Abstract: The research method is a purposeful petrophysical interpretation of the gravitational field. The object under study appeared during prospecting geological and geophysical work as a hindrance to the solution of the main geological problem. Its density is 1 g/cm3, the height of the sole is 35 m, the area is 1420 km2, the volume is 20 km3. The object is defined as an abnormally light Ice Complex (ALIC). The revealed density is explained by peat-ice performance. In ALIC, a near-surface lenticular-layered formation ice has been uncovered, the structure of which indicates the generation of the mass of the complex ahead of sedimentation. The gravimetric data, the landscape and the details of the ALIC structure are interconnected and make up the first — the most complete view of the complex at the moment. The main elements of the presentation are the three phases of the development of the complex. The first is classical, generally accepted for polygonal—vein structures, the second differs from the classical one by the absence of frost-breaking cracking, the third is the growth of formation ice. The qualitative difference of the thermophysical components of the cryolithozone of the territory is given, which made it possible to introduce several concepts concerning the generation of peat-ice mass ALIC. Such as: heat dissipation capacity of the middle layer, stabilization of the zero isotherm at the petrophysical boundary; conditions for the beginning of the growth of lenticular-layered ice; accelerated lateral segregation growth of powerful ice veins; constancy of the thermal resistance of the cryolithozone. On the basis of these concepts, models of the development of the second and third phases of ALIC are compiled, and a view on the theory of the formation of cover glaciers is formed, which follows from the model of the third phase. The novelty of the research consists: in identifying a unique petrophysical object, in defining this object as ALIC, in identifying an ice massif on the territory of ALIC, in presenting the development of the complex as a sequence of three phases, in compiling models of the second and third phases of ALIC and in an original approach to the formation of cover glaciers.

Keywords: freezing, formation ice, ice complex, geocryology, cryolithozone, climate, thermophysics, Nettleton's method, gravimetry, segregation ice formation