14:15 〜 14:30
[MIS10-14] 東南極舟底池における完新世の古環境変化
キーワード：東南極、完新世、微化石、古環境
Accelerated melting of the Antarctic ice sheet (AIS) is one of the major contributors to global sea-level rise. To better constrain future climatic and environmental consequences, it is important to understand the history and mechanisms of AIS melting and associated sea-level changes. Since the Last Glacial Maximum, regional sea-level reconstructions are a critical component of these efforts to resolve past fluctuations in ice sheets and global sea-level.
Regional sea-level reconstructions have previously been attempted across the Skarvsnes area of Lützow-Holm Bay, East Antarctica (Takano et al., 2012; Verleyen et al., 2017). However, these sea-level curves were different from GIA (glacial-isostatic adjustment) models (Whitehouse et al., 2012; Argus et al., 2014) and need to be reviewed. Further, the paleoenvironmental changes around Skarvsnes need to be clarified and the local records need to be cleared to reconstruct the sea-level changes. Therefore, our aim in the present study was to reconstruct the paleoenvironmental changes in the marine sediments on the raised beach near Lake Funazoko-Ike in Skarvsnes, Lützow-Holm Bay based on grain size, CNS (carbon, nitrogen, and sulfur) elemental, and siliceous microfossil analyses.
We collected 123 sediment samples from the outcrops of the beach raised during the Holocene and located around Lake Funazoko-Ike in Skarvsnes, Antarctica, during geomorphological surveys conducted by the 38th and 46th Japanese Antarctic Research Expeditions (JARE). The estimated age of the raised beach outcrop is approximately 4300 to 1400 cal. year BP. We identified at least 54 species belonging to 29 genera of siliceous microfossils from six samples and an arenaceous foraminifera was identified from another sample. Our analysis revealed the following paleoenvironmental changes: Lake Funazoko-Ike was an open marine environment from about 4300 to 1400 cal. year BP, detached from the sea at approximately 800 to 1400 cal. years BP. In addition, Lake Funazoko-Ike until ca. 1400 cal. year BP inferred the marine environment with the sea ice flows, and different from a salt lake at present.
Regional sea-level reconstructions have previously been attempted across the Skarvsnes area of Lützow-Holm Bay, East Antarctica (Takano et al., 2012; Verleyen et al., 2017). However, these sea-level curves were different from GIA (glacial-isostatic adjustment) models (Whitehouse et al., 2012; Argus et al., 2014) and need to be reviewed. Further, the paleoenvironmental changes around Skarvsnes need to be clarified and the local records need to be cleared to reconstruct the sea-level changes. Therefore, our aim in the present study was to reconstruct the paleoenvironmental changes in the marine sediments on the raised beach near Lake Funazoko-Ike in Skarvsnes, Lützow-Holm Bay based on grain size, CNS (carbon, nitrogen, and sulfur) elemental, and siliceous microfossil analyses.
We collected 123 sediment samples from the outcrops of the beach raised during the Holocene and located around Lake Funazoko-Ike in Skarvsnes, Antarctica, during geomorphological surveys conducted by the 38th and 46th Japanese Antarctic Research Expeditions (JARE). The estimated age of the raised beach outcrop is approximately 4300 to 1400 cal. year BP. We identified at least 54 species belonging to 29 genera of siliceous microfossils from six samples and an arenaceous foraminifera was identified from another sample. Our analysis revealed the following paleoenvironmental changes: Lake Funazoko-Ike was an open marine environment from about 4300 to 1400 cal. year BP, detached from the sea at approximately 800 to 1400 cal. years BP. In addition, Lake Funazoko-Ike until ca. 1400 cal. year BP inferred the marine environment with the sea ice flows, and different from a salt lake at present.