Tectonic Geomorphology of the Zagros Orogen

As part of the Alpine–Himalayan orogenic system, the Zagros Orogen represents a mountainous region along ∼1500 km with an extensive active crustal deformation and intense seismic activity in a northwest–southeast direction. The orogen is divided into various tectonic zones longitudinally according to their structural patterns and stratigraphic successions. There are also transversely defined morphotectonic subzones in the orogen distinguishable from their structural and geomorphic patterns. Our goal is to differentiate the variations among the mentioned morphotectonic subzones by geomorphic and geomorphometric approaches. We used some well-known methods (i.e., hypsometric and swath profile analyses) proved to be useful in studying large orogens to understand both the endogenic and exogenic factors that could be effective for the topography of the Zagros Orogen on a large-scale. We also compared our results with current structural, seismotectonic, and global positioning satellite–derived data (i.e., strain axes, zonation of strain rates, and vorticity directions) to discuss their possible relations. Our results indicate a tectonically highly active landscape in the middle part of the Zagros Orogen in Iran related to right-lateral shearing between the Izeh and Sabz–Pushan fault zones that could be evaluated as a transfer zone accommodating the shortening difference between the southeastern and northwestern parts of the orogen. However, the southeastern half of the Fars subzone and the entire Lurestan subzone represent relatively more stable or monotonic landscape features. In addition to such tectonic controls on the large-scale geomorphology, our analyses indicate the imprints of climate and related erosion to be effective on the orogeny scale.