First principles thermoelasticity of MgSiO3‐perovskite: Consequences for the inferred properties of the lower mantle
- 15 July 2001
- journal article
- Published by American Geophysical Union (AGU) in Geophysical Research Letters
- Vol. 28 (14) , 2699-2702
- https://doi.org/10.1029/2001gl012910
Abstract
Some key thermoelastic properties of MgSiO3‐perovskite (pv) have been determined at lower mantle (LM) pressures and temperatures using the quasi‐harmonic approximation in conjunction with first principles phonon dispersions. The adiabatic bulk moduli (KS) of pv and of an assemblage of 80 vol% pv and 20 vol% MgO were obtained along the thermodynamically inferred adiabat and compared with the seismic counterpart given by the preliminary reference Earth model (KPREM). The discrepancy between calculated KS's and KPREM in the deep LM suggests a super‐adiabatic gradient, or subtle changes of composition, or phase, or all beginning at about 1200 km. The Anderson Grüneisen parameter, δS=(∂lnKS/∂lnρ)P, was predicted to decrease rapidly with depth (from 2.7 to 1.2 across the LM) supporting the thermal origin for the lateral heterogeneities throughout most of the LM.Keywords
This publication has 28 references indexed in Scilit:
- The composition and geotherm of the lower mantle: constraints from the elasticity of silicate perovskitePhysics of the Earth and Planetary Interiors, 2000
- Thermoelastic properties and crystal structure of MgSiO3 perovskite at lower mantle pressure and temperature conditionsGeophysical Research Letters, 2000
- Effects of temperature and composition on the bulk modulus of (Mg,Fe)OAmerican Mineralogist: Journal of Earth and Planetary Materials, 1999
- Thermal expansivity of lower mantle phases MgO and MgSiO3 perovskite at high pressure derived from vibrational spectroscopyPhysics of the Earth and Planetary Interiors, 1996
- Melting of mantle and core materials at very high pressuresPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1996
- Thermoelastic properties of MgSiO3 perovskite determined by in situ X ray observations up to 30 GPa and 2000 KJournal of Geophysical Research, 1996
- A thermodynamic method for computing thermal expansivity, α, versus T along isobars for silicate perovskitePhysics of the Earth and Planetary Interiors, 1994
- δs at high pressure and dlnVs/dlnVp in the lower mantleGeophysical Research Letters, 1990
- Green’s-function approach to linear response in solidsPhysical Review Letters, 1987
- Preliminary reference Earth modelPhysics of the Earth and Planetary Interiors, 1981