Physics and Chemistry of Minerals

, Volume 43, Issue 8, pp 597–613

Texture development and slip systems in bridgmanite and bridgmanite + ferropericlase aggregates

Original Paper

DOI: 10.1007/s00269-016-0820-y

Cite this article as:
Miyagi, L. & Wenk, HR. Phys Chem Minerals (2016) 43: 597. doi:10.1007/s00269-016-0820-y

Abstract

Bridgmanite (Mg,Fe)SiO3 and ferropericlase (Mg,Fe)O are the most abundant phases in the lower mantle and localized regions of the D″ layer just above the core mantle boundary. Seismic anisotropy is observed near subduction zones at the top of the lower mantle and in the D″ region. One source of anisotropy is dislocation glide and associated texture (crystallographic preferred orientation) development. Thus, in order to interpret seismic anisotropy, it is important to understand texture development and slip system activities in bridgmanite and bridgmanite + ferropericlase aggregates. Here we report on in situ texture development in bridgmanite and bridgmanite + ferropericlase aggregates deformed in the diamond anvil cell up to 61 GPa. When bridgmanite is synthesized from enstatite, it exhibits a strong (4.2 m.r.d.) 001 transformation texture due to a structural relationship with the precursor enstatite phase. When bridgmanite + ferropericlase are synthesized from olivine or ringwoodite, bridgmanite exhibits a relatively weak 100 transformation texture (1.2 and 1.6 m.r.d., respectively). This is likely due to minimization of elastic strain energy as a result of Young’s modulus anisotropy. In bridgmanite, 001 deformation textures are observed at pressures <55 GPa. The 001 texture is likely due to slip on (001) planes in the [100], [010] and \(\left\langle {110} \right\rangle\) directions. Stress relaxation by laser annealing to 1500–1600 K does not result in a change in this texture type. However, at pressures >55 GPa a change in texture to a 100 maximum is observed, consistent with slip on the (100) plane. Ferropericlase, when deformed with bridgmanite, does not develop a coherent texture. This is likely due to strain heterogeneity within the softer ferropericlase grains. Thus, it is plausible that ferropericlase is not a significant source of anisotropy in the lower mantle.

Keywords

Diamond anvil cell Bridgmanite Ferropericlase Deformation Slip systems Seismic anisotropy 

Supplementary material

269_2016_820_MOESM1_ESM.pdf (346 kb)
Supplementary material 1 (PDF 345 kb)

Funding information

Funder NameGrant NumberFunding Note
Division of Earth Sciences
  • 0337006
  • 1343908
Directorate for Geosciences
  • CSEDI 1067513
Carnegie DOE Alliance Center

    Copyright information

    © Springer-Verlag Berlin Heidelberg 2016

    Authors and Affiliations

    1. 1.University of UtahSalt Lake CityUSA
    2. 2.University of California BerkeleyBerkeleyUSA

    Personalised recommendations