Geochemistry and mineralogy of a recent sabkha along the coast of Sinai, Gulf of Suez

Abstract

Most efforts in the study of sea‐marginal sabkhas have concentrated on the Persian Gulf, but little is known about the sediments and mineralogy of sabkhas marginal to other seas. The purpose of this paper was to present some geochemical and mineralogical observations in a recent sabkha on the coast of Sinai along the Gulf of Suez. The sabkha is composed of coarse clastic sediments with marine‐derived groundwater at depth of about 1 m. The general morphology, climate and water salinity of the Gulf of Suez resemble those of the Persian Gulf, despite the fact that the content of authigenic evaporites in this sabkha is more sparse. The evaporite minerals accumulated only in the upper 30–40 cm of the sabkha, below that and down to the groundwater table, there is no accumulation of evaporites. Laterally, the salinity of the groundwater in the sabkha and the concentration of evaporites in the sediments above it increase constantly with distance from the shore. In contrast to the Persian Gulf where anhydrite is a major evaporite mineral, in Belayim gypsum is the only calcium sulphate mineral in the recent sabkha. Anhydrite is found only in an old elevated sabkha where it recrystallized from gypsum. The gypsum occurs as interstitial crystal concentrations or lithified horizons almost exclusively at the depth of 20–40 cm below the sabkha surface. Above that, in the uppermost horizons, there is in situ accumulation of interstitial halite crystals. The total concentrations of gypsum and halite are almost equal in this sabkha. The sea water recharge in El Belayim is almost exclusively by seepage through the sabkha sediments and not by flooding. The groundwater under this sabkha is only slightly more saline than the Gulf water, thus, not heavy enough for extensive downward refluxing. The major hydrodynamic process must be upward migration of the brines from the groundwater, precipitating on the way gypsum and later halite with some magnesite. Since the sediments of the sabkha are too coarse to support extensive capillary movement, the brines must, therefore, migrate upwards due to ‘evaporative pumping’.

Eolian dust in the coastal desert of the sudan: Aggregates cemented by evaporites

“…3) Hydrologic models of this sort have been described for egbkhas at the coasts of the Sinai Peninsula [14] 6) The sebkha is a likely place for this dust to be deposited tern L porarily, cemented partially by evaporites, and then eroded uy dust storms.…”

Ras Shukeir sabkha and associated salina deposits: Comparison with a Holocene depositional equivalent

“…This evaporite sequence forms concomitant to the capillary rise of the interstitial brines, and during the water movement through the vadose zone it becomes more and more concentrated. This pattern of progressive concentration is probably caused by both interstitial and surface evaporation of groundwater by the evaporative pumping system as in the sabkha along the coast of the Sinai, Gulf of Suez described by Gavish (1974) where also gypsum and halite are the only evaporite minerals recorded with no anhydrite among the sedimentary components in both sabkhas. Interestingly, anhydrite is not recorded in this area.…”

Recent sabkhas of Ayun Musa and El-Shatt, Sinai, Egypt

“…Development of dolomite in sabkha sediments through this reaction has been demonstrated from the Persian Gulf sabkhas and elsewhere by many workers, among them Shearman (1963) Kinsman (1966, Patterson and Kinsman (1981), Butler (1969), Bush (1970and 1973, Gavish (1974), Levy (1980), Ali (1981) and others.…”

“…Raup (1970). and Gavish (1974 Ayun Musa sabkha formed due to evaporative precipitation in the lowest areas of the enclosed drainage-basin. The area is characterized by flat.…”