Modification post-impact des cratères par le volcanisme sur les planètes telluriques

On terrestrial planets such as Mars, Venus or the Moon, traces of past or recent volcanic activity are visible. These are often associated with impact craters. On each of these bodies, however, the alteration of craters by volcanism manifests itself in different ways: radar observations of the surface of Venus indicate that two-thirds of the craters are partially filled, from within, by magma. On Mars and the Moon, many craters have uplifted and fractured floors, but show no evidence of volcanic eruptions; they are thought to be subjected to sill-like magma intrusions at shallow depths. In this thesis, we are interested in these post-impact modifications of craters by volcanism, and in explaining their variety across the different planets studied. Based on observations of unaltered craters, we reconstruct the typical crater topography for each of the bodies studied and calculate the stress field generated by the crater topography. These fields are then used in simulations of the propagation of magma as dykes within planetary crusts in order to study the consequences of the presence of craters on the ascent of magma towards the surface. It has been shown that the perturbation generated by a crater helps the ascent of magma that is denser than the crust, which would normally remain stored at depth. We show here that the differences in the post-formation modification of craters on the planets studied and resulting from this phenomenon can be explained by a greater deflection of the dyke on the Moon and Mars, even going as far as horizontalisation the dyke beneath the crater. On Venus, deflection will be smaller, allowing the magma to reach the surface only within the crater. This also allows us to place constraints on the properties of the crust and magma that are favorable to these observations.