Can Earth-like plate tectonics occur in ocean world ice shells?

摘要

The outer H2O ice shell of Europa, a Galilean satellite of Jupiter thought to exhibit a global interior water ocean, shows evidence for plate-like surface motions along tectonic boundaries. In this study, we investigate whether forces similar to those that drive plate tectonics on Earth may drive plate motions on icy satellites. We focus on whether the forces of slab pull and ridge push, driven by thermal and compositional buoyancy, can overcome the mechanical forces resisting plate motions to sustain interaction between surface ice and the interior ocean. We find that Earth-like plate tectonics is implausible within the outer ice shell of icy satellites because the forces resisting self-sustaining plate cycling are of significantly greater order than the driving forces. In the case of Ganymede and Triton, if it has a thick shell, plate tectonics would require warm, low-viscosity slabs to remain intact for timescales that are orders of magnitude longer than those of interior convection.