ISOTOPE-GEOCHEMICAL HETEROGENEITY OF PLIOCENE-QUATERNARY VOLCANICS FROM KAMCHATKA AND THE ASTHENOSPHERIC DIAPIRISM PROBLEM

Isotope-geochemical material for Pliocene-Quaternary volcanoes of the Kamchatka region is generalized on a cartographic basis. The Sr-isotope anomalies of moderate and elevated radiogenicity, geochemically confirmed, are spatially conjugated. This made it possible to interpret these anomalies not only as a reflection of mantle plume material in the composition of volcanic rocks, but also of its hybrid environment, as a consequence of plum-lithosphere remobilization. The presence of multi-directional geochemical trends made it possible to propose the concept of moving boundary values for the composition of indicator rocks of the intraplate type and adakites, which significantly expanded the possibilities of their diagnostics. The isotope-geochemical heterogeneity of basaltoids of the region is generally determined by the peculiarities of concentration of rocks with intraplate and adakite geochemical characteristics, which allows considering the asthenospheric diapirism as the main factor of petrogenesis of Pliocene-Quaternary volcanism in Kamchatka.