EQUATION OF STATE OF MAGNESITE FOR THE CONDITIONS OF THE EARTH'S LOWER MANTLE

Abstract

A semiempirical equation of state was derived for magnesite under the thermodynamic conditions of the Earth's mantle. Within experimental uncertainties, it is consistent with thermochemical, ultrasonic, X-ray, and shock-wave data at temperatures from 15 K to the melting point and pressures of up to 100-130 GPa. The following values were recommended for the isothermal bulk modulus and its pressure derivative: KT = 111.71 GPa and K' = 4.08. Thermodynamic analysis showed that magnesite does not decompose to periclase and CO2 under the thermodynamic conditions of the Earth's lower mantle and outer core. © Pleiades Publishing, Ltd. 2007.