Deformation of (Mg,Fe)SiO3 post-perovskite and D″ anisotropy

Sébastien Merkel; Allen K. McNamara; Atsushi Kubo; Sergio Speziale; Lowell Miyagi; Yue Meng; Thomas S. Duffy; Hans Rudolf Wenk

doi:10.1126/science.1140609

Deformation of (Mg,Fe)SiO₃ post-perovskite and D″ anisotropy

Sébastien Merkel, Allen K. McNamara, Atsushi Kubo, Sergio Speziale, Lowell Miyagi, Yue Meng, Thomas S. Duffy, Hans Rudolf Wenk

Earth and Space Exploration, School of (SESE)

Research output: Contribution to journal › Article › peer-review

133 Scopus citations

Abstract

Polycrystalline (Mg_0.9,Fe^0.1)SiO₃ post-perovskite was plastically deformed in the diamond anvil cell between 145 and 157 gigapascals. The lattice-preferred orientations obtained in the sample suggest that slip on planes near (100) and (110) dominate plastic deformation under these conditions. Assuming similar behavior at lower mantle conditions, we simulated plastic strains and the contribution of post-perovskite to anisotropy in the D″ region at the Earth core-mantle boundary using numerical convection and viscoplastic polycrystal plasticity models. We find a significant depth dependence of the anisotropy that only develops near and beyond the turning point of a downwelling slab. Our calculated anisotropies are strongly dependent on the choice of elastic moduli and remain hard to reconcile with seismic observations.

Original language	English (US)
Pages (from-to)	1729-1732
Number of pages	4
Journal	Science
Volume	316
Issue number	5832
DOIs	https://doi.org/10.1126/science.1140609
State	Published - Jun 22 2007

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title = "Deformation of (Mg,Fe)SiO3 post-perovskite and D″ anisotropy",

abstract = "Polycrystalline (Mg0.9,Fe0.1)SiO3 post-perovskite was plastically deformed in the diamond anvil cell between 145 and 157 gigapascals. The lattice-preferred orientations obtained in the sample suggest that slip on planes near (100) and (110) dominate plastic deformation under these conditions. Assuming similar behavior at lower mantle conditions, we simulated plastic strains and the contribution of post-perovskite to anisotropy in the D″ region at the Earth core-mantle boundary using numerical convection and viscoplastic polycrystal plasticity models. We find a significant depth dependence of the anisotropy that only develops near and beyond the turning point of a downwelling slab. Our calculated anisotropies are strongly dependent on the choice of elastic moduli and remain hard to reconcile with seismic observations.",

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T1 - Deformation of (Mg,Fe)SiO3 post-perovskite and D″ anisotropy

AU - Merkel, Sébastien

AU - McNamara, Allen K.

AU - Kubo, Atsushi

AU - Speziale, Sergio

AU - Miyagi, Lowell

AU - Meng, Yue

AU - Duffy, Thomas S.

AU - Wenk, Hans Rudolf

PY - 2007/6/22

Y1 - 2007/6/22

N2 - Polycrystalline (Mg0.9,Fe0.1)SiO3 post-perovskite was plastically deformed in the diamond anvil cell between 145 and 157 gigapascals. The lattice-preferred orientations obtained in the sample suggest that slip on planes near (100) and (110) dominate plastic deformation under these conditions. Assuming similar behavior at lower mantle conditions, we simulated plastic strains and the contribution of post-perovskite to anisotropy in the D″ region at the Earth core-mantle boundary using numerical convection and viscoplastic polycrystal plasticity models. We find a significant depth dependence of the anisotropy that only develops near and beyond the turning point of a downwelling slab. Our calculated anisotropies are strongly dependent on the choice of elastic moduli and remain hard to reconcile with seismic observations.

AB - Polycrystalline (Mg0.9,Fe0.1)SiO3 post-perovskite was plastically deformed in the diamond anvil cell between 145 and 157 gigapascals. The lattice-preferred orientations obtained in the sample suggest that slip on planes near (100) and (110) dominate plastic deformation under these conditions. Assuming similar behavior at lower mantle conditions, we simulated plastic strains and the contribution of post-perovskite to anisotropy in the D″ region at the Earth core-mantle boundary using numerical convection and viscoplastic polycrystal plasticity models. We find a significant depth dependence of the anisotropy that only develops near and beyond the turning point of a downwelling slab. Our calculated anisotropies are strongly dependent on the choice of elastic moduli and remain hard to reconcile with seismic observations.

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Deformation of (Mg,Fe)SiO₃ post-perovskite and D″ anisotropy

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