Tectonic lineations and frictional faulting on a relatively simple body (Ariel)

Andersonʹs model of faulting and the Mohr-Coulomb failure criterion can predict the orientations of faults generated in laboratory triaxial compression experiments, but do a much poorer job of explaining the orientations of outcrop- and map-scale faults on Earth. This failure may be due to the structural complexity of the Earthʹs lithosphere, the failure of laboratory experiments to predict accurately the strength of natural faults, or some fundamental flaw in the model. A simpler environment, such as the lithosphere of an icy satellite, allows us to test whether this model can succeed in less complex settings. A mathematical method is developed to analyze patterns in fracture orientations that can be applied to fractures in the lithospheres of icy satellites. In a initial test of the method, more than 300 lineations on Uranusʹ satellite Ariel are examined. A nonrandom pattern of lineations is looked for, and the source of the stresses that caused those features and the strength of the material in which they occur are constrained. It is impossible to observe directly the slip on these fractures. However, their orientations are clearly nonrandom and appear to be consistent with Andersonian strike-slip faulting in a relatively weak frictional lithosphere during one or more episodes of tidal flexing.