Identification of microfacies of the Lower Permian sediments in North Tabas (East of Central Iran) and the relationship between identified algae and sedimentary environment

The most prominent events in the Early Permian history of Tethys were the early Early Permian (Sakmarian) regression and the subsequent late Early Permian (Yakhtashian – Bolorian) transgression. Like the other region of Thetys, transgression in Iran begins at the time of Yakhtashian – Bolorian, which carbonate platforms began to form. These carbonate rocks have been named the Jamal Formation in the Tabas Block, where the basal section of the Jamal Formation is designated as the Bagh Vang Formation. In order to investigate and determine the exact conditions of the sedimentary environment, in addition to the sections of the Bagh Formation, the Sardar Formation in the lower part and Jamal Formation in the upper part have also been briefly studied. Thin-section analysis in two sections (Bagh-e-Vang and Shesh Angosht ) makes it possible to distinguish 8 microfacies and tow petrofacies, Bioclast grainstone and Intraclast grainstone within the barriers and Fusulinid grainstones/packstone, Bioclast packstone, Intraclast bioclast packstone and Bioclastic wackstone represent the facies of lagoon. Also, characterized that bar separated a lagoonal area from the open-marine environment. The microfacies of Mudstone and Dolomudstone have been identified in the Mudflats area and Lithic arkose and Arkose petrofacies related to peritidal environment. Among the fossils identified in is study, Calcareous algae are one of the most important shallow water fossil groups of upper Paleozoic deposites, which have been introduced in three groups: Dacycoladasean, Gymnocodiacean and Problematica and Also, increasing their diversity and abundance is related to greenhouse conditions and high sea levels.