Investigation of Lithostratigraphy, characteristics micrifacies and diagenetic processes of the Asmari Formation (Sartang section) in the West of Lorestan, North East of Ilam

In this study, based on petrographic studies, 200 thin sections, field observations, thick changes of the constituent layers, color, genus of the layers, and the size of the sediments, resulted in the identification of 5 units of rocks (unit 1 joint between the Pabdah and Asmari Formations) and 13 sedimentary micro-facies in the diametration of Asmari Formation (Sartang) have been identified. According to biostratigraphy studies, the Asmari Formation in the Sar Tang section is late Rupelian-Aquitanian in age. The gradual change of facies, the absence of turbidite deposits and the reef belt indicate the deposition of the Asmari structure on a shallow carbonate platform overnight (hemoclinical). The results in the study of Asmari Formation indicate that in the lower parts, the texture of most rocks is wackestone and packstone limestone. In the middle section, limestones with grainstone, boundstone and floatestone-rudstone textures containing corals and algae can be seen. Limestone with grainstone texture are mainly distributed in the upper part of the Asmari Formation, which has been significantly reduced due to extensive cementation, voids and porosity. According to the petrographic examination, the main diagenetic processes of the Asmari Formation are bioturbation, micritization, cementation, compaction, dissolution, neomorphism and dolomitization. Generally, sediments of Asmari Formation in the studied sequences have experienced a wide range of diagenetic processes related to different diagenetic environments (marine, meteoric and burial). The dissolution with corrosion and elimination in successions has caused the formation of dissolution porosities (such as intraparticle, inetrparticle, vuggy and moldic porosity). Dolomites are seen as shaped euhedral, rhombus and mosaics of the same size, dense and with subhedral and anhedral borders (dolomicrosprite and rhombus dolomite).