Biostratigraphy of early cretaceous sediments (Fahliyan Formation, Berriasian-Barremian) in Aghar19 (Zagros Basin, SW Iran)

The Fahliyan Formation, which is part of the Khami Group is one of the important oil resources in the lower cretaceous strata in the Zagros area. Index Foraminifera, continuity, and discontinuities have been used to identify the boundaries of this formation. To study biostratigraphy on Fahliyan Formation, the subsurface stratigraphic section of Aghar19 was selected in the southwest province of Iran. The thickness of this formation in this section is measured 215 m, including thin-to-medium-bedded limestone and dolomitic limestone. Fahliyan Formation continuously overlies Surmeh and Hith Formation and underlies Gadvan Formation. Vertical study of this formation has led to the identification of calcareous algae and foraminifera, which include 48 genera, 32 species, and three biozones in the sediments of the Fahliyan Formation. These biozones include: (1) Dukhania zone; (2) Pseudocyclammina lituus, Trocholina zone; and (3) Orbitolina, Choffatella, Salpingoporella Assemblage zone. Based on the established biozones, the age of the Fahliyan Formation in the Aghar19 section was determined from Berriasian to Early Barremian.