The Lomonosov ridge experiment: “Lorex 79”

In the spring of 1979 the Department of Energy, Mines and Resources (EMR) undertook a large-scale, multidisciplinary project to study the nature and origin of the Lomonosov Ridge. The scientific program was planned and coordinated by the Earth Physics Branch, and the logistic support was provided by the Polar Continental Shelf Project/Scientists from other branches of EMR, from the Department of Fisheries and Oceans (DFO), and from a number of universities in Canada and the U.S.A. took part in the project code named Lorex 79.The Lomonosov Ridge is an aseismic submarine mountain range that bisects the Arctic Ocean into the Amerasia and Eurasia Basins (Figure 1). It rises sharply to a height of some 3 km above the adjacent abyssal plains, the Makarov Basin to the west, and the Fram Basin to the east. It is close to 200 km wide where it approaches the North American and Eurasian continental shelves but narrows to 25 km at its midpoint near the North Pole. Its relatively flat top, the steepness of its flanks, and results from previous geophysical measurements indicate that it may be a sedimentary structure of continental origin rather than a structure of oceanic origin [Sweeney et al., 1978]. In this context it has been suggested on several occasions that it is a rafted fragment split off the Eurasian continental shelf at the time of the opening of the North Atlantic and the Eurasia Basin in Early Tertiary times. However, since the available geophysical, geological, and bathymetric data are relatively sparse and often of doubtful quality (because of the enormously difficult operating conditions), the continental nature of the Lomonosov Ridge has never been unambiguously demonstrated.