Investigating the change of direction of long-term stress main axis in southern part of Salafchegan from Neogene: its implication in regional tectonics

In the study area, which is located in the south of Salafchegan, there is a series of intermediate to acidic dykes that have penetrated in two stages of eruption in the Lapilli tuff units and the dark gray andesitic section. according to the age of the host rocks, the injection time of these dykes was late Miocene onwards. In this study, changes in the position of long-term stress axes in this area have been investigated using analysis of slickenline data and slickenside as well as long-term stress trajectories based on dykes’ trend from Miocene onwards. By using the position of the dykes in the area and analyzing the long-term stress data with inversion method, changes in the trend of the main stress axes from Neogene or Plio-Quaternary have indicated, so that the maximum stress direction from north-south direction at the end of Miocene to north east-southwest changed during the Pliocene-Quaternary. This change in trend could be due to the clockwise rotation of the South Caspian block, the impact of which was not limited to Alborz and was also effective in Central Iran. This effect has recently been reported in other studies in the area of the Kushk fault system.