Cenozoic dinoflagellate cysts from the Navarin Basin,Norton Sound and St.George Basin,Bering Sea

Biostratigraphic studies in the Navarin Basin COST No.1 well, Norton Sound COST No.1 well and St. George Basin COST No.2 well in the Bering Sea were carried out based on dinoflagellate cyst and acritarch assemblages. Several local dinoflagellate cyst zones are independently proposed for each well, and then the composite dinoflagellate cyst zones are established for the central to eastern Bering Sea based on the composite ranges of dinoflagellate cysts obtained from the three wells. These zones are follows in descending order ; Filisphaera filifera Zone (late Pliocene to early Pleistocene), Filisphaera pilosa Zone (early to late Pliocene), Hystrichosphaeropsis variabile Zone (late Miocene), Heteraulacacysta campanula Zone (latest late Oligocene to early Miocene) , Impagidinium velorum Zone (early Oligocene) and Areosphaeridium diktyoplokus Zone (late Eocene). Correlation of these zones with other Cenozoic dinoflagellate zonations are also discussed. Totally thirty-four genera and seventy species of dinoflagellates including one new genus (Algidasphaeridium) and twenty new species, and three genera and three species of acritarchs containing one new genus and species (Joviela magnifica) are recorded from the three wells.