Space-time partitioning of the Mesozoic deformation alongthe Iberia/Eurasia diffuse plate boundary

National audienceSince the 1970s, the Mesozoic kinematic evolution of the Iberian plate has been largelydebated. In particular, no consensus exists on the timing, kinematics and partitioningof the deformation along the Iberia/Eurasia plate boundary during the Late Jurassic-Early Cretaceous. Most of the plate kinematics models suggest that this plate boundarymust have accommodated ~400 km of left-lateral displacement between the two platesin this time lapse. However, no field evidence exists for a narrow transform plateboundary that could have accommodated such displacement. In the last decade, severalauthors have tried to partition this deformation between two/three transtensionalcorridors centered in the Pyrenean realm, but still without resolving the discrepancybetween postulated and observed displacement. In this work, we propose a reappraisalof the Mesozoic Iberia/Eurasia plate boundary by reviewing the tectonic and kinematicevolution of the numerous rift basins located between the Iberian Chains System (to theS) and the Armorican Shelf/Northern Aquitaine System (to the N). This allows todefine the transition between the two plates as a~400 wide NW-SE trending diffuse plate boundary across which the deformation ispartitioned. Its polyphased evolution consists of four main steps: i) a Late Jurassicphase of left-lateral transtension localized at the northern and southern boundaries ofthe system, while the rest of the rift basins underwent orthogonal rifting; ii) aNeocomian phase of tectonic quiescence; iii) a Barremian-Aptian phase of diffuse leftlateraltranstensional rifting, while the North Pyrenean Rift System underwentorthogonal rifting; iv) an Albian- Cenomanian phase of transtension localized along theBasque-Cantabrian/North Pyrenean corridor, following the onset of oceanic spreadingin the Bay of Biscay margins, while the rest of the rift basins underwent post-rift stage.Finally, we discuss the role of structural inheritance and pre-rift salt in favoringdistributed rather than localized deformation at the plate boundary. This review allowsto make inferences on the timing of rotation of Iberia during the Mesozoic and tohighlight the contribution to the evolution of the plate boundary of some domainswithin the Cenozoic foreland basins of the Pyrenees which have been often disregarded