OCEANIC COMPLEXES IN THE EAST KUMROCH RANGE, KAMCHATKA

Abstract

In East Kamchatka, Cretaceous oceanic rocks are known on the Cape Kamchatskiy peninsula and in the melange zones of the East Ranges. The authors' investigations in 1985-1987 revealed oceanic rocks in the eastern part of the Kumroch Range as well. The previously-identified Veltovaya Formation of this region, consisting of basalts and cherty, carbonaceous and clastic rocks, was thought to be a single stratigraphic section dated as Late Cretaceous to Miocene. Two rock complexes of different compositions (cherty-clastic and cherty-basaltic) and exhibiting tectonic relationships can be identified in the Vetlovaya Formation. In the eastern Kumroch Range there are oceanic rocks that constitute tectonic slabs in similar-age rocks of the ocean-side slope of the island arc. This phenomenon is best explained by accretion of oceanic blocks in middle Paleogene time.