Mars's Crustal and Volcanic Structure Explained by Southern Giant Impact and Resulting Mantle Depletion

Abstract

Mars features a crustal dichotomy, with its southern hemisphere covered by a thicker basaltic crust than its northern hemisphere. Additionally, the planet displays geologically recent volcanism only in its low latitude regions. Previous giant impact models coupled with simulations of mantle convection have shown that the crustal dichotomy can be explained by post-impact melt crystallization that emplaced a thick crust in the southern hemisphere. In this study, we show that the depleted residue left behind by the original post-impact crustal formation can spread laterally, potentially persisting beneath the northern hemisphere to the present-day. Such a large-scale mantle province would concurrently explain both the prevalence of long-term magmatism on Mars and its strong preference for localized equatorial regions.