Pedogenesis in the Tundra Zone of Coastal Lowlands of Northeastern Siberia

Coastal lowlands of northeastern Siberia are composed of the Pleistocene ice-rich organic-containing loamy sediments of the Ice Complex (yedoma) and products of their transformation in the Holocene. In the tundra zone, three major trends of modern pedogenesis depending on the geomorphic position and age of particular landforms have been identified. On the interfluves affected by thermokarst processes in the Holocene, somewhat elevated remains of the Late Pleistocene Ice Complex alternate with vast thermokarst depressions (alases) with lakes. Cryozems are developed in automorphic plain positions and on the upper parts of slopes. The profiles of these soils are strongly affected by cycles of frost boiling and cryoturbation; under their influence, specific suprapermafrost accumulative organomineral horizons are formed. Gleyzation predominates in the soils of the low- and middle-level Holocene terraces of alases. Peat accumulation is progressively developed in the bottoms of alas depressions.