NEW PALEOMAGNETIC MESOZOIC DATA FROM THE ALGARVE (PORTUGAL) - FAST ROTATION OF IBERIA BETWEEN THE HAUTERIVIAN AND THE APTIAN

We sampled nine sites of Jurassic and Cretaceous limestones in the Alg arve region, Portugal. Our study yields a paleopole for the Portlandia n-Valanginian (phi = 256 degrees, lambda = 58 degrees, A(95) = 5 degre es) and a paleopole for the Aptian-Albian (phi = 232 degrees, lambda = 75 degrees, A(95) = 8 degrees). These results allow better constraint of the relative rotation of Iberia with respect to Europe: this rotat ion of 22 degrees +/- 14 degrees is a rather fast event occurring duri ng the Barremian, between 132 and 124 Ma. Confinement of Iberia betwee n Africa and Eurasia would explain the rapid rotation of this micropla te. The Iberian plate was probably attached to Europe until 132 Ma, th en detached from Europe and acted as an independent plate during the t ime of fast rotation preceding the oceanic spreading in the Bay of Bis cay.