With the recent increased interest in the evolution of volcanism, tectonism and volatiles on Mars, several studies have been initiated to infer the mass of water vapour and carbon dioxide that might have been released from magmas erupted on the martian surface over geological time (see refs 1,2). Such studies are complementary to investigations of the global volatile inventory for Mars^3,4, which trace a constant mass of volatiles to various sinks in the regolith, atmosphere and polar caps. Of necessity, these volatile distribution models are generalizations of Mars-wide averages. Here we present what we believe to be the first estimates for the amount of water vapour and/or carbon dioxide released, together with the corresponding release rates, from specific volcanic deposits on a relatively young martian volcanic construct (Alba Patera).