ネオジム同位体比分析による過去の海洋循環研究

Neodymium (Nd) isotopic compositions of ferromanganese (Fe–Mn) crusts, bulk sediment leachates, foraminiferal Fe–Mn hydroxides, biogenic apatite, and deep-sea corals have been used as a proxy of Nd isotopes in bottom seawater to reconstruct continental weathering and ocean circulation and mixing changes over various time scales. Proper understanding and appropriate use of this proxy are the basis for more detailed and accurate reconstructions of paleoceanographic variability recorded in marine sediments. In this review, I summarize current knowledge on the behavior of Nd isotopes in the modern ocean and the characteristics of bottom-water Nd isotope proxies to further advance the study of past ocean circulation. In addition, several noteworthy Nd isotope studies are presented to provide basic knowledge to researchers who will work on paleoceanography using Nd isotopes.