[M-IS15] Global Antarctic Science: connecting the chain of changing huge ice sheets and global environments

[MIS15-P15] Holocene readvance of the Antarctic Ice Sheet: Evidence from lake sediments in Langhovde, Lützow-Holm Bay, East Antarctica

*Takeshige Ishiwa^1,2, Kota Katsuki³, Yuki Tokuda⁴, Takuya Itaki⁵, Satoshi Sasaki⁶, Kaihe Yamazaki⁷, Takayuki Omori⁸, Jun'ichi Okuno^1,2, Minoru Ikehara⁹, Yusuke Suganuma^1,2 (1.National Institute of Polar Research, 2.SOKENDAI, 3.Shimane University, 4.Tottori University of Environmental Studies, 5.AIST, 6.Gunma University, 7.University of Tasmania, 8.University of Tokyo, 9.Kochi University)

Keywords:Antarctica, Lake sediments, Holocene

The Antarctic Ice Sheet (AIS) has changed over various timescale, and its current mass balance is a composite of these changes. Therefore, in order to accurately assess its mass balance, we need not only satellite observations to detect changes over periods of several decades to seasons, but also geological records, which are essential for reconstructing changes over longer timescales of several decades or more. Recent studies indicate that the AIS advanced again during the Holocene (e.g., Balgo et al., 2023; Berg et al., 2020; Simms et al., 2021) after the ice-sheet volume maximum of the Last Glacial Maximum. As this readvance affects current mass balance assessments, it is crucial to determine where, to what extent, and when it occurred.
We present evidence for Holocene AIS readvance from lake sediments collected at Lake Nurume in Langhovde, Lützow-Holm Bay, East Antarctica. Sediments were collected during the 61st Japanese Antarctic Research Expedition, and diatom assemblages and major element analyses were conducted to reconstruct sedimentary environment. Radiocarbon dating of molluscs and organic carbon in the sediments was performed to determine the timing of the fluctuations. The results indicate that sea-level changes play a key role in altering the water mass structure of the lake, but about 2,000 years ago, the readvance of the ice sheet reached the vicinity of the lake, increasing the freshwater inflow to the lake. This timing is earlier than in West Antarctica and the Antarctic Peninsula but is consistent with a report from Bunger Hills in East Antarctica. This is important for understanding the spatio-temporal variation of ice sheet readvance in Antarctica.