Paleogeography and geochronology in the Russian eastern Arctic during the second half of the Quaternary

During the conclusion of the Middle Pleistocene, continental glaciation was initiated in the western part of Northern Eurasia, while alpine glaciers developed in the mountain ranges in the east. Small ice caps developed on Wrangel and DeLong Islands, and most of the Chukchi Peninsula was glaciated. The continental shelves of the Laptev and East Siberian Seas remained ice-free and subaerially exposed, as indicated by cryogenic and aeolian sediments, xerophytic herbaceous palynological assemblages, and remains of Mammuthus primigenius. The initiation of the Late Pleistocene was marked by a major marine transgression over the eastern part of the Arctic Ocean shelf, correlative with the Pelukian transgression of Alaska and the Sangamonian interglacial (isotope stage 5e) of North America. Sea levels exceeded present values by approximately 10-15 m. A subsequent regression marked the onset of Sartanian glaciation, ca. 25,000 BP. Climate warming began ca. 14,000 BP, reaching an optimum ca. 8000 BP, and was accompanied by renewed marine transgression. Climate fluctuations persisted throughout the Holocene, as indicated by alternating tundra, shrub-tundra, and taiga palynomorph assemblages. (C) 1997 INQUA/Elsevier Science Ltd.