Quantitative analysis of relative active tectonics using geomorphic indices in Band-Golestan basin, northeastern Iran

Abstract

Investigation of geomorphic indices is a useful approach to identify the specific characteristics of active tectonics in each region. In this study, five geomorphic indices including stream length-gradient index, basin asymmetry, hypsometric integral, ratio of valley-floor width, and index of basin shape were estimated to assess relative active tectonics in the Band-Golestan basin, as a part of Binaloud mountainous zone, located in northeastern Iran. This region includes several faults, formed mainly by contact, fraction, and re-crystallization processes between shale and sandstone rocks. An average index of the active tectonics was produced to categorize the intensity classes of tectonic activity of the study area. According to the mean values of indices, the whole basin has active or semi-active tectonics. After that, the overall index of Iat with a value of 1.88 indicated the high class of tectonic activity for the study area. Furthermore, the obtained result of tectonic activity was confirmed by fieldwork and previous literature. In this regard, the active tectonics of the study area has corresponded to the highest values of sediment yield, soil losses, dynamic failures, and various types of landslide events.