The Miocene basalt with high Sr isotopic ratios and low Nd isotopic ratios distributed in Kanuma, southern margin area of NE Japan arc

Abstract

Early to middle Miocene basalt are distributed in Kanuma, southern margin of NE Japan arc. These volcanic rocks are divided into two types, Hinata basalt (Hn-type) and high Sr isotopic basalt (HSr-type) based on their petrological, and Sr-Nd isotopic characteristics.
The Hn-type basalt show Sr-Nd isotopic ratios close to the mantle, suggesting that the Hn-type was originated from the mantle.
The HSr-type basalt show has extremely high Sr isotopic ratios and low Nd isotopic ratios. Therefore, the HSr-type cannot be produced by partial melting of mantle added to the slab-fluid.