Facies analysis and depositional setting of the upper pliocene Akchagyl Formation in southeastern Caspian Basin, NE Iran

Source Rock Evaluation and Basin Modelling in the Gorgan Plain, Se South Caspian Basin, Northern Iran

“…4) which is 226 m thick in well C. In wells I and Q, the Cheleken Formation unconformably overlies the Cretaceous with progressive onlap above the unconformity (Fig. 2d) (Soltani et al, 2020a). In these wells, the Cheleken Formation consists of silty claystones, claystones, sandy conglomerates and sandstones (but without index fossils) deposited in shallow lacustrine to fluvial-deltaic settings.…”

“…Paleocene to Pliocene sediments onlap the Cretaceous -Paleocene unconformity in the east and south of the Gorgan Plain (Fig. 2c and d) (Robert et al, 2014;Omrani and Raghimi, 2018;Soltani et al, 2020a).…”

“…Limited biostratigraphic and sedimentological reports for the area are available (e.g. Faridi, 1964;Vatan and Yassini, 1969;Soltani et al, 2020a;Soltani et al, 2020b). The unconsolidated nature of Cenozoic sediments has resulted in drilling problems and poor core recovery (Asadi et al, 2012).…”

“…In these wells, the Cheleken Formation consists of silty claystones, claystones, sandy conglomerates and sandstones (but without index fossils) deposited in shallow lacustrine to fluvial-deltaic settings. The sediments are interpreted to have been eroded from the outcropping Cretaceous -Miocene succession, which in turn consists of material eroded from the Alborz and Kopeh Dagh foldbelts (Soltani et al, 2020a). In well C, the Cheleken Formation comprises red and grey claystones, sandstones and limestones.…”

“…1a), where it directly overlies the Cretaceous succession. Five sub-environments have been recognised for Akchagyl Formation deposition ranging from offshore, shoreface and foreshore to mud-flat and alluvial (Soltani et al, 2020a).…”