Palaeomagnetic results from the Permian Saint-Affrique basin (France) and implications for late and post-Hercynian tectonics

Abstract

Palaeomagnetic analyses have been carried out in sedimentary formations of the Permian Saint-Affrique basin of France and indicate a late Saxonian-early Thuringian age (the Dourdou sandstones) and at the top of the succession a middle Thuringian age (the Saint-Pierre pelites). Important rotations, clockwise and anticlockwise, respectively, on the northern and southern borders of the basin, affected the Saint-Affrique area between the late Autunian and Saxonian. The opening of the basin occurred without rotation from the Saxonian to the middle Thuringian. Comparison with corresponding results from stable Europe, and in particular from the neighbouring Lodève basin, indicates an anticlockwise rotation of the entire Saint-Affrique area of the order of 7° after the middle Thuringian (Palatine phase or a more recent tectonic event).