Drastic shift of lava geochemistry between pre- and post- Japan Sea opening in NE Japan subduction zone: constraints on source composition and slab surface melting processes

Satoshi Okamura, Hokkaido Education University, Sapporo, Japan, Mitsuru Inaba, GeoPuck Associate, Tochigi, Japan, Satoshi Igarashi, Hosei Univ. Daini Junior and Senior High School, Kawasaki, Japan, Masataka Aizawa, University of the Ryukyus, Okinawa, Japan and Ryuichi Shinjo, Univ Ryukyus, Nishihara, Okinawa, Japan