Geochemistry and the diagenetic sequence of the Taleh Zang Formation in southwest of Kermanshah

In this study, the Late Paleocene Taleh Zang Formation in the southwest of Kermanshah hasbeeninvestigatedfor elemental geochemistry and effective diagenetic processes during burial. The thickness of the studied section is 282 meters that mainly composed of shallow marine limestones with interbedded of marl and dolomite. The main diagenetic processes affecting the TalehZangFormation include micritization, various types of porosity, cementation, dolomitization and compaction. Due to the texture and the abundance of unstable skeletal particles (green algae and bivalve), porosity and cementation aremorecommon among the identified processes. Microscopic and geochemical studies have shown that these processes have taken place in eogenesis and early mesogenesis stages in marine, meteoric and shallow burial environments. Evidences indicate that the carbonates of the TalehZangFormation didnot tolerate deep burial after the deposition during diagenesis. Fluids that affected the lower parts of the formation during burial were mainly marine. Moreover, tothetop ofthe sequence in addition to seawater less meteoric fluids have affected the marine carbonates of the Taleh Zang Formation during diagenesis. The high amounts of Sr/Mn (mean27/51) and Sr/Ca (mean 1/61) and also low Mn (mean 27ppm) and Fe (mean 78ppm) values indicate close digenetic system with low water/rock interaction for the carbonate samples of the TalehZangFormation.