Geochemical, Mineralogical and Isotopic Fracturing during the Progressive Evaporation of Chott Djerid Brine (Southern Tunisia)

Djerid Chott, in southwestern Tunisia, is one of the biggest salt lakes in the world. This work follows the specific precipitation of evaporites through progressive evaporation of Chott Djerid brines using geochemical, isotopic and mineralogical approaches, to explain the intricacy of the working of saline frameworks controlled basically by climatic driving and the underlying geochemical structure acquired from the geographical system. Toward the finish of every evaporation step, solid and liquid samples went through analyses. Djerid brine is remarkably saline (427.7 g/l) and it is supersaturated contrasted with halite. The outcomes indicated that the Chott Djerid brines shaped fundamentally Cl--Na+-SO4- type geochemistry. Added to halite and gypsum as significant minerals, other minor minerals including carnallite, hexahydrite and sylvite were recognized in various phases of progressive evaporation of Djerid brine. Regardless of their low costs, significant minerals are of geo-economic interest because of their high amounts of production. Then, minor valuable minerals secure their geo-economic interest from their excessive costs. In this work, we find the window of precipitation of these valuable minerals' at the evaporation paces of 80% and 100%.

Multidisciplinary Study of Cores From the Wetland of El Melah, Southwestern Tunisia

Saline systems are candidates to be threatened by climatic change. In terms of methodology and materials, color identification, geochemistry, and mineralogy analysis were used. The spectral analysis of data of the amount of active K and Na firstly shows the individualization of a cycle stretching along with 1000 yr. Then, a less pronounced cycle of 2500 years is marked with a lower intensity. Also, on the spectral analysis of K data, the drowned cycles of 650 and 500 years are marked by weak intensities not reaching the threshold level. These two comparable cycles may be artifacts due to analysis errors or variability in the rate of sedimentation resulting in the bifurcation of two hybrid cycles from one real cycle. This work confirmed the cycles found by color studies through real analyses such as geochemical and magnetic measurements. As a matter of fact, the majority of cycles found out by the spectral analysis of colors data are confirmed through analyses.