Biostratigraphy of index Brachiopods and Conodonts of Shishtu Formation in the East of Tabas (Niaz Section)

The Niaz section is located in 22 Km East of Tabas. The thickness of Shishtu Formation is about 14 meters and its lithology consists of coraly biostrome, nodular limestone and marly limestone with abundant fossils (especially brachiopods). Brachiopods of the section were collected and twenty species identified as follows:Schizophoria striatula, Aulacella cf. eifeliensis, Gypidula sp.,Coeloterorhynchus tabasensis, Spinatrypina bodini, Spinatrypina chitralensis, Spinatrypina cf. robusta, Desquamatia sp., Athyris chitralensis, Athyris cf. concentrica, Athyris sp., Anathyris sp., Crurithyris cf. inflata, Cyrtospirifer sp., Cyrtospirifer cf. minor, Indospirifer sp., Warrenella sp., Caucasiproductus sardarensis, Productella e. g. belanskii, Spinulicosta sp.,In addition, conodont specimens were collected from brachioped – bearing beds. Ident lified conodonts are as follows: Palmatolepis winchelli, Palmatolepis sp, Palmatolepis sp, Ancyrodella curvata, Ancyrodella nodosa, Icriodus alternatus alternatus, Icriodus expansus, Polygnathus webbi, Polygnathus capolloci, Polygnathus evidence.As a result, the accurate age for Shishtu Formation (member 1) based on the its brachiopods and conodonts can be proposed as Late Frasnian (linguiformis Zone).