Deposits of the Ice Complex with thick ice wedges are ubiquitous in the North-East of Russia. Due to syngenetical freezing and the persisting permafrost, a great volume of organic matter has been preserved. These organics are a valuable archive of palaeoecological information. The bulk of monotonous grey and brown silts and silty sands of the Ice Complex on the coastal plains of northern Yakutia is proved to be modified by pedogenesis. Four fossil epigenetic soils, formed during the time span of 40 to 26 kyr BP, have been found. Younger sediments have no epigenetic soils - they are modified by background synsedimentary pedogenesis without distinct paleosols. Relatively warm and dry summers, cold and snow-deficient winters with vigorous influx of mineral particles, mostly by winds, are characteristic for intervals of synsedimentary pedogenesis. Arid conditions, disturbed soils, weak turf with steppe and pioneer vegetation are evidenced by fossil rodent burrows (ground-squirrels Urocitellus) with diverse palaeoecological material: more than 800 thousand plant seeds can be recovered from certain fossil burrows. At the same time there were habitats of more hydrophilous plants.

Epigenetic soils of the Karginsky interval were formed in a warmer climate and weaker influx of mineral matter. The best developed lowermost fossil soil has some traces of taiga pedogenesis. It was formed с 37-40 radiocarbon kyr BP and prior to this time. Above it, within the silty sequence, there are three more soils belonging to the early Karginsky pedocomplex. They have quite similar hydromorphous profiles structured as the At-Bg-BCg type. Weak traces of taiga pedogenesis are noted only in the 1st soil formed с 35 kyr BP. The 2nd and 3d buried soils of this pedocomplex were formed under cold tundra conditions. Traces of hydromophism in soil profiles distinctly abate upwards in the Karginsky interval. The 3d paleosol of the late Karginsky pedocomplex is often a weak dry-peaty soil. The 2d soil is 33 and the 3d one is 26 radiocarbon kyr old.

The presence of four fossil soils within the Karginsky part of the Ice Complex can be used for its stratigraphic identification and subdivision.

Reference:

Gubin S.V., Zanina O.G. Fossil soils in the Late Pleistocene Ice Complex (the Yedoma formation) of the Russian North-East. Correlation of Pleistocene Events in the Russian North. International Workshop Abstracts. 4-6 December 2006. Saint-Petersburg, 2006, p. 34.