Palaeo-records of rapid ice stream retreat are important as they can be used to identify the processes involved, and inform investigations of present-day ice masses. Here we document a previously unknown retreat stage in northernmost Bjørnøyrenna (Bear Island Trough) in the northern Barents Sea, representing the youngest stage in a stepwise retreat of the Bjørnøyrenna Ice Stream. We present a descriptive landsystem model for retreat of a marine-based ice stream, which provides new insights into the glacial dynamics of the episodic retreat stages. This model captures the landforms produced during a cycle of 1) fast ice stream flow, 2) intense calving of large icebergs locked in a dense matrix of smaller icebergs, probably from a collapsed ice shelf, 3) ice-stream stagnation, 4) ice-stream floating off, forming an ice shelf as the grounding line retreats, and eventually 5) ice-shelf disintegration. We hypothesize that the presented ice-stream retreat model reflects glacial surging. The formation of corrugated furrows in the study area is consistent with interpretation of similar features in Pine Island Bay, West Antarctica, which are interpreted to have been formed during a massive ice shelf break-up and associated grounding line retreat.
Two directions of past ice flow are indicated from streamlined glacial landforms in the study area. Ice flow from north north-east is indicated for the Last Glacial Maximum and an early phase of deglaciation, whereas a shift to flow from north north-west, from an ice dome located over Hinlopenstretet, Svalbard is indicated for the latest deglaciation phases of the Bjørnøyrenna Ice Stream.
