*Mutsumi Iizuka¹, Osamu Seki¹, Keiji Horikawa³, Tina van de Flierdt², Tomohisa Irino¹, Masanobu Yamamoto¹, Takuya Itaki⁴, Saiko Sugisaki⁴, Minoru Ikehara⁵, Yusuke Suganuma⁶ (1.Hokkaido university, 2.Imperial College London, 3.University of Toyama, 4.Geological Survey of Japan, 5.Center for Advanced Marine Core Research, Kochi University, 6.National Institute of Polar Research)