La faille transformante Gibbs entre le Rift et la marge du Labrador

The Gibbs fracture moves the central Rift of the Mid-Atlantic Ridge 370 km to the left at latitude 53O north. It is the only fracture located between Europe and America that can be compared to the large equatorial fractures mapped by B.C. Heezen and M. Tharp between Africa and America. Its morphology is a major element in the understanding of the structural framework of the northern Atlantic Ocean. The identification of its extension to the west was one of the proposed focuses for the first Noratlante expedition of the R.V. Jean-Charcot (conducted in August 1969 under the authority of the C.N.E.X.O.). J.T. Wilson (2) suggested, in his hypothesis of sea-bed spreading from the dorsal axis, that such fractures are "transforming faults" that are active only between the portions of staggered ridges and operating in the opposite direction of the visible fault. Sykes (3) confirmed this interpretation through the study of seisms between the ridge portions. The sections found on both sides of the ridges would only be the fossil traces of the transforming fault whose origin would date back from the initial fracturing of the Continent. [...]