The bundle: a mega-scale glacial landform left by an ice stream, Western Bransfield Basin

Abstract

Ice masses were grounded at or near the shelf edge around the Antarctic Peninsula (AP) at the Last Glacial Maximum (LGM). Post-LGM warming led to ice ungrounding and retreat, which proceeded asynchronously from north to south (O Cofaigh et al. 2014). Bransfield Basin (BB) is one of the first places in Antarctica where multibeam bathymetry was systematically collected in the 1990s, resulting in the early imaging of glacial landforms on the modern seafloor (e.g. Canals et al. 2000). BB is a 450 km long marginal rift basin extending between the northern tip of the AP and the South Shetland Islands (SSI) (Fig. 1b). The Western Bransfield Basin (WBB) extends from the mouth of Croker Passage (CP) to Boyd Strait (Fig. 1a). Its deepest part is bounded by the volcanic high of Deception Island to the NE and several continental shelves. WBB bifurcates into SW–NE and SE–NW orthogonal branches (Fig. 1a). Fig. 1. ( a ) Swath-bathymetric image of the Western Bransfield Basin. HFZ: Hero Fracture Zone. Acquisition system Simrad EM12-S. Frequency 12.5 kHz. Grid-cell size 200 m (colour) and GEBCO_08 Grid (grey). Land area from Landsat Image Mosaic of Antarctica (US Geological Survey). ( b ) Location of study area (red box; map from IBCSO v. 1.0). …