EVALUATING THE EFFECT OF TECTONIC ON THE ENTRENCHMENT OF ALLUVIAL FANS’ HEAD AROUND DANEHKHOSHK ANTICLINE

Introduction Alluvial fans are deposit landforms that their development is controlled by a number of factors such as tectonic, climate, lithology, base level change and morphometric properties of catchments. Among mentioned factors, tectonic has a major role in the fan development in tectonically active mountain ranges. The velocity of tectonic uplifting in mountain fronts can affect the rate of river entrenchment and the location of deposition in alluvial fans. When the rate of uplift exceeds the rate of streamchannel down cutting at the mountain front, deposition will tend to be focused near the fan apex. Climatic changes is also an important variable affecting the alluvial fans aggradations and degradation. In the wetter glacial periods, sediment production in the catchments of fans were increased and hence fans surfaces experienced aggradation while during drier present-day climate regime (interglacial period), fans surfaces experience degradation and incision. Although several works have been carried out on tectonic effects on alluvial fan development, little works have been done about tectonic effect on the rate of alluvial fan entrenchment in Iran. The study area is located in the south of SarpoleZahab town, Kermanshah province, in western part of Iran. 103 alluvial fans have been formed around uplifting Danehkhoshk anticline. The purpose of this paper is to evaluate the uplifting effect of Danehkhosh anticline on the entrenchment of alluvial fans.