A new rock-magnetic record indicating variation of ocean circulation during the intensification of Northern Hemisphere glaciation

2014 Fiscal Year Final Research Report

• Project/Area Number: 22241006
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Environmental dynamic analysis
• Research Institution: Kyushu University
• Principal Investigator: OHNO Masao 九州大学, 比較社会文化研究科(研究院), 准教授 (00251413)
• Co-Investigator(Kenkyū-buntansha): KITA Itsuro 九州大学, 大学院比較社会文化研究院, 教授 (10143075) ; KUWAHARA Yoshihiro 九州大学, 大学院比較社会文化研究院, 准教授 (90281196) ; KANO Akihiro 九州大学, 大学院比較社会文化研究院, 教授 (60231263)
• Co-Investigator(Renkei-kenkyūsha): SATO Tokiyuki 秋田大学, 国際資源学部, 教授 (60241668)
• Research Collaborator: HAYASHI Tatsuya 御船町恐竜博物館, 学芸員
• Project Period (FY): 2010-04-01 – 2015-03-31
• Keywords: 岩石磁気 / 古海洋 / 海洋循環 / 深層水 / 大陸氷床

Outline of Final Research Achievements

We studied the evolution of NADW (North Atlantic Deep Water) during the intensification of Northern Hemisphere glaciation using a newly developed rock-magnetic method to determine the constituent magnetic minerals of sediments. We measured isothermal remanence acquisition curves of deep-sea sediments drilled in the North Atlantic and decomposed the first derivatives of these curves into high-coercivity and low-coercivity components. Fractional changes of the high-coercivity component represent variation of the NADW formed at the Nordic Seas. The high-coercivity component increased significantly during an interglacial period just after ~2.68 Ma, which suggests that NADW formation in the Nordic Seas abruptly intensified at this time. In addition, millennial-scale variation in the NADW was observed associated with the Ice rafted debris (IRD) events, repeatedly occurred in glacial period.

Free Research Field

古地磁気・岩石磁気