EARLY SILURIAN CONODONTS FROM THE CANTABRIAN ZONE, NW SPAIN

Extensive black shale formations occur throughout most of the Lower Si lurian in SW Europe. However, a wider array of facies and the presence of stratigraphic gaps in the interval covered by the Ordovician/Silur ian transition, make for complications in the stratigraphic succession . Directely underlying the Silurian graptolitic black shales of the Fo rmigoso Formation, two small intervals in carbonate rocks occur in cer tain localities. These are the Viodo Member of the Castro Formation, f ormally defined here, and the upper part of the Getino beds, both date d here for the first time. Eleven limestone samples from the Viodo Mem ber, and one dolostone sample from the Getino beds, have yielded a rel atively abundant conodont fauna of low diversity, which can be referre d to the A. petila and A. fluegeli Zones, respectively. By comparison with faunas from North Greenland and the Canadian Rocky Mountains, Rhu ddanian to Aeronian ages seem to be present.