Paléomagnétisme dans les Hellénides internes: analyse des aimantations superposées par la méthode des cercles de réaimantation

Abstract

There are very few reliable and well-dated paleomagnetic data on the internal Hellenides, which were strongly affected by successive tectonic events. We have analysed 268 samples from two separate sedimentary formations of this domain. These correspond to two important moments in the geotectonic evolution of the Hellenides: the Toarcian and the Jurassic– Cretaceous boundary. We show that all the analysed samples probably contain both detrital magnetite and secondary haematite and generally carry at least two components of superimposed magnetization. The diversity and convergence of the remagnetization circles allow us to show that these two components are antiparallel and to determine their directions. Because of tectonic disruption, the calculated declinations are only of local interest. On the other hand, inclinations remain significant for calculating paleolatitudes. These constitute important constraints on reconstructions of the Jurassic paleogeography of the Hellenic domain. In light of our results, two paleogeographic reconstructions are proposed for the Early–Middle Jurassic and Jurassic–Cretaceous boundaries.