New data on Pleistocene, Eurasian northern latitudes.
All,
The following titles (from the recent issue of Quaternary Science) are for people who are interested in finding out more about what may have occurred (palaeoenvironmentally and, by extension, palaeoanthropologically) beyond the "classic" pale.
Jacques Cinq-Mars
Astakhov, Valery. 2004. Middle Pleistocene glaciations of the Russian North. In: Quaternary Environments of the Eurasian North (QUEEN), edited by J. Theide, Quaternary Science Reviews 23(11-13: :1285-1311.
Abstract ;
Geological data on the pre-Eemian glaciations of northern Russia, including the latest results by the Russian–Norwegian PECHORA project, are synthesized in order to present evidence for comparison with other early glaciations around the Arctic. The bulk of evidence indicates that Arctic and Subarctic regions of European Russia, of western and central Siberia during the Middle Pleistocene were at least 4 times covered by large ice sheets, which advanced mainly from the shelf ice domes, partly from Fennoscandia and the Putorana Plateau. Ice accumulations in the Ural Mountains were insignificant and did not form any noticeable ice dispersal centres. Unlike the classical glaciated areas, ice sheets of northern Russia acted mainly on a soft, perennially frozen substrate, which was heavily glacitectonised. The Middle Pleistocene ice sheets were much larger than the Weichselian ones. The Fennoscandian ice dispersal centre was most active in northern European Russia during the penultimate glaciation (OIS 6) when shelf-centred ice domes were relatively weaker. Larger continental ice sheets were formed in preceding ice ages, when Kara Sea ice dispersal centre dominated. The lowland ice sheets reached their maximum extent at different stages, from Cromerian Don glaciation in European Russia to OIS 8 in West Siberia. Therefore, the maximum ice limit is time-transgressive in northern Russia.
Hubberten, Hans W., Andrei Andreev, Valery I. Astakhov, Igor Demidov, Julian A. Dowdeswell, Mona Henriksen, Christian Hjort, Michael Houmark-Nielsen, Martin Jakobsson, Svetlana Kuzmina, Eiliv Larsen, Juha Pekka Lunkka, Astrid Lyså, Jan Mangerud, Per Möller, Matti Saarnisto, Lutz Schirrmeister, Andrei V. Sher, Christine Siegert, Martin J. Siegert, and J.I.John Inge Svendsen. 2004. The periglacial climate and environment in northern Eurasia during the Last Glaciation. In: Quaternary Environments of the Eurasian North (QUEEN), edited by J. Theide, Quaternary Science Reviews 23(11-13): 1333-1357.
Abstract:
This paper summarizes the results of studies of the Late Weichselian periglacial environments carried out in key areas of northern Eurasia by several QUEEN teams (European Science Foundation (ESF) programme: "Quaternary Environment of the Eurasian North"). The palaeoglaciological boundary conditions are defined by geological data on timing and extent of the last glaciation obtained in the course of the EU funded project "Eurasian Ice Sheets". These data prove beyond any doubt, that with the exception of the northwestern fringe of the Taymyr Peninsula, the rest of the Eurasian mainland and Severnaya Zemlya were not affected by the Barents–Kara Sea Ice Sheet during the Last Glacial Maximum (LGM).
Inversed modelling based on these results shows that a progressive cooling which started around 30 ka BP, caused ice growth in Scandinavia and the northwestern areas of the Barents–Kara Sea shelf, due to a maritime climate with relatively high precipitation along the western flank of the developing ice sheets. In the rest of the Eurasian Arctic extremely low precipitation rates (less than 50 mm yr-1), did not allow ice sheet growth in spite of the very cold temperatures. Palaeoclimatic and palaeoenvironmental conditions for the time prior to, during, and after the LGM have been reconstructed for the non-glaciated areas around the LGM ice sheet with the use of faunal and vegetation records, permafrost, eolian sediments, alluvial deposits and other evidences. The changing environment, from interstadial conditions around 30 ka BP to a much colder and drier environment at the culmination of the LGM at 20–15 ka BP, and the beginning of warming around 15 ka BP have been elaborated from the field data, which fits well with the modelling results.
Mangerud, Jan, Martin Jakobsson, Helena Alexanderson, Valery Astakhov, Garry K. C. Clarke, Mona Henriksen, Christian Hjort, Gerhard Krinner, Juha-Pekka Lunkka, Per Möller, Andrew Murray, Olga Nikolskaya, Matti Saarnisto, and J.I.John Inge Svendsen. 2004. Ice-dammed lakes and rerouting of the drainage of northern Eurasia during the Last Glaciation. In: Quaternary Environments of the Eurasian North (QUEEN), edited by J. Theide, Quaternary Science Reviews 23(11-13):1313-1332.
Abstract:
During the Quaternary period, ice sheets centred over the Barents and Kara seas expanded several times onto mainland Russia and blocked northflowing rivers, such as the Yenissei, Ob, Pechora and Mezen. Large ice-dammed lakes with reversed outlets, e.g. toward the Caspian Sea, formed south of these ice sheets. Some lakes are reconstructed from shorelines and lacustrine sediments, others mainly from ice-sheet configuration. Ice-dammed lakes, considerably larger than any lake on Earth today, are reconstructed for the periods 90–80 and 60–50 ka. The ages are based on numerous optically stimulated luminescence (OSL) dates. During the global Last Glacial Maximum (LGM, about 20 ka) the Barents–Kara Ice Sheet was too small to block these eastern rivers, although in contrast to the 90–80 and 60–50 ka maxima, the Scandinavian Ice Sheet grew large enough to divert rivers and meltwater across the drainage divide from the Baltic Basin to the River Volga, and that way to the Caspian Sea. Climate modelling shows that the lakes caused lower summer temperatures on the continent and on the lower parts of the ice sheet. The final drainage of the best mapped lake is modelled, and it is concluded that it probably emptied within few months. We predict that this catastrophic outburst had considerable impact on sea-ice formation in the Arctic Ocean and on the climate of a much larger area.
Siegert, Martin J. and Julian A. Dowdeswell. 2004. Numerical reconstructions of the Eurasian Ice Sheet and climate during the Late Weichselian. In: Quaternary Environments of the Eurasian North (QUEEN), edited by J. Theide, Quaternary Science Reviews 23(11-13): 1273-1283.
Abstract:
Geological investigations undertaken through the Quaternary Environments of the Eurasian North programme established ice-sheet limits for the Eurasian Arctic at the Last Glacial Maximum (LGM), sedimentary records of palaeo-ice streams and uplift information relating to ice-sheet configuration and the pattern of deglaciation. Ice-sheet numerical modelling was used to reconstruct a history of the Eurasian Ice Sheet compatible with these geological datasets. The result was a quantitative assessment of the time-dependent behaviour of the ice sheet, its mass balance and climate, and predictions of glaciological products including sediments, icebergs and meltwater. At the LGM, ice cover was continuous from Scandinavia to the Arctic Ocean margin of the Barents Sea to the north, and the Kara Sea to the east. In the west, along the continental margin between the Norwegian Channel and Svalbard, the ice sheet was characterised by fast flowing ice streams occupying bathymetric troughs, which fed large volumes of sediment to the continental margin that were deposited as a series of trough mouth fans. Ice streams may also have been present in bathymetric troughs to the north between Svalbard and Franz Josef Land. Further east, however, the ice sheet was thinner. Across the Kara Sea, the ice thickness was predicted to be less than 300 m, while on Severnaya Zemlya the ice cover may have been thinner at the LGM than at present. It is likely that the Taymyr Peninsula was mainly free of ice at the LGM. In the south, the ice margin was located close to the shoreline of the Russian mainland. The climate associated with this ice sheet is maritime to the west and, in stark contrast, desert-like in the east. Atmospheric General Circulation Modelling has revealed that such a contrast is possible under relatively warm north Atlantic conditions because a circulation system develops across the Kara Sea, isolating it from the moisture-laden westerlies, which are diverted to the south. Ice-sheet decay began through enhanced iceberg calving in the deepest regions of the Barents Sea, which caused a significant ice embayment within the Bear Island Trough. By about 12,000 years ago, further iceberg calving reduced ice extent to the northern archipelagos and their surrounding shallow seas. Ice decay was complete by about 10,000 years ago.
Svendsen, John Inge, Helena Alexanderson, Valery I. Astakhov, Igor Demidov, Julian A. Dowdeswell, Svend Funder, Valery Gataullin, Mona Henriksen, Christian Hjort, Michael Houmark-Nielsen, Hans W. Hubberten, Ólafur Ingólfsson, Martin Jakobsson, Kurt H. Kjær, Eiliv Larsen, Hanna Lokrantz, Juha Pekka Lunkka, Astrid Lyså, Jan Mangerud, Alexei Matiouchkov, Andrew Murray, Per Möller, Frank Niessen, Olga Nikolskaya, Leonid Polyak, Matti Saamisto, Christine Siegert, Martin J. Siegert, Robert F. Spielhagen, and Ruediger Stein. 22004. Late Quaternary ice sheet history of northern Eurasia. In: Quaternary Environments of the Eurasian North (QUEEN), edited by J. Theide, Quaternary Science Reviews 23(11-13): 1229-1271.
Abstract:
The maximum limits of the Eurasian ice sheets during four glaciations have been reconstructed: (1) the Late Saalian (>140 ka), (2) the Early Weichselian (100–80 ka), (3) the Middle Weichselian (60–50 ka) and (4) the Late Weichselian (25–15 ka). The reconstructed ice limits are based on satellite data and aerial photographs combined with geological field investigations in Russia and Siberia, and with marine seismic- and sediment core data. The Barents-Kara Ice Sheet got progressively smaller during each glaciation, whereas the dimensions of the Scandinavian Ice Sheet increased. During the last Ice Age the Barents-Kara Ice Sheet attained its maximum size as early as 90–80,000 years ago when the ice front reached far onto the continent. A regrowth of the ice sheets occurred during the early Middle Weichselian, culminating about 60–50,000 years ago. During the Late Weichselian the Barents-Kara Ice Sheet did not reach the mainland east of the Kanin Peninsula, with the exception of the NW fringe of Taimyr. A numerical ice-sheet model, forced by global sea level and solar changes, was run through the full Weichselian glacial cycle. The modeling results are roughly compatible with the geological record of ice growth, but the model underpredicts the glaciations in the Eurasian Arctic during the Early and Middle Weichselian. One reason for this is that the climate in the Eurasian Arctic was not as dry then as during the Late Weichselian glacial maximum.
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