Mantle Convection and Magma Production on Present-day Mars: Effects of Temperature-dependent Rheology

 

Qingsong Li and Walter S. Kiefer

 

 Lunar and Planetary Institute, Houston, 77058, USA

 

Using recent volcanism on Mars as an important constraint, we explore the nature of present-day mantle convection using numerical simulations with temperature-dependent Arrhenius viscosity. Increasing the activation energy decreases both the magma production rate and the convective heat flux, while increasing the thermal Rayleigh number increases these quantities. For values of the activation energy inferred from lab studies of olivine, a thermal Rayleigh number (defined with a volume-averaged viscosity) exceeding 2×10⁶ best fits the observational constraints, including the recent volcanism rate and the range of melt fractions in the shergottites. The heat flux out of the core is low enough to avoid a magnetic dynamo, an important improvement over prior work. These results indicate that present-day mantle convection on Mars remains relatively vigorous.