JpGU-AGU Joint Meeting 2020

Presentation information

[E] Poster

H (Human Geosciences ) » H-CG Complex & General

[H-CG22] Deltas and estuaries: multidisciplinary analyses of complex river-mouth systems

convener:Yoshiki Saito(Estuary Research Center, Shimane University), David L Dettman(University of Arizona), Kazuaki Hori(Department of Geography, Graduate School of Environmental Studies, Nagoya University)

[HCG22-P03] Offset in radiocarbon ages between marine bioclast and terrestrial plant pairs in the Holocene sediments along the Pacific coasts around Japan

*Nakanishi Toshimichi1, Futoshi Nanayama2, Kazuaki Hori3, Yuichi Niwa4, Junko Komatsubara5, Akihisa Kitamura6, Wan Hong7 (1.Japan Atomic Energy Agency, 2.AIST/Kumamoto Univ., 3.Nagoya Univ., 4.Chuo Univ., 5.AIST, 6.Shizuoka Univ., 7.KIGAM)

Keywords:Radiocarbon dating, Marine reservoir, Sedimentary facies, Pacific coast

To identify chronological and spatial changes in the radiocarbon (14C) marine reservoir effects, the 14C ages of eight pairs of marine shells and terrestrial plants were measured from the same horizons of one core of Holocene sediments around Japan. The reservoir ages ranged from 60 to 1100 years, scattered over the period 100-10,200 cal BP, which were significantly larger than the values from “prebomb” samples of known age, before AD 1955 in this area. These results indicate that the information on reservoir effects is indispensable for chronological control not only from prebomb samples but also from geological and archaeological samples. Moreover, the effects also reflects the influence of complex river-mouth systems such as deltas and estuaries. To determine the direct chronological changes of the marine reservoir effect between the Kuroshio and Oyashio Currents, radiocarbon ages were measured from the same stratigraphic horizons within Holocene sediment cores alomg the Pasific coast of Japan (eastern Hokkaido; Nanayama et al., 2003, Nanayama, 2020, Sanriku Coast; Niwa et al., 2017, 2019, Arakawa Lowland; Komatsubara et al., 2009, 2010, Shimizu Plain; Kitamura & Kobayashi, 2014; Nobi Plain) and Taiwan. Subsequently, the results were compared with values from the Oita Plain and Hakata Bay on the northern coast of Kyushu, as well as the Korean Peninsula. The study was partially funded by the Japan Society for the Promotion of Science Kakenhi grant number JP18H01310.

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