Diagenetic history of chalky-marl couplets in Ab-Deraz Formation, East Kopet-Dagh Basin

Diagenetic processes in chalky-marl couplets of Ab-Deraz Formation are studied in Hamam-Qale and Padeha sections, which are located in east Kopet Dagh basin. Chalk units are composed of chalk-marl couplets with different diagenetic features. The common diagenetic processes in chalky and marly limestones are cementation, dissolution, compaction, aggrading neomorphism, pyritization, bioturbation and fracturing. The present of clay minerals and lack of grain framework in marly interbeds led to more dissolution and compaction, while the fewer amounts of clay minerals and abundance of grains in the chalky beds provide available condition for more cementation. Paragenetic sequence interpretation of Ab-Deraz Formation indicates that diagenetic processes have affected these sediments in marine, burial and uplift conditions.