Abstract
Valence, spin states, and crystallographic sites of Fe in (Mg,Fe)SiO3perovskite were investigated using energy-domain 57Fe-synchrotron Mössbauer spectroscopy and powder X-ray diffraction up to 86 GPa. The volumes of Fe3+-bearing perovskite in this study are slightly smaller than those of Mg endmember perovskite. Our Mössbauer data suggest that Fe3+prefers A sites coupled with Mg vacancies, which is consistent with previous data at ambient conditions. Fe3+in the A site remains in a high-spin state up to 86 GPa, and some fraction of the A site is occupied by Fe2+at pressures above 30 GPa. Fe2+in the A sites is also in a high-spin state up to 86 GPa. The coupled substitution from Mg2+to a highspin state of Fe3+and Mg2+vacancy would make the volume of perovskite smaller than that of Mg end-member perovskite. If the lower mantle is saturated in silica, perovskite containing high-spin Fe3+in A site has a higher density. Such silica oversaturated regions could sink by the density difference.
Original language | English |
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Pages (from-to) | 1555-1561 |
Number of pages | 7 |
Journal | American Mineralogist |
Volume | 99 |
Issue number | 8-9 |
DOIs | |
Publication status | Published - 2014 Aug 1 |
Keywords
- Mössbauer spectroscopy
- Perovskite
- X-ray diffraction
- ferric iron
- spin state
ASJC Scopus subject areas
- Geophysics
- Geochemistry and Petrology