Palynology of the Permian succession from the Ajabshir area (Azerbaijan, Central Iran): a preliminary report

Permian stratigraphic sequences are widely distributed throughout Iran, making this one of the best locations in the world to study this geological time interval. Nevertheless, some units lack detailed biostratigraphic characterization which is essential for palaeogeographic reconstructions. This preliminary study comprises a palynological assessment of a Permian stratigraphic section cropping out in the Ajabshir area (SW Azerbaijan, NW Iran). The continuous and relatively well-exposed Ajabshir section comprises Unit 3 of the Dorud Formation and the Ruteh and Nesen formations. In this area, the Dorud Formation starts with the Unit 3 unconformably overlying the Mila Formation, with its lower units missing. Unit 3 (48 m thick) is characterized by sandstones with siltstones and shale intercalations and an upward increase of limestones. The overlying Ruteh Formation (192 m thick) consists mainly of carbonates with scattered coarse sandstone intercalations and dolomitic limestones. The Nesen Formation (43 m thick) is characterized by dark, locally bituminous, bioclastic limestones with intercalations of sandstones, siltstones and shales. Due to the lack of fossil, Unit 3 of the Dorud Formation has been previously attributed to the Asselian-Sakmarian by correlation with the Bagh Vang Formation which crops out in the Central Iranian Basin and with the Vazhnan Formation in the Abadeh area. In the present study, we document for the first time well preserved and diverse palynological assemblages from Unit 3 of the Dorud Formation and from the Nesen Formation. The microflora from Unit3 mainly consists of sporomorphs which shows close morphological similarities with assemblages from the lower-middle Faraghan Formation (Zagros Basin, SW Iran) and with the OSPZ5 Biozone from the Upper Gharif Member in Oman (?Roadian-Wordian). The overlying Ruteh Formation proved barren in terms of palynomorph content. Studies on the foraminifer content are still in progress and will be the subject of a later publication. Sporomorphs from the Nesen Formation suggest a Capitanian-Wuchiapingian age. The results presented here constitute a good starting point for detailed studies in other areas of NW Iran in order to establish a palaeogeographical framework for the Permian of Northern Gondwana regions.