Description and Mode of Formation of the Supratidal Evaporite Facies in Northern Sinai Coastal Plain

Abstract

ABSTRACT In the Northern Sinai coastal plain, to the south of the Bardawil lagoon, two types of sabkhas occur: coastal sabkhas or salt flats connected at present to the lagoon and flooded occasionally by lagoon water, and inland sabkhas cut off from the lagoon by sand dunes. At present lagoon beach sabkhas are under the influence of lagoon waters. The evaporitic minerals forming in them depend mainly on the hydrography of the lagoon and especially along the shoreline reaches of the lagoon. Inland sabkhas on the other hand are presently under the influence of groundwater discharging to them after rainy periods, which redissolves part of the evaporitic minerals (halite) precipitated in earlier evaporitic cycles. In sabkhas in which carbonate sediments are in contact with brines, arid zone suprat dal diagenesis takes place, thus causing the formation of diagenetic dolomite. In other sabkhas only gypsum and halite occur. It is concluded that the evaporitic facies developed in the different sabkhas depend primarily on the salinity of the lagoon water, the type of host sediment in the sabkha, and the extent of flushing of the sabkha by groundwater.