High resolution age model and paleoenvironmental change for K/Pg boundary

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05674
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Geology
• Research Institution: Tohoku University
• Principal Investigator: Takashima Reishi 東北大学, 学術資源研究公開センター, 准教授 (00374207)
• Co-Investigator(Kenkyū-buntansha): 西 弘嗣 東北大学, 学術資源研究公開センター, 教授 (20192685) ; 黒田 潤一郎 東京大学, 大気海洋研究所, 准教授 (10435836) ; 佐藤 隆文 東北大学, 多元物質科学研究所, 助手 (30643332) ; 折橋 裕二 弘前大学, 理工学研究科, 教授 (70313046)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 根室層群 / 白亜紀 / 古第三紀 / 絶滅事変

Outline of Final Research Achievements

The Cretaceou/Paleogene (K/Pg) boundary Event, occurred at 66 million years ago, is one of the most famous extinction events in the earth’s history, and is characterized by dying out dinosaur and ammonites. Our study discovered a continuous succession from the uppermost Cretaceous to the basal part of Paleocene in the Nemuro Group at Kawaruppu section based on planktic foraminifers, calcareous nannofossils and carbon isotope stratigraphy. We also identified prominent positive peak of iridium and platinum contents at the K/Pg boundary strata in the studied sequence. The K/Pg boundary at Kawaruppu section is 1 m thick strata which is considered to be the thickest K/Pg boundary muddy strata in the world. High resolution study of this strata has a potential to clarify detailed faunal and environmental change in the western North Pacific region during the K/Pg boundary Event.

Free Research Field

地質学

Academic Significance and Societal Importance of the Research Achievements

本研究により，明瞭な白亜紀/古第三紀境界が東アジアで初めて発見された．また，今回発見された境界層は古環境変動の解析に適した泥質の堆積物の中では世界でも最も厚いため,同イベント発生時における北西太平洋の古環境変動を高解像度で明らかにすることができる．