Active Tectonics Zonation in Saveh Area, SW Tehran

Geomorphic indexes can be a useful tool for investigating the impact of active tectonics and the identification of related anomalies, especially in areas that quantitative research work has been done. The study area is a part of the Central Iranian structural-sedimentary zone, located in the Saveh area. By studying the geological and topographic maps and using digital elevation data, it was evaluated the rate of relative active tectonics of this area, using some of the geomorphic indexes such as Hi, Re ,Bs, AF, Vf, Vc, V, SL, Smf and Iat. These indexes which have been measured and compared in eight fronts and nine basins (Shur-payeinii, Lar, Bidlu, Amirabad, Shur-baleii, Eshtehard, Buin Zahra, Arab and Kharrud) resulted to present the active tectonic zonation map for the study area. The measured Hi index shows the relative maturity of all basins and the Arab basin has the most relative tectonic activity compared to other basins. The Re index shows the highest elongation for Lar, Bidlu and Kharrud basins and the least elongation for Shur-payeinii basin. The AF index shows the highest uplift for the Bidlu basin, which is located on the right side of this basin. Vf, Vc and V indexes represent the lowest rate of activity in the valleys which are located on the border between the Shur-baleii and Amirabad basins, the southern part is the Lar basin and the border between Amirabad and Bidlu basins. The Kharrud, Buin Zahra and Arab basins are the most active basins based on the SL index. The Smf index indicates the high activity for all basins. According to active tectonic zonation map, it is possible to show that on the border between the Eshtehard, Shur-baleii, Lar, Bidlu and Amirabad basins which are located in 1 class, have the highest degree of activity. These basins are affected by behavior Jaru, Gomorkan, Ipak, Takidagh, and Alishar faults. Other parts along the mountain fronts are also located in 2 class and are active. The low-lying areas (Kharrud, Buin Zahra and Arab basins) located in 3 class, have the least degree of activity. The highest rate of SL index is for Kharrud, Buin Zahra and Arab basins. This high rate resulted to the seismic and active Ipak fault. According to Smf index, Amirabad basin is the most active basins. Vf index represent the lowest rate which are located on the border between the Shur-baleii and Amirabad basins. This border is located on Jaru and Gomorkan faults.