Duration, causes, and geodynamic significance of the Middle Cenozoic hiatus in sedimentation in the near-polar part of the Lomonosov Ridge (based on IODP-302-ACEX drilling data)

The paper analyzes the duration and causes of the Middle Cenozoic hiatus in sedimentation in the near-polar part of the Lomonosov Ridge, revealed during biostratigraphic research of ACEX borehole deposits. Arguments are presented against the existence of a long hiatus between sediments of lithological complexes 1/5 and 1/6. The Lomonosov Ridge naturally subsided in the Cenozoic as a result of cooling of the lithosphere after riftogenesis. However, the level of the Arctic Ocean in its isolation period (49(?)–36.6 Ma) could have been lower than the level of the World Ocean due to decelerated spreading in the Eurasian Basin. A brief hiatus in sedimentation was caused by opening of the Fram Strait around 36.6 Ma and the infiltration of intermediate Atlantic waters, which could have interacted with the Lomonosov Ridge, leading to the erosion or nondeposition of particles on its surface.