Article révisé par les pairs
Résumé : The co-isotopic composition, both in δD and in δ18O, of interbedded debris-rich and clear ice layers, thought to have been formed at the grounding line of Hells Gate Ice Shelf, indicates freezing by a double-diffusion effect between continental meltwater and sea water within a subglacial sediment. A source of meltwater is required to sustain the process, since the temperature of the bed is below the freshwater melting point. The most likely source is a surficially frozen meltwater lake.Rock outcrops, kept mostly snow-free by the action of katabatic winds, absorb solar radiation so local production of liquid water becomes possible in an area with year-round subfreezing air-temperature conditions. The meltwater accumulated in a marginal lake can eventually reach the subglacial substratum near a pinning point where the ice is relatively thin and fractured