Les problemes du massif de l'Aston dans les Pyrenees de l'Ariege

Abstract The Aston gneiss-migmatite massif (Hercynian) on the headwaters of the Ariege river in southern France is made up of the Riete augen gneiss, small bodies of the Peyregrand gneiss to the south and southwest, and migmatite bordering these except on the north. The Ax-les-Thermes muscovite granite, accompanied by abundant aplite and pegmatite, lies in the northeastern part of the massif. This granite is similar to the granite stringers in the Riete gneiss. Small granite bodies crop out in the southwestern part of the massif. The massif is surrounded by Paleozoic mica schists except on the south, where the boundary is the Merens fault. The pattern of folding peripheral to the massif suggests movement of a sole under the massif, renewed during the Alpine tectonism.