Thermoelasticity of perovskite: An emerging consensus



The current status of how well the thermoelastic properties of (Mg,Fe)SiO3 perovskite are known was addressed at a Special Session and Panel Discussion during the Fall 1993 AGU Meeting. Interest in the topic stems from the fact that silicate perovskite is the predominant mineral phase of the Earth's lower mantle, a region comprising over 60 (atomic) percent of the planet. Consequently, the properties of silicate perovskite largely control the evolution and state of the planetary interior.

The view emerging from the discussion was that after 10 years of intense study, the thermal and elastic properties of silicate perovskite are finally coming into focus. Indeed, the bulk modulus of (Mg,Fe)Si03 perovskite is now among the best determined of any mineral's. In addition, this is perhaps the only material for which the thermal expansion coefficient has been directly measured at lower-mantle conditions of pressure and temperature. A number of other properties of silicate perovskites—some of which were discussed peripherally in the Special Session—are the subject of ongoing research and remain to be established. In contrast, there seems to be a growing consensus regarding several key thermoelastic properties that are vital for understanding the Earth's deep interior.