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Strongly Anisotropic Magnesiowüstite in Earth's Lower Mantle
Author(s) -
Finkelstein Gregory J.,
Jackson Jennifer M.,
Said Ayman,
Alatas Ahmet,
Leu Bogdan M.,
Sturhahn Wolfgang,
Toellner Thomas S.
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2017jb015349
Subject(s) - wüstite , mantle (geology) , anisotropy , geology , silicate , inner core , alloy , core–mantle boundary , stishovite , materials science , silicate perovskite , mineralogy , oxide , metallurgy , geophysics , chemistry , optics , physics , quartz , organic chemistry
The juxtaposition of a liquid iron‐dominant alloy against a mixture of silicate and oxide minerals at Earth's core‐mantle boundary is associated with a wide range of complex seismological features. One category of observed structures is ultralow‐velocity zones, which are thought to correspond to either aggregates of partially molten material or solid, iron‐enriched assemblages. We measured the phonon dispersion relations of (Mg,Fe) O magnesiowüstite containing 76 mol % FeO, a candidate ultralow‐velocity zone phase, at high pressures using high‐energy resolution inelastic X‐ray scattering. From these measurements, we find that magnesiowüstite becomes strongly elastically anisotropic with increasing pressure, potentially contributing to a significant proportion of seismic anisotropy detected near the base of the mantle.