Landform assemblage produced by ice-grounding events on the Yermak Plateau

Abstract

The landforms and sediments preserved on the Yermak Plateau (Figs 1, 2, 3) provide information on the glacial history and past dynamics of the northwestern-most sector of the Eurasian Ice Sheet (Dowdeswell et al. 2010; Gebhardt et al. 2011), as well as the exchange of ice and water between the North Atlantic and the Arctic Ocean via Fram Strait (Fig. 1a) (Jakobsson et al. 2010). Early ideas about Quaternary ice cover in the Arctic Ocean proposed the existence of a circum-Arctic ice shelf prior to the last glaciation (e.g. Mercer 1970). More recent work suggested that the major glaciations since the interglacial period of marine oxygen isotope stage (MIS) 5.5 did not extend beyond the Eurasian continental shelf edges. However, geophysical data reveal that ice extended across the Yermak Plateau prior to MIS 5.5 during the particularly extensive glaciation in MIS 6 (Dowdeswell et al. 2010; Jakobsson et al. 2010). By contrast, the presence of a grounding-zone complex beyond NW Spitsbergen (Fig. 3) implies that grounded ice did not extend onto the Yermak Plateau during the Last Glacial Maximum (LGM) (Ottesen & Dowdeswell 2009). Fig. 1. ( a ) Merged multibeam data from the Yermak Plateau (from cruises: ARK-XVIII/2 and ARK-XX/3 Polarstern ; JR142 James Clark Ross ; and 2007, 2008 and 2009 Oden ). Polarstern multibeam acquisition system Atlas Hydrographic DS-2. Frequency 15.5 kHz. James Clark Ross and Oden multibeam acquisition systems Kongsberg EM120 and EM122. Frequency 12 kHz. Grid-cell size 20–50 m. Background is IBCAO v. 3.0 bathymetry. HS, Hinlopen Slide; HT, Hinlopen Trough; MS, Mosby Seamount; NBH, NE basement high; S, Spitsbergen; SB, Sverdrup Bank; SC, southern ridge crest. Red circle is ODP Site 910. ( b ) Location of study area (red box; map from IBCAO v. 3.0). FS, Fram Strait; YP, Yermak Plateau. ( c ) Multibeam image …