Middle Ordovician U-Pb age of the Aston and Hospitalet orthogneissic laccoliths: their role in the Variscan evolution of the Pyrenees

摘要: Two identical zircon U-Pb ages have been obtained from the Riete orthogneisses at 470 ± 6 and 472 2 Ma in Aston Hospitalet domes (Ariege, Pyrenees), respectively. New mapping data show that protolith of these corresponds to Ordovician granitic laccoliths. Combined study thin-sections magnetic susceptibility on rocks laccoliths correspond a suite consisting granodiorites leucogranites. U-Pb orthogneisses, very similar recently Canigou (473 4 Ma) Montagne Noire (southern French Massif Central) 469 point major Early Middle event laccolith emplacement southwestern part France, more generally western Europe. We underline influenced mechanical thermal behaviour Variscan crust Pyrenees. Indeed, they induced rheological heterogeneity middle crust, which is origin structural contrast between upper crust. Moreover, played role screens, controlled transfer magmas lower