Mechanics of evenly spaced strike-slip faults and its implications for the formation of tiger-stripe fractures on Saturn’s moon Enceladus

Abstract

We present the first mechanical analysis based on realistic rheology and boundary conditions on the formation of evenly spaced strike-slip faults. Two quantitative models employing the stress-shadow concept, widely used for explaining extensional-joint spacing, are proposed in this study: (1) an empirically based stress-rise-function model that simulates the brittle-deformation process during the formation of evenly spaced parallel strike-slip faults, and (2) an elastic plate model that relates fault spacing to the thickness of the fault-hosting elastic medium. When applying the models for the initiation and development of the tiger-stripe fractures (TSF) in the South Polar Terrain (SPT) of Enceladus, the mutually consistent solutions of the two models, as constrained by the mean spacing of the TSF at ∼35km, requires that the brittle ice-shell thickness be ∼30km, the elastic thickness be ∼0.7km, and the cohesive strength of the SPT ice shell be ∼30kPa. However, if the brittle and elastic models are decoupled and if the ice-shell cohesive strength is on the order of ∼1MPa, the brittle ice shell would be on the order of ∼10km.