 
Summary: Physics of the Earth and Planetary Interiors 157 (2006) 181187
Elasticity of Mg2SiO4 ringwoodite at mantle conditions
Li Lia,b,, Donald J. Weidnera,b, John Brodholta, Dario Alf`ea, G. David Pricea
a Department of Earth Sciences, University College London, Gower Street, London WC1E6BT, UK
b Mineral Physics Institute, Department of Geosciences, University of New York at Stony Brook, Stony Brook, NY 11790, USA
Received 31 January 2006; received in revised form 14 March 2006; accepted 5 April 2006
Abstract
The themoelastic properties of Mg2SiO4 ringwoodite at mantle pressure and temperature conditions are reported based on ab
initio molecular dynamic simulations. A thirdorder BirchMurnaghan equation at a reference temperature of 2000 K is defined by
K0 = 138 GPa, K0 = 5.2, and V0(2000 K) = 560.3 °A3
. The Gruneisen parameter is determined to be (V) = 0(V/V0(298 K))q
with
0 = 1.22 and q = 1.44(5), with V0(298 K) = 524.56 °A3
. The thermal expansion is determined to be (/0) = (V/V0(298 K))T
in
which 0 = 2.74 × 105
K1
and T = 5.2(1). The bulk modulus is temperature independent at constant volume, while the shear
moduli vary with temperature at constant volume. Elastic anisotropy decreases with both pressure and temperature becoming
isotropic by the bottom of the upper mantle.
