Assessment of evolution of the sedimentary environment of Paleocene-Eocene succession in Shiraz area based on sequence stratigraphic evidences

Paleocene-Eocene succession in the Shiraz region includes Sachun and Jahrom-Pabdeh formations. In order to study petrography, sedimentary environment, and sequential stratigraphy, 4 stratigraphic sections of Beiza, Sadra (auxiliary), Sarvestan, and Shahneshin were selected and analyzed. Based on field studies, manual samples, and detailed microscopic study, 800 thin sections prepared from the studied samples were identified as 23 microfacies and lithofacies deposited in a homoclinal carbonate ramp model. This model the time evolved to steepened ramp sedimentary environment model. By studying about 1700 meters of Paleocene-Eocene sediments, 9 depositional sequences were identified and separated depending on the location of the sections under study in sequence stratigraphy. During the Paleocene and FSST systems tract formation toward to southwest of the study area (Sarvestan section) evaporites sediments in the lower part of Sachun formation correlative deposited the equivalent of Pabdeh formation in the outer ramp. The evolution of steepened carbonate ramps in shallow parts of the carbonate platform of Jahrom Formation and in deeper parts of the Pabdeh formation was deposited in the Middle Paleocene to Middle Eocene period. In the HST systems tract and high carbonate production rate (Highstand Shedding) in the sloping part of the environment calciturbidite has been deposited as a layer between the Pabdeh Formation. Studies show that the facies of Sachun Formation in the study area gradually changes from west to evaporitic-marly facies to marl, limestone, dolomitic limestone, and purple shale facies.