Gabbro and orthopyroxenite dikes intruding into peridotites in the Mineoka belt

Abstract

The Mineoka peridotites are sometimes intruded by gabbro and orthopyroxenite dikes. Mineral compositions in the gabbro dikes are more depleted in light rare earth element than those of the orthopyroxenite. This is consistent with the relationship in the whole-rock compositions between gabbro and diorite-tonalite in the Mineoka belt. Our recent study suggested that the Mineoka plutonic rocks are fragments of the middle to lower crust beneath the IBM arc. The orthopyroxenite and gabbro dikes in the residual mantle are derived from the IBM basaltic and felsic melts, respectively.