Ferric iron content in (Mg,Fe)SiO3 perovskite and post-perovskite at deep lower mantle conditions

We have determined the Fe3+/ΣFe ratio of Al-free (Mg,Fe)SiO3 perovskite, post-perovskite, and (Mg,Fe)O ferropericlase synthesized at 99 to 187 GPa and 1830 to 3500 K based on the electron energy-loss near-edge structure (ELNES) spectroscopy. The results demonstrate that post-perovskite includes mino...

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Bibliographic Details
Published inThe American mineralogist Vol. 93; no. 11-12; pp. 1899 - 1902
Main Authors Sinmyo, Ryosuke, Ozawa, Haruka, Hirose, Kei, Yasuhara, Akira, Endo, Noriaki, Sata, Nagayoshi, Ohishi, Yasuo
Format Journal Article
LanguageEnglish
Published Mineralogical Society of America 01.11.2008
De Gruyter
Subjects
crystal chemistry
D double prime layer
diffractograms
D″ layer
ELNES
experimental studies
ferric iron
Geophysics
iron
lower mantle
mantle
metals
oxides
perovskite
perovskite structure
Post-perovskite
post-perovskite structure
pressure
related to mantle
spectra
synthetic materials
ultrahigh pressure
X-ray diffraction data
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Summary:We have determined the Fe3+/ΣFe ratio of Al-free (Mg,Fe)SiO3 perovskite, post-perovskite, and (Mg,Fe)O ferropericlase synthesized at 99 to 187 GPa and 1830 to 3500 K based on the electron energy-loss near-edge structure (ELNES) spectroscopy. The results demonstrate that post-perovskite includes minor amounts of ferric iron with Fe3+/ΣFe ratios of 0.11 to 0.21. These values are substantially lower than those of Al-rich post-perovskite (Fe3+/ΣFe = 0.59 to 0.69) reported in a previous study, suggesting that the Fe3+-Al3+ coupled substitution is important in post-perovskite, as in the case of perovskite. The Al-bearing post-perovskite in a pyrolitic mantle composition likely contains a considerable amount of ferric iron, which affects various physical properties in the lowermost mantle.
ISSN:0003-004X
1945-3027
DOI:10.2138/am.2008.2806