The new data on the lithostratigraphic subdivision of the Vazhnan formation (Latest Carboniferous-Early Permian) in the Shahreza-Abadeh belt

The Vazhnan Formation in the Shahreza-Abadeh belt, apparently extending from latest Carboniferous to Asselian, consists of conglomerate, limestone, sandstone and shale, which is correlative to the Dorud Formation of the Alborz Mountains and the Zaladou Formation of Central Iran. This work is presenting some results on revision of the lithostratigraphy of the Vazhnan Formation in the Tang-e-Darchaleh section (northeast of the Shahreza town). Introduction of this interval in the Banarizeh section (north of the Abadeh town) and correlation of the Vazhnan Formation in the sections understudied are other purposes. Based on the results of this study, Vazhnan Formation in the Tang-e- Darchaleh (as the type section) and Banarizeh (as the reference section) section is distinguished with the distinct eroded surface at the base and rests disconformably on the sandstones of Late Carboniferous, corresponding to the Sardar Formation. The upper part of this interval is disconformably overlain by the Surmaq Formation (late Early–Middle Permian) in the Banarizeh section. Field investigations revealed that the contact between the Vazhnan and Surmaq Formations in the Tang-e-Darchaleh section is faulted. The vertical and lateral changes of the lithofacies in the Vazhnan Formation indicate the depositional system which is evolved from a distal into a homoclinal ramp setting.