日本の火山岩のREEとSr同位体

概要

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It is believable that three petrographic provinces in the Japanese Islands: low-alkali tholeiite, high-alkali tholeiite (high-alumina basalt), and alkali basalt provinces which are arranged in parallel to the island arcs from the ocean side to the continental side in this order. Rare earth concentrations in the low-alkali tholeiite bear a strong resemblance to those in abyssal basalts. However, some of the basalt show the deplete concentration of the rare earth elements, with the depletion in the light rare earth elements characteristic of the abyssal basalts. In the Japanese rocks, the differentiated suite, generally being identified by anomalous Eu concentrations with differentiation of magma. There is a positive correlation between Rb/Sr and ^<87>Sr/^<86>Sr r.tios in the East Japan arc suite and a decrease of ^<87>Sr/^<86>Sr ratios with increasing distance from the trench in the arc. The opposite trend in the West Japan are, but this is due to high ratios in the alkali basalts of Southwest Japan is also observed. In the West Japan arc, the intermediate to felsic differentiates are isotopically not uniform and significantly higher ratios of ^<87>Sr/^<86>Sr than the basalt of this area and to the East Japan arc. The Oki-Dogo suite are not appreate for the rock of the continental side of a typical island arc traverse.
特定非営利活動法人日本火山学会の論文
1977-12-15