Tectonostratigraphic complexes of the southern Kronotskii paleoarc (Eastern Kamchatka): Structure,age, and composition

The eastern peninsulas of Kamchatka are mostly composed of tectonostratigraphic complexes, which were formed within the Late Cretaceous-Eocene Kronotskii-Kamchatka arc. The accretion of this paleoarc to the Kamchatka margin of northeastern Asia in the terminal Cenozoic represented the last collisional event in the formation of the present-day structure of Kamchatka. The article presents new data on the age, composition, and structure of the tectonostratigraphic complexes constituting the southern segment of the Kronotskii-Kamchatka paleoarc. It is shown that the oldest rocks of these complexes are the Campanian in age and represented by volcano-sedimentary rocks that were formed in different geodynamic environments. The investigated igneous rocks are attributed to two types: (1) the tholeiite series of a mid-oceanic ridge (MOR) (Vetlovaya Complex); (2) tholeiite and calc-alkaline series of island arcs (Shipunskii Sequence of the Kronotskii Group).