CLIMATIC FLUCTUATIONS IN THE SECOND HALF OF THE PLIOCENE IN EASTERN CHUKOTKA

Abstract

As far as the climatic history of the Late Cenozoic is concerned, the second half of the Pliocene is especially interesting because during that comparatively short time interval there were many important paleogeographic events in the northern hemisphere. For example, the Arctic Ocean became ice covered and permafrost began to develop in northern Asia and North America. Therefore, our new palynologic data on the second half of the Pliocene in the central part of eastern Chukotka could be particularly interesting. We studied a section penetrated in two pits near the town of Vostochnyy, in the transition zone from the northern foothills of the Chukotka Range to the Vankarem basin south of latitude 68° N. These pits are 100 to 150 m apart and expose the same section, consisting at the top of glacial deposits with moraines and, at the bottom, of an overlaid ('constrative') sequence of alluvium, which is about 20 m thick. The study shows that the climatic history of the second half of the Pliocene was more complex than hitherto supposed as is reflected in the abundant hiatuses in the overlaid sequence of buried alluvium.