Thermally triggered viscous flow and formation of the tiger-stripe fractures in the South Polar Terrain of Saturn’s moon Enceladus

Wed, Mar 9, 2016 at 3:00 pm

131 Campbell Hall

An Yin (UCLA)

The tiger-stripe fractures in the South Polar Terrain of Saturn’s icy moon Enceladus emit vapor jets contributing to the formation of Saturn’s E ring. Despite their spectacular display of active geologic processes, the origin of the fractures and their hosting South Polar Terrain remains poorly understood. In this talk I will show, via systematic analysis of high-resolution satellite images, that the South Polar Terrain was developed by glacier-like flow of a strip of Enceladus’ ice shell driven by gravity. The flow is accompanied by clockwise rotation of the South Polar Terrain, which is accommodated by horizontal shifting along the tiger-stripe fractures. I will demonstrate the mechanics of the inferred geological process using simple analogue experiments. Finally, I will use a stress-shadow model to quantify the relationship among the spacing of the tiger-stripe fractures, the ice shell thickness, and the fracture strength of the South Polar Terrain.