The seafloor imprint of the Gerlache–Boyd Ice Stream (65–62° S), northern Antarctic Peninsula

Abstract

The northern Antarctic Peninsula (NAP) forms a narrow stretch of land that extends to a relatively low latitude (63° S) and is subject to a humid, maritime-influenced climate, especially on its western side. During the Last Glacial Maximum (LGM), the NAP was covered by the northern part of the Antarctic Peninsula Ice Sheet (APIS) (Lavoie et al. 2015). The APIS fed ice streams flowing on both sides of the NAP, including the Gerlache–Boyd Ice Stream (GBIS) (Canals et al. 2000). Fast-flowing ice streams are the most dynamic components of ice sheets and largely determine ice-sheet mass loss and stability (Bentley 1987; Bamber et al. 2000). They transport large volumes of sediments both subglacially and englacially, and shape a variety of landforms both on land and the seafloor (e.g. Dowdeswell & Elverhoi 2002). During the LGM and throughout deglaciation, the role of ice streams was particularly significant. We describe the landforms associated with the GBIS based on a comprehensive compilation of multibeam bathymetry. The set of landforms and deposits left by the GBIS ranges in age from LGM to present, and illustrates both the products of ice-stream dynamics and how post-glacial processes can mask this glacial imprint. Our aim is to understand the dynamics of the GBIS and its temporal evolution since the LGM. In addition, the role of underlying geological control on the overall physiography of the GBIS is assessed. The study area extends 365 km from the southern end of Gerlache Strait (GS) to the South Shetland deep-sea trench and is fed by a glacierized catchment of about 23 000 km2 (Fig. 1a) (Canals et al. 2000). The height difference from the ice divide to the deep-sea trench is c. 6700 m. The GBIS system was the main drainage pathway of this catchment (O Cofaigh et …