Late Albian–Early Turonian Grebenka Flora of the North Pacific: Systematic Composition, Age, Distribution

Beginning from the mid-Cretaceous and in the Late Cretaceous, the landscape features of the North Pacific make it possible to divide this region into a number of territories called subregions. The earliest Cenophytic (with a significant number and diversity of angiosperms) late Albian–early Turonian Grebenka flora and its analogs are known only in three subregions of the North Pacific: Anadyr–Koryak, Northern Alaska, and Yukon–Koyukuk. In the middle of the Cretaceous, these subregions represented coastal plains and lowlands periodically flooded by the sea. Cenophytic floras populated the area of terrestrial volcanism of the Okhotsk–Chukotka subregion and the Asian continental interiors of the Verkhoyansk–Chukotka subregion later, in the Turonian–Coniacian. However, Mesophytic vegetation with the predominance of Early Cretaceous ferns and gymnosperms continued to exist there at least until the Coniacian. Consequently, the invasion of evolutionarily new Cenophytic vegetation into the continental interiors of Northeast Asia was gradual and extended over time. This should be taken into account when studying the Cretaceous nonmarine phytostratigraphy of the North Pacific region.