Permafrost history in Arctic Siberia - insights from the cryogenic weathering record at Elgygytgyn crater, NE Siberia
Zusammenfassung der Projektergebnisse
Brittle, flaky and fragile sandy and silty grains are produced in Siberian near surface permafrost. They cover much of the landscape in the terrestrial Arctic. These features stem from the cryogenic destruction following numerous seasonal freezing and thawing events in the uppermost soil. Once a grain is moved it still keeps the weathering traces even when soil creeps down a slope, even when grains are transported with a river, even when they are washed into a lake. This is also valid for a mineralogical peculiarity, since frost weathering is a selective grain break-up. Unlike in lower latitudes quartz is most sensitive to weathering in high latitudes. Quartz quickly reacts to cryogenic break-up and small grains disintegrate due to the explosive power of expanding ice in micro-meter scale fissures. This quartz enrichment in the fines also evolves from seasonal freeze-thaw weathering and is demonstrated by an experimental set-up. Both, the grain micromorphology and the quartz enrichment as related to soil cryogenic weathering are preserved in El´gygytgyn lake sediments. This is a record of landscape and climate change that stretches back several hundred thousands of years. It is the longest book of climate history of the terrestrial Arctic right now. The mineralogical analysis of this El´gygytgyn permafrost and lake sediments shows that the permafrost is at least as old as 220.00 years back from now. Even when periods were as warm as or warmer than today (for example during the Eemian) in that time the permafrost did not disappear. The transport of grains prevents an in-situ signal of soil conditions, thus the results from the mineralogical analysis are seen as way to integrate soil weathering dynamics over long term time scales, e.g. 10.000 of years. Now, new and long cores from ICDP drilling into El´gygytgyn permafrost and lake sediments are available since 2008/9. The method described will help to date and make visible the onset of permafrost conditions in the area.
Projektbezogene Publikationen (Auswahl)
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(2008). The permafrost record of Elgygytgyn Impact Crater, Second International Conference and Workshop of Arctic Palaeoclimate and its Extremes (APEX) – Recent Advances, April 1 - 4, 2008, Durham University, Department of Geography, Durham City, UK
Schwamborn, G., Fedorov, G., Schirrmeister, L., Meyer, H., Hubberten, H. -W.
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(2008). Tracing Siberian Permafrost History, IODP-ICDP Kolloquium 2008, Hannover, 12-14 March, p. 117
Schwamborn, Georg, Fedorov, Grigorij, Schirrmeister, Lutz, Hubberten, Hans-Wolfgang
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(2009). A record of permafrost conditions for Arctic Siberia from El´gygytgyn Impact Crater, IODP/ICDP Kolloquium Potsdam, 16.-18.03.2009, p. 148
Schwamborn, G., Förster, A., Fedorov, G., Schirrmeister, L., Diekmann, B.
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(2009). Frozen ground history at El´gygytgyn Meteorite Crater in the Russian Arctic, European Geosciences Union (EGU) General Assembly, April 19-24, 2009, Vienna, Austria. Geophysical Research Abstracts, Vol. 11, EGU2009-10324
Schwamborn, G., Fedorov, G., Schirrmeister, L., Diekmann, B., Chapligin, B., Hubberten, H. -W.
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(2009). Permafrost as palaeo-environmental archive - potentials and limitations, European Geosciences Union (EGU) General Assembly, April 19-24, 2009, Vienna, Austria. Geophysical Research Abstracts, Vol. 11, EGU2009-5683
Schirrmeister, L., Wetterich, S., Meyer, H., Grosse, G., Schwamborn, G., Siegert, C.
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2009). Cryogenic weathering recorded through glacial-interglacial cycles at El´gygytgyn Impact crater, Siberian Arctic, Arctic Palaeoclimate and its EXtremes- beyond the frontier, APEX Third International Conference and Workshop, Copenhagen, March 31st - April 3rd, 2009, p. 67
Schwamborn, G., Förster, A., Schirrmeister, L., Diekmann, B.
