Skip to content

Shallow Cryovolcanic Melt as a Test of Subduction in Europa's Ice Shell

Stephanie Menten, Michael Sori, Brandon Johnson

Abstract

Europa is an icy moon of Jupiter whose surface is tectonically active. Kattenhorn and Prockter [2014] suggest a region of this active surface is mobile and undergoing subduction into Europa's subsurface. Evidence for subduction includes the mapping of smooth, lobate flows on the identified overriding plate as potential cryovolcanic flows. However, flux melting (which drives arc volcanism on Earth by releasing water into the overlying mantle) is not relevant to icy subduction. Here, we test different subduction-induced melting scenarios on Europa using other melt formation mechanisms, such as heating via friction or the incorporation of relevant Europan salts into the subducting slab.   We use a one-dimensional subduction model to evolve temperature through time to track change in temperature as an icy slab subducts into Europa's subsurface. Additionally, we measured that putative cryolavas extend 90 km away from the margin, meaning the subduction angle must be shallow (4.4--18.4°) to provide melt to form the lavas. We find melt can form as shallow as 4 km in Europa's subsurface, which is 26 km shallower than the depth of the ocean (if Europa's ice shell were 30 km in thickness).   Overall, we find that shallow melt from subduction is feasible in an icy subduction scenario with the aid of frictional heating and salt. We predict that if there is cryovolcanic melt formed from subduction in the region proposed by Kattenhorn and Prockter [2014], the upcoming Europa Clipper mission could use its radar instrumentation to look for cryomagma at our predicted depths.