TY - JOUR A1 - Angelopoulos, Michael A1 - Overduin, Pier Paul A1 - Westermann, Sebastian A1 - Tronicke, Jens A1 - Strauss, Jens A1 - Schirrmeister, Lutz A1 - Biskaborn, Boris K. A1 - Liebner, Susanne A1 - Maksimov, Georgii A1 - Grigoriev, Mikhail N. A1 - Grosse, Guido T1 - Thermokarst Lake to Lagoon Transitions in Eastern Siberia: Do Submerged Taliks Refreeze? Y1 - 2020 VL - 125 IS - 10 JF - Journal of Geophysical Research: Earth Surface DO - 10.1029/2019JF005424 DO - 10.23689/fidgeo-4729 N2 - As the Arctic coast erodes, it drains thermokarst lakes, transforming them into lagoons, and, eventually, integrates them into subsea permafrost. Lagoons represent the first stage of a thermokarst lake transition to a marine setting and possibly more saline and colder upper boundary conditions. In this research, borehole data, electrical resistivity surveying, and modeling of heat and salt diffusion were carried out at Polar Fox Lagoon on the Bykovsky Peninsula, Siberia. Polar Fox Lagoon is a seasonally isolated water body connected to Tiksi Bay through a channel, leading to hypersaline waters under the ice cover. The boreholes in the center of the lagoon revealed floating ice and a saline cryotic bed underlain by a saline cryotic talik, a thin ice-bearing permafrost layer, and unfrozen ground. The bathymetry showed that most of the lagoon had bedfast ice in spring. In bedfast ice areas, the electrical resistivity profiles suggested that an unfrozen saline layer was underlain by a thick layer of refrozen talik. The modeling showed that thermokarst lake taliks can refreeze when submerged in saltwater with mean annual bottom water temperatures below or slightly above 0°C. This occurs, because the top-down chemical degradation of newly formed ice-bearing permafrost is slower than the refreezing of the talik. Hence, lagoons may precondition taliks with a layer of ice-bearing permafrost before encroachment by the sea, and this frozen layer may act as a cap on gas migration out of the underlying talik. UR - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9075 ER -