Geirud Formation, Central AlborzThe Study of Chondrichtyan Micro remains in upper Famennian

There are many precious microremains of chondrichtyans (cartilage fishes) in calcareous beds of Geirud Formation. These micro remains consist of teeth, branchial denticles and sales species and genus of the family and subfamily: Phoebodontidae, Protacrodontoidea, Hybodontoidea and Ctenacanthoidea. Geirud Formation consists of alternating silisiclastics and calcareous beds with 1-2 basaltic units well distributed in Central Alborz. The upper Devonian/Lower carboniferous age assigned to Geirud Formation. The name of the Formation has been driven from type locality - Geirud village in north of Tehran. The upper Devonian/Lower carboniferous deposits have been studied along Alborz Mountain range and Central Iran. Faunal similarity between Famennian deposits of Central Iran and Eastern Alborz with Geirud Formation (Hairapetian & Klug 2002) confirm the basin relationship between these areas, also faunal relationship between these fauna and the fauna of Famennian in Morocco and Algeria confirm that these deposits belong to shelves of North Gondwanaland (Ginter & al., 2002). These fauna are associated with conodonts of expansa zone.