P-V-T equation of state of MgSiO3 perovskite

A pressure-volume-temperature data set has been obtained for MgSiO3 perovskite, using synchrotron X-ray diffraction with a laser-heated diamond-anvil cell. The unit cell parameters of the silicate perovskite were measured by angle dispersive X-ray diffraction using imaging plates up to pressures of 57 GPa and temperature in excess of 2500 K. These measurements are in good agreement with the previously reported data of Funamori et al. [Funamori, N., Yagi, T., Utsumi, W., Kondo, T., Uchida, T., Funamori, M., 1996. J. Geophys. Res. 101 (B4), 8257-8269] at lower pressure and yield (partial derivative K/partial derivative T)(P) = -0.027 GPa K-1 for a fixed value K-0' of 4 and a zero-pressure thermal expansion parameter alpha = 1.55 X 10(-5) K-1 at 300 K. Assuming that the thermoelastic parameters of MgSiO3 perovskite are applicable to perovskites with moderate iron content, the comparison of the density and K-T profiles calculated for a mixture of perovskite and magnesiowustite and for PREM model indicates that a pure perovskite lower mantle is very unlikely. On the other hand, we obtain a very good match with PREM density and K-T profiles for a mixture of 83 vol % (Mg0.93Fe0.07)SiO3 perovskite and 17 vol % (Mg0.79Fe0.21)O magnesiowustite, compatible with a pyrolytic lower mantle. (C) 1998 Elsevier Science B.V.