The main purpose of this work is to establish the formation time of Holocene syngenetic ice wedges that have been exposed on the coast of Baydarata Bay near the village of Yarynskaya, 500 m to the southeast from the mouth of the Ngarka-Tambyakha River.Radiocarbon dating of microinclusions of organic matter, extracted directly from three Holocene syngenetic ice wedges, was conducted using accelerator mass spectrometry (AMS). The dating of the wedges correlates to their formation approximately 6.4, 5.0, and 1.9 cal ka BP. A comparison of the oxygen isotopic composition of the Holocene ice wedges (in which the δ18О values vary mainly from -21.8 to -13.73%) and modern ice wedges (the age of which, as a rule, does not exceed 100 years) showed a close range of variations in values. According to isotope oxygen data, the average January air paleotemperature in the Middle and Late Holocene at the coast of the Baydarata Bay was calculated. It is shown that the average January air temperature during this period here varied from about -20 to -25 °C, however, during milder winters it could be about -18 °C. Ice samples were collected from ice wedges along the vertical profile every 10 cm using Makita DDF481rte 18B and Bosch GSR 36 VE-2-LI drills with steel ice crowns with a diameter of 51 mm. Measurements of the oxygen isotopic compositions in ice were performed on a Picarro L 2130-i laser infrared spectrometer at the Center for X-ray Diffraction Studies at the Research Park of St. Petersburg State University (XRD Center SPbU). The following international standards were used: V-SMOW-2, GISP, SLAP, USGS-45, and USGS-46. The measurement errors were ±0.02‰ for δ18O. In total,63 samples of ice wedges were analyzed.

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.