Fluid-mediated alteration of (Y,REE,U,Th)–(Nb,Ta,Ti) oxide minerals in granitic pegmatite from the Evje-Iveland district, southern Norway

Abstract : We document the textural relations and chemical composition of (Y,REE,U,Th)–(Nb,Ta,Ti) oxide minerals in a granitic pegmatite from the Evje-Iveland district, southern Norway, using a combination of scanning and transmission electron microscopy, electron probe micro-analysis and infrared absorption spectroscopy. The (Y,REE,U,Th)–(Nb,Ta,Ti) oxide mineral is euxenite, which is strongly radiation damaged and surrounded by radial fractures. Within euxenite grains, three domains of distinct composition comprising unaltered, intermediate and altered euxenite, have been identified. In most cases pyrochlore occurs as corroded grain boundaries around euxenite and within relict fractures. Intermediate and altered euxenite are depleted in U, Pb, Ti, Nb, and Y, but enriched in Si and Ca relative to unaltered euxenite. Pyrochlore is also enriched in Fe, Pb, Zr and LREE relative to all euxenite phases. Altered domains of euxenite have deficient analytical totals and contain O-H. These domains are metamict and contain nanopores and nanodomains enriched in U and Ca. We suggest that as radiation damage accumulated in euxenite, radial fractures developed around the euxenite grains, thus allowing fluid infiltration. In the presence of fluid, euxenite was replaced by secondary euxenite then pyrochlore, owing to dissolution-precipitation and diffusion reactions. During alteration, U and the strategic metals Nb, Ti, and REE were mobilized at both the nanoscale and the scale of the pegmatite.
Type de document :
Article dans une revue
Mineralogy and Petrology, Springer Verlag, 2016, 110 (5), pp.581 - 599. 〈10.1007/s00710-016-0436-4〉
Liste complète des métadonnées

https://hal-clermont-univ.archives-ouvertes.fr/hal-01637125
Contributeur : Sylvaine Jouhannel <>
Soumis le : vendredi 17 novembre 2017 - 13:06:06
Dernière modification le : jeudi 11 janvier 2018 - 06:23:33

Identifiants

Collections

Citation

Charley Duran, Anne-Magali Guillaume, Bernard Bingen, Sophie Gouy, Philippe De Parseval, et al.. Fluid-mediated alteration of (Y,REE,U,Th)–(Nb,Ta,Ti) oxide minerals in granitic pegmatite from the Evje-Iveland district, southern Norway. Mineralogy and Petrology, Springer Verlag, 2016, 110 (5), pp.581 - 599. 〈10.1007/s00710-016-0436-4〉. 〈hal-01637125〉

Partager

Métriques

Consultations de la notice

112