*Nakajima Toru¹, Shigeru Sueoka¹, Mitsuhiro Nagata¹, Barry P. Kohn², Noelynna T. Ramos³, Hiroyuki Tsutsumi⁴, Takahiro Tagami⁵ (1.Tono Geoscience Center, Japan Atomic Energy Agency, 2.School of Geography, Earth and Atmospheric Sciences, University of Melbourne, 3.University of the Philippines, 4.Department of Environmental Systems Science Faculty of Science and Engineering Doshisha University Kyotanabe, 5.Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University)

*Hideki Iwano^1,2, Harutaka Sakai³, Tohru Danhara¹, Toru Nakajima^3,4, Takafumi Hirata² (1.Kyoto Fission-Track Co., Ltd., 2.Geochemical Research Center, The University of Tokyo, 3.Department of Earth and Planetary Science, Kyoto University, 4.Tono Geoscience Center, Japan Atomic Energy Agency)