Sedimentary characteristics, sequence stratigraphy and geochemistry of the Tiz Kuh Formation in the Pol-e-Zoghal section (South of Chalus)

In this study, the Tiz Kuh Formation of Aptian age in the Pol-e-Zoghal section (south of Chalus) with a thickness of 113 m was evaluated for depositional environment, sequence stratigraphy, and elemental geochemistry. The Tiz Kuh Formation in this section with disconformity lies on the Lower Cretaceous volcanic unit and associated disconformity of the Upper Cretaceous volcanic subdivision. According to calcimetric studies, the Tiz Kuh Formation in this section is composed of limestone and argillaceous limestone. Field and laboratory investigations led to the identification of eight microfacies belonging to 3 sub-environments of lagoon, shoal, and shallow open marine. Gradual microfacies changes and the absence of large barrier reefs, oncoids, pisoids, aggregate grains, and slump structure along with the presence of dasycladeceae family algae (e.g. Terquemella sp. and Bakalovaella elitzae.) and gymnocodiaceae (Permocalculus sp.) confirm the existence of a ramp-type carbonate platform. This evidence may indicate warm marine shallow very saline environment; These conditions highlight the shallow sedimentary and aragonitic environment. Sequence stratigraphic studies in this section identified three third order sedimentary sequences associated with the HST and TST with SB1 and SB2 sequence boundaries depositional sequence. In this study, sedimentary depth resulted in variation of orbitolinid shape The results of the geochemical analysis, of major and minor elements, Sr / Na values of more than one, Sr / Mn values (mean 7) and plotting of Sr / Ca values against Mn indicate that the primary mineralogy was aragonite and have been affected by non-marine diagenesis in a closed to slightly open diagenetic systems. Variation of elements along the stratigraphic section shows that the amount of Sr in the upper part decreases as the Mn content increases; These conditions indicate the greater impact of meteoric diagenesis on the upper part.