The Assesment of Neotectonic Activity in Raveh-Rahjerd Volcano-Sedimentary Area (Salafchegan)

Tectonics geomorphology is one of the most important modern scientific disciplines. Quantitative analysis based on defined morphometric indices is an available and relatively low-cost and fast method that is used to understand the differences in the amount of tectonic activities in young landscapes. These indices are used as a basic identification tool to detect tectonic deformations or to estimate the relative variations of tectonic activity in a particular area. However, these studies are more sensitive in areas consisting of volcanic rocks, especially for the precise definition of sub-basin boundaries. The study area that consists of outcrops of volcanic rock and young deposits is located in the south of Salafchegan; on the border of Qom-Markazi provinces. Six morphometric indices were measured to determine neotectonic activity: Stream length gradient index (SL), Ratio of valley Floor width to valley height (Vf), hypsometric integral (Hi), drainage basin shape (Bs), drainage basin asymmetry (Af), and transverse topographic symmetry (T) for each sub-basins. After calculating the indices, averages of them, and the relative active tectonic index (Iat), the area was divided into four different tectonic zones based on activity ratio. In this categorazation, category 1 to 4 respectively represent the highest to lowest tectonic activity. It was also found that 2.86% of the basins are in category 2, 51.43% in category 3, class and 45.71% in category 4.