Structural Evolution and Halokinesis of Khaje Salt Diapir, North‒West of Iran

The northeastern part of the Tabriz, Khaje area has been studied to determine the relationship between the orientation of local structures and regional tectonics, and the influence of both on salt deformation. All the pre-Pliocene sedimentary rocks in the area belong to the Miocene Upper Red Formation. Sandstones form most of the outcrops because the other main components of the formation, marl and gypsum, are easily eroded and therefore recessive. The small thickness of sedimentary rock overlying the salt layer indicates that buoyancy of the salt was not the main factor causing diapirism. Folds related to the main faults of the region have been formed as result of the compressive tectonic forces. Two compressive stress systems have operated in the study area. In the first one, the direction of principal stress was NE‒SW and the resulting geological structures have an approximate E‒W trend. This stress system also controlled the salt tectonics in the region. The principal stress in the second system was oriented NW‒SE and is responsible for the most recent structures. The stress systems also caused rapid salt movement. The Khaje diapir is characterized by a series of salt walls trending NW‒SE that has been caused by the first stress system. This diapirism was principally the result of compressive tectonic stresses and faulting, particularly related to the North Tabriz Fault.