Active faulting and its effects on Quaternary landforms deformation in north-east of Lake Urmia, Iran

Iran forms a relatively compact zone of active continental deformation resulting from the northward collision of Arabia with Eurasia during late Cenozoic times, and which continues to the present‐day at a rate of 25 mm/yrs. (from GPS data). Evidences of active tectonic in different parts of Iran, has been studied and identified. The arid climate, low rates of erosion, and minimal vegetation cover across the majority of the country result in excellent preservation and exposure of surface deformation produced by active faults. Geomorphic indexes are useful tools in the evaluation of active tectonics because they can provide rapid insight concerning specific areas within a region which is undergoing adjustment to relatively rapid, and even slow, rates of active tectonics. Alluvial fans, river terraces, runoff anomaly and horizontal and vertical displacement of faults are the most important landforms that indicate active tectonics and active faults. Active tectonics have a very important role on the alluvial fans deformations. Without continued tectonics, fans may become minor or short-lived features. Morphological evidences of different types of faults such as thrust faults and strike-slip faults can be determined in surface of quaternary landforms. For example Late Quaternary activity on strike-slip faults can be determined from the lateral displacement of young landforms such as river terraces and alluvial fans, or from scarps introduced by slight dip-slip components of motion. In this study, the evidences and impacts of the active faults have investigated in quaternary landforms such as river terraces, stream displacements and spatially alluvial fans morphometry and morphology located at the south part of the MishoDagh maountain north west of Iran.
The method is based on the obtained qualitative and quantitative data. The quantitative data includes satellite image interpretation and digital elevation models, alluvial fan morphometry, channel displacement and rate of sediments uplift. Longitudinal and cross profile and gradient analysis used to interpret the active fault effects on alluvial fans. Topography maps (1:25000), ETM, SPOT and Quickbird satellite image with 30, 15 and less than 3 m spatial resolution, geology maps (1:100000) and digital elevation models (10m pixel resolution) were utilized in this study. For such interpretation, ArcGIS, ENVI and Freehand software were utilized. All of the maps were produced using freehand and ArcGIS software. Also, field work for investigation of evidences of faults activities were performed. Field studies was performed for the identification and measurement of parameters such as the uplift of sediments, displacements of river, alluvial fans, and channel avulsion and river terraces. Finally, the data obtained during field studies are compared and analyzed through quantitative and descriptive methods and amount and effectiveness of active tectonic on Quaternary landforms spatially, alluvial fans was estimated.
study area located in south part of MishoDagh maountains, northwest of Iran (north of Lake Urmia). Tabriz fault is located in east part of study area. There are three main Faults in this area. South Misho Fault (SMF) is located in mountain front and affects the apex of alluvial fans and river terraces. Whereas Shabestar, Daryan-Heris-Shanlan and Sharafkhane faults are located far from mountain front. South Misho Fault has caused the displacement of the main channel in fan apex, and alluvial terrace sequence. This fault have elevated river terraces about 150m from river bed. while evidences of the two other faults activities are more, and has caused uplifting surfaces, derelict of fan surface, change of intersection point, uplift of fan sediment and lateral change of fan surface channels. The slope of most alluvial fans is 3-5 percent. The Sis fan is the largest fan in the study area. This fan combined from several quaternary surface that elevated in response to fault activity. Sis fan are affected by faults more than the others and reformate to present landform since quaternary. Shabestar, Sharafkhane and Heris-Daryan-Shanjan faults are strike-slip faults that have been changed rivers and runoff laterally.
The findings show that Shabester, Sharafkhane, Heris-Daryan-Shanjan and South Misho faults were active in quaternary epoch and position and forms of alluvial fans is affected by activities of these faults. Faults have had either lateral or vertical displacements. Findings show that the alluvial fan forms and their longitudinal and lateral profiles are affected by Shabester, Sharafkhane, Heris-Daryan-Shanjan faults. Investigations show that there is no statistical correlation among the variables that affect the alluvial fans. Generally, tectonic activities disrupt natural evolution of alluvial fans. Each fault has a different effect on alluvial fan evolution. South Misho fault has caused the displacement of the main channel and the formation of river terraces. And therefore has increased slope of this part. Other fault have caused uplift of fan deposits, change the intersection point and reconstruction of new alluvial fans in the lower of this point. Remote sensing studies can provide a valuable first step in the identification and analysis of active faulting in actively deforming regions.