Structural evolution of Neogene sedimentary units in the eastern part of Tarom Basin

Tarom basin with a general trend of NW-SE is located in the western Alborz structural zone. This basin has been formed due to the extensional stress regime after the collision between the Central Iran and Eurasian block and formation of the Alborz mountain range. In this study, we aimed to identify and introduce of structures toghether with geometric and kinematic analysis of faults and folds to complete the previous researches about the tectonic setting of the eastern part of the Tarom basin. According to our data and previous studies, formation of the Tarom basin started during Oligocene and continued until the early Neogene. The result of this extension is NW striking normal faults in the region. From the Middle Neogene to the Recent, the pressure resulting from the collision of the Arabic plate and Central Iran and the subsequent clockwise rotation of the Caspian block have created two transpressional phases in the western Alborz. One is the dextral transpression with NW compressional component (in the Pliocene) which caused the folds with NE axial trend and the other is the sinistral transpression with NE compressional component (during the Pleistocene to the Recent) which caused the NNW folding and E-W striking normal faults in the Neogene layers. Also the NE striking normal faults and folds with E-W axial trend in the area, show the effect of reactivation of NE stiking left lateral Sefidrud basement fault which continues to the south of Manjil dam.