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Experimental calibration of vanadium partitioning and stable isotope fractionation between hydrous granitic melt and magnetite at 800°C and 0.5 GPa

Sossi, Paolo; Prytulak, Julie; O'Neill, Hugh

Description

Vanadium has multiple oxidation states in silicate melts and minerals, a property that also promotes fractionation of its isotopes. As a result, vanadium isotopes vary during magmatic differentiation, and can be powerful indicators of redox processes at high temperatures if their partitioning behaviour can be determined. To quantify the partitioning and isotope fractionation factor of V between magnetite and melt, piston cylinder experiments were performed in which magnetite and a hydrous,...[Show more]

dc.contributor.authorSossi, Paolo
dc.contributor.authorPrytulak, Julie
dc.contributor.authorO'Neill, Hugh
dc.date.accessioned2021-04-23T00:07:35Z
dc.identifier.issn0010-7999
dc.identifier.urihttp://hdl.handle.net/1885/230966
dc.description.abstractVanadium has multiple oxidation states in silicate melts and minerals, a property that also promotes fractionation of its isotopes. As a result, vanadium isotopes vary during magmatic differentiation, and can be powerful indicators of redox processes at high temperatures if their partitioning behaviour can be determined. To quantify the partitioning and isotope fractionation factor of V between magnetite and melt, piston cylinder experiments were performed in which magnetite and a hydrous, haplogranitic melt were equilibrated at 800 °C and 0.5 GPa over a range of oxygen fugacities (fO2), bracketing those of terrestrial magmas. Magnetite is isotopically light with respect to the coexisting melt, a tendency ascribed to the VI-fold V3+ and V4+ in magnetite, and a mixture of IV- and VI-fold V5+ and V4+ in the melt. The magnitude of the fractionation factor systematically increases with increasing logfO2 relative to the Fayalite–Magnetite–Quartz buffer (FMQ), from ∆51Vmag-gl = − 0.63 ± 0.09‰ at FMQ − 1 to − 0.92 ± 0.11‰ (SD) at ≈ FMQ + 5, reflecting constant V3+/V4+ in magnetite but increasing V5+/V4+ in the melt with increasing logfO2. These first mineral-melt measurements of V isotope fractionation factors underline the importance of both oxidation state and co-ordination environment in controlling isotopic fractionation. The fractionation factors determined experimentally are in excellent agreement with those needed to explain natural isotope variations in magmatic suites. Furthermore, these experiments provide a useful framework in which to interpret vanadium isotope variations in natural rocks and magnetites, and may be used as a potential fingerprint the redox state of the magma from which they crystallise.
dc.description.sponsorshipPAS was funded by an Australian Postgraduate Award and an ANU Vice-Chancellor's Scholarship. Analytical costs and JPs visit to ANU were funded by Australian Research Council Discovery Grant DP130101355 to H. St. C. O’Neill and J. Prytulak.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherSpringer
dc.rights© 2018 Springer-Verlag GmbH Germany, part of Springer Nature
dc.sourceContributions to Mineralogy and Petrology
dc.subjectRedox
dc.subjectMagnetite
dc.subjectMagma
dc.subjectVanadium
dc.subjectStable isotope fractionation
dc.subjectEquilibrium
dc.titleExperimental calibration of vanadium partitioning and stable isotope fractionation between hydrous granitic melt and magnetite at 800°C and 0.5 GPa
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume173
dcterms.dateAccepted2018-02-15
dc.date.issued2018-03-12
local.identifier.absfor040304 - Igneous and Metamorphic Petrology
local.identifier.ariespublicationa383154xPUB9561
local.publisher.urlhttps://link.springer.com/
local.type.statusPublished Version
local.contributor.affiliationSossi, Paolo, College of Science, ANU
local.contributor.affiliationPrytulak, Julie, Imperial College London
local.contributor.affiliationO'Neill, Hugh, College of Science, ANU
local.description.embargo2099-12-31
dc.relationhttp://purl.org/au-research/grants/arc/DP130101355
local.bibliographicCitation.startpage1
local.bibliographicCitation.lastpage27
local.identifier.doi10.1007/s00410-018-1451-8
local.identifier.absseo970104 - Expanding Knowledge in the Earth Sciences
dc.date.updated2020-11-23T11:40:46Z
local.identifier.scopusID2-s2.0-85043602678
CollectionsANU Research Publications

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