Geologic phenomena related to water on Mars: Post-impact hydrothermal systems, impact excavation and valley network evolution

The southern highlands of Mars record abundant geomorphic and geochemical signatures for the presence of liquid water on the surface. Crater age-dating places the formation of these signatures deep in the past, at least 3.7 billion years ago. We now benefit from a surge in lander and orbiter mission data acquired over the last decade that is allowing all aspects of Mars science to mature from qualitative supposition to rigorous quantitative description. By quantifying various geological phenomena associated with liquid water on ancient Mars, we can better understand the interplay between climate, surface and interior evolution over geologic time.This dissertation presents numerical and analytic models for three geologic processes related to water on Mars: post-impact hydrothermal systems that incorporate the effects of freezing aquifers, impact excavation and redistribution of subsurface clay-rich material, and valley network evolution under different climate scenarios. Key findings include: a mechanism for forming water-altered rock at the central peaks of craters: an explanation for the distribution of phyllosilicates (clays) on Noachian surfaces and geomorphic evidence for prolonged and episodic valley network formation.