Active Folding Induced by Recent Movements of Dorouneh Fault System

Dorouneh Fault System (DFS) is located along northern border of Central Iran microplate. Its mechanism is left-lateral strike-slip with reverse dip-slip component. Considering curve geometry of DFS, it is divided into three major parts: eastern, middle and western. Middle part extends from Torbat-e-Heidarieh city in the east to Anabad village in the west. It passes through Quaternary loose alluviums. DFS is composed of different segments in this part. Bend and right-lateral en echelon geometry at surface and left-lateral strike-slip movement of DFS cause local transpression that is observed as young folding. Fold core is composed of Neogene marl, sandstone and siltstone and fold limbs are composed of Pleistocene loose gravely sediments. Mentioned folds were formed by two different mechanisms: first, Anticlines that formed in right-step bends of DFS and second, pressure ridges that are limited among parallel branches and overlaps of DFS. Estimation of relative uplift rate along mentioned folds indicates that more earthquakes occur in regions with higher uplift rate.