Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Oral

M (Multidisciplinary and Interdisciplinary) » M-ZZ Others

[M-ZZ41] Marine manganese deposits: from basic to applied sciences

Wed. May 23, 2018 10:45 AM - 12:15 PM A11 (Tokyo Bay Makuhari Hall)

convener:Akira Usui(Marine Core Research Center, Kochi University), Yoshio Takahashi(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo), Katsuhiko Suzuki(国立研究開発法人海洋研究開発機構・海底資源研究開発センター, 共同), Takashi Ito(Faculty of Education, Ibaraki University), Chairperson:Usui Akira, Suzuki Katsuhiko(JAMSTEC), Takahashi Yoshio(東京大学)

10:45 AM - 11:00 AM

[MZZ41-01] Magnetostratigraphy and environmental magnetism of ferromanganese crust using scanning SQUID microscopy

*Hirokuni Oda1, Akira Usui2, Yuhji Yamamoto2, Takashi Ito3, Jun Kawai4 (1.Institute of Geology and Geoinformation, Geological Survey of Japan, AIST, 2.Kochi University, 3.Ibaraki University, 4.Kanazawa Institute of Technology)

Keywords:ferromanganese crust, Scanning SQUID microscope, magnetostratigraphy, environmental magnetism, age model

Ferromanganese crusts are chemical sedimentary rock composed mainly of iron-manganese oxide. Because the ferromanganese crusts grow very slowly on the sea floor at rates of 3-10 mm/Ma, longterm deep-sea environmental changes can be reconstructed from the ferromanganese crusts. Thus, it is important to provide reliable age model for the crusts. A new technology, scanning SQUID (superconducting quantum interference device) microscope (SSM) has been used for paleomagnetism (e.g. Weiss et al., 2000, 2007; Gattacceca et al., 2006; Fu et al., 2014). SSM enable to obtain magnetic image at a scale of ~0.1 mm by measuring vertical component of magnetic field over geological thin sections. Oda et al.(2011) applied SSM on a ferromanganese crust sample from Shotoku Seamount in the northwestern Pacific and successfully developed age model based on magnetostratigraphy. Recently, Geological Survey of Japan (GSJ), AIST has developed an SSM in collaboration with Kanazawa Institute of Technology (Kawai et al., 2016; Oda et al., 2016). Using the SSM, Noguchi et al (2017) successfully applied the same technique on ferromanganese crust from the Takuyo Daigo Seamount and confirmed that the age model based on magnetostratigraphy is consistent with that based on 10Be/9Be. In addition, they are successful in producing a map of environmental magnetic parameters and suggested an increase in higher coercivity minerals after ~3Ma. In the presentation, environmental magnetic mapping will be conducted together with the magnetostratigraphy for ferromanganese crust samples from Hanzawa Seamount, Ryukyu trench and the Shotoku Seamount.