Sedimentology, mineralogy and geochemistry of Al-Awshaziyah inland sabkha, central Saudi Arabia

• Published in: Arid land research and management Vol. 20; no. 2; pp. 117 - 132
• Main Authors: Al-Harbi, O.A, Hussain, G, Khan, M.M
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01.07.2006
• Subjects: aquifers; geochemistry; groundwater; groundwater recharge; hydrochemistry; inland sabkha; mineralogy; sedimentary facies; sediments; soil chemistry; soil salinity; surface water; wells; Saudi Arabia
• ISSN: 1532-4982; 1532-4990
• DOI: 10.1080/15324980500545991

In the Kingdom of Saudi Arabia, a rising demand of municipal, agricultural and industrial sectors require better utilization of surface and groundwater resources. Some of the wadi and low depressions in the central Saudi Arabia are covered with salt (Inland sabkha). It is also suspected that the aquifers below receive substantial amounts of recharge from the above ground salt flat. It is, therefore, important to investigate the mineralogy and geochemistry of these salt-flats to determine their impact on groundwater chemistry. Al-Awshaziyah inland sabkha is a saline dry/wet land with an area of 18 km 2 in the central Saudi Arabia. The study area was divided into six transverses beginning at a permanent marker. The distance of different profiles ranged between 200-300 m. Soil, groundwater and well water samples were collected for physical and chemical composition. Additionally, different soil and salt facies were measured in each profile. Three sedimentary facies, viz., silty sand; black mud, and salt facies (from bottom to top) had been delineated. The mineralogy by X-ray diffraction analysis (XRD) for silty-sand facies composed of quartz (25-74%), halite (11-16%), dolomite (5-27%), calcite (4-21%), and gypsum (4-8%); black mud facies composed of quartz (14-16%), halite (25-33%), dolomite (18-25%), calcite (20-25%) and gypsum (8-11%); and salt facies is dominated only by halite (100%). The delineated facies led to highlight the depositional environment; mineralogy and geochemistry were studied. The elemental concentrations of CaO, MgO, K 2 O, Na 2 O, Al 2 O 3 , and SiO 2 have been analyzed in order to understand the element behavior of each delineated sedimentary facie of sabkha basin. The geochemistry data reveals that SiO 2 increases with the depth and CaO, MgO, Al 2 O 3 , and K 2 O behave in the reverse with the depth of sabkha sediments. The geochemical data has good correlation with the mineralogy of the same profile. Thus, the relationship has been established for the evolution of sabkha basin on the basis of sedimentary facies, mineralogy, and geochemistry.