[M-ZZ43] 宇宙地球環境科学と歴史学・考古学を結ぶ超学際ネットワーク形成

[MZZ43-P03] 長崎県伊万里湾の鷹島神崎遺跡から出土した鉄製遺物内包コンクリーションの炭素14年代測定

*垣内田 滉¹、南 雅代²、門脇 誠二³、吉田 英一³、柳田 明進⁴、脇谷 草一郎⁴、天野 由記⁵ (1.名大院環境、2.名大ISEE、3.名古屋大学博物館、4.奈良文化財研究所、5.日本原子力研究開発機構)

キーワード：炭素14年代測定、鷹島神崎遺跡、鉄製遺物、コンクリーション

It is believed that the Mongolian fleet, dispatched to Japan for the 1281 invasion, sank due to a storm around Takashima in Imari Bay, Nagasaki. Numerous artifacts, including anchors, wooden planks, and iron concretions, have been excavated from the underwater site at Takashima, and these are thought to have originated from Mongolian ships. The iron concretions consist of corroded iron, sediments and shells, with hollow spaces where the original iron objects once existed. Studying the process of concretion formation is important to obtain information about the original iron objects. It is inferred that the iron concretions formed through a chemical reaction between the iron objects and substances in seawater and sediments after the objects were submerged. During this process, calcium carbonates derived from shells could be incorporated into the iron concretions. However, the exact mechanism and rate of iron concretion formation process are not fully understood. It is thought that the shells embedded in the iron concretions have the carbon isotopic ratio corresponding to the seawater present when the concretion formed. Clues to understanding the concretion formation process can be obtained by ¹⁴C dating and chemical analysis. This research aimed to investigate the concretion formation process by ¹⁴C dating of iron concretions and sediments from the underwater site at Takashima. The date of a wooden plank was determined to be 1053-1268 cal AD, which aligns with the period of Mongolian invasions in Japanese history. Two shells, located in the inner and outer parts of the same iron concretion, showed nearly identical dates. This suggests that the formation of iron concretions occurred rapidly. In this presentation, we will discuss the formation process based on additional results.