Paleomagnetic Evidence for Pre-21 Ma Independent Drift of South Sardinia From North Sardinia-Corsica: "Greater Iberia" Versus Europe

It is unanimously acknowledged that the Corsica-Sardinia microplate rotated counterclockwise (CCW) by 40-50 degrees between 21 and 15 Ma, synchronous with Liguro-Provencal Basin oceanic spreading. Conversely, 60-120 degrees CCW rotations with respect to Europe from Sardinia (Permian dykes, volcanics and sediments, Mesozoic carbonates, and lower Eocene limestones) have been interpreted to be related to (a) late Permian intra-Pangea shear events, (b) Aptian Iberia rotation, and (c) Eocene Valais Ocean closure. We report paleomagnetic data from 31 red-bed sites from the mid-late Eocene (45-32 Ma) Cixerri Fm. exposed in SW Sardinia. Characteristic paleomagnetic directions from 25 dual polarity sites (240 samples) define an 86 +/- 7 degrees CCW rotation. We suggest that a S Sardinia block located NE of Balearic Islands rotated 30 degrees CCW during the 30-21 Ma Liguro-Provencal rifting, and was decoupled from N Sardinia along the left-lateral Nuoro fault. After 21 Ma, Corsica-Sardinia underwent a drift-related 60 degrees CCW rotation as a whole. A re-analysis of available paleomagnetic results shows that Permian data from N Sardinia-Corsica align with European directions considering a 60 degrees CCW rotation, whereas Permian and mid Jurassic data from S Sardinia match European directions only after considering a similar to 35 degrees CCW Iberia rotation besides the 90 degrees post-Eocene event. We suggest that S Sardinia was part of Iberia, and rotated CCW during both Aptian Iberia drift and Oligo-Miocene Liguro-Provencal opening. Our data, along with recent paleomagnetic results from Calabria, suggest that S Sardinia, Balearic Islands, Calabria, Peloritan, Kabylies, and Alboran were fragments of "Greater Iberia," joined to Iberia before 30 Ma Liguro-Provencal rifting.