[M-IS08] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

[MIS08-P10] Preliminary report of ostracod assemblages in the recent past from Totten Glacier in East Antarctica

*Satoshi Sasaki¹, Takuya Itaki², Yuki Tokuda³, Takeshige Ishiwa^4,5, Yusuke Suganuma^4,5 (1.Institute for Space–Earth Environmental Research, Nagoya University, 2.Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 3.Tottori University of Environmental Studies, 4.National institute of Polar Research, 5.The Graduate University for Advanced Studies (SOKENDAI))

Keywords:Totten Glacier, Ostraacod, Paleoenvironment

Recently, the accelerated ice-mass loss of the Antarctic ice sheet has been reported through satellite and oceanographic observations (e.g. Jacobs et al., 2011; Paolo et al., 2015; Shepherd et al., 2018; Rignot et al., 2019). Regarding the melting of the ice-shelf base, the inflow of Circumpolar Deep Water (CDW), a relatively warm seawater, under the ice sheet terminus has a greater effect on melting the ice shelf than the previous thought (Favier et al., 2014). In particular, a potential pathway of warm water access has been discovered off Totten Glacier, whose ice discharge is accelerating (e.g. Greenbaum et al., 2015; Hirano et al., 2021; Sasaki et al., 2023). Above all, Sasaki et al. (2023) reported a surface sediment sample from Totten Glacier with low dissolved oxygen and high water temperature, the genus Krithe was the most abundant taxon, indicating the presence of warm deep seawater such as modified Circumpolar Deep Water, and ostracods could be useful indicators for reconstructing the paleoceanography and for anthropogenic climate changes in the Antarctic Ocean. Therefore, this study aims to reconstruct the paleoenvironment changes using ostracod analysis from a 19 cm short core sample at the same site collected by the 61th Japanese Antarctic Research Expedition (JARE61). A total of 19 samples were cut at 1cm intervals after the lithological description. As a result, five species belonging to 5 genera were found in 4 samples, and only a core top sediment sample (0-1 cm) included the genus Krithe. In addition, poorly preserved foraminifera fossils were observed from the core bottom to 5 cm core depth. Thus, we suggested these sediments except for surface sediments might be allochthonous or redeposition by tidal current, but it is unclear as of this moment whether it was influenced by the warm deep seawater at that time.