Water on Mars: Clue to accretional history

Geological evidence for large amounts of water at the Martian surface appears to be in conflict with geochemical evidence from SNC meteorites that suggests that the Mars mantle is dry and should have lost almost all of its initially large inventory of water during accretion. Here, several possibilities are suggested as to how the apparently conflicting data from two sources may be reconciled. The considerations examined indicate that several plausible explanations for the apparent conflict between geochemical evidence of little water on Mars and geologic evidence of abundant water. One possible conclusion is that Mars has a primitive volatile-rich crust that has been partly overplated with young, dry, mantle-derived volcanoes of which we have samples in the SNC meteorites.