Gebra Slide: glacial and tectonic controls on recurrent submarine landsliding off the northern tip of the Antarctic Peninsula

Abstract

Late Quaternary–Holocene submarine landslides occurring in high-latitude, glacial-influenced continental margins have been increasingly investigated during the last three decades. Both relatively small and large landslides have been identified in these settings (e.g. Canals et al. 2004; Vanneste et al. 2006). However, much more evidence on submarine instabilities is available from the Arctic than the Antarctic. Bransfield Basin (BB) is a 450 km long, SW–NE-orientated, marginal rift basin opening between the South Shetland archipelago and the northern tip of the Antarctic Peninsula (AP) (Fig. 1a, b). The middle part of BB is occupied by the 215 km long and 120 km wide Central Bransfield Basin (CBB), bounded at its ends by transverse ridges forming the volcanoes of Deception (not shown) and Bridgeman islands. CBB is asymmetrical, with a narrow and steep South Shetland margin and a broader and gentler AP margin, where the continental shelf is about 70 km wide (Fig. 1a). Fig. 1. ( a ) Shaded-relief bathymetric image of the Central Bransfield Basin. Acquisition system Simrad EM12-S. Frequency 12.5 kHz. Grid-cell size 200 m (colour image) and GEBCO_08 Grid (grey image). Land area is from the Landsat Image Mosaic of Antarctica (US Geological Survey). ( b ) Location of study area (red box; map from IBCSO v. 1.0). SSI and BB refer to South Shetland …