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Titolo:
Pressure-volume-temperature equation of state of MgSiO3 perovskite from molecular dynamics and constraints on lower mantle composition
Autore:
Marton, FC; Ita, J; Cohen, RE;
Indirizzi:
Carnegie Inst Washington, Geophys Lab, Washington, DC 20015 USA Carnegie Inst Washington Washington DC USA 20015 Washington, DC 20015 USA Carnegie Inst Washington, Ctr High Pressure Res, Washington, DC 20015 USA Carnegie Inst Washington Washington DC USA 20015 Washington, DC 20015 USA
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
fascicolo: B5, volume: 106, anno: 2001,
pagine: 8615 - 8627
SICI:
0148-0227(20010510)106:B5<8615:PEOSOM>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
EARTHS LOWER MANTLE; V-T EQUATION; SITU X-RAY; SILICATE PEROVSKITE; (MG,FE)SIO3 PEROVSKITE; THERMOELASTIC PROPERTIES; PHASE-TRANSFORMATIONS; SEISMIC VELOCITIES; ELASTIC PROPERTIES; CRYSTAL-CHEMISTRY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
86
Recensione:
Indirizzi per estratti:
Indirizzo: Marton, FC Carnegie Inst Washington, Geophys Lab, 5251 Broad Branch Rd, Washington, DC 20015 USA Carnegie Inst Washington 5251 Broad Branch Rd Washington DC USA 20015
Citazione:
F.C. Marton et al., "Pressure-volume-temperature equation of state of MgSiO3 perovskite from molecular dynamics and constraints on lower mantle composition", J GEO R-SOL, 106(B5), 2001, pp. 8615-8627

Abstract

The composition of the lower mantle can be investigated by examining densities and seismic velocities of compositional models as functions of depth. In order to do this it is necessary to know the volumes and thermoelastic properties of the compositional constituents under lower mantle conditions. We determined the thermal equation of state (EOS) of MgSiO3 perovskite using the nonempirical variational induced breathing (VIB) interatomic potential with molecular dynamics simulations at pressures and temperatures of the lower mantle. We fit our pressure-volume-temperature results to a thermal EOS of the form P(V,T) = P-0(V,T-0) + DeltaP(th)(T), where T-0 = 300 K and P-0 is the isothermal Universal EOS. The thermal pressure DeltaP(th) can be represented by a linear relationship DeltaP(th) = a + bT. We find V-0 = 165.40 Angstrom (3), K-T0 = 273 GPa, K-T0' = 3.86, a = -1.99 GPa, and b = 0.00664 GPa K-1 for pressures of 0-140 GPa and temperatures of 300-3000 K. By fixing V-0 to the experimentally determined value of 162.49 Angstrom (3) andcalculating density and bulk sound velocity profiles along a lower mantle geotherm we find that the lower mantle cannot consist solely of (Mg,Fe)SiO3perovskite with X-Mg ranging from 0.9-1.0. Using pyrolitic compositions of67 vol % perovskite (X-Mg = 0.93-0.96) and 33 vol % magnesiowustite (X-Mg 0.82-0.86), however, we obtained density and velocity profiles that are;in excellent agreement with seismological models for a reasonable geotherm.

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Documento generato il 04/04/20 alle ore 12:04:37