No magmatic driving force for Europan sea-floor volcanism

Abstract

The internal ocean of Jupiter’s moon Europa is thought to be a prime candidate for hosting extraterrestrial life. Europa’s silicate interior may contribute to habitability through the generation of reactants from hydrothermal activity, serpentinization or other geological processes occurring on or just below Europa’s sea floor. However, silicates are thought to melt at depths >100 km in Europa’s mantle, and it is unknown whether this magma can penetrate and travel through the moon’s probably thick, brittle lithosphere to erupt at the sea floor. We combine previous approaches for modelling melt generation in the Europan interior and lithospheric dyke transport to show that Europan sea-floor volcanism is strongly inhibited by its lithosphere. The low stress state of the Europan interior hinders the ability of dykes to penetrate through the lithosphere. Should dykes form, they penetrate <5% of the 200–250-km-thick lithosphere. Low mantle melt fractions (3–5%) drive a sluggish pore-space magma flow, leading to dyke influxes 10,000 times lower than that necessary for sea-floor eruption. These results strongly indicate that models of Europan habitability reliant on present-day volcanism at its sea floor are implausible. Magma produced at depth in Europa’s mantle is unable to penetrate its rigid lithosphere to erupt on the sea floor. The presence of habitability-supporting volcanic activity at the base of Europa’s water ocean is thus extremely unlikely.