Sea Ice Reconstruction Over the Last 3ka BP in the Ross Sea (Antarctica)

Reconstruction of past changes to sea ice extent is central to understanding the factors that control its distribution and informs how changes in sea ice might occur in the future. Such reconstructions are often hindered, however, by poor age control (or resolution) in marine archives, or the absence of robust proxy signatures. Here, we show preliminary results from a 14.6 m long piston-core collected in the Edisto inlet (Cape Hallett, Ross Sea, Antarctica). The aim of the project was to obtain a continuous and highly resolved record of sea ice dynamics and other environmental parameters during the late Holocene. With this goal in mind, the coring site was chosen in the inner bay where the Holocene unit is particularly expanded (up to 60 m thick). Bottom core AMS 14C dating of the acid insoluble organic fraction (2820 cal. aBP after reservoir correction) indicates an average annual sedimentation rate of ca. 0.5 cm/y. X-ray radiographs show well-preserved laminated sediments dominated by diatom oozes alternating with dark-like sediments likely supplied from the inner bay. In this abstract, we present high resolution bulk organic carbon geochemistry (δ13C and carbon content), XRF core scanning data, diatom assemblages and lipid biomarker results. Specific focus will be placed on the di-unsaturated highly branched isoprenoid biomarker IPSO25, which has been recently proposed as a proxy of Antarctic landfast sea ice.