Constraints on the mineralogy of an iron-rich Martian mantle from high-pressure experiments

The high-pressure mineralogy of a model Martian mantle composition has been determined experimentally up to 24 GPa. Experiments have been performed in the anhydrous multi-component CaOMgOFeOAl2O3SiO2Na2O system with a mantle composition derived from the SNC meteorites. The phase transitions which occur along a model liquid core marstherm have been determined. The importance of magnesiowüstite and stishovite in the Martian mantle, two phases generally overlooked in models of Martian mantle mineralogy are also discussed, Magnesiowüstite is found to be present in the transition zone of the model mantle. The presence of magnesiowüstite is attributed to the shift in olivine, β-phase, γ-spinel and clinopyroxene or majorite towards more Mg-rich compositions as pressure increases. At lower mantle pressures an assemblage of stishovite and magnesiowüstite with perovskite and majorite is shown to be consistent with the high iron content of the Martian mantle. These results may have important implications mantle. These results may have important implications for seismic discontinuities in the Martian interior.