Foraminiferal patterns in deglacial sediment in the Western Ross Sea, Antarctica: Life near grounding lines

Improved multibeam swath bathymetry allows targeted coring of glacial landforms aiming at improving our understanding of sedimentary facies that developed in glacimarine settings during the post-Last Glacial Maximum (LGM) deglaciation. Coupled with radiocarbon dates, we explore foraminiferal records from 18 sediment cores from the western Ross Sea largely from sites near paleo–grounding lines. We investigate post-LGM foraminiferal assemblages from glacimarine environments, including those proximal and more distal to paleo–grounding lines, including environments influenced by subglacial meltwater outflow and further removed from direct glacial influence and subject to different oceanographic conditions. Agglutinated benthic foraminiferal assemblages dominate open marine facies deposited under the presence of High Salinity Shelf Water and significant primary production, while calcareous foraminiferal assemblages characterize grounding line-proximal settings, some of which were potentially influenced by Modified Circumpolar Deep Water. Rapid deposition of meltwater plume deposits inhibited and, in some cases, significantly altered foraminifera abundance and diversity. Broadly in the Ross Sea, it appears that the high bathymetric gradient of grounding zone wedges is a key factor promoting rich benthic foraminiferal communities in habitats proximal to grounding lines. Therefore, we demonstrate that paleo–grounding line settings may archive high quality in situ foraminiferal data, which is imperative for paleoenvironmental and geochemical studies on glaciated continental margins worldwide.