Document Type : Applied Article
PhD Student, Department of Geology, Science and Research Branch, Islamic Azad University, Tehran, Iran
Associate Professor, Department of Geology, Science and Research Branch, Islamic Azad University, Tehran, Iran
Associate Professor, Research Institute of Earth Sciences, Geological Survey of Iran, Tehran, Iran
Assistant Professor, Department of Geology, Science and Research Branch, Islamic Azad University, Tehran, Iran
The study area is located in the northern part of Jask, southeastern Hormozgan. The drainage basin is of the North-South trend and mostly except for one case that flows into the Strait of Hormuz, the rest flows into the Oman Sea and the main ones are Bahmadi and Tabarkan Rivers. From a geomorphological point of view, the study area can be divided into two parts, the high part near the fault and the low part that flows into the deltas of the Oman Sea and the Strait of Hormuz. The highest points in the region are Mount Riman, Samuki, Perke and Mubarak. The most important geomorphological controlling factors in the Jask area are the type of rock units, structural features, deformed landforms, and erosive activities due to the greater weakness of rock units and their lithological compositions, which cover large parts of the area as low and eroded lands. The erosional activities in the southern part, which mostly composed of marl, is much higher than the northern part, and the impact of the Zendan Fault in the erosion, followed by floods and landslides, is very evident.
Materials and Methods
The area is one of the most hazardous areas in the South Iran due to its location on the border between two plates of Zagros and Makran, and the compressional stress caused by the movement of these two plates. So, to better understand and identify, prevent and deal with natural disasters and hazards, in this study using the geomorphological indices of SL, Smf, Vf, Af, T, Bs and Iat, which determine the tectonic conditions prevailing in each region, the high-risk points in terms of geodynamic processes occurring on the area and the impact of the Zendan Fault on these indicators are discussed.    
Discussion and Results
A set of several geomorphic indices can be used to study the relative active tectonics. These indicators can be used as a quantitative method to study geomorphology related to erosional and sedimentation processes in the river channel, longitudinal profile and morphology of the river valley, or tectonic features such as fault escarpment. Tectonic indicators are able to determine the different zones created as a result of local change in tectonic activity. In this research, several geomorphic indices in the basins of the Jask region were investigated and the results of each index were analyzed based on the values obtained for that index.
The various geomorphic indices mentioned in the above section in relative tectonics (Iat) were divided into four categories: very high activity, high activity, medium activity, low activity. By calculating the average class category of indices (S / n) in each basin and evaluating it by the method , the relative tectonic index (Iat) was divided into four class categories. In this classification, category one is very high tectonic activity (S / n between 1.5 to 1), category two is high tectonic activity (S / n between 2 to 1.5), category three is medium tectonic activity (S / n is between 2.5 to 2) and category four is low tectonic activity (S / n is more than 2.5). According to this classification, the following results were obtained in the study area (table 1-1).
Table 1. Tectonic activity index (IAT) in the case study area of the author 1400
After examining the geomorphological indices and calculating them, it was found that the study area is relatively affected by the three major tectonic phenomena of the Zendan Fault, uplift and rough topography, oceanic subduction, and the presence of soft sedimentary rocks as the value of Iat index indicates moderate tectonic activity in this region.