Anhydrite fabrics of the Kangan Formation in Fars sub-basin, Zagros

The Kangan Formation with age of Early Triassic (Scythian) is one of the most important gas reservoir in southwest of Iran and Persian Gulf. This formation is mainly composed of carbonate, evaporite and shale facies. In this research, several sub-surface sections of the Kangan Formation in Fars sub-basin related to Zagros Basin were selected and studied for recognition and interpretation of anhydrite facies and its fabrics. In the studied area, the Kangan Formation unconfomably overlies the Dalan Formation (late Permian) and conformably underlies the Dashtak Formation (Middle- Late Triassic). Investigations of the Kangan Formation facies in the studied sections show that these facies were deposited in sabkha/tidal flat, lagoon, shoal/barrier and open marine environments that related to a ramp or epeiric carbonate platform. Petrographic studies of the cores and thin sections of the carbonate- evaporite deposits of the Kangan Formation indicate that anhydrite in this formation has a variety thicknesses and fabrics such as individual nodules, chicken-wire, enterolithic, lenticular, tabular/bladed, spheroid/fan, decussate, acicular/fibrous, mosaic and pore-filling cement. Investigation of these fabrics shows that the most of them were formed syndepotional and/or early diagenetic.