Age and Platform variations evaluation of the Taleh Zang Formation based on the Early Paleogene LBFs changes trend, in two adjacent Rit and Daryagirveh anticlines in SW Lurestan

The carbonate-dominated Taleh Zang Formation is one of the exclusive formations of the Lurestan area, which was deposited in a shallow carbonate platform in the Amiran foreland basin during the Late Thanetian-Middle Cuisian and is rich in swarms of the Early Paleogene larger benthic foraminifera. Despite of short distance between the examined sections in the Rit and Daryagirveh anticlines, there are major differences in thickness, the Paleogene LBF assemblages and their ages as well as the platform evolution settings. From the Rit anticline toward the Daryageriveh anticline, thickness increases significantly and the sedimentary processes being younger.The identified SBZs and comparing the detected platform evulotion stages with the global scale, revealed that, Taleh Zang Formation can be attributed to SBZ4 and SBZ10-SBZ11, in the Rit and Daryagirveh anticlines, respectively. According this data, the Taleh Zang Formation platform evolution settings can be defined as follow; the Rit section is similar to the platform evolution stage II or coral-agal and the first larger foraminiferal platform and the Daryagirveh section resembles the platform evolution stage III or larger foraminiferal platform of the Early Paleogene low paleolatitude platforms of the Tethys. In the studied area, the reasons for the obvious age difference, microfossil assemblages, microfacies, and platform evolution settings in Taleh Zang Formation can be attributed not only to the depositional processes but also to the tectonic activities. The processes which caused obvious thickness and facies variations and record the diachronicity of the lithostratigraphic units across the basin.