Study of the fluvial activity on Mars through mapping, sediment transport modelling and spectroscopic analyses

Abstract

Mars is the only planet, other than Earth, for which there are several evidences that liquid water was abundant at the surface. Among them, one of the best evidence is that the ancient terrains of Mars are covered with fluvial and lacustrine features such as valley networks, longitudinal valleys and basin lakes. In addition, spectroscopic data have shown the widespread presence of aqueous alteration minerals on the Martian surface, including clays composed by phyllosilicates and hydrated salts. The main subject of my PhD is the study of these specific features (such as valley networks and paleolakes) on Mars surface, both from the geological and spectroscopic point of view through mapping, sediment transport modelling and CRISM spectra analyses. There are, in fact, no doubts that these structures were carved by liquid water, but several questions remain about the mechanisms of their formation and the climatic conditions under which this formation occurred. In this context, the study of these structures along with the identification of hydrated minerals, are a key in the investigation of the past climatic conditions of the planet which can have, in turn, important astrobiological implications. I updated previous global maps of Martian valleys using a new photomosaic of the Martian surface and data at higher resolution with respect to those used in the previous works. Furthermore, I selected a subset of the mapped valleys which includes 63 large fluvial systems and evaluated their formation timescales on the basis of sediment transport modelling. In addition, analyses of CRISM spectral data were performed on a sample of open/closed basin lakes (associated with the mapped valleys) detecting the possible presence of hydrated minerals, in particular (Fe/Mg-smectite), sometimes in association with mafic materials (olivine).