1. Department of Natural History Sciences, Hokkaido University, Sapporo 060-0810, Japan
2. * E-mail: minami@ep.sci.hokudai.ac.jp
3. UTokyo Organization for Planetary and Space Science, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
4. Isotope Imaging Laboratory, Hokkaido University, Sapporo 001-0021, Japan
5. Department of Earth Science, Tohoku University, Sendai 980-8578, Japan
6. Institute of Space and Astronautical Science, JAXA, Sagamihara 252-5120, Japan