Englacial and subglacial hydrological conditions responsible for the generation of Fountain Glacier proglacial icing: Bylot Island, Canada

The proglacial icing adjacent to Fountain Glacier, Bylot Island, is unique in the Canadian Arctic due to its perennial character. Observations show that the icing is partially eroded during the summer and is fully regenerated throughout the Arctic winter. Pressurized subglacial water storage is fundamental for the icing's regeneration since it provides the water used in the icing accretion. In addition, the combined action of a body of buried glacier ice and a proglacial thermal talik provide the subsurface connectivity needed to allow water to flow to the outwash plain in spite of the freezing temperatures of the Arctic winter. Studies have shown that there is a close relationship between the retreat of Fountain Glacier and morphological changes in the icing's thickness and in the location of its associated proglacial fountain. Although the interactions between glacier and icing have been well established, the specific hydrological conditions at the ice bed interface responsible for allowing the generation of the icing have not been yet fully explored. This study analyzes Fountain Glacier's subglacial hydrological, morphological and thermal characteristics, by means of geophysical, topographical, photogrammetric and remote sending techniques. Results indicate that Fountain Glacier presents favourable subglacial conditions to store and conduct water, thus assuring the annual generation of the icing. First, low creep rates of cold ice lead to the preservation of a well defined channelized subglacial drainage system. A subglacial drainage model predicts two main waterways used by subglacial water. The termini of both of these match the location of current ice collapse features and remnants of sediment filled subglacial conduits. Second, a reflection power analysis, conducted over the shallow geophysical data, suggests that the lower ablation area has a high accumulation of liquid water, particularly beneath the centre part of the glacier along the glacier's main supraglacial stream. Finally, a dielectric permittivity model constructed over the glacier - sediment interface, indicates that a considerable portion of the glacier is warm based; allowing water to flow through unfrozen subglacial sediments towards the proglacial icing.