New data on the Frasnian/Famennian boundary in Kal-e-Sardar section, Eastern Tabas (Central Iran)

Frasnian - Famennian boundary in the Kal-e-Sardar section (East of Tabas، Central Iran) is investigated on the basis of conodonts. Distribution of thirty-three species and subspecies in the stratigraphic column enables us to recognize a barren interval and five biozones; Upper rhenana، upper part of Upper rhenana - linguiformis، Lower to Middle triangularis، Upper triangularis، Lower crepida. Biofacies analysis shows a deepening trend through the Late Frasnian and then a sharp sea level fall present at the base of early Famennian sequences. Deeper environment governs through the Famennian stage. A new range is proposed for P. planarius; Lower hassi - linguiformis zones.