[M-IS15] 遠洋域の進化

[MIS15-04] 美濃帯坂祝セクションの層状チャートから解読した三畳紀海水Os同位体比変動

★招待講演

*野崎 達生^1,2,3,4、二階堂 崇⁵、尾上 哲治⁶、高谷 雄太郎^7,1,2,4、佐藤 佳子¹、木村 純一⁸、常 青⁸、山下 大輔⁶、佐藤 峰南^4,1、鈴木 勝彦¹、加藤 泰浩^2,4、松岡 篤⁵ (1. JAMSTEC・資源、2.東大・工、3.神戸大・理、4.千葉工大・次世代資源、5.新潟大・自然科学、6.熊本大・自然科学、7.早大・創造理工、8.JAMSTEC・D-SEG)

キーワード：チャート、Re-Os同位体、三畳紀、付加体、美濃帯、西南日本

Pelagic cherts preserved in accretionary complexes represent former seafloor sediment that can retain geochemical evidence of paleoceanographic conditions that predate the oldest extant oceanic crust. The ratio of Os isotopes in seawater, in particular, is of wide interest as a source of insight into notable geologic events such as oceanic anoxic events, rapid global warming episodes, and eruption of large igneous provinces, but marine Os isotope records from before 80 Ma are scarce. We present a record of secular variations of marine Os isotope ratios from a thick, continuous succession of Middle and Upper Triassic pelagic chert in the Sakahogi section of the Mino Belt accretionary complex.