Koloskov A.V.1, Kovalenko D.V.2

1Institute of Volcanology and Seismology Far East Branch of the Russian Academy of Sciences, Petropavlovsk-Kamchatsky e-mail: kolosav@kscnet.ru
2Institute of Geology of Ore Deposits, Petrography Mineralogy and Geochemistry, Russian Academy of Science, Moscow e-mail: Dmitry@igem.ru

The authors analyzed rock samples from intrusive massifs in Kamchatka by K-Ar method. The results of this analysis revealed 17 new age data. The geological and isotope-geochronolocgical analyses showed that a boundary between the late Cretaceous (Paleocene) – Paleogene is an important critical stage in development of magmatism in Kamchatka and adjacent territory. In early Paleozoic time the magmatism was basic and ultrabasic. It enclosed the whole territory of the peninsular in the late Cretaceous – Paleogene time. Since Eocene the magmatism has significantly changed in intensity and composition of volcanic products containing mostly andesites and andesite-dacites. Large granitoid massifs set up their formation at this time. The age of the boundary falls within the age span about 44-36 Ma.

Keywords: age data, magmatism, granitoid massifs, Kamchatka.