THE MAIN STAGES OF THE FRAM STRAIT FORMATION IN THE NEOGENE: ANALYSIS OF GEOLOGICAL AND GEOPHYSICAL DATA

The opening of the Fram Strait began in the Early Miocene (~19.5 Ma) as a result of movements of the North American and Eurasian lithospheric plates, which resulted in the formation of the narrowest segment of the strait, the Lena Trough. In the Miocene (~19.5–9.8 Ma), the opening of the central part of the Fram Strait led to formation of the central and northwestern parts of the Molloy Basin, which had an extended basement consisting of blocks of the West Spitsbergen fold-and-thrust belt. In the Late Miocene (~9.8 Ma), in the central part of the Fram Strait, a jump in the axis of its opening to the east occurred in the segments between the Molloy and Spitsbergen transform faults, and spreading began in the northernmost segment of the Knipovich Ridge. In the Late Miocene (~9.8 Ma), the deep-sea exchange of waters between the North Atlantic and the Arctic Ocean took place west of the Barents Sea continental “fragments” – the Hovgaard Ridge and Mount Hovgaard. In the Late Miocene (~6.7 Ma), the Molloy Basin began to open, which coincides with the beginning of the continuous subsidence of the Hovgaard Ridge, which was in subaerial conditions, and with a three-fold increase in the sedimentation rate in the central part of the Molloy Basin. In the Late Miocene‒Early Pleistocene (~9.8‒1.8 Ma), a warm current from the North Atlantic could have passed along the eastern continental margin of Greenland and, at the peak of its maximum intensity, ensured the existence of biological diversity in the conditions of the “polar desert” and “polar night” in the north‒northeast of Greenland and the shallow sea areas adjacent to the coast. The modern direction of the cold and warm currents in the Fram Strait could have formed in the Early Pleistocene (~1.8 Ma) and be associated with the opening of the northernmost segment of the Knipovich Ridge.