Oxidation state of uranium in mantle melts

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dc.contributor.authorBerry, AJen_AU
dc.contributor.authorO'Neill, HSCen_AU
dc.contributor.authorForan, GJen_AU
dc.date.accessioned2009-10-06T05:57:01Zen_AU
dc.date.accessioned2010-04-30T04:56:56Zen_AU
dc.date.available2009-10-06T05:57:01Zen_AU
dc.date.available2010-04-30T04:56:56Zen_AU
dc.date.issued2008-07en_AU
dc.date.statistics2008-07en_AU
dc.description.abstractThe oxidation state of U exerts a first order control on its partitioning during partial mantle melting. An understanding of U partitioning, and its abundance relative to other members of the U decay series, is important for interpreting U series disequilibrium, with implications for the rate of melt transport at mid-ocean ridges. U LIII-edge X-ray absorption near edge structure (XANES) spectra were recorded for a synthetic mid-ocean ridge basalt (MORB), and a number of CMAS (CaO-MgOAl2O3-SiO2) compositions, containing 0.5 wt % U3O8, equilibrated at 1400 ˚C and controlled oxygen fugacities (fO2)at one-atmosphere. Spectra were obtained for both quenched glasses, and in situ at magmatic temperatures (Berry et al. 2003). In situ measurements allowed changes in the spectra in response to the imposed fO2 to be followed in real time. The spectra were recorded in fluorescence mode at the Australian National Beamline Facility (beamline 20B), Photon Factory, Japan. The spectra exhibit systematic variations in absorption edge energy and crest intensity with fO2. These changes occur between -4 and +6 log units of the nickel-nickel oxide (NNO) fO2 buffer. The fO2 range of the spectral variation indicates that U4+ must oxidise to U6+ through two stepwise one-electron reactions, involving a U5+ intermediate, rather than a direct two-electron process. The results also suggest that U5+ may be the dominant oxidation state at the fO2 conditions of MORB generation. © 2008 Elsevier Ltden_AU
dc.description.sponsorshipGeochemical Society; European Association of Geochemistry.en_AU
dc.identifier.citationBerry, A. J., O'Neill, H. S. C., & Foran, G. J. (2008). Oxidation state of uranium in mantle melts. 18th Annual V.M. Goldschmidt Conference (Goldschmidt 2008) - "from Sea to Sky", University of British Columbia, Vancouver, Canada, 13th - 18th July 2008. Geochimica et Cosmochimica Acta, 72(12), A79. doi:10.1016/j.gca.2008.05.005en_AU
dc.identifier.conferenceenddate18 July 2008en_AU
dc.identifier.conferencename18th Annual V.M. Goldschmidt Conference (Goldschmidt 2008) - 'from Sea to Sky'en_AU
dc.identifier.conferenceplaceVancouver, Canadaen_AU
dc.identifier.conferencestartdate13 July 2008en_AU
dc.identifier.govdoc1031en_AU
dc.identifier.issn0016-7037en_AU
dc.identifier.issue12en_AU
dc.identifier.journaltitleGeochimica et Cosmochimica Actaen_AU
dc.identifier.paginationA79en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/1935en_AU
dc.identifier.urihttp://dx.doi.org/10.1016/j.gca.2008.05.005en_AU
dc.identifier.volume72en_AU
dc.language.isoenen_AU
dc.publisherElsevier; Cambridge Publicationsen_AU
dc.subjectOxidationen_AU
dc.subjectUraniumen_AU
dc.subjectMeltingen_AU
dc.subjectAbsorptionen_AU
dc.subjectSpectraen_AU
dc.subjectNickel oxidesen_AU
dc.titleOxidation state of uranium in mantle meltsen_AU
dc.typeConference Abstracten_AU
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