*Pearlyn Manalo¹、Akira Imai^1,3、Ryohei Takahashi¹、Kyoka Yanagi²、Nigel Blamey⁴ (1.Graduate School of International Resource Sciences, Akita University、2.Faculty of Engineering and Resource Science, Akita University, Akita, Japan、3.Faculty of Engineering, Kyushu University, Fukuoka, Japan、4.Department of Earth Sciences, Western University, London, Ontario, Canada)