AGE AND COMPOSITION OF EOCENE SANDSTONES IN WESTERN KAMCHATKA: APPLICATION TO THE STUDY OF PROVENANCE FOR PETROLEUM RESERVOIRS OF THE SEA OF OKHOTSK

The lithology, composition, U-Pb LA-ICP-MS ages of detrital zircons from sediments of the Western Kamchatka Basin (Russian Far East) provide important insight into paleogeography and tectonic setting of the Sea of Okhotsk in the Eocene. Our study is based on mapping, structural observations, descriptions of the sections and lithology, composition of the sandstones, and U-Pb LA-ICP-MS dating and morphology analysis of detrital zircons from the Eocene sandstones of the Western Kamchatka Basin. The provenance for the sandstones is mainly associated with orogen recycling in magmatic arcs. The analysis of heavy minerals indicates mafic to sialic sources. The mafic terranes of the Asian margin on the west or/and Olyutorka-Kamchatka ensimatic island arc affected the mechanism transferring the basic material to the Western Kamchatka Basin in the Eocene. The sialic clasts originated from continental blocks of the Asian margin and the Okhotsk-Chukotka volcanic belt. New data allow us to prove that the erosion of the Okhotsk-Chukotka belt had a significant influence on the sedimentation system in the north of the Sea of Okhotsk in the Eocene. We can assume that the Paleo-Penzhina River system already existed in the Eocene. The existence of the sialic sources in Eocene allows us to assume the possibility of finding the good quality collectors in the Eocene deposits of the Western Kamchatka Basin and the north of the Sea of Okhotsk.