Paleogene floral assemblages around epicontinental seas and straits in Northern Central Eurasia: proxies for climatic and paleogeographic evolution

Abstract

Paleogene connection of Tethyan and Paleoarctic water masses and biotas was largely enhanced by a N-S trending epicontinental seaway in northern Central Eurasia, which extended from the Aral Sea to the Amerasian deep basin of the Paleoarctic. This seaway enabled warm waters to impinge into polar latitudes, being a kind of “radiator” for the Arctic. Its closure had immediate effect on climatic conditions and terrestrial flora in the Arctic and entire North Eurasia. The Kara and West Siberian epicontinental seas, which were the major components of this N-S trending seaway, were connected to adjacent oceanic basins by a system of straits. Opening, closure, narrowing and widening of these straits in the Early Cenozoic determined the evolution of the marine ecosystems and current development, as well as the related depositional processes and biota (especially flora). The evolution of these straits also influenced on the Northern Hemisphere climatic fluctuations that took place during the Paleogene transition from a warm to a colder paleoclimatic state of the Earth system.