oa Carbon- and Oxygen-isotope Stratigraphy: A Tool for Confirming Sequence Stratigraphy in the Early Triassic Kangan Formation, Northern Part of the Arabian Plate

The Early Triassic Kangan Formation, which is equivalent to the Upper Khuff Formation, is the main reservoir for natural gas in southwest Iran and the northern Gulf. Investigations of this formation in offshore “Field A” indicate that it is composed of 14 facies deposited in tidal flat, lagoon and oolitic barrier settings in the inner part of a carbonate ramp or platform. Vertical variations of microfacies and gamma-ray, log profiles show that the formation consists of three depositional sequences (KG1 to KG3), each consisting of transgressive and highstand systems tracts and each bounded above by a Type-2 unconformity. Carbon- and oxygen-isotope profiles from a well-dated carbonate section were compared to sedimentological data and the results from a sequence-stratigraphic study. The profiles showed negative and positive peaks coinciding with sequence boundaries and maximum flooding surfaces, respectively.