Late Neogene geomorphological and glacial reconstruction of the northern Victoria Land coast, western Ross Sea (Antarctica)

This study is a contribution to the reconstruction of the geomorphology and the glacial history of the northern Victoria Land coastal glaciers. High-resolution single-channel reflection seismic lines were collected in 2002 within the framework of the Italian Antarctic programme (PNRA), in Wood Bay and Lady Newnes Bay, north to Cape Washington (western Ross Sea, Antarctica). The data provide evidence of overdeepened marine subglacial valleys, more than 1 km deep and 1–2 km wide, formed along the seaward extension of the Tinker, Aviator, Fitzgerald and Icebreaker glaciers and converging into the major SW–NE ice stream system. The spatial distribution and the geometry of the seismic facies, as well as the direct correlation with the seismic sequences in the Northern Basin, are interpreted to document 1) the depositional activity of a coastal glacial system seaward of northern Victoria Land (NVL) after 18 Ma (based on the seismic correlation with the base of DSDP 273) and possibly in the early Pliocene, in coalescence with expanded ice streams coming from the south along the Drygalski Basin, possibly draining from the WAIS as documented at AND-1B in the McMurdo Sound (Naish et al., 2007, 2008, 2009), followed by 2) the development of TAM tidewater glaciers that carved sea valleys near the Victoria Land coast, onto the shelf. The transition from a dynamic thick ice sheet covering the coastal area of NVL to the NVL valley glaciers advancing and retreating up to about 100 km from the coast in the middle Pliocene would represent a significant environmental change, possibly from interglacial conditions more temperate than today and gradually cooling to a cold and dry coastal regime.