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Partitioning of Fe within high‐pressure silicate perovskite: Evidence for unusual geochemistry in the lower mantle
Author(s) -
Jackson W. E.,
Knittle E.,
Brown G. E.,
Jeanloz R.
Publication year - 1987
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl014i003p00224
Subject(s) - extended x ray absorption fine structure , silicate , perovskite (structure) , synchrotron radiation , silicate perovskite , absorption spectroscopy , spectral line , absorption (acoustics) , mineralogy , absorption edge , crystallography , analytical chemistry (journal) , coordination number , xanes , mantle (geology) , geology , materials science , geochemistry , chemistry , physics , optics , band gap , organic chemistry , chromatography , astronomy , composite material , ion , optoelectronics
Using synchrotron radiation, Fe x‐ray absorption spectra have been collected from a Mg 0.88 Fe 0.12 SiO 3 perovskite quenched from 50 GPa and ∼ 2000 K. Least‐squares fits of the Extended X‐ray Absorption Fine Structure (EXAFS) data yield an Fe coordination number of 5.5 (±0.8) oxygens, an Fe‐O distance of 214 (± 4) pm, and a static and thermal disorder parameter of 147 pm². The absorption edge spectrum shows a weak pre‐edge feature suggesting little deviation from centrosymmetry for the Fe site. These results indicate that Fe in this silicate perovskite partitions predominantly into the six‐coordinated site and may provide the first evidence for Si occupying an 8‐12 coordinated site.