Dynamical and chemical evolution of Mars- and Venus-like Planets

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2D and 3D models of convection and melting in Mars, Venus, and similar one-plate planets will be combined with models of the mineralogy and the thermoelastic properties of the mantle in order to simulate the evolution of these planets since solidification of the mantle 4.4-4.5 billion years ago, and to explain certain geological structures on their surface. Issues of particular interest include the stability of their lithospheres, the various volcanic structures on Venus, and the formation of two apparently long-lived volcanic centers on Mars. Central aspects are the effect of phase transformations of mantle minerals on global convection patterns and mantle plumes dynamics and the effect of trace components (radionuclides and volatiles) and their redistribution through convection, melting, and volcanism. In view of the limited knowledge of the composition and the mantle-to-core ratio certain model parameters such as the thickness of the mantle, the ratio of magnesium and iron, and the radionuclide and water content will be varied. Furthermore, the influence of surface temperature and, in the case of Mars, the effect of lateral temperature and thickness variations in the lithosphere caused, e.g., by the crustal dichotomy as well as the role of ancient compositional heterogeneities will be explored. In this context parameter combinations will be considered that are not relevant for Mars or Venus but are of general interest e.g. with respect to exoplanets. The models will yield geophysical and geochemical observables that can be compared with real observations.