USING MICROFOSSIL AND BIOGEOCHEMICAL DATA TO RESOLVE THE DEGLACIAL HISTORY OF THE ANVERS ISLAND TROUGH, WEST ANTARCTIC PENINSULA MARGIN

Foraminifera and diatoms are some of the most widely used proxies for paleoceanographic reconstructions in the high latitudes. Foraminiferal assemblages and foraminiferal-based geochemical proxies are critical for establishing past environmental conditions, and their use in Antarctic continental margin marine sediments is evolving. Diatom assemblage and phenotypic variation are used as proxies for sea-ice and surface ocean conditions. Here, we demonstrate the strength of applying a suite of microfossil (foraminifera and diatom) and biogeochemical analyses for reconstructing Holocene paleoenvironmental conditions on the western margin of the Antarctic Peninsula.

Marine sediment cores collected from a North-South transect through the Anvers Island Trough to the Palmer Deep, western Antarctic Peninsula (WAP) were analyzed for foraminiferal and diatom assemblages and stable oxygen and carbon isotopes. Earlier work revealed foraminiferal assemblage, water mass, and ice condition associations on the WAP margin. Assemblages dominated by Bulimina aculeata are associated with warm modified Circumpolar Deep Water (mCDW) and increased productivity, assemblages dominated by agglutinated taxa are associated with High Saline Shelf Water, and Globocassidulina spp. dominated assemblages are associated with ice proximal conditions. Morphologic variability, and changes in the relative and absolute abundance of the diatom Eucampia antarctica reflect temporal and spatial variability in the timing of sea ice formation and the role of iron fertilization in driving primary productivity. Using these assemblage associations, in association with foraminiferal stable isotopic analyses, this study reveals the influence of mCDW across mid- and outer WAP continental shelf coincident with deglaciation of the Anvers Island Trough.