Primera identificación de materiales del Ordovícico Medio en la sección de Los Barrios de Luna (Zona Cantábrica, noroeste de España)

Abstract

Fossiliferous shales of the Luarca Formation are identified for the first time in the southern part of the Pliegues y Mantos domain of the western Cantabrian Zone. The outcrop consists of 10,6 m of dark shales and micaceous silts tones, tectonically intercalated between the La Matosa (Middle and Upper Cambrian) and Tanes (Arenig) members of the Barrios Formation, close to the classical section of this unit. The occurrence of a diverse assemblage of trilobites, graptolites, ostracods, brachiopods, echinoderms, molluscs and some acritarchs and chitinozoans confirms a Middle Ordovician age for the shales, whereas the age of the top of the Barrios Formation does not exceed the Arenig