1. Research Institute of Geology and Geoinformation, Geological Survey of Japan, AIST, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan (e-mail: ito-t@aist.go.jp)
2. School of Earth Sciences, China University of Geosciences, 388 Lumo Road, Hongshan, Wuhan 430074, China
3. State Key Laboratory of Geo-processes and Mineral Resources, China University of Geosciences, 388 Lumo Road, Hongshan, Wuhan 430074, China