Gneiss and structural domes in the Variscan Pyrenees: a limited role for extension?
Mezger, Jochen E.
The basement of the Variscan Axial Zone of the Pyrenees is exposed at four different levels in two elliptical gneiss dome pairs, the Bossost and Aston-Hospitaletdomes. Microstructural analyses of augengneisses of the dome core and metasedimentaryrocks of the mantle reveal that the main Variscan deformationphases reflect an overall compressionaltectonic regime. Strain partitioningat the roof of rigid orthogneiss or in the metasedimentary cover above ascending granitic magma resulted in discrete shear zones. Orogenparallel extensional shear zones developed only locally to facilitate uplift of the core zones. No major extensional tectonic regime needs to be evoked.