Deglacial sea ice variability at the continental margin off western Dronning Maud Land

Reconstructions of sea ice conditions proximal to the Antarctic coast are often hampered by a limited preservation potential of diatoms in these areas. While silica frustules are affected by opal dissolution, specific organic molecules, highly branched isoprenoids (HBIs) produced by diatoms, are well preserved in continental margin and shelf sediments and may help to overcome this gap. Here, we present biomarker and geochemical data obtained from a very well ¹⁴C-dated gravity core from the continental slope off Atka Bay in the northeastern part of the Weddell Sea. HBIs, the HBI-based PIPSO₂₅ index (Vorrath et al., 2019), glycerol dialkyl glycerol tetraether (GDGT) proxies and phytosterols reveal highly variable sea ice conditions and water temperatures as well as primary productivity changes over the last deglacial. These biomarker records are compared to ice core data and further complemented by physical property and XRF scanning data to estimate potential linkages between oceanic forcing and ice-shelf dynamics.

 

References

Vorrath, M.E., Müller, J., Esper, O., Mollenhauer, G., Haas, C., Schefuß, E., and Fahl, K., 2019. Highly branched isoprenoids for Southern Ocean sea ice reconstructions: a pilot study from the Western Antarctic Peninsula. Biogeosciences, v. 16, no. 15, p. 2961-2981.