Planetary Science Seminar spring-2016

Crystallization of terrestrial cores: Insights from high-pressure experiments and thermochemical modeling with application to Mars.

The decline of Mars’ global magnetic field some 3.8-4.1 billion years ago is thought to reflect the demise of the dynamo that operated in its liquid core. The dynamo was probably powered by planetary cooling and so its termination is intimately tied to the thermochemical evolution and present-day physical state of the Martian core. This talk will investigate the crystallization regimes of the Martian core by combining thermochemical modeling and high-pressure experiments. In a first part, a systematic study of the thermochemical evolution of the core compatible with all available constraints and the estimated thermal, chemical and structural properties will be presented. In a second part, the effect of redox conditions on the structure and dynamics of the Martian deep interior will be presented, based on high- pressure and high-temperature phase-equilibria experiments. The scenario that reproduces best geodetic observations and Mars’ magnetic history involves top- down crystallization (so-called iron snow regime).