DEGLACIAL- HOLOCENE ENVIRONMENTAL EVOLUTION FROM A MULTIDISCIPLINARY STUDY ON THE CENTRAL BASIN, WESTERN ROSS SEA

Late Quaternary deglacial evolution is well investigated in the continental shelf area of the Ross Sea, meanwhile, the slope basin system remains still poorly studied. Although recent works studied marine sediments in this slope area, they are mainly focused on the glacial-interglacial transitions (Kim et al., 2020; Tolotti et al., 2013). Here we conduct a multidisciplinary study on three box cores collected in the Central Basin (Western Ross Sea, Antarctica). In this area, located at the month of the JOIDES Basin, the dense and cold High Salinity Shelf Water (HSSW) outflows from the shelf margin and mixes with the Antarctic Bottom Waters (AABW). On the other hand, the relatively warm Circumpolar Deep Water (CDW) intrudes locally into the continental shelf mixing with the dense shelf water (ISW) and HSSW. This study is developed in the framework of the STREAM Project (Late Quaternary evolution of the ocean-ice sheet interactions: the record from the Ross Sea continental margin, Antarctica), funded by the XII executive program for scientific and technological cooperation between Italy and Republic of Korea (period 2019-2021). Several analyses have been performed on three box cores (X-ray image, magnetic susceptibility, grain-size, diatom and foraminifera assemblages, tephra identification, ¹⁴C dating, etc). The box cores analyses confirm the different water mass influence. Box core KI13-BC4 is mainly influenced by HSSW and KI13-BC2 by CDW, while KI13-BC3, is located on a sector of Hallett Ridge where downslope processes are also present. Based on this study, we propose the reconstruction of the Late Quaternary deglacial – Holocene transition, together with the environmental and oceanographic evolutions of the area. The results allow us to recognize four principal phases: before 18 ka BP we document the disintegration of the ice shelf front. The deglaciation with the inflow of CDW, which triggered the base of the ice shelf and produced many icebergs develops from 18 ka BP to 11.3 ka BP. The Holocene conditions are established between 11.3 – 4 ka BP. Finally, rapid cooling is recognized from 4 ka.