1. Research Institute of Geology and Geoinformation, Geological Survey of Japan (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan
2. Department of Geology and Paleontology, National Museum of Nature and Science, Japan, 4-1-1 Amakubo, Tsukuba, Ibaraki 305-0005, Japan
3. Hokkaido Research Center of Geology, Yamanote 2-3-5-24, Nishi-ku, Sapporo, Hokkaido 063-0002, Japan