ABSTRACT

Four gabbros, two diabases and one basalt from a volcanic suite in Japan were analyzed for ten rare earth elements, Ba and Sr. The rare earth patterns normalized against the Leedey chondrite are of solid-type. Europium anomalies, both positive and negative, are found to be correlative with normative anorthite. These chemical features of the volcanic suite have some resemblance to those of abyssal basalts and gabbros. The REE partition coefficients which had prevailed during the formation of source materials of these basic rocks were estimated from these REE data. It can be concluded that (1) the source materials may have been solid-type mantle which was separated from less fractionated liquid-type (rectilinear REE pattern) magma compared with chondrite, and that (2) both groups of gabbros and basalts were derived from different parts of the mantle which had been formed in the cource of sequential magmatic processes at a certain stage of the earth's history.