Analyses of stable isotope compositions are widely used in palaeoclimate studies. Mostly known as a tool for the interpretation of ice cores, parameters such as d18O, dD and d excess can analogously be used for the reconstruction of the palaeoclimate from permafrost features such as ice wedges. Since ice wedge growth is caused by the repeated frost cracking of the frozen ground, followed by penetration and refreezing of melt water of winter snow, the isotopic signal of wedge ice may reflect winter temperatures.Within the research project Process studies of permafrost dynamics in the Laptev Sea field work was carried out in summer 2003 at Cape Mamontovy Klyk, Northern Siberia (73°36 N; 117°10 E). The research area is located in the Lena-Anabar lowlands at the Laptev Sea coast. It is part of the zone of continuous permafrost reaching thicknesses of 400-600m in that region. Generally, the cliff consists of ice-rich sediments with a complicated depositionary and cryolithological situation. Nevertheless, four units can be distinguished representing changing environmental conditions. The Late Pleistocene Ice Complex as the main unit is one of the most peculiar cryolithological formations in this region characterised by silty sands with huge syngenetic ice wedges. It is underlain by a peat-sand-complex with small ice wedges probably linked with fluvial activity. Bottom sands with ice-sand-wedges represent the oldest unit in this section. The Ice Complex is covered by a 2 m thick horizon of peat-rich, silty sediments likely to be of Holocene age.Samples representing different generations of ice wedges were taken over the whole vertical profile of the cliff of Cape Mamontovy Klyk and d18O and dD analyses were carried out. Preliminary results indicate that todays climate seems to be the warmest for that area. Furthermore, the isotopic signals of recent ice wedges seem to be closely linked to those of snow patches as they are found in the same range of isotope values. A clear jump can be identified in the isotopic composition of all ice wedges which is likely to be related to the transition from Pleistocene to Holocene.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > POL-MARCOPOLI
Helmholtz Research Programs > MARCOPOLI (2004-2008) > POL6-Earth climate variability since the Pliocene