[M-IS14] Paleoclimatology and paleoceanography

[MIS14-P29] Radiocarbon Dating of Fossil Pollen for Lacustrine Sediment Chronology: A Case Study from Lake Kawaguchi

*Ren Tsuneoka^1,2, Yusuke Yokoyama^1,2, Yosuke Miyairi¹, Shinya Yamamoto³, Atsunori Nakamura⁴, Osamu Fujiwara⁴, Aurélia Hubert-Ferrari⁵, Vanessa M.A. Heyvaert^6,7, Marc De Batist⁷, the QuakeRecNankai Team (1.Atmosphere and Ocean Research Institute, The University of Tokyo, 2.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 3.Mount Fuji Research Institute, Yamanashi Prefectural Government, 4.Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 5.Department of Geography, University of Liège, 6.OD Earth and History of Life, Royal Belgian Institute of Natural Sciences, Geological Survey of Belgium, 7.Ghent University, Department of Geology)

Keywords:Radiocarbon dating, Fossil pollen, Flow cytometry, Lacustrine sediment, Lake Kawaguchi, Fuji Five Lakes

Lacustrine sediments serve as valuable archives of past environmental conditions in terrestrial ecosystems. To reconstruct paleoenvironmental changes, it is crucial to establish precise sediment chronologies, enabling accurate comparisons with global climatic and environmental records. Radiocarbon (¹⁴C) dating is one of the most widely used methods for determining the age of these deposits, covering timescales of up to 55,000 years. However, in lake environments, carbon from various sources is incorporated into the sediment, complicating age determinations. This study explores the use of fossil pollen to improve dating accuracy of lacustrine sediments. Recent advancements in ¹⁴C dating techniques and pollen extraction using flow cytometry have facilitated sediment dating based on the ¹⁴C ages of fossil pollen. For example, Ota et al. (2024) successfully extracted fossil pollen from sediments in Lake Motosu (one of the Fuji Five Lakes) and determined the lake's reservoir age using fossil pollen ¹⁴C ages.
In this study, we applied fossil pollen ¹⁴C dating to establish a high-resolution chronology for the sediment of Lake Kawaguchi, which shares similar catchment characteristics and climatic conditions with Lake Motosu but differs in sedimentary environment. Unlike the deep (max. 121.2 m) and isolated Lake Motosu, Lake Kawaguchi is shallower (max. 14.0 m) and receives riverine inputs, leading to different sedimentary dynamics. This contrast allows us to assess the applicability of fossil pollen ¹⁴C dating under varying depositional conditions.
In this presentation, we will report the results of ¹⁴C analysis on fossil pollen extracted from a sediment core obtained from Lake Kawaguchi (KAW15-2), which spans the late Holocene, to evaluate the applicability of fossil pollen ¹⁴C dating in this lake.