Research Abstract


Elastic anisotropy of experimental analogues of perovskite and post-perovskite help to interpret D′′ diversity

2014年3月27日 Nature Communications 5 : 3453 doi: 10.1038/ncomms4453


米田 明1, 福井 宏之2,3, Xu Fang1, 中塚 晃彦4, 吉朝 朗5, 瀬戸 雄介6, 小野 謙弥7, 筒井 智嗣8, 内山 裕士8 & Alfred Q.R. Baron3,8

  1. 岡山大学 地球物質科学研究センター
  2. 兵庫県立大学 理学部
  3. 独立行政法人 理化学研究所
  4. 山口大学 工学部
  5. 熊本大学 理学部
  6. 神戸大学 理学部
  7. 富山大学 理学部
  8. 公益財団法人 高輝度光科学研究センター(JASRI)
Recent studies show that the D′′ layer, just above the Earth's core–mantle boundary, is composed of MgSiO3 post-perovskite and has significant lateral inhomogeneity. Here we consider the D′′ diversity as related to the single-crystal elasticity of the post-perovskite phase. We measure the single-crystal elasticity of the perovskite Pbnm-CaIrO3 and post-perovskite Cmcm-CaIrO3 using inelastic X-ray scattering. These materials are structural analogues to same phases of MgSiO3. Our results show that Cmcm-CaIrO3 is much more elastically anisotropic than Pbnm-CaIrO3, which offers an explanation for the enigmatic seismic wave velocity jump at the D′′ discontinuity. Considering the relation between lattice preferred orientation and seismic anisotropy in the D′′ layer, we suggest that the c axis of post-perovskite MgSiO3 aligns vertically beneath the Circum-Pacific rim, and the b axis vertically beneath the Central Pacific.