In-situ measurement of texture development rate in CaIrO3 post-perovskite

Simon A. Hunt, Andrew M. Walker, Elisabetta Mariani

Research output: Contribution to journalArticlepeer-review

Abstract

The rate of crystallographic preferred orientation (CPO) development during deformation of post-perovskite is crucial in interpreting seismic anisotropy in the lowermost mantle but the stability field of MgSiO 3 post-perovskite prevents high-strain deformation experiments being performed on it. Therefore, to constrain the rate of CPO development in post-perovskite, we deformed CaIrO 3 , a low-pressure analogue of MgSiO 3 post-perovskite, in simple shear at 3.2 GPa and 400 °C to a shear strain ($) of 0.81. From X-ray diffraction patterns acquired during deformation, we invert for CPO as a function of strain. By comparing the CPO that develops with visco-plastic self-consistent (VPSC) models we constrain the critical resolved shear stresses (CRSS) of the non-primary slip-systems in CaIrO 3 to be of order 6 times stronger than the primary [100](010) slip system. This value is significantly less than has been assumed by previous studies and if applicable to MgSiO 3 implies that seismic anisotropy in the D ″ layer develops slower than has previously been assumed.
Original languageEnglish
Pages (from-to)91-104
Number of pages14
JournalPhysics of the Earth and Planetary Interiors
Volume257
Early online date24 May 2016
DOIs
Publication statusPublished - 1 Aug 2016

Keywords

  • D layer
  • Electron back-scatter diffraction (EBSD)
  • Inverse pole figure
  • Lattice preferred orientation (LPO)
  • Orientation distribution function (ODF)

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