[B-PT03] バイオミネラリゼーションと古環境プロキシー

[BPT03-08] Evidence for late-glacial oceanic carbon redistribution and discharge from the Pacific Southern Ocean

★Invited Papers

*岩崎 晋弥¹、Lester Lembke-Jene²、長島 佳菜³、Helge Arz⁴、原田 尚美⁵、木元 克典³、Frank Lamy² (1.MARUM - Zentrum für Marine Umweltwissenschaften der Universität Bremen、2.Alfred-Wegener-Institut Helmholtz-Zentrum für Polar und Meeresforschung、3.海洋研究開発機構、4.Leibniz Institute for Baltic Sea Research、5.東京大学大気海洋研究所)

キーワード：浮遊性有孔虫、炭酸塩溶解、退氷期、海洋炭素循環

Southern Ocean deep-water circulation plays an important role in the global carbon cycle. On geological time-scales, upwelling along the Chilean continental margin likely contributed to the deglacial atmospheric carbon dioxide rise, but little quantitative evidence exists of carbon storage. Here, we use a new X-ray Micro-Computer-Tomography method to assess foraminiferal test dissolution as proxy for paleo-carbonate ion concentrations ([CO₃^2–]). Our subantarctic Southeast Pacific sediment core depth transect shows significant deep-water [CO₃^2–] variations during the Last Glacial Maximum and Deglaciation (10 – 22 ka BP). We provide evidence for an increase in [CO₃^2–] during the early deglacial period (15-19 ka BP), followed by a ca. 40 µmol kg^–1 reduction in Lower Circumpolar Deepwater (CDW). This decreased Pacific to Atlantic export of low-carbon CDW contributed to significantly lowered carbon storage within the Southern Ocean, highlighting the importance of a dynamic Pacific–Southern Ocean deep-water reconfiguration for shaping late-glacial oceanic carbon storage, and subsequent deglacial oceanic-atmospheric CO₂ transfer.