Clay Minerals in relation to depositional environments and water chemistry of Wadi El Natrun area, Egypt [electronic resources].

Includes reference.

The objective of the current work is to study the mineralogy of the different water bearing formations in Wadi El Natrun and its vicinities in relation to depositional environments and water quality. The presence of illite with biotite, muscovite and montmorillonite or kaolinite in Miocene aquifer, West of the studied area is an indication of typical fluviomarine and marine environments which reflects high water salinity. In contrast, the disappearance of illite with biotite and muscovite in both Pleistocene and Pliocene aquifers at east of the studied area reflect continental condition and low water salinity. Several indices; an alkali number and cation exchange index, are used for the identification of water that undergone cation exchange processes. All groundwater samples of fluviatile Pleistocene, Pliocene and Miocene aquifers in all hydrochemical profiles display an alkali number above100 and negative values of cation exchange index. This means that the alkaline earths (Ca²⁺ and Mg²⁺) in their sulfates and carbonates in groundwater replace alkalis on the surface of fluviatile clay minerals in aquifers matrices (equations 1and 2). These groundwater types have the assemblage of salt combinations (1): NaCl, Na₂SO₄, NaHCO₃, Mg(HCO₃)₂, Ca(HCO₃)₂ and (III): NaCl, Na₂SO₄, MgSO₄, CaSO₄ and Ca(HCO₃)₂. These assemblages reflect the effect of leaching and dissolution of terrestrial salts (continental facies groundwater) with some contribution of cation exchange processes.

Summary in Arabic.

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