1. Earth and Planetary Science Kyushu University, 744 Nishiku Motooka Fukuoka 819‐0395 Japan
2. Department of Geology University of Johannesburg PO Box 524, Auckland Park, Johannesburg 2006 South Africa
3. Center for Advanced Marine Core Research Kochi University, Nankoku City Kochi 783‐0093 Japan
4. College of Education Ibaraki University, Mito City Ibaraki 310‐8512 Japan
5. Department of Chemistry Toho University Funabashi City Chiba 274‐8510 Japan
6. NNASA Astrobiology Institute