The Stress Shadowing Effect of the Tiger-stripe Fractures on Saturn’s Moon Enceladus

Abstract:

We present the first mechanical analysis on the formation of evenly spaced strike-slip faults. Two quantitative models based on the stress-shadow concept, which is 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 plate. 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 ~35 km, requires that the brittle ice-shell thickness be < 30 km and most likely in the range of 6-7 km, and the elastic ice-shell thickness be 0.7-3.5 km in the SPT. Modeling the TSF spacing also requires that the cohesive strength of the SPT ice shell be 30 kPa, much lower than the experimentally determined cohesive strength of 1.7-5.7 MPa under the laboratory conditions.