Modeling the volcanism on Mars

The total amount of melt produced in Mars during its evolution is estimated by means of a parameterized, one-dimensional, analytic mantle convection m odel that assumes a stagnant lid and whole mantle convection. The fertility of the mantle-defined as the potential to create basalt-and its variation with time are taken into account. The model is composed of core, mantle, an d lithosphere, with two boundary layers separating them. The contributions to volcanism by pressure release melting (PRM), and by plumes from the core -mantle boundary layer, are compared and discussed. We show that such model s tend to produce considerable melting during the early evolution of the pl anet, and that the amount of melting depends strongly on the abundances of radioactive elements. Although the model's assumptions may not be valid for the early evolution of the planet, the model is relevant to the later hist ory, which is insensitive to initial conditions. We find that PRM volcanism should have ceased between 1 and 2.5 Byr ago and any recent volcanic activ ity must have originated in plumes. (C) 2001 Academic Press.