Geochemistry and Mineralogy of the Miocene and Pliocenesediments of the Northern Margin of the Lower Chelif Basin (Western Tellian Domain, North Algeria)

Abstract

The Chelif basin is one of the basins in the Mediterranean that preserve sedimentary deposits that span the Miocene including evaporites from the Messinian Salinity Crisis (MSC). Mineralogical and geochemical analyses were integrated in this study and conducted on a set of fifteen samples, collected from a selected section (Amarna). The lithostratigraphic succession of this section is represented by three formations, which are, from bottom to top: the Tortonian Blue marls formation, the Messinian marls, including gypsy-calcareous beds, and the Zanclean Trubi marls formation. The integration of relating mineralogical and geochemical data allowed us to better constrain the noticeable transition in this region. The onset of the lower Pliocene is marked with a sudden appearance of an important content of a smectite mineral, the occurrence of an abnormal positive peak of a celestine mineral (30%), reflected in the important shift of SrO in the layer A₉, along with an important sulphur content (10%) and reduced environmental conditions.