Post‐Eocene 90° CCW Rotation of Sardinia‐South Corsica: Paleomagnetic Evidence From Permian‐Cretaceous Sediments of Nurra (NW Sardinia)

Abstract The paleomagnetism of Miocene calc‐alkaline volcanics and sediments from Sardinia has firmly showed that the Corsica‐Sardinia microplate rotated 50°–60° counterclockwise (CCW) with respect to Europe between 21 and 15 Ma, during its drift from the Provencal margin. However, Permian to Eocene rocks from central‐south Sardinia revealed higher (up to 120°) CCW rotation values that implied contrasting kinematic models for pre‐Miocene times. Late Permian block rotations, a connection with the Brianconnais and closure of the Valais Ocean, and Oligocene assembly of two Sardinian sub‐microplates of Iberian and European affinity were advocated. In such frame, a total post‐Permian 60° CCW rotation of N Sardinia‐S Corsica was considered a first‐order constraint, given the solid database from Permian dykes and volcanics gathered there. Here we report on the paleomagnetism of 38 sites from Permian, Triassic, Jurassic, and Cretaceous sediments (and one ignimbrite) from Nurra (NW Sardinia). All sites are located on the same crustal sub‐block, thus are pivotal to constrain rotation timing. We find that Lower Triassic to Upper Cretaceous sediments consistently show a ∼90° CCW rotation, whereas Permian data reveal a ∼30° clockwise (CW) rotation occurring in the 290–250 Ma time window. We conclude that the Oligo‐Miocene CCW rotation of a Sardinia‐S Corsica area must be increased to a 90° value, of which 30° occurred before 21–15 Ma microplate drift. The Permian 30° CW rotation occurred 90–50 Myr earlier than Central Atlantic rifting episodes, eventually leading to Pangea breakup. Thus, it unquestionably testifies an intra‐Pangean microplate mobility significantly pre‐dating its fragmentation.