Petrology of mafic to felsic plutons from the Mineoka-Setogawa Belts: Genesis of middle crust of the Izu-Bonin-Mariana Arc

Abstract

We examined the formation age and petrogenesis of mafic to felsic plutons from the Paleogene Mineoka-Setogawa Belts. Zircon U-Pb dating of approximately 35 Ma and whole-rock chemistry of these rocks indicate that theya are fragments of middle to lower crust of the IBM Arc. Plagioclase An content in the diorites indicates that they were formed by magma mixing between mafic and felsic magmas. This is consistent with the current petrogenetic model for the genesis of the IBM middle crust.