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Physics and Chemistry of Minerals

, Volume 36, Issue 4, pp 183–191 | Cite as

Disproportionation of Fe2+ in Al-free silicate perovskite in the laser heated diamond anvil cell as recorded by electron probe microanalysis of oxygen

  • Michel FialinEmail author
  • Gilles Catillon
  • Denis Andrault
Original Paper

Abstract

Experimental evidence is reported for Fe2+ disproportionation in Al-free perovskite (Pv), when submitted to large temperature gradients (i.e., under off-equilibrium conditions) in a laser heated diamond anvil cell (LHDAC). To enable this effect, the experimental procedure was designed to produce large radial and axial temperature gradients. In the Pv and ferropericlase (Fp) assemblage synthesized after dissociation of natural olivine, the three chemical states of iron (i.e., Fe0, Fe2+ and Fe3+) could be evidenced by electron probe microanalysis (EPMA), through variations of oxygen contents attached to the Fe cations. Despite inherent difficulties for determination of O-contents and Fe3+/ΣFe ratios using EPMA, we recorded significant changes in iron oxidation state across the laser-heated strip. These changes are correlated with variations in composition for the major elements (Fe, Mg, and Si), which evidences that the Pv/Fp assemblage experienced large segregation under the strong temperature gradients. Grains of metallic iron were detected in parts of the laser-heated strip coexisting with a Pv phase with Fe/(Mg + Fe) = 6 at% and most of its iron as Fe3+. This Fe2+-disproportionation reaction involves insertion of Fe3+-defects in the Pv lattice. This Fe3+-bearing Pv phase is presumably unstable and decomposes into a mineral assemblage including magnesioferrite, which is detected at the border of the laser-heated strip.

Keywords

Ferrous iron disproportionation Electron probe microanalysis Determination Fe3+/ΣFe ratios 

References

  1. Andrault D, Bolfan-Casanova N (2001) High-pressure phase transformations in the MgFe2O4 and Fe2O3-MgSiO3 systems. Phys Chem Miner 28:211–217CrossRefGoogle Scholar
  2. Andrault D, Bolfan-Casanova N, Bouhifd MA, Guignot N, Kawamoto T (2007) The role of Al-defects on the equation of state of Al-(Mg,Fe)SiO3 perovskite. Earth Planet Sci Lett 263:167–179CrossRefGoogle Scholar
  3. Auzende AL, Badro J, Ryerson FJ, Weber PK, Fallon SJ, Addad A, Siebert J, Fiquet G (2008) Element partitioning between magnesium silicate perovskite and ferropericlase: new insights into bulk lower-mantle geochemistry. Earth Planet Sci Lett 269:164–174CrossRefGoogle Scholar
  4. Ballhaus C, Berry RF, Green DH (1991) High pressure experimental calibration of the olivine-orthopyroxene-spinel oxygen geobarometer: implications for the oxidation state of the upper mantle. Contrib Mineral Petrol 78:27–40CrossRefGoogle Scholar
  5. Bastin GF, Heijligers HJM (1989) Quantitative electron probe microanalysis of oxygen. Internal report, Eindhoven University of Technology (ISBN 90-6819-012-1)Google Scholar
  6. Bell PM, Mao HK (1975) Preliminary evidence of disproportionation of ferrous iron in silicates at high pressures and temperatures. Carnegie Institution Washington Year Book, 74: 557–559Google Scholar
  7. Bell PM, Mao HK, Weeks RA, Valkenburg AV (1976) High pressure disproportionation study of iron in synthetic basalt glass. Carnegie Institution Washington Year Book 75: 515–520Google Scholar
  8. Bodea S, Jeanloz R (1989) Model calculations of the temperature distribution in the laser-heated diamond cell. J Appl Phys 65(12):4688–4692CrossRefGoogle Scholar
  9. Brodholt JP (2000) Pressure-induced changes in the compression mechanism of aluminous perovskite in the Earth’s mantle. Nature 407:620–622CrossRefGoogle Scholar
  10. Campbell AJ, Heinz DL, Davis AM (1992) Material transport in laser-heated diamond anvil cell melting experiments. J Geophys Res B19:1069Google Scholar
  11. Casino (2000) for Windows-based PC in free access on the web: http://www.gel.usherbrooke.ca/casino/index.html
  12. Duba A, Peyronneau J, Visocekas F, Poirier JP (1997) Electrical conductivity of magnesiowüstite/perovskite produced by laser heating of synthetic olivine in the diamond anvil cell. J Geophys Res 102(B12):27723–27728CrossRefGoogle Scholar
  13. Heinrich KFJ, Newbury DE (eds) (1991) Electron probe quantitation. Plenum Press, New YorkGoogle Scholar
  14. Fialin M, Rémond G (1993) Electron probe microanalysis of oxygen in strongly insulating oxides. Microbeam Anal 2:179–189Google Scholar
  15. Fialin M, Rémond G, Bonnelle C (1994) New developments in electron probe microanalysis of oxygen in wide bandgap oxides. Microbeam Analy 3:211–224Google Scholar
  16. Fialin M, Wagner C, Métrich N, Humler E, Galoisy L, Bézos A (2001) Fe3+/ΣFe versus Fe Lα peak energy for minerals and glasses: recent advances with the electron microprobe. Am Mineral 86:456–465Google Scholar
  17. Fialin M, Bézos A, Wagner C, Magnien V, Humler E (2004) Quantitative electron microprobe analysis of Fe3+/ΣFe: basic concepts and experimental protocol for glasses. Am Mineral 89:654–662Google Scholar
  18. Frost DJ, Langenhorst F (2002) The effect of Al2O3 on Fe–Mg partitioning between magnesiowüstite and magnesium silicate perovskite. Earth Planet Sci Lett 199:227–241CrossRefGoogle Scholar
  19. Frost DJ, Liebske C, Langenhorst F, McCammon C, Tronnes RG, Rubie DC (2004) Experimental evidence of iron-rich metal in the Earth’s lower mantle. Nature 428:409–412CrossRefGoogle Scholar
  20. Fujino K, Miyajima N, Yagi T, Kondo T, Funamori N. (1998) Analytical electron microscopy of the garnet-perovskite transformation in a laser heated diamond anvil cell, properties of earth and planetary materials at high pressure and temperature. Geophysical Monograph, pp 409–417Google Scholar
  21. Geller JD, Engle PD (2002) Sample preparation for electron probe microanalysis: pushing the limits. J Res Natl Inst Stand Technol 107(6):627–638Google Scholar
  22. Gessmann CK, Wood BJ, Rubie DC, Kilburn MR (2001) Solubility of silicon in liquid metal at high pressure: implications for the composition of the Earth’s core. Earth Planet Sci Lett 184:367–376CrossRefGoogle Scholar
  23. Gloter A, Guyot F, Martinez I, Colliex C (2000) Electron energy-loss spectroscopy of silicate perovskite-magnesiowüstite high-pressure assemblages. Am Mineral 85:1452–1458Google Scholar
  24. Guyot F, Madon M, Peyronneau J, Poirier JP (1988) X-ray microanalysis of high pressure/high temperature phases synthesised from natural olivine in a diamond anvil cell. Earth Planet Sci Lett 90:52–64CrossRefGoogle Scholar
  25. Heinz DL, Sweeney JS, Miller P (1991) A laser heating system that stabilizes and controls the temperature: diamond anvil cell applications. Rev Sci Instrum 62(6):1568–1575CrossRefGoogle Scholar
  26. Lauterbach S, McCammon CA, van Aken P, Langenhorst F, Seifert F (2000) Mössbauer and ELNES spectroscopy of (Mg, Fe)(Si, Al)O3 perovskite: a highly oxidised component of the lower mantle. Contrib Mineral Petrol 138:17–26CrossRefGoogle Scholar
  27. Luth R, Virgo D, Boyd FR, Wood BJ (1990) Ferric iron in mantle derived garnet: implications for thermobarometry and the oxidation state of the mantle. Contrib Mineral Petrol 104:56–72CrossRefGoogle Scholar
  28. Manga M, Jeanloz R (1996) Axial temperature gradients in dielectric samples in the laser-heated diamond cell. Geophys Res Lett 23(14):1845–1848CrossRefGoogle Scholar
  29. Manga M, Jeanloz R (1998) Temperature distribution in the laser-heated diamond cell: properties of earth and planetary materials at high pressure and temperature. Geophysical monograph 101Google Scholar
  30. McCammon CA (1997) Perovskite as a possible sink for ferric iron in the lower mantle. Nature 287:694–696CrossRefGoogle Scholar
  31. McCammon CA (1998) The crystal chemistry of ferric iron in Fe0.05Mg0.95SiO3 perovskite as determined by Mössbauer spectroscopy in the temperature range 80–293 K. Phys Chem Mineral 25–4:292–300CrossRefGoogle Scholar
  32. O’Neill HStC, Wall VJ (1987) The olivine-orthopyroxene-spinel oxygen geobarometer, the nickel precipitation curve, and the oxygen fugacity of the Earth’s upper mantle. J Petrol 28:1169–1191Google Scholar
  33. O’Neill HStC, McCammon CA, Canil D, Rubie DC, Ross FII, Seifert F (1993) Mössbauer spectroscopy of mantle transition zone phases and determination of minimum Fe3+ content. Am Mineral 78:456–460Google Scholar
  34. Peyronneau J, Madon M, Poirier JP (1984) Indirect pressure measurements in diamond anvil cell up to 1 megabar. J Phys 45:403Google Scholar
  35. Pouchou JL, Pichoir F (1988) Determination of mass absorption coefficients for soft X rays by use of the electron microprobe. In: Newbury DE (ed) Microbeam analysis. San Francisco Press, San Francisco, pp 319–324Google Scholar
  36. Pouchou JL, Pichoir F (1991) Quantitative analysis of homogeneous or stratified microvolumes applying the model “PAP”. In: Heinrich KFJ and Newbury DE (eds) Electron probe quantitation. Plenum Press, New York, pp 31–75Google Scholar
  37. Rouquette J, Dolejš D, Kantor IYu, McCammon CA, Frost DJ, Prakapenka VB, Dubrovinsky LS (2008) Iron-carbon interactions at high temperatures and pressures. Appl Phys Lett 92:121912CrossRefGoogle Scholar
  38. Sweatman TR, Long JVP (1969) Quantitative electron-probe microanalysis of rock-forming minerals. J Petrol 10(2):332–379Google Scholar
  39. Xu Y, McCammon C, Brent TP (1998) The effect of alumina on the electrical conductivity of silicate perovskite. Science 282:922–924CrossRefGoogle Scholar
  40. Yamazaki D, Kato T, Yurimoto H, Ohtani E, Toriumi M (2000) Silicon self-diffusion in MgSiO3 perovskite at 25 GPa. Phys Earth Planet Interior 119(3–4):299–309CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Michel Fialin
    • 1
    Email author
  • Gilles Catillon
    • 2
  • Denis Andrault
    • 3
  1. 1.Centre de Microanalyse Camparis, UMR7097-CNRSParis Cedex 5France
  2. 2.Laboratoire Géomatériaux et Géologie de l’Ingénieur (G2I), Université Paris-EstMarne la Vallée Cedex 2France
  3. 3.Laboratoire Magmas et VolcansUniversité Blaise PascalClermont-FerrandFrance

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