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Title: In-situ measurement of texture development rate in CaIrO 3 post-perovskite

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 (γ) 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.

Authors:
; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1354242
Report Number(s):
BNL-112758-2016-JA¿¿¿
Journal ID: ISSN 0031-9201
DOE Contract Number:  
SC00112704
Resource Type:
Journal Article
Journal Name:
Physics of the Earth and Planetary Interiors
Additional Journal Information:
Journal Volume: 257; Journal Issue: C; Journal ID: ISSN 0031-9201
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Electron back-scatter diffraction (EBSD); Orientation distribution function (ODF); Lattice preferred orientation (LPO); Inverse pole figure; D″ layer

Citation Formats

Hunt, Simon A., Walker, Andrew M., and Mariani, Elisabetta. In-situ measurement of texture development rate in CaIrO 3 post-perovskite. United States: N. p., 2016. Web. doi:10.1016/j.pepi.2016.05.007.
Hunt, Simon A., Walker, Andrew M., & Mariani, Elisabetta. In-situ measurement of texture development rate in CaIrO 3 post-perovskite. United States. doi:10.1016/j.pepi.2016.05.007.
Hunt, Simon A., Walker, Andrew M., and Mariani, Elisabetta. Tue . "In-situ measurement of texture development rate in CaIrO 3 post-perovskite". United States. doi:10.1016/j.pepi.2016.05.007.
@article{osti_1354242,
title = {In-situ measurement of texture development rate in CaIrO 3 post-perovskite},
author = {Hunt, Simon A. and Walker, Andrew M. and Mariani, Elisabetta},
abstractNote = {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 MgSiO3 post-perovskite prevents high-strain deformation experiments being performed on it. Therefore, to constrain the rate of CPO development in post-perovskite, we deformed CaIrO3, a low-pressure analogue of MgSiO3 post-perovskite, in simple shear at 3.2 GPa and 400 °C to a shear strain (γ) 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 CaIrO3 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 MgSiO3 implies that seismic anisotropy in the D" layer develops slower than has previously been assumed.},
doi = {10.1016/j.pepi.2016.05.007},
journal = {Physics of the Earth and Planetary Interiors},
issn = {0031-9201},
number = C,
volume = 257,
place = {United States},
year = {2016},
month = {5}
}