Polyphased geodynamical evolution of the Ougarta (Algeria) magmatic complexes evidenced by paleomagnetic and AMS studies

Magnetic fabric and remanent magnetization of the Ougarta magmatic complexes are carried essentially by secondary hematite, probably related to hydrothermal events at the origin of ore deposits in the Ougarta belt, and are both not of primary origin. Magnetic foliation is of tectonic origin, while magnetic lineation could be related to hydrothermalism. Obtained paleomagnetic directions correspond to syn-folding or post-folding remagnetizations. The comparison with the African APWP indicates Famenian-Tournaisian and Visean ages for these remagnetizations. At least, two deformation phases with different folding orientations, much older than previously assumed, affected the studied area.

► The studied magmatic complexes are located on the north-eastern margin of the West African Craton (WAC). ► AMS fabric and paleomagnetic data are related to secondary hematite. ► Remagnetizations and magnetic fabric highlight at least two tectonic events. ► Variscan tectonics started much earlier than generally admitted.