No Magmatic Driving Force To Supply Europan Seafloor Volcanism

The ocean of Jupiter’s moon Europa is thought to be a prime candidate for hosting extraterrestrial life. In the absence of sunlight, an ice-covered oceanic biosphere cannot be sustained by photosynthesis, instead requiring consistent geochemical input from Europa’s ice shell and rocky interior. Europa’s silicate interior may contribute to habitability via the generation of reactants through hydrothermal activity, serpentinization, or other byproducts of volcanic processes occurring on or just below Europa’s seafloor. However, silicate melting is thought to occur at >100 km depth in Europa’s mantle and it is unknown if this magma is able to penetrate and travel through a thick, brittle lithosphere in order to erupt. Here we combine previous modeling approaches to Europan interior melt generation9 and lithospheric dyke transport to show that Europan seafloor volcanism is strongly inhibited by its lithosphere. The low stress state of the Europan interior hinders breakage of its lithosphere to emplace new dykes. In the event that new dykes do form, they penetrate <5% of the 200–250 km thick lithosphere. Low mantle melt fractions (3-5%) drive sluggish pore-space magma flow, leading to dyke influxes 10,000 times smaller than what is necessary for seafloor eruption. These results strongly suggest that models of Europan habitability reliant on present-day volcanism at its seafloor are implausible, and if seafloor volcanism is required for life in Europa’s ocean, the ocean is uninhabitable.