Geology of the Greenland-Iceland Ridge in the Denmark Strait

Abstract

The continental shelf of East Greenland and the insular shelf of Iceland almost merge in the Denmark Strait, forming the Greenland~ Iceland Ridge. This is the western part of the Scotland-IcelandGreenland aseismic ridge, which is an important oceanographic threshold between the Norwegian Sea and the Atlantic Ocean. Roughly half of the inflow of cold arctic water into the Atlantic takes place through the Denmark Strait (Coachman and Aagaard, 1974). This flow is closely related to the warm Norwegian Stream entering the Norwegian Sea south of Iceland. Changes in the cross section in the Denmark Strait may thus imply important changes in oceanography and climate of northern Europe and Greenland (Eldholm and Thiede, 1980). The Scotland-Iceland-Greenland Ridge joins the lower Tertiary volcanic areas of East Greenland, Iceland, the Faeroes and Northwest Scotland (the Brito-Arctic volcanic province). This lead to the suggestion long ago that the ridge was a foundered landbridge of volcanic origin (Holmes, 1918). In the context of seafloor spreading the ridge has been regarded as the trace of the Iceland mantle plume (see Vogt et al., 1981 for references). In spite of the geological interest of the Denmark Strait area ' very little data are available. This is chiefly due to the pack ice •· which covers the East Greenland shelf area for all but a few weeks of the year. The purpose of this paper is to review the geology of the Denmark Strait area and to report the results of a marine-geological reconnaissance made by the Geological Survey of Greenland in 1974, 1975 and 1979. The magmatic evolution in the East Greenland basalt province and history of seafloor spreading on the East Greenland continental margin are dealt with by H.C.Larsen and Brooks (in preparation).