Marine environmental changes based on stable isotopes of molluscan shells excavated from archaeological sites

2022 Fiscal Year Final Research Report

• Project/Area Number: 17K12961
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Cultural assets study and museology
• Research Institution: Meiji University
• Principal Investigator: Hitoki Eri 明治大学, 研究・知財戦略機構(駿河台), 研究推進員 (60633930)
• Project Period (FY): 2017-04-01 – 2023-03-31
• Keywords: 放射性炭素年代測定 / 沖積層 / 安定同位体比 / 貝塚

Outline of Final Research Achievements

Marine environmental changes around the archaeological sites during the Jomon period were investigated. This research is conducted using radiocarbon dating and stable carbon and oxygen isotopes of molluscan shells excavated from the sites, as well as the Late Pleistocene to Holocene sedimentary sequence around the site. For comparison, stable isotopes analysis was also performed on the modern shells. As a result, we were able to accumulate radiocarbon dates, marine reservoir effects and stable isotope ratios using materials excavated from archaeological sites in Tsuchiura City. In particular, the results of stable isotopes analyses of modern Corbicula japonica revealed a large range of variation. In addition, a study of the Late Pleistocene to Holocene sedimentary sequence in the Sakuragawa lowlands provided a new perspective.

Free Research Field

第四紀学

Academic Significance and Societal Importance of the Research Achievements

これまで測定例のなかった遺跡の年代が明らかになるとともに，縄文時代の霞ケ浦周辺の海洋リザーバー効果を検討し，地域補正値を算出することが可能となった。これにより日本各地の地域補正値に新たな結果を加えることができ，年代学や第四紀学に与える意義は大きい。また、桜川低地における沖積層研究では、かつて流れていた古鬼怒川の流路変遷とも大きく関わり、沖積層のスタンダードとして捉えられてきた奥東京湾の沖積層研究とは大きく異なる様相が明らかとなってきた。これらは、地質学や地形学、第四紀学に大きな成果をもたらすとともに、地下地質の基礎資料として強振動予測やインフラ建設の参考となる。