The ice content and internal structure of candidate debris-covered glaciers on mars and earth : insights from radar sounding

Martian lobate debris aprons are enigmatic mid-latitude landforms known to contain a significant fraction of water ice preserved at depth beneath a surface debris layer. They are thought to be important records of climate history and potential water resources for manned missions to Mars. However, their internal structure remains poorly constrained and regional variability in their ice purity is unknown. In this dissertation we report on a regional orbital radar sounding survey of lobate debris aprons in Deuteronilus Mensae – the region of highest concentration of lobate debris aprons on Mars – to constrain trends in lobate debris apron composition and possible internal structure. We also present a geophysical survey of Galena Creek Rock Glacier to constrain its internal structure as an analog to Martian lobate debris aprons. We found that the majority of radar observations imaged a basal reflector, from which we determined that the apron body is composed of material with dielectric properties consistent with relatively pure water ice and that there is no evidence for region-wide variability. Combining our compositional results with apron volumes constrained by Levy et al. (2014) sets the regional ice budget at 0.9-1.0 x 10⁵km³, the equivalent of roughly 4x the combined volume of water in the Great Lakes. We additionally showed that non-detection of basal reflectors in 13% of the observations may be attributed to high apron thickness and surface roughness-induced signal loss. In our analog work on Galena Creek Rock Glacier, we imaged its internal structure consisting of a network of englacial debris layers. This internal structure is indicative of intermittent debris and ice accumulation, with debris fall potentially playing a role in enhancing and facilitating ice accumulation. Similar englacial debris layers may exist in Martian lobate debris aprons, but are not imaged by the available orbital radar dataset due to their dip and thickness.