Diagenetic processes of the Ghorban Member of the Sachun Formation in type section- (Tang-e- Mehdi, Southern flank of the Ghareh Anticline- south east Shiraz)

The Ghorban Member of the Sachun Formation (Paleocene-early Eocene) at type section in south east Shiraz composed of limestone, dolomitic limestone and dolomite .This carbonate member has been affected by various diagenesis processes in marine, meteoric and burial digenetic environment. Result of this study indicates that botryoidal aragonite and bladed calcite cements and micritic envelope are the product of marine phreatic diagenetic environment. Anhedral dolomicrite with fenestral porosity and absence of fossils has been formed in marine vadose diagenetic environment. Mixing zone of marine and phreatic water in the Jahrum and the Sachun Formations boundary has provided favorable conditions for formation of porous dolosparite. Oxidation conditions of meteoric vadoze has played important role for oxidizing of outcropped sediment that subsequently have been transported to basin as oxidizing extra clast and bioclasts. Products of meteoric phreatic diagenetic environment include dissolution, neomorphism, silicification and dog tooth, blocky and drusy calcite cements. Diagenetic processes of burial environment include physical and chemical (stylolite) compaction, drusy calcite cement along with dolosparite and dolomicrosparit. Results of uplifting of succession and exposure to the surface had been accompanied with fracture and calcite veins development, dissolution and iron oxide in iron bearing sediments.