Controls of palaeoclimate condition on facies characteristics and diagenetic processes in the Cenomanian–Turonian sequences (upper Sarvak Formation) in the Abadan Plain, SW Iran

The Sarvak Formation, a crucial reservoir rock in the Abadan Plain, is extensively studied due to its sedimentary attributes and diagenetic evolution, heavily influenced by tectonic activities and palaeoclimatic conditions. This research focuses on analyzing palaeoclimatic indicators within the Sarvak Formation in a selected oil field in the Abadan Plain. Through a comprehensive approach integrating core data, thin section analyses, and electron microscopy, the study characterizes various facies, diagenetic processes, and sequence stratigraphy of the formation. Five distinct microfacies representing different depositional environments, such as lagoon, shoal, reef, reef-talus, and open marine belts, are identified, suggesting a ramp-type depositional setting. The investigation also reveals a paragenetic sequence of diagenetic processes, including transitions from marine to meteoric diagenesis and from shallow to deep burial environments. Notably, two palaeoexposure surfaces are identified, characterized by meteoric dissolution, brecciation, iron oxide staining, and silicification. Scanning electron microscopy analysis indicates prevailing kaolinite and montmorillonite clay mineral assemblages, indicative of warm and humid palaeoclimatic conditions. These findings provide insights into the palaeoclimatic conditions and paleaogeographical positioning of the Arabian Plate during the Cenomanian–Turonian period, suggesting a close proximity to low latitudes near the Equator.