Foraminiferal patterns in deglacial sediment in the western Ross Sea, Antarctica

Thanks to improved multibeam swath bathymetry, targeted coring of glacial landforms is now possible. In turn, it is possible to improve our understanding of sedimentary facies that developed in glacimarine settings during the post-Last Glacial Maximum (LGM) deglaciation. We explore foraminiferal records from 18 sediment cores from the western Ross Sea largely from sites near paleo-grounding lines. Based on general foraminiferal indices and radiocarbon dates, we identify environments and geomorphic settings from which high quality in situ foraminiferal data can be obtained, which is imperative for paleoenvironmental reconstructions and geochemistry on glaciated continental margins worldwide. We investigated post-LGM foraminiferal assemblages from distinct glacimarine environments, including those from proximal and more distal locations with respect to paleo-grounding lines as well as an unusual assemblage influenced by the drainage of subglacial meltwater into the ocean. Despite clear differences in post-LGM foraminiferal records between the western and the eastern 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. Additionally, rapid deposition of meltwater plume sediments inhibited - and in some cases, significantly altered - foraminifera abundance and diversity. This knowledge will enable better site selection in future studies on the Antarctic continental shelf and potentially other glaciated margins.