Petrography and chemistry of tungsten-rich oxycalciobetafite in hydrothermal veins of the Adamello contact aureole, northern Italy

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dc.contributor.authorLumpkin, GRen_AU
dc.contributor.authorGieré, Ren_AU
dc.contributor.authorWilliams, CTen_AU
dc.contributor.authorMcGlinn, PJen_AU
dc.contributor.authorPayne, TEen_AU
dc.date.accessioned2024-02-28T00:21:31Zen_AU
dc.date.available2024-02-28T00:21:31Zen_AU
dc.date.issued2017-09en_AU
dc.description.abstractTungsten-rich oxycalciobetafite occurs in complex Ti-rich hydrothermal veins emplaced within dolomite marble in the contact aureole of the Adamello batholith, northern Italy, where it occurs as overgrowths on zirconolite. The betafite is weakly zoned and contains 29–34 wt% UO2. In terms of end-members, the betafite contains approximately 50 mol% CaUTi2O7 and is one of the closest known natural compositions to the pyrochlore phase proposed for use in titanate nuclear waste forms. Amorphization and volume expansion of the betafite caused cracks to form in the enclosing silicate mineral grains. Backscattered electron images reveal that betafite was subsequently altered along crystal rims, particularly near the cracks. Electron probe microanalyses reveal little difference in composition between altered and unaltered areas, except for lower totals, suggesting that alteration is primarily due to hydration. Zirconolite contains up to 18 wt% ThO2 and 24 wt% UO2, and exhibits strong compositional zoning, but no internal cracking due to differential (and anisotropic) volume expansion and no visible alteration. The available evidence demonstrates that both oxycalciobetafite and zirconolite retained actinides for approximately 40 million years after the final stage of vein formation. During this time, oxycalciobetafite and zirconolite accumulated a total alpha-decay dose of 3.0–3.6 × 1016 and 0.2–2.0 × 1016 α/mg, respectively. © 2024 Springer Natureen_AU
dc.identifier.citationLumpkin, G. R., Gieré, R., Williams, C. T., McGlinn, P. J., & Payne, T. E. (2017). Petrography and chemistry of tungsten-rich oxycalciobetafite in hydrothermal veins of the Adamello contact aureole, northern Italy. Mineralogy and Petrology, 111(4), 499-509. doi:10.1007/s00710-017-0525-zen_AU
dc.identifier.issn0930-0708en_AU
dc.identifier.issn1438-1168en_AU
dc.identifier.issue4en_AU
dc.identifier.journaltitleMineralogy and Petrologyen_AU
dc.identifier.pagination499-509en_AU
dc.identifier.urihttp://dx.doi.org/10.1007/s00710-017-0525-zen_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15461en_AU
dc.identifier.volume111en_AU
dc.languageEnglishen_AU
dc.language.isoenen_AU
dc.publisherSpringer Natureen_AU
dc.subjectPetrographyen_AU
dc.subjectChemistryen_AU
dc.subjectTungstenen_AU
dc.subjectItalyen_AU
dc.subjectDolomiteen_AU
dc.subjectMarbleen_AU
dc.subjectPyrochloreen_AU
dc.subjectSilicatesen_AU
dc.subjectZirconoliteen_AU
dc.subjectActinidesen_AU
dc.subjectAlpha decayen_AU
dc.titlePetrography and chemistry of tungsten-rich oxycalciobetafite in hydrothermal veins of the Adamello contact aureole, northern Italyen_AU
dc.typeJournal Articleen_AU
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