Evaluation of Neotectonic Activities Using Geomorphological Indicators: A Case Study of Sadrabad Basin, Taft

Tectonic geomorphology, or morphotectonics, studies the changes and the activity of faults using the geomorphic indicators belonging to the Quaternary period. The main goal of this research is to investigate tectonic activities and topographic changes using seven geomorphic indices including Stream Length Gradient Index, Sinuosity of the Main River, Index of Drainage Basin Shape, Inverse Topographic Symmetry Factor, Mountain Front Sinuosity, Hypsometrical Integral, and Basin Asymmetry Factor. These indices are studies in the Sadrabad catchment in the southeast of the town of Taft. According to the results, the region is still active from the tectonic viewpoint and has undergone great changes in terms of the longitudinal profile of the main river, the basin form, and  the surface of the alluvial sediments of the Neogenic period. In addition, it has caused uplifting of the mountains in the region. For example, the rate of SL index reaches 750 in the middle part of the basin. The Smr index shows 1.8. The average rate of the Bs index is about 2.1, showing that the basin stretches due to the function of faults. To evaluate the average of the Itsf index, we measured it at 20 points and obtained 0.27, which represents changes in the basin form by active tectonics. The value obtained for the Smf factor is 1.8 for the east mountain fronts that are relatively high. The results from the field studies prove the activities of faults. For example, the alluvial sediments of the Quaternary and Travertine periods have been cut. Also, the stone escarpments in the front of mountains and the gradient of the river longitudinal profile represent neotectonic activities in the region.