Thermal convection with a water ice I rheology: Implications for icy satellite evolution

Abstract

We model stagnant–lid convection for water ice I using a multicomponent rheology, combining grain boundary sliding, dislocation and diffusion creep mechanisms. For the superplastic flow–dislocation creep rheology, dislocation creep ( n = 4 ) dominates the deformation within the actively convecting sublayer whilst superplastic flow ( n = 1.8 ) is the dominant process within the stagnant–lid whilst for the superplastic flow–diffusion creep rheology, superplastic flow is the dominant deformation mechanism within the convecting sublayer while diffusion creep ( n = 1 ) is the dominant deformation process in the stagnant–lid. These results suggest deformation in the actively convecting sublayer is likely to be dominated by the mechanism with the largest stress exponent. We also provide heat flux scaling relationships for the superplastic flow, basal slip, dislocation creep–superplastic flow and superplastic flow–diffusion creep rheologies and provide a simple parameterized convection model of an icy satellite thermal evolution.