Tectonics on the icy satellites and dynamics of the icy shell

Kimura, Jun

Most eminent feature of tectonic activity on the icy satellites is extensional signatures, which have been formed by tensional stress. The example is narrow ridges and bandshaped terrain on Europa, and parallel, periodically spaced fractures called by Tiger Stripes on Enceladus. These features suggest a possibility that the surface have been fractured and extended due to tensional stress. We have focused on the solidification of the liquid water and the accompanying volume change as one of the dominant sources for such stresses. To estimate the stress state in the solid ice region surrounding the water region, we first performed numerical simulations of the thermal history. Based on the resulting structural evolution, we calculated stresses in the viscoelastic ice region due to the solidification of the liquid water. Europa's liquid layer solidifies slowly and may partially survive at present, and its solidification induces sufficient tensional stress to drive extensional tectonic activity. Moreover, we investigated the possibility that solidification of subsurface water reservoir in Enceladus can attain enough excess pressure to explain the geysering. If the viscosity of the surrounding ice is viscous enough to inhibit relaxation, as high as 10^20-21Pas, sufficient excess pressure can be accumulated and the crack will be created to drive the internal water to the surface.

Tectonics on the icy satellites and dynamics of the icy shell

Bibliographic Information

Description

Journal

Details 詳細情報について

Export

Report a problem