La cinématique de l'Atlantique Nord : la question de la déformation intraplaque

The main features of geodynamic evolution in the North Atlantic and the lithospheric plates surrounding it have been known for a quarter of a century now. However, a number of questions raised by the first models published have still not been clearly answered in detail. Among them, the difficulty in adjusting the domain to the north and the south of the Faeroe-Iceland-Greenland ridge should be highlighted. This study addresses the issue by using fracture zones as the main data for our reconstructions. We show that they accurately bound the kinematical reconstructions. They also enable kinematical reorganisation periods to be studied on the scale of oceans, as well as their duration. Reconstructions carried out on these bases confirm the existence of various magnitudes of discontinuity in the kinematical adjustment, the main one being the Faeroe-Iceland-Greenland ridge. Geological data help explain these discontinuities by phenomena of intraplate deformation. Our model gives the beginnings of this deformation's chronology and an idea of its scope. Apart from the known phenomena of compressive intraplate deformation, this model envisages the existence of intraplate phenomena due to distension on the ocean floor west of Iberia. One of the most remarkable results concerning the reorganisation of the relative plate movements was the confirmation that the general convergence between Africa and Europe stops between the C31 and C24 anomalies. Finally, this model gives the Rockall shelf a mixed nature (continental and oceanic), like that of other shelves in the Indian Ocean.