Pennsylvanian stratigraphy and fusulinids of Central and Eastern Iran

The Pennsylvanian succession of Central and Eastern Iran (Sardar Group) is studied in two key sections: Zaladu and Anarak. The Sardar Group (previously Sardar Formation) has been divided into two formations: the predominantly carbonate Ghaleh Formation and the predominantly siliciclastic or mixed carbonate-siliciclastic Absheni Formation. These two formations were earlier identified as Sardar 1 and Sardar 2 sub-formations. The Ghaleh Formation (formerly Sardar 1), of early Bashkirian age, is characterized by Eostaffella, Eostaffellina, Millerella, Plectostaffella, Semistaffella, primitive Pseudostaffella, and numerous archaediscids. The Absheni Formation (formerly Sardar 2) is upper lower Moscovian in age (late Vereian-early Kashirian) and is characterized by Profusulinella, Aljutovella, Neostaffella, Putrella, Moellerites, and Fusiella fusulinids. Poorly preserved upper Moscovian fusulinids (derived Fusiella, Fusulina, and Beedeina) occur at the top of this sequence. The hiatus between the Ghaleh and Absheni Formations corresponds to an interval from the upper Bashkirian, and probably to the lowermost Moscovian, and coincides with the replacement of predominantly carbonate sedimentation with mixed carbonate-siliciclastic sedimentation. The recently established late Gzhelian-Asselian Zaladu Formation unconformably overlies the Absheni Formation. The new data disagree with the previously proposed paleogeographic reconstruction of Central Iran and surrounding regions (including Iran-Afghanistan territory) during the Carboniferous-Early Permian. The foraminiferal assemblages from the Bashkirian-Moscovian sections of Alborz and Eastern Iran show a close resemblance in every respect. It is evident that these regions were located within a single basin connected with the basins of Taurus and Anatolia in the west and those of the Donets, Russian platform, and Urals in the north.