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GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L14603, doi:10.1029/2004GL020278, 2004

Elasticity of post-perovskite MgSiO₃

Taku Tsuchiya

Department of Chemical Engineering and Materials Science, Minnesota Supercomputing Institute for Digital Technology and Advanced Computation, University of Minnesota, Minneapolis, Minnesota, USA

Jun Tsuchiya

Department of Chemical Engineering and Materials Science, Minnesota Supercomputing Institute for Digital Technology and Advanced Computation, University of Minnesota, Minneapolis, Minnesota, USA

Koichiro Umemoto

Department of Chemical Engineering and Materials Science, Minnesota Supercomputing Institute for Digital Technology and Advanced Computation, University of Minnesota, Minneapolis, Minnesota, USA

Renata M. Wentzcovitch

Department of Chemical Engineering and Materials Science, Minnesota Supercomputing Institute for Digital Technology and Advanced Computation, University of Minnesota, Minneapolis, Minnesota, USA

Abstract

We have determined by first principles the athermal elastic constant tensor, single crystal and aggregated acoustic velocities, and anisotropy of the recently discovered post-perovskite MgSiO₃ polymorph. This phase may be the most abundant mineral in the D″ region. We find that the post-perovskite phase has similar bulk modulus and larger shear modulus than perovskite at relevant pressures. This phase is remarkably anisotropic. Analyses of horizontal shear wave splittings in transversely isotropic aggregates indicate that diverse lattice preferred orientations could produce large variation in anisotropy consistent with seismic observations in D″.

Received 16 April 2004; accepted 16 June 2004; published 17 July 2004.

Index Terms: 1025 Geochemistry: Composition of the mantle; 3909 Mineral Physics: Elasticity and anelasticity; 3924 Mineral Physics: High-pressure behavior; 5102 Physical Properties of Rocks: Acoustic properties; 7207 Seismology: Core and mantle.

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Citation: Tsuchiya, T., J. Tsuchiya, K. Umemoto, and R. M. Wentzcovitch (2004), Elasticity of post-perovskite MgSiO₃, Geophys. Res. Lett., 31, L14603, doi:10.1029/2004GL020278.

Copyright 2004 by the American Geophysical Union.