Assessment of tectonic activities of Ghorveh- Dehgolan basin by using geomorphic indices

The morpho-tectonic indices of the basin are used to investigate the active tectonics. The study area is part of the Sefidrud basin. In this study, to assess tectonic activities in the Ghorveh- Dehgolan basin, five morphometric indices of the Relative relief (Bh), Drainage density (Dd), Form factor (Ff), Hypsometric integral and curve (Hi), and Stream gradient index (SL) have been assessed. First, sub basins and streams were extracted by using geographic information systems (GIS) and using hydrological functions of GIS (Arc Hydro). To calculate indices in each sub-basin, Topographic maps with scale 1:25000, geology maps 1: 100000 and digital elevation map (DEM) with a horizontal resolution of 30 m were used and for each index, the zoning map of the current tectonic activity level in the study area in five categories was plotted. Finally, according to the calculated values for each index, the relative active tectonic index (Iat) for each sub-basin was calculated. According to (Iat) index, the zoning map of total tectonic activity level was plotted and the study area was divided into four classes of tectonic activity. Class 1 (very high tectonic activity), class 2 (high tectonic activity), class 3 (intermediate), class 4 (low), class 5 (very low tectonic activity). The results of this study indicate high tectonic activity in the study area that is due to faults activity in the area. Bane abad, Sormeh ali, Parishan, Mahmud abad, Siah and Khalkhal faults are some of the most important faults in this area.