[S-IT06] Early Earth - from accumulation to formation -

[SIT06-25] Single-crystal elastic property of bridgmanite and seismic anomalies in the lower mantle

*Hiroshi FUKUI¹, Akira YONEDA², Seiji KAMADA³, Eiji OHTANI⁴, Alfred Baron⁵ (1.Graduate School of Material Science, University of Hyogo, 2.Institute for Study of the Earth's Interior, Okayama University, 3.Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 4.Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, 5.Materials Dynamics Laboratory, RIKEN)

Keywords:bridgmanite, inelastic x-ray scattering, single crystal elasticity, cation substitution, lower mantle, seismic anomaly

Single crystal elasticity of bridgmanite is essential information to understand the seismic velocity structure of the lower mantle from the viewpoint of chemical and thermal structures. We have performed inelastic x-ray scattering measurement at BL35XU of SPring-8 on 100-micron size (Mg,Fe,Al)(Si,Al)O₃ single crystals synthesized by thermal gradient method. Analysis of the obtained spectra gives single crystal elastic stiffness constants. The cation substitution is seen to cause the anti-correlation between the bulk sound and shear wave velocities as well as to enhance the elastic anisotropy of bridgmanite, and consequently allows us to make a quantitative model that is consistent with seismological observations.