On the relative importance of thermal and chemical buoyancy in impact-induced melting on Mars

Convection in planetary mantles is driven by buoyancy that results from density variations, which may have thermal or compositional causes. We study the relative importance of the thermal and compositional contributions to the buoyancy of melt-induced density heterogeneities in Mars by coupling two-dimensional, fully dynamical convection models with a detailed model of the mineralogy and material properties of martian peridotite. The main focus lies on the anomalies created by giant impacts, which lead to particularly intense, high-degree melting that may reach deeper than the regular global asthenospheric melting zone. We investigate the differences in the evolutions of models with only thermal and with both thermal and compositional buoyancy for impacts of different sizes; the compositional aspect has been neglected in most previous studies