Assessment of relative tectonic activity in the Lar region, Zagros Fold‐Thrust Belt, SW Iran: Insights from geomorphometric analysis

Abstract

AbstractThe Zagros Fold‐Thrust Belt is a tectonically active region within the Alpine‐Himalayan orogenic system resulting from ongoing convergence between Afro‐Arabian and Central Iranian plates. The presence of various geomorphic features in this region provides an ideal natural case for identifying deformed landforms resulting from active tectonics. The relative tectonic activity along the Lar and Didehban faults within the Zagros Fold‐Thrust Belt, SW Iran was evaluated using six DEM‐derived geomorphic indices: the stream‐gradient index (SL), drainage basin asymmetry (AF), hypsometric integral (HI), valley floor width‐valley height ratio (Vf), drainage basin shape (Bs), and mountain‐front sinuosity (Smf). These indices were combined to yield the relative active tectonics index (Iat) that allows the variation of tectonic activity along the Lar and Didehban faults to be related to variations in rates of incision, tectonic tilting and uplift. This variable tectonic activity was characterized by different Iat values along the faults. The low to high relative tectonic activity (class 1: 1 < Iat < 1.5, class 2: 1.5 < Iat < 2, class 3: 2 < Iat < 2.5, class 4: 2.5 < Iat) correlates with variable geomorphic features along the faults. The results of this study present an approach for assessing the effects of active tectonics and also for sustainable land use planning over a large area.