Submarine glacial-landform distribution along an Antarctic Peninsula palaeo-ice stream: a shelf–slope transect through the Marguerite Trough system (66–70° S)

Abstract

The Antarctic Peninsula comprises a thin spine of mountains and islands presently covered by an ice sheet up to 500 m thick that drains eastward and westward via outlet glaciers (Davies et al. 2012). The peninsula has undergone recent rapid warming, resulting in the collapse of fringing ice shelves and the retreat, thinning and acceleration of marine-terminating outlet glaciers (e.g. Pritchard & Vaughan 2007). At the Last Glacial Maximum (LGM), the ice sheet expanded to the continental shelf break around the peninsula, and was organized into a series of ice streams that drained along cross-shelf bathymetric troughs (O Cofaigh et al. 2014). Marguerite Bay is located on the west side of the Antarctic Peninsula, at about 66–70° S (Fig. 1). A 12–80 km wide and 370 km long trough extends across the bay from the northern terminus of George VI Ice Shelf to the continental shelf edge. Extensive marine-geophysical surveys of the trough reveal a suite of glacial landforms which record past flow of an ice stream which extended to the shelf edge at, or shortly after, the LGM. Subsequent retreat of the ice stream was underway by c. 14 ka ago and proceeded rapidly to the mid-shelf, where it slowed before accelerating once again to the inner shelf at c. 9 ka (Kilfeather et al. 2011). Fig. 1. Regional bathymetry and shelf architecture of the Marguerite Trough shelf–slope system, Antarctic Peninsula (AP). The location of subsequent figures is shown. ( a ) Multibeam-bathymetric coverage of the Marguerite Trough system. Light grey is grounded ice; dark grey is floating ice. Inset: location of study area on the Antarctic Peninsula (red box; map from IBCSO v. 1.0). Regional bathymetry from IBCAO v. 3.0. Arrows denote perspective of oblique views in Figures 2a and 3a. ( b ) 130 km along-dip seismic-reflection profile showing Antarctic …