Thermal history, core formation and tectonics of Mars

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We have constructed a new numerical model of early thermal history and metal/silicate separation of Mars during accretion in which we evaluate thermal disturbance due to each impact by taking into account the effects of shock propagation, crater excavation, isostatic rebound of transient crater and change in size of isobaric core. According to this study it is shown that settling of metal blob formed at the bottom of magma pond results in formation of metal rich layer just after accretion of Mars. However, core formation does not proceed during accretion because of high viscosity of undifferentiated core located at the center. To trace numerically gravitational overturn process of metal-rich layer and central undifferentiated core after the accretion of Mars we also developed a new numerical code to calculate core formation process of Mars. It is shown that the overturn process is dependent on the structure of viscosity in the central undifferentiated core. If the viscosity of the central core is 1023 Pa s, time of the overturn is less than 107 years. This result suggests that the core formation of Mars occurs at about 2 billion years after accretion of Mars.