Geophysical study of the opening of the Labrador Sea

Abstract

Deep seismic reflection profiling has been used to outline the main features of the basement topography of the Labrador Sea. Two major sedimentary reflectors, tentatively dated as Paleocene and Eocene, are correlated throughout the survey. A large basement feature extends southwest below a sedimentary ridge from Cape Farewell. It is interpreted as a transform fault created by the movement of the tip of Greenland during the early stage of opening. On the basis of the sedimentary history of the sea, of transform fault geometry, and of magnetic anomaly pattern, a preliminary history of the opening of the Labrador Sea is given in terms of plate tectonics. Two main episodes are proposed. The first one, from Upper Cretaceous to Paleocene, would correspond to an opening rate of slightly less than 1 cm/yr accompanied by rapid subsidence of the margins. The second one, from Paleocene to Eocene, would correspond to the opening of the final third of the basin at a rate of about 0.5 cm/yr. Very slow movement would have continued up to the present.