GNGTS 2021 - Atti del 39° Convegno Nazionale

GNGTS 2021 S essione 3.1 408 GEOPHYSICAL SURVEY OF A LGM GROUNDING ZONE WEDGE OFFSHORE THE BORCHGREVINK COAST IN THE NORTH-WESTERN ROSS SEA (ANTARCTICA) C. Sauli 1 , M. Zecchin 1 , D. Accettella 1 , L. Baradello 1 , M. Burca 1 , M. Caffau 1 , E. Colizza 2 , N. Corradi 3 , R. Melis 2 , D. Morelli 3 , R. Tolotti 3 1 National Institute of Oceanography and Applied Geophysics - OGS, Sgonico ( TS ) - Italy 2 Department of Mathematics and Geosciences, University of Trieste, Italy 3 Distav, University of Genova, Italy In the northwestern Ross Sea (Antarctica) a glacial trough in the strait between the North Victoria Land coast and the Coulman Island and a wide coastal sediment bank ahead the trough were respectively carved and built up by the paleo Borchgrevink -Mariner valley glaciers likely during the LGM. Single channel and Sub bottom profiles combined with the morpho bathymetry allow to survey this Grounding Zone Wedge (GZW) offshore the southern Borchgrevink Coast and focus the research on four main objectives that are described as follows: 1. to identify within the GZW the shallowest glacial units and unconformities linked to the glaciers advance and retreat previous and during the LGM, in order to study the NVL valley glaciers influence on the deglaciation of the area; 2. to map the GZW and evaluate its thickness and volume in order to attempt an estimate of the potential glacial sediment flux by assuming different durations of the grounding event; 3. to investigate the more surficial sediment section and correlate it with the cores located on the GZW top or on the distal area; 4. to recognize the subglacial ice sheet/shelf seafloor signatures which were left on the GZW during the growth and withdrawal of the glaciers. The purpose is to verify the inferred presence of a floating ice in front of the retreating valley glaciers and the coexistence farther offshore of an ice shelf in front of the East Antarctica Ice Sheet (EAIS) grounded north of the Coulman Island.