Water content in arc basaltic magma in the Northeast Japan and Izu arcs: an estimate from Ca/Na partitioning between plagioclase and melt

Masashi Ushioda1, Eiichi Takahashi2, Morihisa Hamada3 and Toshihiro Suzuki2, (1)Geological Survey of Japan, AIST, Tsukuba, Japan, (2)Tokyo Institute of Technology, Tokyo, Japan, (3)Japan Agency for Marine-Earth Science & Technology, Yokosuka, Japan