[S-EM22] Geomagnetism, paleomagnetism and rock magnetism

[SEM22-08] Systetmatic examination of the properties of remanent magnetizations carried by magnetotactic bacteria Magnetospirillum magnetotacticum MS-1 in early process of sediment formation

*Kohei Masaoka¹, Yuki Morono², Naotaka Tomioka², Go-Ichiro Uramoto¹, Yuhji Yamamoto¹ (1.Kochi University, 2.Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology)

Variation of the past geomagnetic field is recorded in marine sediments as a fossil magnetization, called natural remanent magnetization (NRM). NRM is carried not only by detrital magnetic grains but also by biogenic magnetic grains originated from magnetotactic bacteria. To investigate characters of NRM carried by biogenic magnetic grains we have cultured the magnetotactic bacteria Magnetospirillum magnetotacticumMS-1 (here under, MS-1) in laboratory and made samples using them for remanent magnetization measurements by simulating a very early process of sediment formation. The samples were made under the four different conditions: (A) constant magnetic field (50 µT) and constant cell numbers (~3×10⁹cells); (B) constant magnetic field (50 µT) and variable magnetic field (1.0-4.5×10⁹cells); (C) variable magnetic field (0-90 µT) and constant cell numbers (~3×10⁹cells); (D) variable magnetic field (0-90 µT) and zero cells (blank speciments).We will report and discuss results.