Tectonic activity level evaluation using geomorphic indices in the Shekarab Mountains, Eastern Iran

Abstract

In order to evaluate the level of tectonic activities in the Shekarab Mountains, several geomorphic indices such as stream length gradient index (SL), valley floor width to valley height ratio (Vf), hypsometric curve (Hc), hypsometric integral (Hi), drainage basin shape (Bs), and relative tectonic activity (Iat) were calculated. Vf values show fastest uplift, deepest valleys, and highest river incision are associated with the basin 24. The high values of SL in the range of 900 to 3250 on the high resistance rocks related to the western basins indicate that the western part of the Shekarab Mountains has had recent tectonic activities. Moreover, distribution of high Hc and Hi values are related to the highest tectonic activity in the western and northeastern basins. Accordingly, the study area was divided into four subareas based on Iat values, which are the following: class 1, very high relative tectonic activity (10.17%); class 2, high relative tectonic activity (11.77%); class 3, moderate relative tectonic activity (29.96%); and class 4, low relative tectonic activity (48.10%). It can be concluded from the Iat values that different parts of the study area had undergone unequal uplift and tectonic activities in the NE-SW direction are showing the highest uplift rate, which is in consistency with the present time compression direction in the Shekarab Mountains.