Naoto Fukuyo¹, Hirokuni Oda², Geoffrey Clark³ and Yusuke Yokoyama¹, (1)Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Japan, (2)National Institute of Advanced Industrial Science and Technology (AIST), Geological Survey of Japan, Tsukuba, Japan, (3)Archaeology and Natural History, College of Asia and the Pacific, The Australian National University, Canberra, Australia