Depositional environments and sequence stratigraphy of Sachun and Jahrum Formations in Shiraz area

Abstract

To study depositional environment and sequence stratigraphy of Sachun and Jahrum formations 2 stratigraphical sections have been chosen (Sarvestan, Tange Kheyare).petrographic study shows that Sachun formation consist of 5 microfacies, gypsum, dolomite, red and green marl, dolomitic limestone and stromatolite that deposited in tidal flat and lagoon. Petrographic study on Jahrum formation recognized of 11 microfacies that including pelagic bioclast mudstone, pelagic bioclast wackestone, Algal bioclast grainstone, Orbitolites bioclast grainstone, Miliolide bioclast grainstone, Miliolide bioclast wackestone, Nummulite Alveolina bioclast wackestone, Pelloidal bioclast packestone, Intraclast bioclast packestone, Dolomudstone, Mudstone with birds eyes, Stromatolite boundstone. These microfacies deposited in open marine, bar, lagoon and tidal flat. Sequence stratigraphy studies shows that Sachun formation conformed 1 depositional sequence (DS1).lower contact of Tarbur formation erosional (SB1) and upper contact with Jahrum formation transitional (SB2). TST systems tract consist of green marl interbedded of dolomite, gypsum and dolomitic limestone. HST systems tract conformed of red marl interbed of gypsum. Jahrum formation in Sarvestan and Tange Kheyare sections conformed of 1 deposional sequence (DS1). lower contact of Sachun formation transitional (SB2) and upper contact erosional (SB1).TST systems tract related to lagoon environments and HST systems tract conformed of shallowing upward parasequences and consist of dolomite and dolomitic limestone.