Ryoma Setoguchi¹, *Masafumi MURAYAMA¹, Akira Ijiri², Juichiro Ashi³, Takeyasu Yamagata⁴, Hiroyuki Matsuzaki⁴ (1.Faculty of Agriculture and Marine Science, Kochi University, 2.Kochi Institute for Core Sample Research, JAMSTEC, 3.The Atmosphere and Ocean Research Institute, The University of Tokyo , 4.The University Museum,The University of Tokyo)