Analysis of Some Morphotectonic Indices of Shirinrud Subcatchment, Central Kopeh Dagh

Geomorphic indices are useful for determining level of tectonic activity which is used for planning research to obtain detailed information about active tectonics. In this paper، in order to evaluate rate of tectonic activity، the drainage basin asymmetry index (AF)، stream length-gradient index (SL)، ratio of valley floor width to valley height (Vf)، transverse topographic system (T)، and drainage basin shape (Bs) were calculated. Goal of this research is to separate high activity areas to low activity. For calculating morphometric indices we utilize topographic map & satellite images in GIS & Global mapper. AF index of main basin is 17. 20 obtain which is indicating high tilting of this sub-catchment. It seems that folds and trusts parallel to the basin caused such tilting. The results show that the value of AF index in the west and east part of the basin is high. The highest value of SL index is related to the intersection of the conjugate faults and fractures which cut the stream. Computing of Vf for study area shows that almost valleys particular at the north of the basin are V shape and suggest a high rate of incision associated with tectonic uplift. Values of Vf index is high at the areas that SL index increased. High rate erosion of rock is، at the result of، different type of rock''s erosion and strike slip faulting. Results of this research show that study area is tectonically active.