Permafrost Evolution in the Rusanov Area, South Kara Basin

Thermal history of the subsea permafrost in the sedimentary section of the Rusanovskaya‐2 well in the South Kara sedimentary basin has been numerically reconstructed using the ICE2020 software package, which is a part of the GALO flat basin modeling system. The thermal evolution of the sedimentary section during the last 3.5 My is considered as a final stage of the basin evolution, which began with continental rifting in the Upper Permian. The basin history of the last 3.5 My included repeated periods of sea transgressions and regressions. The thickness of permafrost could decrease to 30–40 m during the transgressions and increase to 300–600 m in the time of the sea regressions. The simulation results suggest that the thickness of permafrost increased during the last period of maximum cooling, reaching a maximal depth of 312 m about 14.5 Ky. After that, the permafrost degraded in response to marine transgression and climate warming. The depth of the base of current permafrost is estimated to be 152 m, and the permafrost is degrading from below at a rate of about 12 m/1000 years.