Late Quaternary Paleoclimate Information from Stable Water Isotopes in Ice Wedges at the Dmitry Laptev Strait, Northeast Siberian Arctic

• Main Authors: Opel, Thomas, Meyer, Hanno, Derevyagin, Alexander Yu, Wetterich, Sebastian, Schirrmeister, Lutz
• Format: Conference Object
• Language: unknown
• Published: 2013
• Subjects: Arctic; Yar; Ice; laptev; permafrost; Polar Research; Thermokarst; wedge*
• Online Access: https://epic.awi.de/id/eprint/32697/; https://hdl.handle.net/10013/epic.41254

Ice wedges are the most abundant type of ground ice in the ice-rich permafrost deposits of the Northeast Siberian Arctic. They are formed by the periodic repetition of frost cracking and subsequent crack filling in spring, mostly by melt water of winter snow. Ices wedges can be studied by means of stable-water isotopes. Their isotopic composition is directly linked to atmospheric precipitation (i.e. winter snow) and, therefore, indicative of past winter climate conditions even though also genetic aspects, i.e. sublimation, melting and refreezing in the snowpack and the frost crack, have to be taken into account. Here we present stable-water isotope data of ice wedges at the Oyogos Yar coast of the Dmitry Laptev Strait (72.7°N, 143.5°E). The ice wedges from different stratigraphic units comprising pre-Eemian sediments, Middle Weichselian Ice Complex (Yedoma) sediments and Holocene themokarst (Alas) sediments were studied and sampled in 2002 and 2007. Stable-water isotopes were measured in the stable-isotope lab of the Alfred Wegener Institute in Potsdam, Germany. Ice wedge stable-water isotope data indicate substantial variations in Northeast Siberian Arctic winter climate conditions (δ18O) as well as shifts in the moisture generation and transport patterns (d excess) during the Late Quaternary, in particular between Glacial and Interglacial but also during the last centuries. Ice wedges of the pre-Eemian Kuchchugui and Bychchaguy Suites exhibit mean δ18O values of about -30‰ and -34‰, respectively, indicating cold to extreme cold winter temperatures. The latter represents the coldest conditions found in ice wedges at the Oyogos Yar coast. Mean d-excess values are about 3‰ and 6‰, respectively. Small ice wedges in Eemian sediments show distinctly warmer mean δ18O values of about -24‰ and mean d-excess values of about 4‰. However, probably they represent younger epigenetically grown ice wedges with an isotopic composition that might be influenced by sediment-ice interaction. Huge syngenetic ice wedges of the Weichselian Yedoma Suite are characterized by mean δ18O values of -29‰ to -33‰ and mean d-excess values around 6‰ in different altitude levels, reflecting cold to extreme cold winter temperatures. On top of the Ice Complex as well as in a thermokarst depression, formed during the Late Glacial, Holocene ice wedges could be found. They have been grown predominantly in the Middle and Late Holocene and exhibit mean δ18O values of about -25‰ and mean d-excess values of 8‰, mirroring distinctly warmer winter temperatures in the Holocene. Recent ice wedges grown in the last decades are characterized by mean δ18O values of about -22‰ and mean-d excess values of 8‰, testifying the recent winter warming in the Arctic.