MID-CRETACEOUS PHYTOSTRATIGRAPHY AND PALEOBOTANY OF NORTHERN ASIA

Abstract

The analysis of the general sequence of mid-Cretaceous stratofloras of northeastern Asia, proposed by Samylina, including the age and spatial position of various phytostratigraphic subdivisions, revealed local Chauna and Arkagala floras in the northern part of the Siberian-Canadian Cretaceous paleofloral area in addition to the widely spread super-regional floras. The floras were generated during the great mid-Cretaceous reconstruction of the vegetation kingdom (the replacement of Mesophytic floras with Cenophytic plants) accompanied by a sharp change and differentiation of the physico-geographical environment in northern Asia. The phylogenetic relationship between the Chauna and Arkagala floras was confirmed. It was shown that, during the Cenomanian-Santonian, the Arkagala flora dominated in the volcanic upland of northeastern Asia, whereas nearby, in the Penzhina-Anadyr' coastal plains and islands, new coenoses evolved with Cenophytic conifers and angiosperms dominating.