Geology, mineralogy, and chemistry of the M’zila bentonitic clay deposit (Mostaganem, NW Algeria)

Abstract

Bentonitic clay deposit of M’zila locates in the North border of the upstream portion of the Chelif basin “Bas Chelif” down to 35 km NE of Mostaganem. It consists of 14 layers (most recent) 1 to 14 (oldest) forming the North and South flanks of an E–W Syncline. These layers are enclosed in the median blue marls formation of the Upper Miocene of the “Bas Chelif” basin lying unconformably on the ante thrust sheet sandstone formation. This median member contains metric cinerites thick continuous levels and could beings originally bentonitic clay region of M’zila. The cinerites are the product of explosive type in the volcanic eruption, usually deposited in the marine environment. They are formed by a more or less rich feldspar and biotite volcanic glass dust. Bentonitic clay layers have average thicknesses vary between 2 and 6 m. They are distributed by centimeter to decimeter levels of soft sandstone, sandy, and rich black mica. Sandstone is greywacke clay and carbonated cemented, matrix consisting of quartz, feldspars, biotite as major minerals, zircon, and glauconite as accessory minerals. They deposited in a marine, reduced, and confined environment. Mineralogical composition of bentonitic clay region of M’zila is as follows: (1) Clay minerals are represented by the montmorillonite with a small amount of kaolinite. (2) Non-clay minerals are composed mainly of quartz, albite, biotite, calcite, heulandite, chlorite, dolomite, and gypsum. Infrared spectroscopy shows that bentonitic clay has highlighted the presence of the disorderly a high temperature silica tridymite. Geochemistry of the major elements of M’zila bentonitic clay shows high a percentage of SiO2 and Al2O3. Chemical analysis shows that the 10, 12, 14 B 7, 4 A, and 4 clay layers are ferric clay; 11 and 3 layers are magnesian clay. Particle size analysis by sedimentation shows bentonitic clays are accrued mainly clay fractions to silt. Bentonitic clay deposit of M’zila has probably volcanic origin and deposited in a marine, reduced, and confined environment.