R6: Plutonic rocks, volcanic rocks and subduction factory

[R6-02] Isotope and REE compositions of Miocene basalt in the central Kii Peninsula, Japan

*Takaharu Sato¹, Masataka Aizawa² (1. Osaka Museum Nat. Hist., 2. Ryukyus Univ.)

Keywords:Primary basalt, Isotope, REE, Miocene, Kii Peninsula

A caldera complex was formed in the southeastern to central Kii Peninsula. Basalt in the northern part of caldera complex, constitute a composite dike with rhyolite. The isotopic ratios of Sr and Nd in basalt and rhyolite are different, indicating that they are derived from different materials. The REE composition of the basalt shows similar pattern to that of the E-MORB, and spider diagram normalized by the primitive mantle shows no negative anomalies of Nb or Ta, indicating that the magma was formed by partial melting of the mantle without the contribution of subduction fluids.