Upper Silurian Trilobitesof Bohemian affinities from the West Asturian-Leonese zone (NW Spain)

Abstract

Fossiliferous localities within chloritoid slates of Upper Ludlow age from the West Asturian-Leonese Zone (N.W. Spain) in the Peñalba and Sil synclines are here reviewed. On a regional scale, the occurrence of similar facies and faunas within both synclines indicates that the limit between the West Asturian-Leonese Zone and the Central-Iberian Zone most probably runs within the Sil syncline. Trilobite faunas with representatives of the genera Crotalocephalus, Cerauroides, Cromus, Denckmannites? and Lioharpes (Fritchaspis) have clear affinities with the Prionopeltis archiaci Assemblage of the Upper Ludlow in Bohemia. From a palaeogeographical point of view, the occurrence of Silurian trilobites with Bohemian affinities in N.W. Spain as well as in Pyrenees and Catalonia may suggest the possible existence of a North-Iberian. Domain including these regions and southern France (Aquitaine, Montagne Noire).