Linking planetary–scale spatio-temporal trends in magma compositions and volcanic resurfacing on Mars

Martian volcanism exhibits two key global trends: magmas evolved from alkali- and silica-rich compositions in the Noachian epoch to alkali depleted mafic compositions in the Amazonian, while spatially, young (Amazonian) volcanic resurfacing is confined to the Northern hemisphere and the Tharsis region, with no evidence of recent volcanism in the Southern highlands. A unifying model linking these observations has been lacking. Here, we investigate the relationship between spatio-temporal variations in volcanic resurfacing and the evolution of magma chemistry throughout martian geological history. By analyzing the physical conditions required for volcanic eruptions to be sourced from magma reservoirs located within the martian crust, we model how these conditions influence mantle-derived magma compositions. Our results show that dike propagation from magma chambers is controlled by crustal rheology, with dike height depending on chamber size, magma overpressure, and volatile exsolution (both in the reservoir and within the dike). During the Noachian, the thin crust allowed eruptions of both low- and high-degree mantle melts, consistent with the diverse alkalinity of ancient surface rocks. In contrast, the thickened Amazonian crust selectively filtered low-degree melts, necessitating high recharge rates in large magma reservoirs for eruptions. This filtering effect explains the alkali – depleted compositions of Amazonian basalts, as only high-degree melts could reach the surface. Our study provides a holistic framework connecting magma reservoir dynamics, crustal evolution, and the observed geochemical and spatio-temporal trends in martian volcanism.