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

Abstract The outer H 2 O 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. Highlights • Earth-like plate tectonics unlikely in the outer ice shells of icy satellites • Mechanical resisting forces are much greater than driving buoyancy forces. • Buoyancy forces most important on large ocean worlds w/ thick ice shells • Secular stresses on the order of 10 MPa required to produce Europa features • Forcing most likely to be from a decoupled ice shell or global freezing/thawing [ABSTRACT FROM AUTHOR]