GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 - POSTER GNGTS 2023 Early Western Antarctic ice sheet retreat from an ultra-high-resolution Holocene paleoclimatic record F. Battaglia, L. Baradello, L. De Santis, E. Colizza, V. Kovacevic, L. Ursella, F. Colleoni, D. Accetella, M. Rebesco, D. Morelli We report for the first time the discovery of an ultra-high resolution Holocene paleoclimate record from the Edisto Inlet fjord, located on the northern Victoria Land coast in the western Ross Sea. Edisto Inlet is a small fjord about 16 km long and 4 km wide, formed by glacial processes and separated from Moubray Bay by a sill. Bathymetric and seismic reflection data combined with geologic samples and oceanographic measurements indicate that most of the post-LGM sedimentation here was influenced by deposition of seasonally flourishing biogenic material (mainly diatom ooze) that was essentially redistributed locally by water currents. The interaction of rapid sediment deposition due to high productivity and persistent fjord-like circulation resulted in the formation of a confined drift and the accumulation of a sediment layer up to 130 m thick in the inner fjord. This indicates that the Edisto Inlet fjord was subject to seasonal sea ice-free conditions with regular warm water intrusions. The undisturbed acoustic character of sediment drift in the central parts of the fjord suggests that the fjord was not shaped by ground ice after the Holocene climatic optimum, when ice ran aground on the fjord margins. The results of this work, based on marine data, suggest that glaciers on the NVL coast retreated by about 11 Ky. This would preclude the presence of extensive ground ice on the north-western Ross Sea continental shelf after the late Holocene.