δ18О in ice wedges (δ18Оiw) and reconstructed mean January air temperature (ТmJ) in Kolyma Lowland region for three key Holocene stages

Oxygen isotope measurements of most of the ice wedges studied were carried out using a G-50 device in the isotope geology laboratory at the Institute of Geology, Tallinn, Estonia (Prof. R. Vaykmäe) and in the isotope hydrology laboratory at the Institute of Water Problems of Russian Academy of Science (Dr. A. Esikov). Control measurements were carried out in both laboratories. The ice wedges sampled during field work in 2018 were analyzed in the stable isotope laboratory of the Geography Faculty at Lomonosov Moscow State University (Prof. Y. Vasil'chuk and Dr N. Budantseva) using a Finnigan Delta-V Plus mass spectrometer, applying equilibration techniques. International water standards (SMOW, GRESP, and SLAP) were used for calibration. Analytical precision was ±0.4‰ for δ18O and ±1‰ for δ2 H. All values are presented in δ-notation in per mille (‰) relative to the Vienna Standard Mean Ocean Water (VSMOW). Deuterium excess (dexc) is calculated as dexc = δ2 H-8δ18O.38 14C ages of bulk samples were obtained at the Institute of Geology RAS (lab. code GIN) and at the Institute for the History of Material Culture, St. Petersburg (lab. code Le). Radiocarbon ages were calibrated using OxСal 4.3 based on the IntCal13 data set and given as yrs cal BP.39,40