Strontium isotope ratio in certain manifestations of acid magmatism in the Southern Kamchatka

First results of investigations into isotopic strontium composition in acid rocks in the Southern Kamchatka: miocenic granitoid Ahomten and Luntos massives and Quaternary Cupol and Khangar volcanos are stated. Rocks composing the region studied are described. Rubidium and strontium contents were measured by the isotopic dilution method at an error not worse than ±1%. Strontium isotope ratios in the give series were measured with an error of about ±0.00005. The rubidium-strontium age determined from the biotite - plagioclase pair for the Ahomten massive (14 million years) agrees with earlier determined K-Ar age of these rocks. Age of young lava stream rocks of the Khangar volcano constituted 9-14 million years. With the exception of the Luntos massive the strontium isotope ratios in acid rocks of the objects studied are very low and are practically equal to such ones in the Kamchatka modern basalts. It is concluded that the Southern Kamchatka acid rocks are not the product of direct material melting of sialic foundation