Contributions of saline meltwater to ice flow and its remote sensing signatures

Icy moon interiors and terrestrial glacier environments often contain a degree of saltwater melt. This liquid phase can modify the flow of ice, creating preferred directions for deformation through a melt preferred orientation (MPO) that may form in response to stress. Ice crystals adjust on the microscale to drive flow, imparting a crystallographic orientation fabric (COF) that can also be measured to infer the subsurface stress and strain conditions. We show results from laboratory experiments on compressive flow, characterizing the response of both ice crystals and saltwater melt as they together define the geophysical properties of multiphase, partially melted ice. We observe conclusively that an MPO forms parallel to the compressive stress direction, enhancing and possibly tracking material flow, and note that the extent of solid material deformation may decrease with increasing melt fraction. Finally, we combine evolving COF and MPO to define potential radar sounding returns as indicators of subsurface flow, finding that MPO imparts distinct signatures that may be useful in decoding the stress and strain state of icy settings from remote sensing observations.