Volatiles in Martian Magmas and the Interior: Inputs of Volatiles Into the Crust and Atmosphere

Abstract Martian basaltic magmas are presumably the primary mechanism of transfer of volatiles from the mantle to the surface and atmosphere. Therefore in order to understand the concentrations of volatiles in the crust, it is vital to first constrain the volatile budget of the Martian interior, the preeruptive volatile content of Martian magmas, and evidence within the Martian meteorites for magmatic degassing. However, the concentrations of volatile species in ascending magmas and in their mantle source regions are highly uncertain and probably variable in space and time. Here, we discuss the constraints on the volatile content (water, halogens, sulfur, carbon, and nitrogen) of the Martian interior and basaltic magmas, and evidence for degassing of magmatic fluids into the Martian crust. Volatile elements are distributed heterogeneously in the crust and mantle of Mars, due to the combination of distribution from primary differentiation, presumably in a magma ocean, fractionation during magma genesis and evolution, loss from magmas at low pressure, and redistribution in the crust by aqueous processes.