Lithostratigraphy and biostratigraphy of Asmari Formation at the Katula stratigraphic section(Izeh area) and introduce it as a reference section of Asmari Formation in the Zagros basin

The Asmari Formation is one of the most important rock unit as oil-producing reservoirs in the Zagros basin. The type section of the Asmari Formation is located at Tang-e-Gel-e-Tursh approximately 50 km south-west flank of Kuh-e-Asmari Anticline. The Asmari Formation has informaly been divided into the Lower، Middle and Upper parts in the Zagros Basin. The Asmari Formation only consists of Middle and Upper parts at the type locality and the lower Asmari is replaced by basinal shale of Pabdeh Formation. The Asmari Formation has a thickness of 631 meters in Katula stratigraphic section at northern flank of Kuh-e- Safid Anticline of Izeh area. This section is one of the most completed outcrops in the Zagros Basin. Based on stratigraphic value of identified well-known microfossils، six biozones were recognized throughout the Asmari Formation as followings: 1. Nummulites intermedius -Nummulites vascus Assemblage Zone 2. Lepidocyclina-Operculina-Ditrupa Assemblage Zone 3. Archaias asmaricus-Archaias hensoni  Assemblage Subzone 2b 4. Elphidum sp. 14-Miogypsina Assemblage Subzone 2a 5. Neoalveolina (Borelis) melo curdica Zone 6. Globigerinoides spp. Acme Zone Therefore، based upon the above-mentioned biozones، the Asmari Formation is assigned to the Early Oligocene-Early Miocene in katula area. As a result the stratigraphic section of Katula is one of the most completed outcrops in Zagros Basin for the Asmai Formation. Therefore، we propose Katula stratigraphic section as reference section for the Asmari Formation.