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

[SIT06-25] ブリッジマナイトの単結晶弾性と下部マントルの地震波速度異常の関連性

*福井 宏之¹、米田 明²、鎌田 誠司³、大谷 栄治⁴、Alfred Baron⁵ (1.兵庫県立大学大学院物質理学研究科、2.岡山大学地球物質科学研究センター、3.東北大学学際科学フロンティア研究所、4.東北大学大学院理学研究科地学専攻、5.理化学研究所バロン物質ダイナミクス研究室)

キーワード：ブリッジマナイト, Ｘ線非弾性散乱, 単結晶弾性, 陽イオン置換, 下部マントル, 弾性波速度異常

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.