Geologic evolution of the Dukhan salt flats in Western Qatar Peninsula, Arabian Gulf

Abstract

Photo-interpretation of landsat Thematic Mapper images of the Dukhan salt flats, on the west coast of Qatar, reveals several deposit zonations within the salt flats. The deposit zonations occupy a restricted sub-evaporite basin in the lowest northeastern part of a large inland sabkha area. This sabkha occurrence is oflimnic type, filling a recent synclinal depression bounded by a broad and gentle anticline forming the Qatar Arch to the east, and a conspicuous sharp anticline of the Dukhan anticline to the west. The sediments filling the depression are mainly calcareous silts, mud and sand, which are highly impregnated with crystalline salts and contain layers of algae. The Dukhan salt flats are characterized by a markedly high salinity (hypersaline), as a result of the prevailing dry climatic conditions, seawater intrusion, and saline influx from surface runoff. The present deposits consist primarily of gypsum and an uppermost dazzling white crust of halite, surrounded by minor amounts of calcite. With their high salt content, the hygroscopic sediments can absorb moisture during summer nights, when relative humidity may exceed 90 %. In the uppermost section of the flat profile, gypsum may lose its water and is transformed into anhydrite. Accordingly, Dukhan salt flats are considered to have undergone an evaporitic cycle of ephemeral saline basins. The Dukhan sabkha was developed within the last 5,000 year.