The Maastrichtian flora of the Amaam Lagoon area (Northeastern Russia)

Abstract

The Maastrichtian Koryak flora from the Amaam Lagoon area is comprehensively studied with reference to available data on the stratigraphy of the study area and age assessment of the flora-bearing deposits. In the Koryak flora 32 species of plant fossils are identified and systematically described in the work. The established traits of the Koryak floristic assemblage are used to correlate it with the other assemblages close in age from different localities of Northeastern RNortheastern Russiaussia and Alaska. The results of correlation and taxonomic revision of plant fossils from the upper part of the Prince Creek Formation, Northern Alaska show that in the Anadyr-Koryak and Northern Alaska circum-Pacific regions the Koryak stage of flora development and the respective phytostratigraphic horizon (upper Maastrichtian-Selandian), of key significance for interregional correlation of continental deposits, are distinguishable. Floristic changes recorded in the northern circum-Pacific regions across the Cretaceous-Paleogene boundary suggest that the evolution of vegetation was gradual, controlled by climatic change, evolutionary factors and plant migration. These results are inconsistent with the postulated global significance of the ecological crisis at that time.