On the Chaun Paleoflora in the Chukotka Nonmarine Cretaceous

摘要

The Cretaceous fossil flora in deposits of the Okhotsk–Chukotka volcanic belt is drastically different in systematic composition from the paleoflora of similar ages in deposits of the Northeast Asian coastal lowlands and inland depressions. In the volcanic burials, paleoflora features are the most evident in the Chaun flora found in the Pegtymel trough in the Central Chukotka region and described in the monograph by L.B. Golovneva “The Chaun Flora of the Okhotsk–Chukotka Volcanic Belt.” Based on these data and our own experience in studying the Okhotsk–Chukotka belt stratigraphy and the vegetation cover dynamics in the Kamchatka recent volcanism area, we have proven that the Chaun flora was formed not on the volcanic highlands, as Golovneva stated, but on the lowlands, on a periodically renewed juvenile surface of the central part of the vast volcanic field separately from the background diaspora sources. This flora is not characterized by a clear lateral and stratigraphic confinement, because the characteristic plant fossils can be found in deposits of different ages throughout the volcanic belt. They are indicative of particular vegetation and burying conditions in the surface volcanism from the Turonian to the Campanian inclusive.