R6: Plutonic rocks, volcanic rocks and subduction factory

[R6-01] Origin of Na/K diversity of basaltic magmas from Rishiri Volcano

*Hajime Taniuchi^1,2, Takeshi Kuritani², Mitsuhiro Nakagawa² (1. Shizuoka Univ., 2. Hokkaido Univ.)

Keywords:Slab-derived supercritical liquid, Primary magma, Rishiri Volcano, Water, Melt

By comparing the magma generation conditions of high-Na/K and low-Na/K basaltic lavas from Rishiri Volcano, we find that the primary magma of the high-Na/K basalt was formed by the influx melting of aqueous fluid separated from the supercritical liquid, while the low-Na/K basalt was generated by supercritical liquid-fluxed melting. These findings show that elemental partitioning during the separation of supercritical liquid can induce chemical diversity within the primary basaltic magmas.