日本地球惑星科学連合2018年大会

講演情報

[EJ] Eveningポスター発表

セッション記号 M (領域外・複数領域) » M-IS ジョイント

[M-IS08] 地球掘削科学

2018年5月22日(火) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:山田 泰広(海洋研究開発機構 海洋掘削科学研究開発センター)、黒田 潤一郎(東京大学大気海洋研究所 海洋底科学部門)、氏家 恒太郎(筑波大学生命環境系、共同)、菅沼 悠介(国立極地研究所)

[MIS08-P02] Stratigraphic occurrence ranges and paleoceanographic significance of Amphimelissa setosa (radiolarian) at IODP Site U1417

*Kenji Marc Raymond Matsuzaki1Noritoshi Suzuki2 (1.Department of Earth and Planetary Science, Graduate School of Science, the University of Tokyo、2.Department of Earth Science, Graduate School of Science, Tohoku University)

キーワード:Integrated Ocean Drilling Program, Biostratigraphy, Radiolarians, Paleoceanography

During the Expedition 341 of the Integrated Ocean Drilling Program (IODP), sediment cores were retrieved at several sites in the southern Gulf of Alaska for clarify the linkage between tectonic uplift and the evolution of global climate since the Miocene. The preservations and abundances of siliceous microfossils were relatively poor in the collected sediment cores except at Site U1417, where the siliceous microfossils were better preserved in the upper 200 meters CCSF-B corresponding to the Pleistocene. In this study, we have analyzed radiolarian assemblages from sediment core samples of the correponding depth interval in order to first re-define the onboard radiolarian biostratigraphy. Then, we propose to focus and discuss the spatio-temporal distribution of Amphimelissa setosa. This species records its last occurrence at the MIS 4/ MIS 5 boundary (77 ka) in the North Pacific, while in the Arctic Ocean, this species is still extant. For accurately discuss the spatio-temporal distribution of this species, the major concern is that the first occurrence (FO) of this species is poorly constrained at that time. Therefore, through this study, we newly defined the age of the FO of Amphimelissa setosa based on the onboard magnetostratigraphy and tried to propose few hypothesis for explain its migration to the arctic seas around the MIS 4/ MIS 5 boundary.