Thermal history, core formation and tectonics of Mars

我们已经构建了一个新的数值模型的早期热历史和金属/硅酸盐分离的火星吸积过程中，我们评估的热扰动，由于考虑到冲击波传播的影响，陨石坑挖掘，均衡反弹的瞬态陨石坑和等压核心的大小变化。根据这项研究，它表明，在岩浆池底部形成的金属滴的沉降导致形成的富金属层后不久，火星吸积。然而，核心的形成并没有进行在吸积，因为高粘度的未分化核心位于中心。为了数值追踪火星吸积后富金属层和中央未分异核的引力翻转过程，我们还开发了一个新的数值程序来计算火星核的形成过程。结果表明，翻转过程依赖于中央未分化核的粘性结构。如果中心核的粘度为1023 Pa·s，则翻转时间小于107年。这一结果表明，火星的核心形成发生在火星吸积后约20亿年。

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.