JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Oral

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS17] [JJ] Marine manganese deposits: from basic to applied sciences

Sun. May 21, 2017 10:45 AM - 12:15 PM 106 (International Conference Hall 1F)

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), Takashi Ito(Faculty of Education, Ibaraki University), Katsuhiko Suzuki(Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology), Chairperson:takashi ito(Faculty of Education, Ibaraki University), Chairperson:Akira Usui(Marine Core Research Center, Kochi University)

11:45 AM - 12:00 PM

[MIS17-05] Measurement of ferromanganese crust using a scanning SQUID microscope: Age model by sub-millimeter scale magnetostratigraphy

*Atushi Noguchi, Yuhji Yamamoto1, Hirokuni Oda2, Akira Usui1, Masahiko Sato2, Jun Kawai3 (1.Center for Advanced Marine Core Research, Kochi University, 2.Institute of Geology and Geoinformation, Geological Survey of Japan, AIST, 3.Applied Electronics Laboratory, Kanazawa Institute of Technology)

Keywords:scanning SQUID microscope, ferromanganese crust, Age model, remanent magnetization

Ferromanganese crusts are chemical sedimentary rock composed mainly of iron-manganese oxide. Because the ferroman- ganese crusts grow very slowly on the sea floor at rate 3-10 mm/Ma, long-term deep-sea environmental changes can be obtained from the ferromanganese crusts. It is important to provide reliable age model and growth rate reconstructed from the ferromanganese crusts, while there are few studies on sub-millimeter scale age dating. To obtain sub-millimeter scale age, we conduct magnetic study on a ferromanganese crust sample using scanning SQUID (superconducting quantum interference device) microscope (Kawai et al., 2016; Oda et al., 2016). The ferromanganese crust using this study was sampled from Takuyo-Daigo Seamount, Hanzawa Seamount, Ryukyu trench. Methods of magnetic measurements were adapted from Oda et al. (2011), which pioneered the investigation that estimate sub-millimeter growth rate using SSM. The vertical component of the magnetic field above a thin section sample of the ferromanganese crust was measured using SSM. As the result, sub-millimeter scale magnetic stripes originating from approximately magnetized regions oriented parallel to lamina were obtained by two samples few supply of dust and sediment from continents (Takuyo-Daigo Seamount, Hanzawa Seamount). In addition, we attempted to remove noises retaining resolution of raw measurement data. After analyses, magnetic stripes could be recognized on the magnetic image. By correlating the boundaries of magnetic stripes with known geomagnetic reversals, we estimated that average growth rate of Takuyo-Daigo Seamount, Hanzawa Seamount is 3.37 +/- 0.06 mm/Ma, 2.67 +/- 0.04 mm/Ma , which is consistent with that deduced from the 10Be/9Be dating method (2.93 +/- 0.15 mm/Ma, 2.56 +/- 0.04 mm/Ma).