Role of hyperextension for the formation of rift systems and its implication for reactivation processes and orogen formation : the example of the Bay of Biscay and Pyrenees

• Main Author: Tugend, Julie
• Language: English
• Published: Université de Strasbourg 2013
• Subjects: [SDU:STU] Sciences of the Universe/Earth Sciences; [SDU:STU] Planète et Univers/Sciences de la Terre; Crustal thinning; Rifting; Reactivation; Orogen formation; Inheritance; Pyrenees; Bay of Biscay
• Online Access: http://tel.archives-ouvertes.fr/tel-01019111; http://tel.archives-ouvertes.fr/docs/01/01/91/11/PDF/Tugend_Julie_2013_ED413.pdf

Knowledge on lithosphere extensional mechanisms has greatly benefited from studies made both at presentday rifted margins and onshore fossil analogues. Nevertheless, the spatial and temporal evolution of the processes leading to continental break-up and oceanic crust formation remains poorly constrained. The Bay of Biscay and Pyrenees is used in this study as a natural laboratory to investigate the formation and reactivation of rift systems. A new offshore-onshore approach is developed and applied to identify, characterize and map the rift domains inherited from the Bay of Biscay opening and partly integrated into the Pyrenean orogen. This mapping reveals the complex architecture of European-Iberian plate boundary resulting from a strongly polyphased evolution. Several rift systems spatially distinct are preserved at different evolutionary stages. An important segmentation partially inherited from the pre-rift structuration controls the formation of the rift systems, an observation that has important implications for regional kinematic restorations. Several steps in compressional deformation can be distinguished and related to the rift inherited architecture. Reactivation is initiated in the exhumed mantle domain. Following the subduction of hyperthinned crust, continental collision processes are controlled by the proximal and necking domains acting as buttresses. These results emphasize the role of pre-rift inheritance for the spatial evolution of rift systems and the importance of the rift-related architecture to unravel the formation of collisional orogen.