9 - Characteristics of the basic genetic types of frozen ground

Summary

Features of the cryogenic types of frozen strata

Currently the strata of perennially frozen materials are subdivided into two basic types with respect to conditions of their freezing, namely, epicryogenic and syncryogenic. Under certain conditions (locally) a third type can be distinguished – diacryogenic perennially frozen materials.

In the majority of cases the frozen strata represent different combinations of these types and are then called polycryogenic (polygenetic) types.

Epicryogenic frozen strata are formed by freezing (usually from the top downwards) of lithified materials in which complex diagenetic physicalchemical processes have already taken place. With respect to their cryogenic structure they are subdivided into epicryogenic Pre-Quaternary bedrock (with rigid bonds, monolithic and others) and epicryogenic Neogene-Quaternary materials of the loose mantle.

Syncryogenic strata are formed by processes of sediment accumulation and freezing occurring simultaneously (synchronous in a geological sense). Therefore, frozen strata of this kind can be represented only by loose, Quaternary deposits. Their accumulation and freezing take place from below upwards. At the commencement of syngenetic freezing the base of the accumulating series would be composed of epigenetically frozen strata.

Diacryogenic strata are formed by the freezing from the top, from below and laterally of oversaturated non-lithified materials – newly deposited sediments and silts in which complex diagenetic physical-chemical processes have either just begun or are far from completion, being stopped by the processes of freezing.