*Jiwon Eom¹, Shigeyuki Wakaki², Norikatsu Akizawa¹, Tsuyoshi Ishikawa², Kyoko Yamaoka³, Eiichi TAKAZAWA⁴, Hodaka Kawahata¹ (1.Atmosphere and Ocean Research Institute, The University of Tokyo, 2.Kochi Institute for Core Sample Research, JAMSTEC, 3.Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 4.Department of Geology, Faculty of Science, Niigata University)