Fusulinoids from the Bashkirian–Moscovian transition beds of the Shahreza region in the Sanandaj–Sirjan Zone, Iran

Abstract

The presence of the Bashkirian–Moscovian (lower Pennsylvanian) sequence with mixed siliciclastics and fossil-rich carbonates has long been known from the Sanandaj–Sirjan Zone in Iran. However, except for a few studies, its biostratigraphy was not previously investigated in detail. A fusulinoid fauna is recovered from newly measured section, which we named the Asad Abad II section. It is located near the Shahreza town in the Sanandaj–Sirjan Zone. The most important fusulinoids of this assemblage are Aljutovella cf. aljutovica Rauser-Chernosouva, Tikhonovichiella tikhonovichi (Rauser-Chernosouva), and Profusulinella (Depratina) prisca (Deprat); they occur in association with species of Ozawainella, Staffellaeformis, and Pseudostaffella. This fauna overall represents a fauna of the latest Bashkirian–earliest Moscovian transition period in the Sanandaj–Sirjan Zone. This new fusulinoid fauna shares some common species with the concurrent faunas of the Alborz, East Iran, and Central Iran. Furthermore, it can be easily compared with those of the Russian Platform, Southern and Northern Urals, and Central Taurides (Turkey). The four species of the current fauna, namely Eostaffella compressa Brazhnikova, E. primitiva (Dutkevich), Pseudostaffella timanica Rauser-Chernosouva, and Profusulinella postpararhombiformis Dzhenchuraeva are reported from Iran for the first time. This study also presents the first occurrence of the genera Aljutovella and Tikhonovichiella in the Sanandaj–Sirjan Zone of Iran.