ENCELADUS'S TECTONIC HISTORY IN DEEP TIME

Previous work on Enceladus has shown that nonsynchronous rotation stresses and diurnal tidal stresses have played a leading role in forming and driving the geologic activity both within and outside of the south polar terrain (SPT). In particular, the cratered terrains of the sub-Saturn and anti-Saturn hemispheres may have recently undergone tectonic deformation, in the form of features called pit chains. Greater scrutiny of the cratered terrains has revealed ancient fracture systems, which appear to predate most of the cratering. We suggest that these older fractures may record a period of tectonic deformation early in Enceladus’s history. The distribution, orientation, and morphological characteristics of the tectonic structures underlying the cratered terrains on the leading and trailing hemispheres have been characterized. We aim to determine if patterns of these ancient fractures, predominantly within the cratered terrains, can be related to a global-scale stress mechanism acting during some of the earliest stages of tectonic deformation on Enceladus. Detailed fracture mapping of the underlying tectonic structures within the cratered terrains may reveal fracture patterns that can be compared with theoretical stress fields produced by different stress mechanisms. Agreement between observed and theoretical fracture patterns will pinpoint stress mechanism(s) relevant to the earliest stages of Enceladus’s geologic activity. We present preliminary maps of ancient fractures within the cratered terrains and possible stress mechanisms they may have produced these fracture patterns.