Nature and movement of thrusts in the Paleogene orogen of eastern Iran: curved northern border of the Lut and Sistan terrains, Sechengi area

The eastern Iranian ranges appearing with a NS-trending strike on the satellite images, were already known as the Sistan suture zone, but have recently been identified as the eastern Iranian orogen. The N40E first-generation folds and thrusts with slaty cleavage (parallel folds) have appeared parallel to the NE edge of the Lut block. The structural analysis shows that most of the thrusts dip to the northwest, so that the Permo-Triassic and Jurassic microdiorite units in Lut have been thrusting on the younger rocks. The structural studies show that the tectonic vergence in this deformation event is northwest to the southeast and from the outside (hinterland) to the inside (foreland) of this orogen in the Sechengi area. Younger thrusts of the second deformation event were either directly formed due to the second deformation event, or they were older thrusts that reactivated and folded, so that often two sets or more slickenlines can be recognized on the thrust plane. The recent N44W thrusts have been redistributed in perpendicular to the edge of the Lut block and parallel to the axial plane of the northwest second-generation large-scale folds (radial folds). Both the northwest folds' axial plane and penetrative shear cleavage, have dips to the northeast and southwest. These structures are parallel to the axial planes of the second-generation folds and younger thrusts. Such consecutive deformation events perpendicular to each other are inconsistent with the models of simple linear orogens presented for eastern Iran (i.e., rifting of eastern Iran continental crust and subsequent linear collision) and seem more consistent with the buckling orogens (Orocline).