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Geography and Natural Resources

2021 year, number 1

RESIDUAL RELICT PERMAFROST ON THE COAST OF THE STRAIT OF TARTARY

A.N. Bragin
JSC Far Eastern Design and Exploration Institute of Transport Construction, 680000, Khabarovsk, ul. Sheronova, 56a, Russia
Keywords: cryochrone, permafrost zone, complex of frost mounds, cryogenic landforms, streaky ice accumulation, migration frost mounds

Abstract

This article describes for the first time the fragments of relict permafrost discovered by the author on the coast of the Strait of Tartary in the valley of the Medvezhya river, represented by a complex of frost mounds located in the intermontane area of the Kupol and Malaya Medvezhka mountains. The form, main features and the area of occurrence were studied as well as identifying the landscape-indication and identification features of the complex of frost mounds on the territory of the Strait of Tartary were revealed. On one of the clearly pronounced frost mounds, a well was drilled to the full depth of permafrost occurrence, with the description of the core (rock composition, presence of signs of permafrost, depth and thickness of permafrost), and its ground-geological conditions: rock thickness and composition were determined. The main soil-geological and climatic factors of the preservation of the complex of frost mounds in the Medvezhya river valley, including a thick peat horizon, geomorphological conditions and microclimatic features, are characterized. A probable estimate is made of the time of formation of relict cryogenic forms. The issues related to the origin of hummocky peatlands with respect to the identified relict permafrost forms are discussed. In addition, the role of paleogeographical conditions on the territory of the Lower Amur region is pointed out and interpolated using, as an example, the nearest research object: the Tyapka peat bog in the Bolshaya Mar’ urochishche. A similarity with migration frost mounds associated with migration of moisture to the freezing front at the time of freezing of heavily waterlogged bogs with pools was determined. It is found, however, that the dominant role is played by erosion and thermokarst processes in the formation of relictt permafrost forms in the Medvezhya river valley.