Document Type : Original Research Paper
Authors
1 Ph.D. Student, Department of Geology, Islamic Azad University (IAU), Science and Research Branch , Tehran, Iran
2 Associate Professor, Department of Geology, Islamic Azad University (IAU), Science and Research Branch, Tehran, Iran
3 Associate Professor, Department of Geology, Islamic Azad University (IAU), North Tehran Branch; Research Institue for Earth Sciences, Geological Survey of Iran, Tehran, Iran
4 Assistant Professor, Department of Geology, Islamic Azad University (IAU), Science and Research Branch, Tehran, Iran
5 Assistant Professo, Department of Geology, Islamic Azad University (IAU), Karaj Branch, Alborz, Iran
Abstract
Geomorphic indices of active tectonics are useful tools to analyze the influence of active tectonics. These indices have the advantage of being calculated from ArcGIS and Remote Sensing software packages over large areas as a reconnaissance tool to identify possible geomorphic anomalies related to active tectonics. This method is particularly new and useful in areas where relatively little work has been carried out on active tectonics based on this method. Based upon the values of stream length-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), index of drainage basin shape (Bs), and index of mountain front sinuosity (Smf), we used an integrated index (Iat) that is a combination of the other indices. This index divides the landscape into four classes of relative tectonic activity. According to the Iat results, sub-basins 4 and 6 show zones of low tectonics activity (Class 4), sub-basins 1, 2, 7, 9, 10, 11, 12, 14, 15 and 19 fit to areas of moderate tectonic activity (Class 3), and high tectonic activity is represented by sub-basins 3, 5, 8, 13, 16, 17 and 18 (Class 2). The Tranverse Topographic Symmetry (T) was also studied using morphometric measurements, which finally gave a plot of T-vectors defining anomalous zones of basin asymmetry. A comparison between T index and map of relative tectonic activity showed a consistent coincidence between areas of higher Iat classes with zones of greater asymmetry.
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