THE MAGMATIC EVOLUTION OF THE PLOSKIE SOP KI VOLCANO, KAMCHATKA (ANALYSIS OF THE SR ISOTOPE GEOCHEMISTRY)

First results concerning the study of both geochemistry and Sr isotope systematics in the volcanic series from Ploskie Sopki volcano are pre sented. Sr isotope data differ significantly for basalts from the shie ld volcano (0.70342 +/- 2), andesitic basalts of the strata volcano (0 .70357 +/- 2), andesites of caldera (0.70370 +/- 5), thes testifying t o the existence of both deep (initial)-and subsurface (secondary) magm atic chambers. Fractional crystallization is considered as the main pr ocess responsible for diversity of rocks derived from the certain unit of magma generation. Assimilation of crust metamorphic rocks by primi tive basaltic melt corresponds to the change between the deep source o f magma generation and the within-crust magmatic chamber, where the mi xing between 87 wt.% of basaltic magma and 13 wt.% of minimum-temperat ure granitic crust-derived melt occurs in the presence of water fluid.