Although water ice is one of the most common substances in the solar system, it is also one of the most enigmatic, with much remaining unknown about its flow and frictional properties. Our understanding and interpretation of geophysical data of glaciers and icy satellite surfaces can be significantly enhanced through improved knowledge of the rheology of ice, which is controlled by features at the grain scale. Impurities, second phases, grain size, and textures (including partial melt) in multiphase systems can all influence the mechanical response and therefore the morphology of geological features. Depending on the solidification conditions, solid second phases can form an interwoven network with ice when forming from a liquid solution. This eutectic microstructure influences the viscous and anelastic behavior of the aggregate and can be predicted by thermodynamics, applying the same physics as used to describe growth of metal alloys. At temperatures above the solidus, melt phases (for instance, those evidenced by geysers and surface flow features on icy moons) and equilibrium melt geometry have significant impact on solid-state convection, tidal dissipation, modulus, and friction, and are significant because they could additionally provide pathways for pollutants and nutrients. I will share results from ultrasonic measurements, creep tests, and friction experiments at subsolidus and suprasolidus conditions on several ice binary systems that have significance to Earth and Planetary science. I will discuss how these properties can influence glacier and ice stream flow rates on Earth, as well as surface expressions of tectonics and cryovolcanism on icy moons of the outer solar system.

Microstructures and mechanical response of ice mixtures, with application to terrestrial glaciers and icy satellites

2019 Fall National Meeting

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