Pleistocene Glacial Ice Cover and Interglacial Paleoclimatic History in the NE Russian Arctic - Comparisons with Alaska

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Abstract This award supports a project to study the late Pleistoceneglacial geology of the regions bordering the Bering Strait. Field work and laboratory analyses of fossil materials collected on Chukotka Peninsula over the last three years indicates that the late Cenozoic stratigraphic framework for NE Russia is in need of significant revision. This work casts doubt on the number of glacial events recorded in the coastal stratigraphy and undermines the correlation by Russian workers of disjunct interglacial marine sequences that has been based on biostratigraphy and elevation above sea level. The development of a unified stratigraphic scheme for those parts of Beringia on both sides of the Bering Strait requires that the Pleistocene stratigraphy of NE Russia be more firmly based upon modern concepts of glacial sedimentology, isostasy, and eustasy and secured with better geochronology. Knowledge of glacial ice extent in the Russian Arctic is important for establishing accurate boundary conditions for paleoclimatic modeling. Likewise, knowledge of interglacial marine conditions in the region is important for understanding changes in the distribution of watermasses and heat transport as well as understanding the role of the Bering Strait in global ocean circulation models. Based upon past field work and a complete inventory of moraines and other glaciogenic deposits using European Space Agency synthetic-aperture-radar images across NE Russia, this project will revise the Late Cenozoic stratigraphy of the region and provide an opportunity for both US and Russian researchers to compare and exchange field methods and laboratory techniques via joint study of crucial stratigraphic sections and moraine sequences on both sides of the Bering Strait. Special attention will be given to the paleoclimatic and paleoceanographic significance of similarities and contrasts in the Pleistocene records. The correlation and geochronology of the deposits will be based upon a variety of modern techniques, including amino acid geochronology of mollusks, soft sediment paleomagnetism, cosmogenic isotope surface exposure dating and quantitative geomorphology of moraines, along with traditional biostratigraphy. The results of this project will be important to developing a complete picture of paleoenvironmental conditions in this region. Beyond the scientific work described here there are ancillary benefits to this US-Russian cooperative venture. Collaboration and joint field work between U.S. and Russian Quaternary researchers active in areas of Beringia is beneficial due to the shared earth and cultural history of our common border. The proposed development in the Bering Strait region of a jointly managed Beringian Heritage Park by the National Park Service and Russian counterparts highlights this shared legacy. Shared problem-solving in the field is necessary due to national differences in sedimentologic and stratigraphic terminology and concepts. An important benefit will be the opportunity to expose our Russian colleagues to geochronological techniques not presently available in their country.