1. Mahidol University Kanchanaburi Campus 199 M.9 Lumsum Kanchanaburi-Sangkraburi Road, Sai Yok, Kanchanaburi, 71150 Thailand (e-mail: )
2. Institute of Geology and Geoinformation, Geological Survey of Japan, AIST, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan
3. Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8572, Japan