بررسي تاريخچه دياژنتيكي سازند داريان بر اساس مطالعات پتروگرافي و ژئوشيميايي در كوه سياه (شمال شرق شيراز) و چاه شماره 1 سبزپوشان

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 microfacies analysis and diagenesis trend 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 homoclinal carbonate ramp depositional environment. Important diagenetic processes were observed in Dariyan Formation including cementation, bioturbation, dissolution, physical and chemical compaction and replacement processes such as dolomitization and silicification. With the observations of transmitted and cathodoluminescence microscopes different generations of spary calcite cement were recognized that suggest diagenetic alteration of Dariyan Formation occured in a burial setting. Prosities in these sections are secondary, including vugy, fracture and channel types. Major and minor element 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 non-marine diagenetic processes (burial) 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.