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 (K-PREM) The discrepancy between calculated Ks's and K-PREM 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 Cruneisen parameter, delta (S) = (partial derivative lnK(S)/partial derivative ln(P))(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.
First principles thermoelasticity of MgSiO3-perovskite: consequences for the inferred properties of the lower mantle / Karki, B. B.; Wentzcovitch, R. M.; De Gironcoli, S.; Baroni, S.. - In: GEOPHYSICAL RESEARCH LETTERS. - ISSN 0094-8276. - 28:14(2001), pp. 2699-2702. [10.1029/2001GL012910]
First principles thermoelasticity of MgSiO3-perovskite: consequences for the inferred properties of the lower mantle
De Gironcoli, S.;Baroni, S.
2001-01-01
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 (K-PREM) The discrepancy between calculated Ks's and K-PREM 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 Cruneisen parameter, delta (S) = (partial derivative lnK(S)/partial derivative ln(P))(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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
