HR: 14:30h
AN: GP73A-03    [Abstracts]
TI: Strong Tectonic Rotation Evidenced by the Study of a Widespread Remagnetization in the Corbières Thrust Sheet (France)
AU: Rouvier, H
EM: henri.rouvier@orange.fr
AF: Paleomagnetisme, IPGP, 4 avenue de Neptune, Saint-Maur cedex, 94107, France
AU: * Henry, B
EM: henry@ipgp.jussieu.fr
AF: Paleomagnetisme, IPGP, 4 avenue de Neptune, Saint-Maur cedex, 94107, France
AU: Le Goff, M
EM: legoff@ipgp.jussieu.fr
AF: Paleomagnetisme, IPGP, 4 avenue de Neptune, Saint-Maur cedex, 94107, France
AB: This study was carried out in the eastern part of the French Pyrénées where the tectonic structures, E-W oriented, bend northward at the Corbières virgation. This change affects the North-Pyrenean zone that overlains the foreland at the North Pyrenean thrust and its eastern extension, the Corbières thrust sheet. In this area, the Corbières thrust sheet is formed by the Mesozoic cover overlying down flat the Cenozoic formations of the Aude basin. The studied sites belongs to the North Pyrenean zone and to the Corbières thrust sheet and correspond to ages from Lias to Lower Cretaceous. Rock-magnetism analyses indicate that magnetite is the main magnetization carrier. Natural Remanent Magnetization mostly corresponds to a viscous component A and a component B determined during treatments from 300 to 400-500°C. Some samples also present a higher temperature component C, which cannot be isolated because of strong mineralogical alteration during thermal demagnetization at these temperatures or of too weak magnetization intensity. Dip variation in neighboring sites allows fold tests indicating synfolding remagnetization (i.e. acquired between or during different tectonic phases) for the component B. Direction of the latter has been then determined using small circles method for groups of neighboring sites. Previous study presented last year and made in the large Saint-Paul de Fenouillet syncline showed that western E-W part of the syncline is only locally affected by weak rotations while a large counterclockwise rotation affected all the eastern part of the syncline at the Corbières virgation during the Tertiary tectonic phase. New data have been acquired in numerous sites from the Corbières thrust sheet south from the Aude River. They point out that the different units of the Corbières thrust sheet also show large counterclockwise rotation. The emplacement of the the Corbières thrust sheet then appears as the result of a large movement of rotation of the North Pyrenean cover rather than a simple northeastward translation of a cover. Use of small circles method also yields the reconstruction of folds at the intermediate stage of folding. Main folding periods were the Upper Cretaceous and the Eocene. In the western part of the Saint-Paul de Fenouillet syncline, the main folding is of Tertiary age, but the relative importance of the two phases of folding is much more variable in the eastern part of the syncline and in the Corbières thrust sheet of more southern origin.
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 1527 Paleomagnetism applied to geologic processes
DE: 1533 Remagnetization
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2009 Joint Assembly