East Antarctic ice flow dynamic based on subglacial landforms near Dibble Glacier

Abstract

Paleo ice sheet reconstruction in Antarctica provides key constrains for understanding and predicting future ice sheet behaviour. Along the East Antarctic margin there are still large sections with little or no information about previous extent and dynamics of the paleo-ice sheet. Here we present new multibeam and Chirp subbottom data from the East Antarctic continental margin between the Frost and Dibble Glaciers (128°E and 134°E), acquired during expedition NBP1503 with the icebreaker NB Palmer. The inner continental shelf shows a moderately deep seafloor (200–600 m) with steep and deeply incised channels, most likely created by subglacial meltwater. On the mid shelf we identified a ~1000 m deep basin with drumlin-shaped and linear glacial features. The shelf break is relatively shallow (300–400 m) and incised by numerous gullies that extent onto the continental slope. The presence of these features suggests that grounded, streaming ice has reached the shelf break during the last glaciation. Both, the subglacial channels on the continental shelf and the numerous gullies near the shelf break are indicative of melt water underneath the grounding ice. Our interpretation suggests that compared to toady the ice flow in this area might have been significantly different during glacial times when the paleo ice sheet cover most or all of the continental shelf.