Brachiopods and Conodonts of Mobarak Formation (Early Carboniferous) in Kalariz Section, Northern Damghan

Investigation on brachiopods and conodonts of Mobarak Formation in Kalariz section confirms the age of Early Tournaisian to Middle Viséan. Some species as Bispathodus aculeatus aculeatus, Bi. stabilis, Spinocarinifera nigra and Shumardella sp. in the lowest part of section show the Early Tournaisisan age, whereas the middle part is Middle to Late Tournaisian on the basis of the presence of Tomiproductus vaughani, Tomiopsis sp., Scabricosta sp., Polygnathus flabellus, P. rostratus, P. longiposticus, Clydagnathus cavusformis. Some faunas as Marginatia kinghirica and Buxtonia cf. praejuresanensis prove the Early to Middle Viséan for the upper part of section. Three domestic biozones are recognized on the basis of faunal distribution in the stratigraphic column. Biozone 1 (Early Tournaisian): this zone can be recognized by the association of these species: Spinocarinifera nigra, Rossirhynchus adamantinus, Shumardella sp., Cleiothyridina transversa, Bispathodus aculeatus aculeatus, Bi. stabilis, Polygnathus communis communis, P. inornatus. Biozone 2 (Middle to Late Tournaisian): Tomiproductus vaughani, Tomiproductus elegantulus, Tomiopsis sp., Scabricosta sp., Tylothyris planimedia, Syringothyris altaica, Leptagonia analoga, Leptagonia cf. regularis, Ripidomella michelini, Athyris hibernica, Spirifer missouriensis, Schelwienella sp., Leptagonia cf. regularis, Torynifer sp., Polygnathus flabellus, P. longiposticus, P. inornatus, P. aff. inornatus, P. rostratus, P. sp., P. communis communis, Bispathodus stabilis, Pseudopolygnathus primus, Clydagnathus cavusformis. Biozone 3 (Early to Middle Visean): this zone is identified by the presence of some index species as: Buxtonia cf. praejuresanensis, Megachonetes sp., Actinoconchus lamellosus, Orthotetes batesvillensis, Marginatia cf. kinghirica, Balakhonia sp. Mobarak Formation conformably overlies the Geirud Formation and disconformably underlies the Dorud Formation demonstrating Late Viséan to Gzelian hiatus as the result of Hercynian epeirogenesis.