Antarctic palaeo-ice streams

We review the geomorphological, sedimentological and chronological evidence for palaeo-icestreams on the continental shelf of Antarctica and use this information to investigate basal conditions and processes, and to identify factors controlling grounding-line retreat. A comprehensive circum-Antarctic inventory of known palaeo-icestreams, their basal characteristics and minimum ages for their retreat following the Last Glacial Maximum (LGM) is also provided. Antarcticpalaeo-icestreams are identified by a set of diagnostic landforms that, nonetheless, display considerable spatial variability due to the influence of substrate, flow velocity and subglacial processes. During the LGM, palaeo-icestreams extended, via bathymetric troughs, to the shelf edge of the Antarctic Peninsula and West Antarctica, and typically, to the mid-outer shelf of East Antarctica. The retreat history of the AntarcticIce Sheet since the LGM is characterised by considerable asynchroneity, with individual icestreams exhibiting different retreat histories. This variability allows Antarcticpalaeo-icestreams to be classified into discrete retreat styles and the controls on grounding-line retreat to be investigated. Such analysis highlights the important impact of internal factors on icestream dynamics, such as bed characteristics and slope, and drainage basin size. Whilst grounding-line retreat may be triggered, and to some extent paced, by external (atmospheric and oceanic) forcing, the individual characteristics of each icestream will modulate the precise timing and rate of retreat through time.

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