Influence of glaciological structures on the spatial distribution of cryoconite holes, northern Victoria Land, East Antarctica

Three blue-ice areas in the upper reaches of Rennick Glacier, East Antarctica, are investigated using satellite remote sensing to assess the influence of meso- to large-scale glaciological structures on cryoconite hole distribution. In total, 15 299 cryoconite holes and 1 600 structures are geospatially analysed, which indicate cryoconite holes are commonly concentrated in areas with prominent meso-scale ice structures. The emergence of debris entrained in primary stratification promotes the development of cryoconite holes along the surface expression of debris-bearing layers. Differential ablation of penetrative structures and their constituent ice facies can form a ridge-and-furrow ice-surface topography that captures supraglacial hydrology and sediments. As a result, trains of cryoconite holes develop in furrows that trace the surface expression of planar layers. Large-scale topographic barriers that form at flow-unit boundaries constrain cryoconite holes within discrete flow units by inhibiting the transport of supraglacial sediments. The majority of cryoconite holes are located in low-slope areas (< 5°) where sediments are less susceptible to stripping events. Cryoconite holes on steeper slopes are preferentially located near to flow-unit boundaries where the topographic expression of meso-scale structures can offset the influence of larger-scale topography by preventing sediments being washed down-slope. Although a range of variables can influence the distribution of cryoconite holes, meso- to large-scale structures play an important role in the development of ice-surface topography and the delivery of sediments from different sources, which can strongly influence the distribution and composition of cryoconite holes.