Investigating the Factors Influencing on the Formation and Development of Karstic in Darparchin Basin in the North East of Iran

Areas of the earth, which are covered by limestone formations and dissolved by water flows, are called karst areas. Due to the fact that karst forms play an important role in water resources, tourism and development activities, their study is considered a necessity. Darparchin basin is one of the sub-basins of the Bidvaz River in northeastern of Iran, that due to the calcareous formations , various forms of karstic has formed in it. In this article, it is tried to study and identify the factors affecting on karst production in this basin, in order to control these factors in development activities and basin planning. In order to achieve this goal, after specifying the boundary of this basin, by using the library method , field studies, topographic maps, geological maps and satellite images , the karsts of this basin were identified and studied. Early studies have suggested that in the formation of karsts in this basin, factors such as lithology, hydrology, tectonic activity, and climate have played a greater role. After studying these factors, lithology was found to be effective in shaping the basin through dissolution, porosity, fracture and type of rocks coating. In terms of hydrology, the high water dissolution capacity of this basin and the lack of conformity of its sub branches with the geological structure played a role in this field. Also, the ranking of this basin revealed that the largest and most diverse forms of karst in the basin formed in its high ranks. In terms of tectonics, the three sides of the basin are surrounded by faults, the fault of Hame Ghaji in the north and Ardaghan fault in the south of the basin has facilitated the process of forming the groove and hammer carneys in this basin. Also, the force exerted by faults has damaged the rocks and provided the situation to dissolve them by water penetration and created karstic forms. Regarding the effects of climate, it has been found that among the climate parameters, the temperature and precipitation had a more important role. Temperature through different forms of weathering and precipitation through its influence on the formation of honeydew carneys, rainfall carneys and vegetation cover has played their role in this respect