Aeromagnetic reconnaissance of the Labrador Sea

Abstract

A total of 12 low‐level aeromagnetic profiles across the Labrador Sea were recorded with digitized rubidium‐vapor and fluxgate magnetometers. The resultant data are presented in the form of profiles with the regional gradient removed. There is good correlation between the anomalies on adjacent flight lines in a number of places, and the area may be divided into two zones having anomalous magnetic signatures. These zones can be followed through the central part of the Labrador Sea and are generally flanked by areas of lesser magnetic relief. The more westerly zone strikes toward Hudson Strait and appears to die out at about 59°N. The presence of the magnetic zones, marine seismic results, and the fact that five earthquakes are known to have occurred in the area between the zones are reasonably good evidence for the existence of an active buried median ridge in the Labrador Sea.

Evolution of the Labrador Sea and its bearing on the early evolution of the North Atlantic

“…This they identified as the mid-Labrador Sea Ridge. Later the aeromagnetic data collected by Godby et al (1966) across the Labrador Sea showed that parallel bands of magnetic anomalies, similar to those observed across regions formed by seafloor spreading, were present on either side of an axial quiet zone in the central region. Since then much more aeromagnetic (Hood & Bower 1973) and sea magnetic data (Mayhew, Drake & Nafe 1970; Le Pichon, Hyndman & Pautot 1971;Laughton 1971Laughton ,1972Vogt & Avery 1974;Srivastava 1975a;Kristoffersen & Talwani 1977) have been collected and they all confirm the presence of similar anomalies in the Labrador Sea.…”

The Southern Labrador Sea—A Key to the Mesozoic and Early Tertiary Evolution of the North Atlantic

“…The almost complete absence of earthquake activity in the Labrador Sea (Barazangi and Dorman, 1969) implies that it has virtually ceased spreading. (A few earthquakes, however, reported by Godby et al, (1966) show some residual activity on the axis of the median valley. )…”

“…Magnetic data in the Labrador Sea have been obtained by air (Godby, Baker, Bower and Hood, 1966), by miscellaneous ships on irregular tracks (Manchester, 1964;Mayhew, 1969;Mayhew, Drake and Nafe, 1970; and by sea survey (Johnson, Closuit and Pew, 1969;Avery, Vogt and Higgs, 1969;Vogt, Avery, Schneider, Anderson and Bracey, 1969). The data reveals the existence of a symmetrical pattern of anomalies trending NW-SE in the central Labrador Sea, and trending E-W south of Cape Farewell (Figure 10).…”

“…An extinct branch of the mid-Atlantic Ridge is believed to underlie the Labrador Sea (Drake, Campbell, Sander and Nafe, 1963;Manchester, 1964;Godby, Baker, Bower and Hood, 1966;Mayhew, 1969;Johnson, Closuit and Pew, 1969;Le Pichon, Hyndman and Pautot, 1971). Apart from a short section south of Cape Farewell, the ridge is totally buried beneath the sediments and has been located only by seismic reflection and magnetic surveys.…”