Differential spreading along the northern North Atlantic ridge and resulting intraplate deformation of the adjacent continental margins

Eline Le Breton (1) , Peter R. Cobbold (1) , Pierrick Roperch (1) , Olivier Dauteuil (1)

1 GR - Géosciences Rennes

The northern North Atlantic and its adjacent continental margins have specific and uncommon features: location of the ridge on a major mantle plume, a history of ridge jump and extinction, and intraplate deformation on the margins (inverted basins and compressional domes). Reconstructions of the opening of the North Atlantic on the basis of two rigid plates (Eurasia and Europe) lead to unacceptable misfits. Furthermore, plate velocities vary significantly across the Jan Mayen Fracture Zone. However, a subdivision of the North Atlantic into micro-plates helps to improve the fits. We have developed a method for palinspastic reconstruction of the opening of the North Atlantic, by iterative least-squares minimization of gaps between conjugate anomalies. For this, we divide the northern North Atlantic region into a finite number of blocks, each one bounded by magnetic anomalies and fracture zones. The gaps close by a series of translations and rotations of the rigid blocks. We have tested various models, assuming (1) that the Earth is either flat or spherical and (2) that the continental margin is rigid in either NW Europe or Greenland. In models where Greenland is rigid, the history of the Aegir ridge is different from that of the nearby Mohns and Reykjanes ridges. The curvature of the Aegir ridge results from variations in the direction and rate of spreading. Reconstruction generates strike-slip displacements along the Jan Mayen and Faeroe fracture zones, which reach a maximum in the late Eocene to early Oligocene. This period was also one of significant inversion offshore Norway and in the Faeroe-Rockall-Shetland area. The origin of the inversion is a subject of debate. Because the oceanic lithosphere was not yet wide and old, and was abnormally thin due to the Icelandic hotspot, ridge push was probably insufficient. Instead, differential seafloor spreading and strike-slip motion along the major fracture zones may explain some of the Tertiary deformation on the continental shelf of NW Europe.

Domaines: Tectonique; Milieux et Changements globaux

Eline Le Breton, Peter R. Cobbold, Pierrick Roperch, Olivier Dauteuil. Differential spreading along the northern North Atlantic ridge and resulting intraplate deformation of the adjacent continental margins. AGU Fall Meeting 2010, Dec 2010, San Francisco, United States. pp.Abstract G43A-0818. ⟨insu-00609439⟩