Age of the Alpha-Mendeleev and Lomonosov ridges (Amerasian Basin)

The geological time of the formation of Alpha-Mendeleev and Lomonosov ridges is determined in a broad range from the Late Cretaceous to the Cenozoic. This does not allow researchers to have reliable insight into the evolution of the entire Amerasian Basin, which is characterized by a high hydrocarbon potential. The genesis of these ridges is still under discussion. For a more precise time assessment, the geothermal method, which is highly informative in the sense of lithospheric age, has been applied. On the basis of numerical geothermal calculations, the formation time intervals were determined at 97–79 Ma for Alpha-Mendeleev Ridge and at 69–57 Ma for Lomonosov Ridge; these ages conform to the geological-geophysical data and verify the fact that these ridges belong to the eastern part of the Russian shelf zone. The formation time of the Alpha-Mendeleev and Lomonosov ridges determined has allowed us to optimize the calculations and plate-tectonic reconstructions for the Amerasian Basin.