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The Sarvak Formation in Bi Bi Hakimeh oil field (well No.29) with the thickness of 324 m consists of limestone in Cenomanian -Turonian period. The upper boundary of the Sarvak Formation is in the form of disconformity with the Gurpi Formation. The lower boundary of Sarvak Formation is not clear because of lack of sequential excavation. According to microbiostratigraphy studies, 4 genera and 2 species of planktonic foraminifera and 22 genera and 28 species of benthic foraminifera are identified and based on them, three biozones were introduced including Nezzazata-Alveolinids assemblage zone, Rudist debris, and Oligosteginid facies. The zones are in consistence with zones introduced by Wynd (1965). In the study area (southwest of Iran), the Sarvak Formation is subdivided into 8 microfacies that are distinguished by petrographic analysis on the basis of their depositional textures and fauna. In addition, four major depositional environments were identified in the Sarvak Formation. These include shelf lagoon, platform margin, slope and basin environmental settings, which are interpreted as a carbonate shelf without an effective barrier separating the platform from the open ocean.

In this research, the Tirgan Formation in the south flank of Ghorogh Syncline (north of Chenaran), northeastern Iran with the thickness of 251 was studied. This section consists of limestone, marly limestone and shale with impressions of echinoderms toxasteridae family, many of foraminifera from orbitolinidae family and also lots of calcareous algae that create facies variation along with other non-skeletal allochems. Micropaleontological investigation has been carried out on 90 thin-sections. These criteria reveal that an equivalent of the Urgonian facies type (in France-Swiss area) and open marine, low depth sedimentary basin are extended in the Kopet-Dagh basin. In this article, we tried to introduce some of the important foraminiferal and calcareous algal assemblages of this area.

Minerals are deposited when evaporation is greater than atmospheric precipitation. Calcium sulfates are one of the most important evaporative minerals which have been expanding over the past few years. In the formation of these minerals, various sedimentary and diagenetic processes play a role from shallow ridges to deep water. The research investigated the types of evaporative minerals (with an emphasis on anhydrite) in Gachsaran Formation in Gotvand dam range (25 km north of Shoushtar city). Investigating the thin sections of evaporative samples of this formation led to the identification of various anhydrite textures. Also, the existence of the main phases of calcium sulfate and NaCl by XRD analyses on a number of samples. The formation of anhydrite, gypsum and halite minerals in Gachsaran Formation in Lagoon and Sabkha environments was identified texture. The most important textures were laths anhydrite, nodule, isolated, radial anhydrite crystals, and porphyroblastic gypsum crystals, most of which are formed at the same stage of precipitation or in the early stages of diagenesis.