Аннотация:Pingos are indicators of modern and past conditions of permafrost. 1620 pingos were identified on the Yamal and Gydan peninsulas in West Siberia. The main purpose of this study is to consider a distribution of stable isotopes in pingo ice cores formed under conditions of open and closed systems. Two pingos from ice cores of different origin in the continuous permafrost zone of the northwest Siberia have been considered: the Messoyaha-1 pingo of 10.5 m in height and the Pestsovoe pingo of 17 m in height. Drilling of the ice core was performed with continuous sampling of an undisturbed frozen core. The ice formation was estimated according to the Rayleigh fractionation in a closed system versus an open system framework. For the Pestsovoe pingo, a pronounced decrease in δ18O values with corresponding increase in dexc with depth indicates a closed system upon the freezing of the lake talik from the top down. For the Messoyakha-1 pingo, the values of δ18O and δ2Н showed a weak tendency to decrease with depth, while the values of dexc varying randomly. Ice that was segregated in the overlying and underlying sediments had similar values of δ18O and δ2Н and a low slope. Isotopically non-equilibrium ice formation was established for ice which had been segregated in a closed system and for ice cores formed in an open to semi-closed system. The vacuum mechanism of water suction from the surrounding lake or lake talik may have played a significant role during the formation of the upper ice core of the Messoyakha-1 pingo and its additional growth.