Altérations du soubassement de la couverture permotriasique en Espagne

In Spain, the superficial part of the Hercynian basement, under the Permo-triassic cover, appears in two quite different ways : - when the Paleozoic basement is directly covered by the Buntsandstein sandstones, it is altered and rubefied on one or some ten meters of thickness ; - when the Paleozoic basement is covered by the Permian detrital formations, it is not altered. Therefore, a comparative study of clay minerals was performed in the Paleozoic basement and in its altered fades, as well as in the Permian and Triassic sediments.