Aluminim in a CaO-MgO-Al2O3-SiO2 lower mantle assemblage

Sofia Akber-Knutson
California Institut of Technology

ABSTRACT

Most compositional models of the Earth's mantle contain at least a few
weight percent of Al2O3, which can have a profound effect on the
chemistry, elasticity, and rheology of the lower mantle. I will
discuss a theoretical approach, based on atomistic simulations, to
derive thermodynamic properties of solid solutions at high pressures
and temperatures. The thermodynamically consistent treatment of Al2O3
incorporation into MgSiO3 and CaSiO3 perovskite yields not only the
relative abundances of Al substitution mechanisms within each
perovskite, but also the partitioning of Al between the two
perovskites in an assemblage with MgO.