Differential spreading along the NE Atlantic ridge system and post-breakup deformation of the adjacent continental margins

• Main Author: Le Breton, Eline
• Other Authors: Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Université Rennes 1, Peter R. Cobbold et Olivier Dauteuil([e-mail])
• Format: Thesis
• Language: English
• Published: HAL CCSD 2012
• Subjects: Atlantique Nord-Est; accrétion océanique; microcontinent de Jan Mayen; zones de fracture; réactivation; compression; marge européenne; Great Glen Fault : panache mantellique islandais; NE Atlantic; seafloor spreading; Jan Mayen microcontinent; fracture zones; european margin; Great Glen fault; Iceland plume; geo; archi; Aegir Ridge; Greenland; Jan Mayen; Jan Mayen Fracture Zone; Kolbeinsey; Kolbeinsey Ridge; Reykjanes; East Greenland; Iceland
• Online Access: https://tel.archives-ouvertes.fr/tel-00714418/file/THESE_LeBreton.pdf; https://tel.archives-ouvertes.fr/tel-00714418

One of the main assumptions of the theory of plate tectonics is that all lithospheric plates are rigid. However, reconstructions of the opening of the NE Atlantic Ocean, on the basis of two rigid plates (Eurasia and Greenland), lead to gaps and overlaps between the plates. The area between Iceland and the Jan Mayen Fracture Zone (JMFZ) had a complex spreading history, including progressive separation of the Jan Mayen Microcontinent (JMMC) and a ridge jump from the Aegir Ridge to the Kolbeinsey Ridge. Moreover, post-breakup compressional structures developed along the continental margin of NW Europe, but apparently not on the East Greenland Margin. We therefore investigate how compressional deformation of the NW European Margin may have resulted from variations in the direction and rate of sea-floor spreading along the various ridges. In order to reconstruct the complex spreading history of the NE Atlantic and to study the evolution of the European Margin during sea-floor spreading, we have developed a method for palinspastic reconstructions of the opening of an ocean, using magnetic anomalies and fracture zones. The best kinematic reconstructions result from subdividing the NE Atlantic into three oceanic segments: Reykjanes, Jan Mayen and Mohns. The method allows all oceanic segments to spread at a different rate and results in accurate determinations of spreading rates and relative displacements between the segments. The model ensures a good fit of the magnetic anomalies and predicts differences in direction and rate of spreading between the Reykjanes, Kolbeinsey/Aegir and Mohns ridges. This differential sea-floor spreading generated leftlateral slip between the oceanic segments: (1) from Early Eocene to Late Oligocene, along the Faeroe Fracture Zone (FFZ); and (2) from Late Eocene to Early Oligocene, as well as during the Miocene, along the JMFZ. Such left-lateral motion and the relative rotation between the oceanic segments are compatible with the development of inversion structures on the NW European Margin ...