著者

南 雅代 隈 隆成 浅井 沙紀 髙橋 浩 吉田 英一

出版者

一般社団法人 日本地質学会

雑誌

地質学雑誌 (ISSN:00167630)

巻号頁・発行日

vol.128, no.1, pp.239-244, 2022-11-03 (Released:2022-11-03)

参考文献数

20

被引用文献数

1

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Numerous carbonate concretion samples were collected during dredging around Nagoya Port in the 1960s. Most of the samples contained biological remains, including crabs, sea urchins, and bivalves, which formed their nuclei. In this study, the radiocarbon (14C) ages of the shells of the biological remains inside the concretions, as well as of the concretions themselves, were determined. Based on the metabolic carbon ratios of the bivalvia and sea urchin shells, which were calculated using δ13C values, the 14C ages of the shells and those of the metabolic carbon were estimated to be 7,350-7,050 cal BP and 9,680-9,430 cal BP, respectively. The 14C ages of the carbonate concretions were older than those of the shells due to the addition of metabolic carbon with older ages to the carbon of the concretion. The corrected age after removal of the old carbon was estimated to be 7,530-7,270 cal BP. The near-identical corrected ages of the shells and concretions indicate that the carbonate concretions in the Nagoya Port area formed rapidly after the death of the organisms, which is consistent with morphological evidence of rapid concretion formation in the sediment.