New geophysical data on the evolution of the northern gateway (Fram Strait, Yermak Plateau)

While evolution of the Eurasian Basin and North Atlantic starting at ~55 Ma are well known, this holds not true for the Fram Strait. The Lena Trough, a mid-ocean ridge in the centre of the Fram Strait, is the only deep water connection of the Arctic Ocean. The lack of geophysical data prevented any detailed model for the geodynamic history of this gateway so far. New multi-channel seismic and aeromagnetic data show the straits opening as far south as 81°N at ~16 Ma. Before, intermediate-depth water exchange might have existed through deep grabens of the recent Yermak Plateau. Its basement topography is very rough and the plateau-like bathymetry is a young feature. Large drift deposits on oceanic crust younger than 10 Ma indicate strong current activity and erosion of the surrounding shelves after opening of the gateway. Furthermore, the data show that the Fram Strait was in place long before the high frequency glacial/interglacial cycles started in the northern hemisphere at ~3 Ma. Though the gateway might have played an important role in the long-term cooling of the northern hemisphere, it is unlikely to have been solely responsible for the intensification of the northern hemisphere glaciations in the Late Pliocene/Pleistocene