This session welcomes presentations about volatile and fluid flows on the Martian surface and subsurface. Hydrothermal fluid circulation in the Martian crust is among the natural processes characterized by the combined involvement of fluids, such as water and methane, so defining a potential set of environments prone to biosphere growth and flourish. Aqueous fluid migration affects a broad range of physical, chemical, mechanical and thermal properties of the upper crust and it is closely linked to the transport of mass, heat, nutrients and chemical species in hydrogeological systems. Thus, fluid flows are central in fields such as volcano-tectonic, deep-biosphere and water/ice cycle. Accordingly, participants are encouraged to apply for this session with contributions concerning fluid migration mechanisms, products and effects, volatile evolution from erosion to deposition, diagenesis and astrobiological potential, both on Mars and terrestrial analogue sites. Experimental and numerical modeling of fluid circulation processes and water-rock interaction are also welcome.