Extending the Solidus for a Model Iron-Rich Martian Mantle Composition to 25 GPa

The solidus for the mantle of Mars is an important geophysical parameter in modeling the thermal history and evolution of the planet. This study provides solidus data for a simplified model Martian mantle composition from the midmantle (8 GPa) to the core-mantle boundary (25 GPa) using multianvil experiments. Combining this work with previous studies, the solidus for the entire mantle of Mars is constrained to within 70 degrees C. The major mineral assemblages and phase transitions observed are consistent with those predicted for an iron-rich Martian mantle. The solidus for the Martian composition falls above the solidus of MORB and below that of terrestrial peridotite, providing direct melting data for geophysical modeling of the Martian interior. Our solidus also predicts that a Martian mantle plume should produce melt at depths over a range of 200-350 km in the mantle.