One of the most important pieces of evidence for the impact of fault lines is the geomorphological characteristics of the landforms around them. Meanwhile, the fans and their hierarchical situation, with regard to time, place and their topography are the most distinct of these characteristics.
This article investigates the morphotectonic rift of Mighan in Arak. The research, explains the hydrologic correlation between Masileh basin and Mighan depression until the late Pleistocene era, so that, Mighan rift was considered as one of the sub-basins of Masileh playa during that era.
Finally, the research findings show that Tabarteh and Talkhab fault margins and their graben subsidence have caused the separation of Mighan depression from Masileh basin. Investigating the present evidence shows that some of them, such as the morphology of old fans and new fans, situation, direction and uplifting of faults, sedimentology of Mighan playa and also the altitude difference between old fans planes and, the watershed between Mighan basin and Masileh depression are the most important pieces of evidence which prove this theory.
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