Conodont biostratigraphy and depositional history of the Middle Devonian to Lower Carboniferous in the Cantabrian zone (Cantabrian Mountains, Spain)

Within the Cantabrian zone during the Devonian and Early Carboniferous three large palaeogeographical units were of importance: the Asturian geanticline, the Palencian basin and the Asturo-Leonesian basin. These units have a different history of sedimentation, particularly the Palencian basin. Further, in the Asturo-Leonesian basin there were some important structural elements: the Intra-Asturo-Leonesian facies line, formed by an active, normal fault parallel to the border of the basin, and two structural highs: the Pardomino high and the Somiedo high which divided the basin into three pieces. The Asturo-Leonesian basin was a narrow, shallow continental shelf which in the south and west passed into the deeper part which extended over the West Asturian-Leonese zone. With help of biostratigraphic correlations of the Middle Devonian to Early Carboniferous deposits in the Cantabrian zone, based on conodonts, an overview is given of the depositional history of the entire area. Several times during the Givetian and Frasnian a biostromal platform developed in the Asturo-Leonesian basin with small bioherms of stromatoporoids and corals at the southern border along the facies line and in the east along the León line, with a lagoon b