TESTING IBERIAN KINEMATICS AT JURASSIC-CRETACEOUS TIMES: HOW COMPATIBLE ARE PALEOMAGNETIC DATA, GAPWP AND KINEMATIC MODELS?

The Cretaceous paleogeography and the kinematic evolution of the Iberian plate are still a matter of debate. Especially problematic is to reconcile Iberian paleomagnetic data with paleomagnetic data of the neighboring plates and with Euler poles derived from seafloor magnetic anomalies. One limitation arises from the Cretaceous Normal Polarity Superchron where paleogeographic reconstruction using marine magnetic anomalies is handicapped. Another arises from the paucity of reliable paleomagnetic poles with satisfactory statistical criteria and age. We present a rigorous selection of Iberian Cretaceous paleomagnetic poles, from which we calculate mean poles for different time intervals. After rotating them with euler poles from the literature, it is found that Iberian paleomagnetic data fit well the global GAPWP between 70 and 120 Ma, but move far away from the APWP at pre-rift times.

We then present a new method to investigate the origin of this misfit. We solve the inverse problem of finding the euler poles that fit paleomagnetic poles with the GAPWP and then test their implications on Iberian reconstructions. We show that Iberian poles from the Early Cretaceous (mean poles for 123 and 130 Ma) are incompatible with the GAPWP, bringing into question their validity. Contrarily, Late Jurassic data (mean pole at 151 Ma) are compatible with the GAPWP and thus can be considered reliable. Based on these results we propose a new magnetic reconstruction of Iberia and surrounding plates at ~150 Ma (M22 anomaly).

This work provides new constraints for the kinematic evolution of Iberia during Jurassic-Cretaceous. However, the development of a detailed and consensual model for the kinematic evolution of Iberia is dependent on the acquisition of new, high-quality paleomagnetic data and a reevaluation of seafloor magnetic anomalies.