Skip to Main content Skip to Navigation
Journal articles

Extensional ductile tectonics of the Sioule metamorphic series (Variscan French Massif Central)

Abstract : In the Northern part of the Variscan French Massif Central, the Sioule series, from top to bottom, consists of a pre-Viséan granite, migmatite, gneiss and mica schist. Two ductile deformations have been recognized. The earlier phase is characterized by a north-east-south-west trending stretching lineation; the second phase, characterized by a north-west-south-east trending mineral, stretching and crenulation lineation, is better marked in the lower mica schist part than in the upper granito-gneissic part. This second phase occurred during retrogression of the metamorphic rocks; related shear criteria indicate a top to the south-west shear. The Namurian-Westphalian magmatic bodies such as the Echassières leucogranite, Pouzol-Servant microgranite and numerous north-east -south-west trending microgranite dykes are emplaced in extensional fractures related to the same north-west-south-east maximum stretching direction. The asymmetrical shapes of the two granitic massifs indicate that they intruded towards the south-east. The synkinematic retrogression of the metamorphic rocks, the shape of the magmatic bodies and a re-examination of the numerous available data support the interpretation that the deformation is due to the extensional tectonic regime related to the Variscan crustal re-quilibration. This interpretation is in agreement with the correlation of the Sioule series with the Chavanon series. The two series belong to a unique tectono-metamorphic unit left-laterally offset by the Stephanian motion of the Sillon Houiller fault. This study also shows that the Sillon Houiller did not play a significant part during the Namurian-Westphalian extensional tectonics of the Massif Central.
Document type :
Journal articles
Complete list of metadatas

https://hal-insu.archives-ouvertes.fr/insu-02886408
Contributor : Nathalie Pothier <>
Submitted on : Wednesday, July 1, 2020 - 3:05:45 PM
Last modification on : Thursday, July 2, 2020 - 3:42:48 AM

Links full text

Identifiers

Collections

Citation

Michel Faure, J. Grolier, José Pons. Extensional ductile tectonics of the Sioule metamorphic series (Variscan French Massif Central). Geologische Rundschau, Springer Verlag, 1993, 82 (3), pp.461-474. ⟨10.1007/BF00212410⟩. ⟨insu-02886408⟩

Share

Metrics

Record views

20