THEME 4
Deep Central Basin of the Arctic Ocean

The deep Arctic Ocean origin is due to seafloor spreading during middle and late Mesozoic time; its opening continued along the Gakkel Ridge from early Tertiary to modern times. The physiography of the deep Arctic basins is structured by two ridges, namely the Lomonosov ridge, which probably comprises a thin sliver of continental crust and which originally was attached to the Eurasian continental margin, and the Alpha Mendeleev Ridge, which according to all indicators is of volcanic origin. However, the history and nature of this volcanism is completely open and volcanic processes range from a hot-spot to a transform origin; however, other mechanisms producing this volcanism can also be imagined.

The age of the crust of the Canada Basin and of the Makarov Basin of the Alpha Mendeleev Ridge is still high disputable and remains to be resolved. Few sediment cores have penetrated sediments older than Quaternary but it is well-known from these cores that the Arctic Ocean has remained ice-free at least until Eocene time if not much later. It must be one of the important scientific targets to obtain long sediment cores to resolve long- and short-term variations of the Arctic Ocean paleoceanography, which over the past 40 million years turned from an ice-free, temperate ocean to a glaciated, cold, ice-covered ocean, both - however - being polar oceans.