Biofacies of Conodonts in Boundary of Frasnian-Famennian, Central Iran

Abstract:
      Statistical investigations on the population of different conodonts genera which are collected from the beds just below and above the Frasnian ? Famennian boundary prove changes or fluctuations of sea level in Central Iran. For example, in Chahriseh section (Esfahan), polygnathid ? icriodid biofacies governs on the Late Frasnian horizons, but the percent of Icriodus elements increases just above the boundary and changes the biofacies to icriodid ? polygnathid that shows a shallower environment. Late Frasnian sequence in Kal-e-Sardar section (east of Tabas) contains fossiliferous beds and some of them at the top of section have a lot of conodonts. These beds have polygnathid biofacies and number of elements reduces toward the boundary that shows a shallowing phase. Conodonts fauna which are recovered from southern Shotori?s Range sections, are different. Late Frasnian beds in Ghale-Kalaghu and Howz-e-Dorah sections have polygnathid ? icriodid biofacies, but these beds are not continues, they overlain by non-marine Early Famennian sediments with an unconformity surface.