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Science 3 February 2006:
Vol. 311. no. 5761, pp. 644 - 646
DOI: 10.1126/science.1121808
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Reports

Plastic Deformation of MgGeO3 Post-Perovskite at Lower Mantle Pressures

Sébastien Merkel,1* Atsushi Kubo,2 Lowell Miyagi,1 Sergio Speziale,1 Thomas S. Duffy,2 Ho-kwang Mao,3 Hans-Rudolf Wenk1

Polycrystalline MgGeO3 post-perovskite was plastically deformed in the diamond anvil cell between 104 and 130 gigapascals confining pressure and ambient temperature. In contrast with phenomenological considerations suggesting (010) as a slip plane, lattice planes near (100) became aligned perpendicular to the compression direction, suggesting that slip on (100) or (110) dominated plastic deformation. With the assumption that silicate post-perovskite behaves similarly at lower mantle conditions, a numerical model of seismic anisotropy in the D'' region implies a maximum contribution of post-perovskite to shear wave splitting of 3.7% with an oblique polarization.

1 Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA.
2 Department of Geosciences, Princeton University, Princeton, NJ 08544, USA.
3 Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA.

* To whom correspondence should be addressed. E-mail: smerkel{at}berkeley.edu

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