Subduction-like process in Europa's ice shell triggered by enhanced eccentricity periods

Abstract

Jupiter's icy moon Europa has a liquid water ocean beneath the ice shell and a geologically young surface, both related to extensive tidal processes. Interlaced by tectonic faults, the surface records convergent motions that induced crustal disappearance in some areas. Subduction has been advocated as an explanation; however, its driving mechanism still remains unexplained. We perform numerical simulations to test under what conditions may lateral compression initiate subduction in Europa's ice shell. We demonstrate that subduction-like recycling can occur only for shells of thickness less than or similar to 10 kilometers, transporting the surface ice into the subsurface ocean. We further show that compression large enough to initiate subduction-like behavior in a thin shell is achieved during brief periods of enhanced eccentricity, implying increased hydrothermal activity at the seafloor. Together with the subduction-like transport of surface oxidants, such conjunction should favor chemical disequilibria in the ocean, increasing its astrobiological potential.