MULTIVARIABLE DEPENDENCE OF FE-MG PARTITIONING IN THE LOWER MANTLE

High-pressure diamond-cell experiments indicate that the iron-magnesiu m partitioning between (Fe,Mg)SiO3-perovskite and magnesiowustite in E arth's lower mantle depends on the pressure, temperature, bulk iron/ma gnesium ratio, and ferric iron content, The perovskite stability field expands with increasing pressure and temperature. The ferric iron com ponent preferentially dissolves in perovskite and raises the apparent total iron content but had little effect on the partitioning of the fe rrous iron, The ferrous iron depletes in perovskite at the top of the lower mantle and gradually increases at greater depth. These changes i n iron-magnesium composition should affect geochemical and geophysical properties of the deep interior.