Ferric Iron in Lower Mantle Phases

抄録

Experiments in the system MgO-FeO-SiO₂ have been the foundation of current beliefs that iron partitions preferentially into (Mg, Fe) O relative to the Mg-perovskite phase and occurs nearly all as Fe²⁺. Recent experiments in the system MgO-FeO-SiO₂-Al₂O₃, however, show that (1) the presence of small amounts of Al stabilises Fe³⁺ in (Mg, Fe) SiO₃ perovskite to values exceeding 50% Fe³⁺/·Fe; and (2) the solubility of Fe³⁺ in (Mg, Fe) O is extremely low at high P, T, regardless of oxygen fugacity. These results have important implications for physical and chemical properties of the lower mantle.