Abstract:

The Konarsiah salt diapir is located in the Simply Folded Zone of the Zagros Mountain, south Iran. Salt,extruding from two vents along a fault, spreads downslope as a salt glacier over the adjacent formations. Eight small permanent brine springs emerge from the Konarsiah salt body, with average total dissolved solids of 327.3 g/L. The diapir is in direct contact with several aquifers, namely, the karstic Eastern and Western Sarvak, karstic Eastern Asmari, Firouzabad, Konarsiah Plain and Shour. It is also surrounded by a number of impermeable formations. The springs and seepage sections emerging from the aquifers adjacent to the diapir are unexpectedly saline or brackish. Electrical conductivity, total dissolved solids, flow rate, temperature and major ion concentrations were measured monthly from September 2007 to August 2008 at 37 sampling sites, including springs, surface waters, boreholes and wells.
The study indicates that the source of salinity of the adjacent aquifers is halite dissolution of the diapir. Conceptual models of groundwater flow are proposed for the adjacent karst aquifers based on the geological setting, water budget, local base of erosion, isotope data and the profile of the water table. The share of the diapir brine in the Eastern Sarvak aquifer, the Western aquifers (Sarvak, Asmari and Shour) and Konarsiah Plain are 1.8 L/s, 0.8 L/s and 9.1 L/s, respectively. Most of this brine ultimately releases into the Firouzabad River and changes the TDS of this river from 9.21 g/L to 11.61 g/L.
To drain the brine flowing into the Eastern Sarvak aquifer and hence reduce the aquifer's salinity it might be feasible to construct a qanat (a man-made underground gallery transferring groundwater to the surface by gravity) at the aquifer's contact with the Konarsiah diapir. To exploit the fresh karst water of the Western Sarvak aquifer before it is contaminated by the Konarsiah brine, several wells could be constructed well away from the diapir.