Document Type: Original paper (Research paper)
Department of Regional Geology, Geological Survey of Iran
Department of Geology, Islamic Azad University, Shiraz Branch, Shiraz, Iran
Department of Geology, Islamic Azad University, Damavand Branch, Tehran, Iran
The Chattian-Burdigalian deposits (Asmari Formation) have been studied from the perspective of the sedimentary environments at the Semirum section, SW of Esfahan province. The section (66 meters in the thickness) is located at the High Zagros subzone from Zagros Basin. Lithostratigraphic studies show that the Asmari Formation is generally composed of medium to thick-bedded limestone. According to paleontological studies and based on the stratigraphic distribution of foraminifera, three Assemblage Zones (Chattian-Burdigalian) have been recognized in the Asmari Formation. In order to determine the Asmari Formation paleoenvironmental model, six facies types were identified base on variety in fabrics, textures and fauna features. The microfacies related to the three facies belts of the lagoon, barrier islands, and Open marine offer a carbonate ramp model for Asmari Formation. The gradual facies shifts are clear from deep to shallow water system during the Oligocene and Early Miocene. Also, the beginning and closure of the Oligocene-Miocene Asmari Sea occurred in the inner ramp environment.