oa The Mid-Atlantic Ridge south of Kane Fracture Zone: A Synthesis of the Geophysical Knowledge

The Mid-Atlantic Ridge south of the Kane Fracture Zone (between 200 and 240 N) was surveyed by the NO "L'Atalante" SEADMA cruise in 1991 out to 10 Ma. This data set allowed the study of the temporal evolution of the ridge segmentation in an area away from the influence of the Azores hot spot. Five segments were identified from the bathymetry, showing complex rhomboedric shapes, suggesting a fast evolution of the spreading configuration during the last 10 Ma. These segments display the characteristic bull's eye Mantle Bouguer Anomalies in a clear three dimensional pattern. Segments centres are associated with circular negative minima, while segments borders, or discontinuities, are marked by less negative values (Gente et al., 1995). Residual gravity inversion yielded a crustal pattern similar to the patterns already observed elsewhere along the Mid Atlantic Ridge (Lin et al., 1990; Rommevaux et al., 1993; Pariso et al., 1995), i.e., thick crust at the segments centres and thin crust at their edges.