Evaluation of the potential of iron-manganese oxides as information on the origin of sediment-carrying water

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03765
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17030:Human geosciences-related
• Research Institution: Waseda University (2019-2020); Research Institute for Humanity and Nature (2018)
• Principal Investigator: Saitoh Yu 早稲田大学, 理工学術院, 講師(任期付) (60469616)
• Co-Investigator(Kenkyū-buntansha): 松本 弾 国立研究開発法人産業技術総合研究所, 地質調査総合センター, 主任研究員 (80709551)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: ネオジミウム同位体比 / 津波堆積物 / 懸濁物

Outline of Final Research Achievements

A study was conducted to verify that the isotope ratios of neodymium in the iron manganese oxides coating the sediments preserve the values of the water in which the sediments were transported. The results of the study on seawater suspensions showed that the isotope ratio of neodymium in the iron manganese oxide in the particles before deposition does not reflect the value of water, but the value of neodymium in the adsorbent or carbonate does reflect the value of water. The isotope ratios of neodymium in the adsorbent and carbonate components of the 2011 tsunami sediment were measured, and the influence of seawater values was confirmed, suggesting that these components conserved the water values that they acted to transport after they left the water.

Free Research Field

堆積学

Academic Significance and Societal Importance of the Research Achievements

堆積物からそれを運搬した作用を読み取ることは，堆積学の重要な課題の一つであるが，水流の物理的強度を読み取ることに比べ，水の質的な特徴を読み取る試みはほとんどなされてこなかった．本研究により，Nd同位体比がそのツールとして有用である見通しが高まった．更なる検証は必要ではあるが，堆積学の解明できる範囲が拡大される可能性はある．そのことで，津波堆積物や洪水堆積物の識別といった，防災に役立つ地質情報の精度，信頼性が向上することが期待される．