THE PLIOCENE-PLEISTOCENE GOLOVNIN FORMATION OF KUNASHIR ISLAND (THE KURILES): STRATIGRAPHY AND FORMATION CONDITIONS

Abstract

Lithology and facies of shelf deposits of the Golovnin Formation have been studied in the Kunashir Island. The deposits may be regarded as an intermediate link between correlative sediments of margina seas and the Pacific Ocean. Based on diatoms, spores, pollen, and paleomagnetic analysis, the Golovnin Formation is subdivided into three subformations representing different transgression-regression cycles of the terminal Pliocene-Pleistocene. Significant hiatuses have been established in formation of the volcanogenic-sedimentary sequence. The Pyxidicula zabelinae and Thalassiosira antiqua zones of the upper Pliocene are distinguished in deposits of the lower subformation. The middle subformation that yields diatom assemblages of the Actinocyclus oculatus and Nitzschia fossilis zones formed in the early Pleistocene, whereas deposits of the upper sub-formation belong to the diatom Proboscia barboi Zone of the middle Pleistocene. Terrestrial deposits are united into the Belozersk Beds of the second late Pleistocene interstadial. Two, the Kunashir I (2.12-2.0 Ma) and Kunashir II (1.8-1.6 Ma) transgression phases of the late Pleistocene are distinguished. The early Golovnin transgression occurred in the early Pleistocene. The late Golovnin transgression (0.43-0.28 Ma) with two phases corresponding to oxygen-isotope stages 11 and 9 complies with the middle Pleistocene. Tephrostratigraphic markers are established for both the diatom zones and the Reunion and Olduvai subchrons. Paleogeo-graphic events in southern Kuriles, Japan, Kamchatka, Chukchi Peninsula, and Alaska are correlated between each other.