Variations in ice-sheet dynamics along the Amundsen Sea and Bellingshausen Sea West Antarctic ice sheet margin

Modern global warming and its possible contribution to sea-level rise and flooding of low-lying coastal areas have moved both the Antarctic and Greenland ice sheets into the focus of public and scientific interest. Research has concentrated on reconstructing the dynamics of the ice sheets in order to understand their vulnerability to a changing climate by collecting multidisciplinary data and conducting numerical simulations. Synchronous changes in ice-sheet extent along its margin are assumed by a number of authors. The study presented here analyzes the regional and chronological appearance, distribution, and modification of sedimentary features and structures identified at the slope and rise off the West Antarctic Ice Sheet margin to test whether this assumption is correct. In general, a synchronous West Antarctic Ice Sheet dynamic is not supported by the analysis presented here; instead, this study documents a west-east trend with an early Miocene ice advance in the Amundsen Sea, while a glacial advance in the Bellingshausen Sea occurred only post-15 Ma. For the Bellingshausen Sea, stronger variability in sediment flux is observed, indicating stronger variability in ice extent. The dominance of downslope or along-slope sediment transport shows opposing trends between the two seas, which also reflects the advance/retreat of the local ice sheet and thus an increase/decrease in sediment input from the continent and a modification in intensity and relocation of the bottom current pathways. A possible reason for this west-east trend in ice-sheet dynamics may be the local geology (hinterland and basal), basal geomorphology, and the geometry of the local ice sheets.