Variations in δ¹⁸О were measured in the samples of Late Pleistocene ice wedge, collected in 2016 on the shore of the Gulf of Ob, near the Seyakha settlement. The values of δ¹⁸О in the upper fragment of the ice wedge vary from –25.75 to –23.15‰. The amplitude of horizontal variations in δ¹⁸О at +15.2 m height is 1.49‰ (–23.41 to –24.9‰). The lower fragment of the ice wedge at +6 m height is characterized by a broader variation range of δ¹⁸O compared to the upper one: δ¹⁸О varies in the horizontal direction from –23.41 to –26.63‰

The isotope dates of water and ice samples were obtained at the isotope laboratory of the Department of Geography, Moscow State University, using a Delta-V mass spectrometer with a standard gas-bench option. For measurements we used the V-SMOW, GISP, and SLAP international standards, and the standards of the laboratory.Data was submitted and proofread by Yurij K Vasil'chuk and Lyubov Bludushkina at the faculty of Geography, department of Geochemistry of Landscapes and Geography of Soils, Lomonosov Moscow State University.The research was financially supported by the Russian Scientific Foundation (grant Nr 19-17-00126, field studies and isotope analysis) and Russian Foundation for Basic Research (grant Nr 18-05-60272, radiocarbon dating and calculations).