The oxidation states of niobium and tantalum in mantle melts

Antony D. Burnham; Andrew J. Berry; Bernard J. Wood; Giannantonio Cibin

doi:10.1016/j.chemgeo.2012.09.002

The oxidation states of niobium and tantalum in mantle melts

Antony D. Burnham, Andrew J. Berry^*, Bernard J. Wood, Giannantonio Cibin

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

32 Citations (Scopus)

Abstract

Niobium K-edge and tantalum L _III-edge XANES spectra were recorded for silicate glasses quenched from melts equilibrated at oxygen fugacities (in log units relative to the iron-wüstite buffer) ranging from IW+6.7 to IW-4.3 at 1400-1650°C and atmospheric pressure to 1.5GPa. Niobium and tantalum were found to occur exclusively as Nb ⁵⁺ and Ta ⁵⁺. This suggests that changes in oxidation state do not contribute to the fractionation of Nb from Ta in arc settings or the generation of the hidden Nb-rich reservoir that is necessary to explain the deviation of the Nb/Ta ratio of the bulk silicate Earth from the chondritic value.

Original language	English
Pages (from-to)	228-232
Number of pages	5
Journal	Chemical Geology
Volume	330-331
DOIs	https://doi.org/10.1016/j.chemgeo.2012.09.002
Publication status	Published - 10 Nov 2012
Externally published	Yes

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10.1016/j.chemgeo.2012.09.002

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title = "The oxidation states of niobium and tantalum in mantle melts",

abstract = "Niobium K-edge and tantalum L III-edge XANES spectra were recorded for silicate glasses quenched from melts equilibrated at oxygen fugacities (in log units relative to the iron-w{\"u}stite buffer) ranging from IW+6.7 to IW-4.3 at 1400-1650°C and atmospheric pressure to 1.5GPa. Niobium and tantalum were found to occur exclusively as Nb 5+ and Ta 5+. This suggests that changes in oxidation state do not contribute to the fractionation of Nb from Ta in arc settings or the generation of the hidden Nb-rich reservoir that is necessary to explain the deviation of the Nb/Ta ratio of the bulk silicate Earth from the chondritic value.",

keywords = "Arc signature, Niobium paradox, Oxidation state, Oxygen fugacity, Silicate melt, XANES",

author = "Burnham, \{Antony D.\} and Berry, \{Andrew J.\} and Wood, \{Bernard J.\} and Giannantonio Cibin",

year = "2012",

month = nov,

day = "10",

doi = "10.1016/j.chemgeo.2012.09.002",

language = "English",

volume = "330-331",

pages = "228--232",

journal = "Chemical Geology",

issn = "0009-2541",

publisher = "Elsevier B.V.",

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TY - JOUR

T1 - The oxidation states of niobium and tantalum in mantle melts

AU - Burnham, Antony D.

AU - Berry, Andrew J.

AU - Wood, Bernard J.

AU - Cibin, Giannantonio

PY - 2012/11/10

Y1 - 2012/11/10

N2 - Niobium K-edge and tantalum L III-edge XANES spectra were recorded for silicate glasses quenched from melts equilibrated at oxygen fugacities (in log units relative to the iron-wüstite buffer) ranging from IW+6.7 to IW-4.3 at 1400-1650°C and atmospheric pressure to 1.5GPa. Niobium and tantalum were found to occur exclusively as Nb 5+ and Ta 5+. This suggests that changes in oxidation state do not contribute to the fractionation of Nb from Ta in arc settings or the generation of the hidden Nb-rich reservoir that is necessary to explain the deviation of the Nb/Ta ratio of the bulk silicate Earth from the chondritic value.

AB - Niobium K-edge and tantalum L III-edge XANES spectra were recorded for silicate glasses quenched from melts equilibrated at oxygen fugacities (in log units relative to the iron-wüstite buffer) ranging from IW+6.7 to IW-4.3 at 1400-1650°C and atmospheric pressure to 1.5GPa. Niobium and tantalum were found to occur exclusively as Nb 5+ and Ta 5+. This suggests that changes in oxidation state do not contribute to the fractionation of Nb from Ta in arc settings or the generation of the hidden Nb-rich reservoir that is necessary to explain the deviation of the Nb/Ta ratio of the bulk silicate Earth from the chondritic value.

KW - Arc signature

KW - Niobium paradox

KW - Oxidation state

KW - Oxygen fugacity

KW - Silicate melt

KW - XANES

UR - https://www.scopus.com/pages/publications/84866641510

U2 - 10.1016/j.chemgeo.2012.09.002

DO - 10.1016/j.chemgeo.2012.09.002

M3 - Article

SN - 0009-2541

VL - 330-331

SP - 228

EP - 232

JO - Chemical Geology

JF - Chemical Geology

ER -

The oxidation states of niobium and tantalum in mantle melts

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