*Jun-ichiro Ishibashi¹, Naru Tsukamoto¹, Yusuke Okazaki¹, Taisei Fujiwara², Naoya Obata², Takashi Goto², Chitaro Gouzu², Shin Toyoda³ (1.Department of Earth and Planetary Sciences, Faculty of Science, Kyushu University, 2.Hiruzen Institute for Geology and Chronology, 3.Okayama University of Science)