain lichen-reindeer-man related to Sami people in Finnish Lapland and other food chain options, from berries or mushrooms to man, have been explored and the activity concentrations of natural radionuclides in biological samples determined. The results from Finnish radioecological studies are summarized and differences in bioaccumulation between different radionuclides are discussed. It was found out that, although a substantial amount of activity concentration data exist from the research projects executed in Finland during the last 6 decades, more data, especially from U and Th, in biological environment and humans would be useful, e.g., for modeling purposes and for improved assessment of bioaccumulation and adverse effects (both radiological and chemical) of radionuclides.

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Uranium oxidation states in allanite, fergusonite and monazite of pegmatites from Finland

Cited by 19 publications

References 0 publications

Dissolution enables dolomite crystal growth near ambient conditions

Dissolution enables dolomite crystal growth near ambient conditions

Radioelements Potentiality Around Gabel Nugrus Area, South Eastern Desert, Egypt: Geological and Mineralogical Implications

Transfer of Natural Radionuclides in Terrestrial Food Chains—A Review of Investigations in Finland

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