Tectonic geomorphology of the Aras drainage basin (NW Iran): Implications for the recent activity of the Aras fault zone

Abstract

Complex geology and tectonics of the NW Iran, the Caucasus region, and Eastern Turkey, are responsible for the present‐day landscapes of the region. The Aras drainage basin located in Iran, Azerbaijan and Armenia borders, provides an appropriate geographical environment for systematically studying the landforms produced or modified by active tectonic processes. Several morphometric indices were calculated for 114 sub‐basins to assess relative tectonic activity levels. Results were evaluated using two different methods; Index of Active Tectonics (IAT) and Analytical Hierarchy Process (AHP) methods. IAT results show that 2% of the sub‐basins belong to very high, 25% to high, 46% to moderate and 27% to low tectonic activity classes. AHP results, display that 12% of the sub‐basins belong to very high, 25% to high, 43% to moderate, and 20% to low tectonic activity classes. Results of both methods show approximate consistency and indicate that the tectonic activity along the Aras drainage basin is moderate to high and decreases from southwest to the northwest which is probably due to terminating fault branches in young unconsolidated deposits or strain partitioning processes. The major fault zones (e.g., Aras, Pambak–Sevan–Sunik, Akera, and Moghan fault zones) include areas with very high and high tectonic activity classes. Accordingly, the uplift rates have been estimated as >0.5 mm/yr for central and western parts, whereas the uplift rates are relatively less in the eastern part (<0.5 mm/yr). The Aras fault zone includes five active structural segments that the main Aras and Horadiz segments of them show relatively higher tectonic activity.