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Sound velocities and elasticity of aluminous MgSiO 3 perovskite: Implications for aluminum heterogeneity in Earth's lower mantle
Author(s) -
Jackson Jennifer M.,
Zhang Jianzhong,
Bass Jay D.
Publication year - 2004
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 - 10.1029/2004gl019918
Subject(s) - brillouin spectroscopy , mantle (geology) , geology , perovskite (structure) , silicate perovskite , mineralogy , shear modulus , bulk modulus , materials science , shear (geology) , thermodynamics , geophysics , chemistry , brillouin scattering , composite material , petrology , crystallography , optics , physics , optical fiber
Aluminum has been reported to have a remarkably strong effect on the thermoelastic properties of MgSiO 3 perovskite. However, the sound velocities of aluminous MgSiO 3 perovskite have not been previously measured, even though this phase likely dominates most of the chemistry in Earth's lower mantle. Here we report the first sound velocity measurements on aluminous MgSiO 3 perovskite using Brillouin spectroscopy and obtain the following values for the room‐pressure room‐temperature adiabatic bulk and shear moduli: K S = 252 ± 5 GPa and μ = 165 ± 2 GPa, respectively. The presence of 5.1 ± 0.2 wt.% Al 2 O 3 in MgSiO 3 perovskite decreases the shear modulus by 5.6%. However, within experimental uncertainties, there is no discernable effect of aluminum on the bulk modulus. We find that variations in the aluminum content of MgSiO 3 perovskite may provide an explanation for some observed lateral heterogeneity in Earth's lower mantle.