Tectonic evolution of the Labrador Sea and Baffin Bay: constraints imposed by regional geophysics and drilling results from Leg 105

Results of drilling in the Labrador Sea and Baffin Bay during Leg 105 confirm an earlier interpretation, based on geophysical data, that the crust under the Labrador Sea is oceanic in nature. The oceanic crust at Site 647 in the Labrador Sea (Chron C24; 56Ma) confirms the age originally assigned to basement at this site on the basis of the magnetic anomaly identification. The crustal age validates the seafloor-spreading model proposed for the Labrador Sea and Baffin Bay. Rates of crustal subsidence obtained at the Baffin Bay site since Oligocene resemble those obtained from a cooling lithospheric plate. The extrapolation of this rate of subsidence shows that Greenland would have separated from Baffin Island about 63Ma ago. The presence of depth anomalies, high heat-flow values at the Labrador Sea sites, and the differences and similarities in the chemical composition of the Labrador Sea and Davis Strait basalts all suggest the possibility of a hot spot under the Davis Strait region during the Paleocene. -Authors