Abstract
The recent Mars explorations brought discoveries of ice-rich materials, which would be formed geologically recently and could flow superplastically, in middle latitudes. It is generally considered that these ice-rich materials were formed during periods of high obliquity when water had been transported from polar regions to low and middle latitudes. Milliken et al. [2003] estimate strain rates of the ice-rich materials by using a flow low for ice proposed by Goldsby and Kohlstedt [2001]. However there are no studies about flow rates of the ice-rich materials. Flow rates of ice-rich materials mostly depend on grain (crystal) size, temperature and thickness of ice-rich materials. In this study, we estimate flow rates assuming one-dimensional laminar flow. Inside temperature of ice-rich materials is calculated by a climate model which includes slope effects and insolation changes by obliquity variations. Thickness is assumed to be several hundred meters. From the flow rates and formation age, we constraint grain size of ice in ice-rich materials.
