Cross-shelf troughs in Central Bransfield Basin, Antarctic Peninsula

Abstract

During the Last Glacial Maximum (LGM), the ice masses covering the western side of the northernmost Antarctic Peninsula (NAP) drained into Bransfield Basin (BB) (Banfield & Anderson 1995). A drainage-basin area of about 60 000 km2 generated an ice flux that entrained significant volumes of englacial and subglacial debris that were subsequently delivered into BB. Multibeam-bathymetric data show a number of deeply sculpted, sub-parallel glacial cross-shelf troughs and associated landforms within the framework of an entire glacial depositional system (Canals et al. 2002; Garcia et al. 2011). Bransfield Basin is a 35 000 km2, SW–NE-orientated marginal basin situated between the South Shetland Islands (SSI) and the NAP and adjacent islands (Fig. 1a). BB consists of three sub-basins, the main one being the 1950 m deep Central Bransfield Basin (CBB) which is 215 km long and 120 km wide. The NAP margin of the CBB hosts several cross-shelf troughs opening into a sedimentary outer shelf (Fig. 1b) including Mott Snowfield, Laclavere and Lafond troughs (Canals et al. 2002). Fig. 1. ( a ) Location of study area (red box; map from IBCSO v. 1.0). SSI, South Shetland Islands; BB, Bransfield Basin. ( b ) Swath-bathymetric image of Central Bransfield Basin (CBB). Acquisition system Simrad EM12-S. Frequency 12.5 kHz. Grid-cell size 200 m (colour) and GEBCO_08 Grid (grey). Land area …