Geometry and Kinematic Analysis of the Normal Faults in Flat Lying Pliocene-Quaternary Sediments in Zanjan Depression

Flat lying Pliocene-Quaternary detritic sediments with various thickness and color were cut by normal faults in restricted area in the Zanjan depression, 45 km northwest of Zanjan city. Along the road cuts, including the Zanjan-Tabriz free-way, young flat-lying Pliocene-Quaternary sediments were cut and displaced by abundant normal faults that exposed locally in 90 square kilometers. These normal faults are approximately E-W in strike and have pure dip-slip movements. Horst and graben structures are abundant in the study area due to conjugate faulting. Along the fault zones, structures like: change of dip due to layers lithology and reology, fibers growth of gypsum, striations and grooves on the fault planes are developed. Striations on the fault planes are parallel to the main dip of the fault planes implying displacement due to gravity. Development of normal faults in restricted area in Zanjan depression produced as a local pull-apart basin along the major Tabriz basement fault.