Eemian records from permafrost archives in the Laptev and East Siberian seas


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Lutz.Schirrmeister [ at ] awi.de

Abstract

Records of the last Interglacial were found in ice wedge casts exposed about 1 - 5 m asl along the Dmitry Laptev Strait in Northeast Siberia (East Siberian Sea) as well as about 900 km to the west on the coast of the western Laptev Sea near Cape Mamontov Klyk in an onshore core in 20 m depth below surface level (b.s.l.), and in a 12 km offshore (submarine) core in about 70 m depth b.s.l.. In both areas Eemian sequences are covered by younger Late Pleistocene deposits.The Eemian records from the Dmitry Laptev Strait contain a rich association of fossil faunal and floral indicators reflecting continental freshwater conditions of a periglacial thermokarst landscape (Andreev et al., 2004, 2009; Ilyashuk et al. 2006; Kienast et al. 2008; Wetterich et al. 2009). Thawing of permafrost ground ice below thermokarst lakes as well as several cryolithological data from the considered permafrost deposits are evidence for the interglacial landscape and permafrost dynamic of the Siberia Arctic shelf region during the last Interglacial.In the permafrost cores from the western Laptev Sea region, stable isotope records in texture ice and pollen associations (Winterfeld et al. under review) indicate an interglacial period. The Eemian segment of the submarine core is characterized by high salinity (11.7 to 30.8 ) and relatively heavy stable isotope values of the pore ice (&#61540;18O: -9.3 to -15.3 ; &#61540;D: -81.0 to -119.2 ), which are interpreted as a marine influence, probably under lagoon conditions. Pollen grains are only scarcely preserved within these well-bedded silty sand deposits. Nevertheless, there are samples containing clear interglacial associations of tree and shrub pollen taxa similar to those of the Eemian ice wedge casts along the Dmitry Laptev Strait. Between 19 and 25 m b.s.l., the onshore core preserved interglacial pollen associations and relatively lighter stable isotope records (&#61540;18O: -14.8 to -18.3 ; &#61540;D: -115.0 to -130.0 ) lacking marine influences (salinity <2 ). Therefore, it is assumed, that during the Eemian the coastal line of the Laptev Sea could have been located between the two core sites.The study areas with Eemian records are located on both sites of the Arctic Rift Zone, the boundary between the Eurasian and the North American plates. Therefore, the current vertical positions of presented Eemian deposits and the corresponding paleogeographical dynamics are probably influenced by Late Quaternary neotectonical processes in this still seismically highly active region.



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Conference (Talk)
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Not peer-reviewed
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Published
Event Details
APEX Fourth International Conference and Workshop: Arctic paleoclimate proxies and chronologies; Höfn, Iceland; May 26th-30th 2010..
Eprint ID
22785
Cite as
Schirrmeister, L. , Wetterich, S. , Winterfeld, M. , Andreev, A. , Meyer, H. and Overduin, P. P. (2010): Eemian records from permafrost archives in the Laptev and East Siberian seas , APEX Fourth International Conference and Workshop: Arctic paleoclimate proxies and chronologies; Höfn, Iceland; May 26th-30th 2010. .


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