Morphometry of Konarsiah Salt Plug Sinkholes, Firoozabad,

Morphometry of Konarsiah Salt Plug Sinkholes, Firoozabad,

Fars Province

There are about 200 salt plugs in the southern part of the Zagros Mountain Ranges and the Persian Gulf. Some of the salt plugs are in direct contact with karstic aquifers, deteriorating the water quality of such aquifers. The study of karst development is a first step characterizing the hydrogeological behavior of salt plugs, especially in regions with limited previous research.

Sinkholes are the most important karstic features in the Konarsiah salt plug. A map of sinkhole distribution is prepared with the aid of 1:20000 aerial photographs and two months of field works. The total numbers of sinkholes having a diameter of more than one meter is 2633. The depths, lengths, widths, orientations of the long axis, and orders of internal drainage were measured in the field. Sinkhole area, depression density, sinkhole area ratio, long diameter-depth relationship, rose diagram of the long axis, frequency of internal drainage order, and the nearest neighbor index were determined. The sinkholes are mainly bowl shaped, with circular geometry, having a single internal drainage.  The Konarsiah salt plug was divided into four zones based on the depression density, dimensions of sinkholes, elevation, slope, and outcrop lithology of the salt plug. The zone with steep slopes and extensive salt layers has the higher depression density and  smaller sinkhole dimensions. The sinkholes are not lined on a straight route and the nearest neighbor index confirms the random arrangement of the sinkholes.  This implies that tectonics is not a controlling factor in sinkhole development.