Lithofacies and depositional regimes of the Kolosh Formation Successions in the Tigran region, North-eastern Iraq

Abstract

The current study depends on lithofacies analysis of Kolosh Formation at Tigran region in north-eastern Iraq. Depending on the physical criteria as grain size, color, texture, and etc., the formation is divided to five lithofacies: pebbly sandstone, coarse sandstone, graded sandstone, mudstone and shale lithofacies. Several sedimentary cycles and depositional regimes were fixed in the studied section represent by high energy regime as pebbly sandstone and medium to low regime as mudstone and shale lithofacies. Based on the data of lithofacies which compared with hypothetical model of the common turbidity deposits, the formation was deposited in submarine fans environments. The secondary depositional environments of the study section are divided into channel and inner fan environments. The Kolosh Formation in northern Iraq was deposited in an active margin basin when the northeast Arabian Plate collided with the Eurasian plate at the final stages of Neo-Tethys closing, which has resulted in large uplifts and subsidence episodes due to eustatic rises and falls.