Permafrost patterns in the SE Laptev Sea, East Siberian Arctic Ocean

Abstract

Polygonal patterns, with dimensions and shapes similar to modern polygons covering extensive parts of the permafrost-dominated land areas of the Arctic and subarctic, exist on the seafloor of the eastern Laptev Sea. The mapped patterns in the Laptev Sea resemble macro-scale frost polygons associated with thermal-contraction cracking of the ground (Lachenbruch 1962). The formation of these permafrost-related landforms probably occurred during the Late Pleistocene when most of the Laptev Sea shelf was sub-aerially exposed and free from ice-sheet cover (Jakobsson et al. 2014). Postglacial sea-level rise transformed these areas from a periglacial permafrost landscape into a modern shallow shelf (Gavrilov et al. 2006). Large numbers of closed, multi-sided, roughly equidimensional seabed polygons are revealed by side-scan sonar imagery and sub-bottom profiles from the SE Laptev Sea (Fig. 1). These landforms are mapped in water depths between about 10 and 17 m over a maximum stretch of around 700 m. The total number of seafloor areas with similar patterns exceeded two dozen. Fig. 1. Geophysical images and profiles showing evidence of …