Contamination of the Konar Siah Karst Spring by Saltdom


Geomatics Engineering, Shiraz University


There are about 200 salt plugs in the southern part of the Zagros Mountain Ranges and the Persian Gulf in Iran (Kent, 1970). The salt comes from the Hormuz salt Formation at the base of the Phanerozoic zone. It moves upward due to the buoyancy, the latteral pressure resulting from the opening of the Red Sea to the southwest, and the weight of several thousand meters of overlying sediments. It merges like a mushroom and its movement faciliated where the area is more fractured. Outcrops of geological formations subject to karst are found in about 23% of the surface area in the middle of southern Iran. They form aquifers of good water quality, especially in Ears province. In general, the electrical conductivity is less than 500 micosiemens per centimeter. In some parts of Ears province, the salt piercements are adjacent to the carbonatic rocks; hence, the karstic waters are of poor quality. The Konar Siah spring, located in the vicinity of Firoozabad, flows out from the Sarvak Limestone Formation. This spring is adjacent to the saltdome; thus, its water is very contaminated. A geologic map on a scale of 1: 50000 is prepared. In addition, the concentration of the following ions: Ca, Na, Mg, K, SO4, HCO3, and Cl; PH, EC and the temperature, and also the discharge of the Konar Siah spring have been determined tri-weekly for a duration of 9 months. The discharge of a few seasonal springs issuing from the saltdome has been measured as well. Based on the observations, the study concludes that the saltdome is the source of water contamination.