Albian Late Cretaceous phytostratigraphy and floral evolution in the NorthPacific

Different views on the composition and stratigraphic succession of the Cret aceous floras in northeastern Asia are considered. These floras populated d ifferent landscapes of that time and their correlation are difficult to cor relate. In the Late Cretaceous time, northeastern Asia and Alaska were part ly occupied by sea basins bordered by coastal plains with well developed fi ver systems. In the inner land areas, there were uplands and plains, which escaped flooding. Continental deposits were accumulated there in isolated d epressions. The upland of the Okhotsk-Chukchi volcanogenic belt extended al ong the eastern coast of the Asian continent. All late Albian-Late Cretaceo us floras in coastal plains of northeastern Asia and Alaska were dominated by angiosperms. The intracontinental depressions and rises of the volcanoge nic upland were occupied by the "Cenophytic" floras with prevailing angiosp erms, which are correlatable with the coastal floras, and by the "Mesophyti c" ones consisting of dominant ferns and gymnosperms associated with sporad ic angiosperms. The coexistence of different floras can be explained by the ability of early angiosperms to occupy the disturbed vegetation-free habit ats of the coastal plains, which permanently originated in response to sea transgressions and river meandering. These plant associations gradually pen etrated along river valleys into the inner areas populated by coniferous-fe rn vegetation.