On the Nonmarine Cretaceous Stratigraphy and Floras of Northeastern Russia

Resumo

Some decisions of the Third Interdepartmental Regional Stratigraphic Meeting on Precambrian, Paleozoic, and Mesozoic of Northeastern Russia (St. Petersburg, 2002) are analyzed in light of the latest data obtained. The regional stratigraphic units (“horizons”) of the nonmarine Cretaceous recognized at this meeting are in fact not the basic subdivisions, but rather specialized biostratigraphic units, namely, “beds with flora.” The ages of some of these units are specified; notably, the beds with Arman flora are Turonian–Coniacian, the beds with Amka flora are Coniacian, and the beds with Arkagala flora are Santonian–Campanian. We recommend keeping the previous names for the Penzhina, Barykov, and Koryak phases of floral development and for the corresponding stratigraphic units. An updated version of the nonmarine Cretaceous stratigraphic chart of the Okhotsk–Chukotka structure-facies region is proposed for discussion.