Diagenetic History of Dariyan Formation based on Petrographic and Geochemical Studies in Kuh-e Siyah (SE Shiraz) and Sabzpushan Well# 1

In this investigation Dariyan Formation with the age of Lower Cretaceous (Aptian- Albian) were studied for geochemical and sedimentology characteristics in the surface section at Kuh-e Siyah Anticline and subsurface section Sabzpushan well number 1. Based on petrographical studies 12 microfacies identified which are belonging to 5 facies belt, such as: intertidal, lagoon, shoal, shallow open marine and deep open marine. The observed facies patterns indicated a carbonate ramp depositional environment. Important diagenetic processes were observed in Dariyan Formation including cementation, physical and chemical compaction and replacement processes such as pyritization and silicification. Prosities in these sections are secondary, including vuggy, fracture and channel types. Major and minor elements and carbon and oxygen isotopes studies are indicated that aragonite was original carbonate mineralogy for this Formation. The plots of elemental values also are illustrated that mainly burial diagenetic processes have been affected this formation in semi- close to semi- open system. A temperature calculation based on the heaviest oxygen isotope value indicates that the very early, shallow burial temperature was around 28.5°C during Dariyan carbonate deposition.