The oxidation state of vanadium in titanomagnetite from layered basic intrusions | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  The oxidation state of vanadium in titanomagnetite from layered basic intrusions

Type de publication:

Journal Article

Source:

American Mineralogist, Volume 91, Ticket 5-6, p.953-956 (2006)

ISBN:

0003-004X

Numéro d'accès:

0002378135-0027

URL:

http://www.minsocam.org/MSA/AmMin/TOC

Mots-clés:

Comparative-planetary-mineralogy; x-ray-absorption; bushveld-complex; upper-zone; basaltic-glasses; oxide-glasses; south-africa; magnetite-; spectra-; oxygen-

Résumé:

The redox conditions prevailing during the formation of vanadiferous titanomagnetites from three layered intrusions (Bushveld; Koillismaa; Skaergaard) have been estimated from the valence state of vanadium using synchrotron X-ray absorption near edge structure spectroscopy (XANES). Using a high energy-resolution X-ray emission spectrometer, we show that vanadium occurs mostly as V3+, with minor V4+. The most concentrated samples (up to 2.4 Wt% V2O3) contain approximately 10% of vanadium as V4+. Both V3+ and V4+ occur in the octahedral site of the spinel structure. Considering the low magnetite/melt V4+ partition coefficients, this suggests that vanadium ores crystallized under specific oxidizing conditions.

Notes:

IRD, UR T058, F-75480 Paris 10, France; Univ Paris 06, CNRS, UMR 7590, IMPMC,IPGP, F-75252 Paris, France; Univ Paris 07, CNRS, UMR 7590, IMPMC,IPGP, F-75252 Paris 05, France; Univ Pretoria, Dept Mat Sci & Met Engn, ZA-0002 Pretoria, South Africa; European Synchrotron Radiat Facil, F-38043 Grenoble, France; Observ Midi Pyrenees, CNRS, UMR 5562, Lab Dynam Terr & Planetaire, F-31400 Toulouse, FranceArticleEnglish