New oxygen isotope diagrams of late pleistocene and holocene ice wedges of Mamontova Gora and Syrdah Lake, Central Yakutia

The aim of the study was to obtain the data of stable oxygen isotope composition of Late Pleistocene and Holocene ice wedges of Mamontova Gora and Syrdakh exposures and their chronology, and reconstruction of winter air temperature during the time of ice wedge formation. Direct dating of organic microinclusions from the ice wedges of Mamontova Gora outcrops allowed to establish that the ice wedges are younger than 20 ka, but older than 10 ka BP. δ¹⁸O values of the Late Pleistocene ice wedges of Mamontova Gora vary from -24.7 to -30.9 ‰, δ¹⁸O values of the Holocene ice wedges of this exposures range from -23.2 to -25.9 ‰. δ¹⁸O values in the Late Pleistocene ice wedges near Syrdakh Lake vary from -29.2 to -32.5 ‰. Reconstructed mean winter air temperature during the most part of the ice wedge growth period in Mamontova Gora site within Late Pleistocene varied from -28 to - 31°C, mean January temperature reached -42, -46°C, for the Syrdakh Lake site Late Pleistocene winter conditions were more severe: mean winter air temperature varied from -30 to -32°C, mean January air temperature reached -44, -48°C. Holocene mean winter air temperature were higher and varied from -24 to - 28°C, mean January temperature varied from -36 to -42°C.