Changes of the terrestrial vegetation at the end of Late Cretaceous (Amur-Zeya Basin, Russian Far East)

Abstract

According to the paleobotanical data, paleoenvironments, climate and evolution of vegetation in eastern Asia have been reconstructed for the Berriasian Maastrichtian stages. During the Cretaceous, two critical boundaries in the development of terrestrial flora: Albian-Cenomanian and Maastrichtian­ Danian (Markevich, 1995) were marked out. The latter is devoted much attention as it was at the boundary between Mesozoic and Cenozoic eras. The first crisis has been thoroughly studied using the fossil insects. 4 stages in the crisis development: preparatory, paradoxical, dramatic and calming were established including additional symptoms ofthe ecological crisis. We attempted to define a reaction of vascular plants, as an indispensable components of biota, to the biocoenosic crisis. Sufficient and diverse palynological material enables us to trace dynamics of the fossil flora changes, while the fossil megaflora characterises the coastal vegetation. As established by the previous researches, development and relaxation of ecological crises in the past were quite long even on a geologic time scale. Our data suggest that the biocoenotic crisis began in the Campanian-Early Maastrichtian and ended in the Paleogene. Using the symptoms of ecological crises and paleobotanic data, it is possible to determine the above­ mentioned stages of crisis evolution for the Cretaceous-Paleogene biocoenosic crisis in the Russian Far East.