Patterns of Fracture and Tectonic Convergence near the South Pole of Enceladus

Abstract

Cassini’s Imaging Science Subsystem (ISS) coverage obtained to date shows that the Saturnianmoon Enceladus has evolved through a long and complex tectonic history[1]. The most recent episodes of major tectonic activity are identified by a peculiar hemispheric pattern of fractures and lineations that exhibit a remarkable symmetry relative to the satellite’s spin-axis. These tectonic patterns appear to be closely tied to a unique, geologically active region known as the South Polar Terrain (SPT) province, where ongoing eruptions of water plumes were recently discovered by Cassini[2] The detailed shapes and symmetry of the young tectonic patterns, detailed below, suggest that they formed in response to a global change in rotational figure. We investigate the extent to which the morphology, geographic placement, and orientations of these tectonic patterns are consistent with axial shortening of Enceladus’ spin axis, as suggested by Porco et al.[2].