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Carbonate microfacies and sedimentary environment of the Sarvak Formation in Khuzestan and Lorestan regions

The Upper Cretaceous (Albian-Turonian) Sarvak Formation is a thick carbonate succession (over 800m) deposited in the southern margin of the Neotethys Ocean. Two stratigraphic sections, one in Khuzestan (Type-Section) and another in Lorestan was studied to determine its fades and paleoenvironments. Fades analysis and petrographic studies led to recognition of 12 microfacies of the open marine, shoal/barrier, shelf lagoon and tidal flat subenvironments. Vertical fades associations indicate that, the Sarvak Formation in the type section consists of two major 3rd order cycles and several small-scale cycles (parasequences). Lateral fades changes from shallow marine Sarvak Formation to deep marine Garau Formation (Neocomian- Coniacian) and the absence of elastics in the Lorestan area indicates the presence of an isolated platform to the northwest of the type section area. A rimmed shelf platform is suggested for the depositional environment of the Sarvak Formation with a slope dipping to the northwest.