COMBINED USE OF HYDROGEOLOGICAL, HYDROGEOCHEMICAL AND ISOTOPIC TECHNIQUES TO IDENTIFY THE IMPACT OF A SALT DIAPIR ON SURROUNDING AQUIFERS, SOUTHERN IRAN

摘要

More than 120 exposed salt diapirs in southern Iran are connected to the adjacent aquifers and likely constitute the main sources of groundwater salinization in the region. Located in southern Iran, the Korsia salt diapir is surrounded by alluvial and karst groundwater aquifers. To investigate the impact of the salt body of Korsia on the groundwater quality of surrounding aquifers, electrical conductivity, total dissolved solids and dissolved calcium, magnesium, sodium, potassium, chloride, bromide, and sulfate concentrations were measured at 41 sampling points, including 32 exploitation wells, 7 springs and 2 surface water stations. Additionally, oxygen-18 and deuterium isotopes were analyzed at 7 sampling points to investigate the source of the salinity in the area. Our hydrogeological, hydrogeochemical, and isotopic evaluations show that the Korsia diapir deteriorates groundwater quality of the eastern karst and southern alluvial aquifers through infiltration of a spring's brine into limestone, and flow of the surface brine originated from the diapir, respectively. A karst aquifer west of the diapir is not influenced by the diapir brine because its hydraulic connectivity is interrupted by an impermeable geological formation. Construction of salt basins or diversion of brine is suggested to increase water quality of the surrounding aquifers. These procedures can be applied not only in the Korsia diapir, but also in tens of diapirs of southern Iran as remediation methods to improve water quality of their adjacent aquifers in this arid region.