*C Ishwar-kumar¹、K Sajeev¹、B.F Windley²、M Satish-kumar³、T Hokada⁴、K Horie⁴、T Itaya⁵ (1.Centre for Earth Sciences, Indian Institute of Science, Bangalore 560 012, India、2.Department of Geology, University of Leicester, Leicester LE1 7RH, UK、3.Department of Geology, Niigata University, 2-8050, Ikarashi, Nishi-ku, Niigata 950-2181, Japan、4.National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo190-8518, Japan、5.Institute of Natural Sciences, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0)