Deformation and kinematic evolution of the subsurface structures: Zagros foreland fold-and-thrust belt, northern Dezful Embayment, Iran

The Dezful Embayment is located in the foreland part of the Zagros fold-and-thrust belt. Structural style of folding and thrusting vary in the Dezful Embayment. In this study, balanced cross sections and subsurface data including 2D seismic profiles and wells data decoded structural style of the subsurface structures in the northern Dezful Embayment. Presence of the multiple decollement horizons is the main controlling factor of the structural style in this area. The subsurface anticlines have been formed between two main decollement horizons, which include the Miocene Gachsaran Formation as upper decollement and Permian Dashtak evaporites and Lower Cretaceous Garau shales as the middle decollement horizons. Geometry of the subsurface anticlines differs much vertically and horizontally. Growth strata indicate folding is started in Middle Miocene time in this region. Anticlines formed as open, wide and disharmonic structures. Active processes in the evolution of anticlines are limb rotation and hinge migration, which was resulted in increase of inhomogeneous shortening rate. More shortening rate indicates more structural relief in anticlines. These anticlines are formed as a detachment folds in initiation and then during their evolution converted to fault propagation fold and fault-bend fold. Final geometric shape of these anticlines depends on the geometry of thrusts propagation that formed in the forelimb.