Abstract Upper Cretaceous depositional systems of the Zagros area were influenced by a series of local and regional tectono-sedimentary events such as progressively southwestward foreland basin migration, which locally was overprinted by salt movements. The Maastrichtian interval is characterized by filling out of the NE foredeep by obducted units and development of SW facing ophiolitic and radiolite nappe in the most interior parts of the Fars area. This tectono-sedimentary loading led to the migration of the mid-foreland basin bulge to the southwest. To reconstruct the depositional settings during this time, three outcrop sections (Kuh-e Chadur, Gach, and Parak) and two wells (Pishvar-1 and Bavush-1) are organized in an SW– NE trending cross section. Maastrichtian sedimentary succession is introduced by pelagic marls of the Gurpi Formation, carbonates of the Tarbur, and evaporates of the Sachun formations along with obducted radiolaritic and ophiolitic complexes. Field and microscopic investigations led to the recognition of several facies’ belts in carbonate domain including intertidal, restricted and open lagoonal, reefal, open marine, and basinal settings, which organized in one regional third- and five local fourth-order sequences that generally show a sharp decreasing trend in sequence thickness of Maastrichtian deposits from NE toward SW. Facies’ variations along this transect show that sequences 1 and 2 are present only in the northern part of the basin. Sequence 3 dominated by rudistid facies, showing progradational pattern toward the southern basinal setting over the time-equivalent pelagic marls of the Gurpi Formation. Sequence 4 has mainly composed of inner shelf deposits in the north and progrades into the outer shelf deposits, toward the south. Sequence 5 consists mainly of dolomites and evaporites of restricted lagoon (Sachun Formation). Accordingly, salt tectonics has resulted in thickness and facies’ variations as well as sequence patterns. In addition, uplifting and migration of the bulge, controlled the exposure area and subsequent diagenetic events such as meteoric dissolution, dolomitization, neomorphism, brecciation, and Fe-staining. Halokinetic events show a strong influence on the intensity and development of diagenetic processes, particularly dolomitization and dissolution.

Keywords