MORB-like basalts dredged from the trench side slope of the Bonin Ridge and the Hahajima Seamount, the Izu-Bonin fore-arc

Abstract

MORB-like basalts have been dredged from the trench side slope of the Bonin Ridge and the Hahajima Seamount, the Izu-Bonin fore-arc. They are characterized by high TiO₂ contents compare to island arc tholeiites. MORB-like basalt from the trench side slope of the Bonin Ridge has low Zr/Nb ratio similar to E-MORB rather than N-MORB. On the other hand, MORB-like basalts from the Hahajima Seamount have high Zr/Nb ratio similar to N-MORB and their compositions are similar to Pacific MORB.