Аннотация:Late Mesozoic and Cenozoic geodynamics of the Arctic region is discussed in the contextof possible mechanisms which provide multistage cyclic transformations and transport of carbonthrough crust and mantle. Geodynamic processes control the abiogenic generation of hydrocarbonsand the patterns of their localization. Possible mechanisms of abiotic hydrocarbon generation areexplained in the context of carbon transport from subduction zones to rifts and serpentinization ofultramafic rocks in the rifts in the case of the Laptev Sea and Gakkel Ridge areas. The carbon ofshallow crust origin migrates with encapsulated fragments of marine sediments which are consumedin the Pacific subduction zone where they become destroyed and transformed by different chemicaland physical processes. The resulting C-species are involved in mantle convection flows and reachthe continental rifts of the Laptev Sea and the Gakkel mid-ocean ridge. Thus, the hydrocarbonsformed in the crust and in the mantle acquire signatures of abiotic origin. According to the authors,the scale of manifestation of abiogenic methanogenesis in the lower parts of the lithosphere and in theupper mantle is not so wide. Numerous small (mm and fractions of the mm) particles of exogenousmatter and dispersed carbon pulled into the mantle can only form a stable crustal geochemical plumethat propagates in the plane of movement of convective flows. Indirectly, the scale of manifestationof this process can be judged by the volumes of degassing of hydrocarbon and carbon dioxide gases,as well as hydrogen and its compounds in the rift systems of the earth’s crust, which are extremelyinsignificant. However, in the cold seas of the Eastern Arctic, massive emissions of bubble methaneof mixed genesis were found. As shown in the literature, the range of variability of stable isotopesof carbon and14C of methane in certain areas of discharge associated with rifting demonstratesvalues (anomalously heavy13C, and young14C) that can be considered as examples of presumablyabiogenic origin. Our work is mostly theoretical and suggests further discussion and improvementof the mechanism of formation of abiogenic hydrocarbons and the processes of their transformation.
