An experimental determination of the effect of pressure on the Fe3/∑Fe ratio of an anhydrous silicate melt to 3.0 GPa

Hugh St C. O'Neill; Andrew J. Berry; Catherine C. McCammon; Kasthuri D. Jayasuriya; Stewart J. Campbell; Garry Foran

doi:10.2138/am.2005.1929

An experimental determination of the effect of pressure on the Fe^3/∑Fe ratio of an anhydrous silicate melt to 3.0 GPa

Hugh St C. O'Neill^*, Andrew J. Berry, Catherine C. McCammon, Kasthuri D. Jayasuriya, Stewart J. Campbell, Garry Foran

^*Corresponding author for this work

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

62 Citations (Scopus)

Abstract

The effect of pressure on the Fe³⁺/∑Fe ratio of an anhydrous andesitic melt was determined from 0.4 to 3.0 GPa at 1400 °C with oxygen fugacity controlled internally by the Ru + RuO₂ buffer. Values of Fe³⁺/∑Fe were determined by Mössbauer spectroscopy on quenched glasses with a precision of ±0.01, one standard deviation. This precision was verified independently by XANES spectroscopy of the same samples. The XANES spectra show a systematic increase in energy and decrease in intensity of the 1s → 3d transition with increasing pressure. The results to 2.0 GPa are in good agreement with predictions from density and compressibility measurements fitted to a Murnaghan equation of state, but the datum at 3.0 GPa has higher Fe³⁺/∑Fe than predicted from the trend established by the lower-pressure data. This might be due to a coordination change in Fe³⁺ at high pressure; although there is no evidence for this in the Mössbauer spectra, such a change could account for the change in intensity of the 1s → 3d transition in the XANES spectra with pressure.

Original language	English
Pages (from-to)	404-412
Number of pages	9
Journal	American Mineralogist
Volume	91
Issue number	2-3
DOIs	https://doi.org/10.2138/am.2005.1929
Publication status	Published - 2006

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title = "An experimental determination of the effect of pressure on the Fe3/∑Fe ratio of an anhydrous silicate melt to 3.0 GPa",

abstract = "The effect of pressure on the Fe3+/∑Fe ratio of an anhydrous andesitic melt was determined from 0.4 to 3.0 GPa at 1400 °C with oxygen fugacity controlled internally by the Ru + RuO2 buffer. Values of Fe3+/∑Fe were determined by M{\"o}ssbauer spectroscopy on quenched glasses with a precision of ±0.01, one standard deviation. This precision was verified independently by XANES spectroscopy of the same samples. The XANES spectra show a systematic increase in energy and decrease in intensity of the 1s → 3d transition with increasing pressure. The results to 2.0 GPa are in good agreement with predictions from density and compressibility measurements fitted to a Murnaghan equation of state, but the datum at 3.0 GPa has higher Fe3+/∑Fe than predicted from the trend established by the lower-pressure data. This might be due to a coordination change in Fe3+ at high pressure; although there is no evidence for this in the M{\"o}ssbauer spectra, such a change could account for the change in intensity of the 1s → 3d transition in the XANES spectra with pressure.",

keywords = "Experimental petrology, M{\"o}ssbauer, Redox ratio, Silicate melt, XANES",

author = "O'Neill, {Hugh St C.} and Berry, {Andrew J.} and McCammon, {Catherine C.} and Jayasuriya, {Kasthuri D.} and Campbell, {Stewart J.} and Garry Foran",

year = "2006",

doi = "10.2138/am.2005.1929",

language = "English",

volume = "91",

pages = "404--412",

journal = "American Mineralogist",

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publisher = "Walter de Gruyter GmbH",

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AU - O'Neill, Hugh St C.

AU - Berry, Andrew J.

AU - McCammon, Catherine C.

AU - Jayasuriya, Kasthuri D.

AU - Campbell, Stewart J.

AU - Foran, Garry

PY - 2006

Y1 - 2006

N2 - The effect of pressure on the Fe3+/∑Fe ratio of an anhydrous andesitic melt was determined from 0.4 to 3.0 GPa at 1400 °C with oxygen fugacity controlled internally by the Ru + RuO2 buffer. Values of Fe3+/∑Fe were determined by Mössbauer spectroscopy on quenched glasses with a precision of ±0.01, one standard deviation. This precision was verified independently by XANES spectroscopy of the same samples. The XANES spectra show a systematic increase in energy and decrease in intensity of the 1s → 3d transition with increasing pressure. The results to 2.0 GPa are in good agreement with predictions from density and compressibility measurements fitted to a Murnaghan equation of state, but the datum at 3.0 GPa has higher Fe3+/∑Fe than predicted from the trend established by the lower-pressure data. This might be due to a coordination change in Fe3+ at high pressure; although there is no evidence for this in the Mössbauer spectra, such a change could account for the change in intensity of the 1s → 3d transition in the XANES spectra with pressure.

AB - The effect of pressure on the Fe3+/∑Fe ratio of an anhydrous andesitic melt was determined from 0.4 to 3.0 GPa at 1400 °C with oxygen fugacity controlled internally by the Ru + RuO2 buffer. Values of Fe3+/∑Fe were determined by Mössbauer spectroscopy on quenched glasses with a precision of ±0.01, one standard deviation. This precision was verified independently by XANES spectroscopy of the same samples. The XANES spectra show a systematic increase in energy and decrease in intensity of the 1s → 3d transition with increasing pressure. The results to 2.0 GPa are in good agreement with predictions from density and compressibility measurements fitted to a Murnaghan equation of state, but the datum at 3.0 GPa has higher Fe3+/∑Fe than predicted from the trend established by the lower-pressure data. This might be due to a coordination change in Fe3+ at high pressure; although there is no evidence for this in the Mössbauer spectra, such a change could account for the change in intensity of the 1s → 3d transition in the XANES spectra with pressure.

KW - Experimental petrology

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KW - Redox ratio

KW - Silicate melt

KW - XANES

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U2 - 10.2138/am.2005.1929

DO - 10.2138/am.2005.1929

M3 - Article

SN - 0003-004X

VL - 91

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EP - 412

JO - American Mineralogist

JF - American Mineralogist

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ER -

An experimental determination of the effect of pressure on the Fe^3/∑Fe ratio of an anhydrous silicate melt to 3.0 GPa

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