*Pahan Abewardana^1,2、Madhusoodhan Satish-Kumar¹、P.L. Dharmapriya²、S.P.K. Malaviarachchi²、Zhao Lei³ (1.GRADUATE SCHOOL OF SCIENCE AND TECHNOLOGY, NIIGATA UNIVERSITY、2.POSTGRADUATE INSTITUTE OF SCIENCE, UNIVERSITY OF PERADENIYA, SRI LANKA、3.INSTITUTE OF GEOLOGY AND GEOPHYSICS, CHINESE ACADEMY OF SCIENCE, CHINA)