Deformation modes and kinematic implications of hyper-extended rifted margins : the examples of the southern North Atlantic

• Main Author: Nirrengarten, Michael
• Other Authors: Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg, Gianreto Manatschal
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2016
• Subjects: Hyper-extended rifted margins; Deformation modes; Southern North-Atlantic; J-magnetic anomaly; Plate modelling; Partitionning and propagation of the deformation; Marges hyper-étirées; Mode de déformation; Sud de l'Atlantique Nord; Anomalie magnétique J; Reconstruction cinématique; Partitionnement et propagation de la déformation; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; North Atlantic
• Online Access: https://theses.hal.science/tel-01546810; https://theses.hal.science/tel-01546810/document; https://theses.hal.science/tel-01546810/file/Nirrengarten_Michael_2016_ED413.pdf

Deformation modes of magma-poor hyper-extended rift systems evolve through time and space. Hence the observed structures and architectures vary along a depth section as well as on a map. This study aims to characterize the deformation modes of hyper-extended systems and their propagation using the examples of the southern North Atlantic. The architecture of the continental crust termination has been compared to the critical Coulomb wedge theory because it has a wedge shape, the final deformation is brittle/frictional and this wedge is gliding over a basal detachment. This theory highlights the distinct behavior of the two conjugate margins. Moreover it constrains crustal architecture of the continental crust termination, integrates continentward dipping faults and explains the formation of extensional allochthons in a sequential faulting model. The integration of deformation modes in an evolving 3D model necessitates a reliable kinematic context, which is not the case for the opening of the southern North Atlantic Ocean. This is linked to the interpretation of the J-magnetic anomaly as an oceanic isochron. Re-investigations of this anomaly revealed its polygenic and polyphased formation, which is inconsistent for an oceanic isochrons or a domain boundary making it unusable for plate reconstruction. The evolution of rift deformation has been analyzed with a new plate reconstruction of the southern North Atlantic. It appears that the continental crust deformation is segmented whereas oceanic crust propagates in a V-shape. The approach developed in this thesis also asks new geodynamical questions on the influence of inheritance and the effect of triple junction. Les modes de déformation des systèmes de rift hyper-étirés pauvres en magma évoluent dans le temps et dans l’espace. Ainsi les structures et architectures observées varient le long d’une section en profondeur ainsi que sur une carte. Cette étude vise à caractériser les modes de déformation des systèmes hyper-étirés et leur propagation en utilisant les ...