Ferric iron and water incorporation in wadsleyite under hydrous and oxidizing conditions: A XANES, Mössbauer, and SIMS study

Nathalie Bolfan-Casanova, Manuel Muñoz, Catherine McCammon, Etienne Deloule, Anais Férot, Sylvie Demouchy, Lydéric France, Denis Andrault, Sakura Pascarelli

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

adsleyites with various iron contents were synthesized at ∼ GPa and 1400°C under oxidizing and hydrous conditions in coexistence with enstatite. The samples were studied using micro-X-ray absorption near edge structure (XANES) and micro-Mössbauer spectroscopy to determine the ferric iron contents in polyphasic samples and secondary ion mass spectrometry (SIMS) to determine the water concentrations. XANES and Mössbauer analyses show that ferric iron content increases with increasing total iron content, and reaches a maximum of ∼e 3+/Fe total. Two XANES results were cross-checked by Mössbauer analysis and both methods are in reasonable agreement. The use of Fourier transform infrared spectroscopy reveals a new protonation scheme in wadsleyite, with a significant proportion of protons associated with the high-frequency band at 3611 cm -1 and a new band located at 3500 cm -1. The intensity of these two bands is higher for Fe 3+-rich wadsleyite. SIMS analyses show that water contents in wadsleyite vary from 4500 to 9400 ppm H 2O by weight. Pyroxene water contents range from 790 to 1600 ppm wt H 2O. The concentration of water in both phases decreases with increasing iron content. The partition coefficient of water between wadsleyite and pyroxene varies between 5 and 9 and increases with increasing Fe-number of wadsleyite [i.e., X Fe/(X Fe + X Mg) ×tio]. The divalent cation concentrations (i.e., Mg 2+ + Fe 2+), the Si as well as the H content in wadsleyite decrease with increasing Fe 3+ content. A indicating an incorporation mechanism via substitution into the metal (Me = Mg 2+ and Fe 2+) and Si sites with a ratio of 5/3 for (Fe 3++H +):Me and of 5/1 for (Fe 3++H +):Si, similarly as in the dry system. Thus, coupled substitution of Fe 3+ and H + does not affect the incorporation mechanism of Fe 3+, but does affect the location of H +, which is partly incorporated at tetrahedral edges forming [Fe Si'-(OH) o·]X neutral defects substituting for Si. In this model 25% of the ferric iron occupies the tetrahedral sites.

Original languageEnglish (US)
Pages (from-to)1483-1493
Number of pages11
JournalAmerican Mineralogist
Volume97
Issue number8-9
DOIs
StatePublished - Aug 1 2012

Fingerprint

wadsleyite
X ray absorption
Secondary ion mass spectrometry
secondary ion mass spectrometry
Iron
mass spectrometry
iron
ion
Water
water
x rays
pyroxene
Water content
substitution
Substitution reactions
moisture content
water content
substitutes
enstatite
Protonation

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

Cite this

Bolfan-Casanova, Nathalie ; Muñoz, Manuel ; McCammon, Catherine ; Deloule, Etienne ; Férot, Anais ; Demouchy, Sylvie ; France, Lydéric ; Andrault, Denis ; Pascarelli, Sakura. / Ferric iron and water incorporation in wadsleyite under hydrous and oxidizing conditions : A XANES, Mössbauer, and SIMS study. In: American Mineralogist. 2012 ; Vol. 97, No. 8-9. pp. 1483-1493.
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abstract = "adsleyites with various iron contents were synthesized at ∼ GPa and 1400°C under oxidizing and hydrous conditions in coexistence with enstatite. The samples were studied using micro-X-ray absorption near edge structure (XANES) and micro-M{\"o}ssbauer spectroscopy to determine the ferric iron contents in polyphasic samples and secondary ion mass spectrometry (SIMS) to determine the water concentrations. XANES and M{\"o}ssbauer analyses show that ferric iron content increases with increasing total iron content, and reaches a maximum of ∼e 3+/Fe total. Two XANES results were cross-checked by M{\"o}ssbauer analysis and both methods are in reasonable agreement. The use of Fourier transform infrared spectroscopy reveals a new protonation scheme in wadsleyite, with a significant proportion of protons associated with the high-frequency band at 3611 cm -1 and a new band located at 3500 cm -1. The intensity of these two bands is higher for Fe 3+-rich wadsleyite. SIMS analyses show that water contents in wadsleyite vary from 4500 to 9400 ppm H 2O by weight. Pyroxene water contents range from 790 to 1600 ppm wt H 2O. The concentration of water in both phases decreases with increasing iron content. The partition coefficient of water between wadsleyite and pyroxene varies between 5 and 9 and increases with increasing Fe-number of wadsleyite [i.e., X Fe/(X Fe + X Mg) ×tio]. The divalent cation concentrations (i.e., Mg 2+ + Fe 2+), the Si as well as the H content in wadsleyite decrease with increasing Fe 3+ content. A indicating an incorporation mechanism via substitution into the metal (Me = Mg 2+ and Fe 2+) and Si sites with a ratio of 5/3 for (Fe 3++H +):Me and of 5/1 for (Fe 3++H +):Si, similarly as in the dry system. Thus, coupled substitution of Fe 3+ and H + does not affect the incorporation mechanism of Fe 3+, but does affect the location of H +, which is partly incorporated at tetrahedral edges forming [Fe Si'-(OH) o·]X neutral defects substituting for Si. In this model 25{\%} of the ferric iron occupies the tetrahedral sites.",
author = "Nathalie Bolfan-Casanova and Manuel Mu{\~n}oz and Catherine McCammon and Etienne Deloule and Anais F{\'e}rot and Sylvie Demouchy and Lyd{\'e}ric France and Denis Andrault and Sakura Pascarelli",
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Bolfan-Casanova, N, Muñoz, M, McCammon, C, Deloule, E, Férot, A, Demouchy, S, France, L, Andrault, D & Pascarelli, S 2012, 'Ferric iron and water incorporation in wadsleyite under hydrous and oxidizing conditions: A XANES, Mössbauer, and SIMS study', American Mineralogist, vol. 97, no. 8-9, pp. 1483-1493. https://doi.org/10.2138/am.2012.3869

Ferric iron and water incorporation in wadsleyite under hydrous and oxidizing conditions : A XANES, Mössbauer, and SIMS study. / Bolfan-Casanova, Nathalie; Muñoz, Manuel; McCammon, Catherine; Deloule, Etienne; Férot, Anais; Demouchy, Sylvie; France, Lydéric; Andrault, Denis; Pascarelli, Sakura.

In: American Mineralogist, Vol. 97, No. 8-9, 01.08.2012, p. 1483-1493.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Ferric iron and water incorporation in wadsleyite under hydrous and oxidizing conditions

T2 - A XANES, Mössbauer, and SIMS study

AU - Bolfan-Casanova, Nathalie

AU - Muñoz, Manuel

AU - McCammon, Catherine

AU - Deloule, Etienne

AU - Férot, Anais

AU - Demouchy, Sylvie

AU - France, Lydéric

AU - Andrault, Denis

AU - Pascarelli, Sakura

PY - 2012/8/1

Y1 - 2012/8/1

N2 - adsleyites with various iron contents were synthesized at ∼ GPa and 1400°C under oxidizing and hydrous conditions in coexistence with enstatite. The samples were studied using micro-X-ray absorption near edge structure (XANES) and micro-Mössbauer spectroscopy to determine the ferric iron contents in polyphasic samples and secondary ion mass spectrometry (SIMS) to determine the water concentrations. XANES and Mössbauer analyses show that ferric iron content increases with increasing total iron content, and reaches a maximum of ∼e 3+/Fe total. Two XANES results were cross-checked by Mössbauer analysis and both methods are in reasonable agreement. The use of Fourier transform infrared spectroscopy reveals a new protonation scheme in wadsleyite, with a significant proportion of protons associated with the high-frequency band at 3611 cm -1 and a new band located at 3500 cm -1. The intensity of these two bands is higher for Fe 3+-rich wadsleyite. SIMS analyses show that water contents in wadsleyite vary from 4500 to 9400 ppm H 2O by weight. Pyroxene water contents range from 790 to 1600 ppm wt H 2O. The concentration of water in both phases decreases with increasing iron content. The partition coefficient of water between wadsleyite and pyroxene varies between 5 and 9 and increases with increasing Fe-number of wadsleyite [i.e., X Fe/(X Fe + X Mg) ×tio]. The divalent cation concentrations (i.e., Mg 2+ + Fe 2+), the Si as well as the H content in wadsleyite decrease with increasing Fe 3+ content. A indicating an incorporation mechanism via substitution into the metal (Me = Mg 2+ and Fe 2+) and Si sites with a ratio of 5/3 for (Fe 3++H +):Me and of 5/1 for (Fe 3++H +):Si, similarly as in the dry system. Thus, coupled substitution of Fe 3+ and H + does not affect the incorporation mechanism of Fe 3+, but does affect the location of H +, which is partly incorporated at tetrahedral edges forming [Fe Si'-(OH) o·]X neutral defects substituting for Si. In this model 25% of the ferric iron occupies the tetrahedral sites.

AB - adsleyites with various iron contents were synthesized at ∼ GPa and 1400°C under oxidizing and hydrous conditions in coexistence with enstatite. The samples were studied using micro-X-ray absorption near edge structure (XANES) and micro-Mössbauer spectroscopy to determine the ferric iron contents in polyphasic samples and secondary ion mass spectrometry (SIMS) to determine the water concentrations. XANES and Mössbauer analyses show that ferric iron content increases with increasing total iron content, and reaches a maximum of ∼e 3+/Fe total. Two XANES results were cross-checked by Mössbauer analysis and both methods are in reasonable agreement. The use of Fourier transform infrared spectroscopy reveals a new protonation scheme in wadsleyite, with a significant proportion of protons associated with the high-frequency band at 3611 cm -1 and a new band located at 3500 cm -1. The intensity of these two bands is higher for Fe 3+-rich wadsleyite. SIMS analyses show that water contents in wadsleyite vary from 4500 to 9400 ppm H 2O by weight. Pyroxene water contents range from 790 to 1600 ppm wt H 2O. The concentration of water in both phases decreases with increasing iron content. The partition coefficient of water between wadsleyite and pyroxene varies between 5 and 9 and increases with increasing Fe-number of wadsleyite [i.e., X Fe/(X Fe + X Mg) ×tio]. The divalent cation concentrations (i.e., Mg 2+ + Fe 2+), the Si as well as the H content in wadsleyite decrease with increasing Fe 3+ content. A indicating an incorporation mechanism via substitution into the metal (Me = Mg 2+ and Fe 2+) and Si sites with a ratio of 5/3 for (Fe 3++H +):Me and of 5/1 for (Fe 3++H +):Si, similarly as in the dry system. Thus, coupled substitution of Fe 3+ and H + does not affect the incorporation mechanism of Fe 3+, but does affect the location of H +, which is partly incorporated at tetrahedral edges forming [Fe Si'-(OH) o·]X neutral defects substituting for Si. In this model 25% of the ferric iron occupies the tetrahedral sites.

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