The First Results of U–Pb Dating of the Nikolka Volcano (Central Kamchatka Depression)

Аннотация

U–Pb dating of zircon from amphibole latite of the central stock of the Nikolka shield volcano in Kamchatka provided the first data on its age. The end of activity falls to about 0.73 Ma (10 analyses). The local U–Pb analyses were carried out at the Isotope Research Center, Schmidt Joint Institute of Physics of the Earth (St. Petersburg) (VSEGEI) using SIMS SHRIMP II. Here, brief information about the geological structure, petrography, and chemistry of the rocks of the volcano are presented. A unique feature of the volcano is the occurrence of a gabbro–anorthosite sheet intrusion with derivates of monzonite and syenite composition in its central part. The correlation of the age obtained with the paleomagnetic data, indicating the formation of the volcano during the magnetic age of Matuyama, is also discussed. The date refers to the period of the change in epochs from the Brunhes to the Matuyama. The obtained age allows dating of the Pliocene volcanic stage in Kamchatka, when large shield volcanoes and plateaus formed.