Study of metasomatose iron deposit of Chaabet El Bellout (Ain Zana, NE of Algeria): mineralogy, geochemistry, and genetic model

Abstract

Chaabet El Bellout iron mine is located in the Medjerda Mountains, constituting a connection zone between the Maghrebides chain and the Saharan Atlas. This deposit is mainly embedded in Upper Cretaceous (Campanian and Maastrichtian) and Miocene limestones with clusters and veins replacing both carbonates and sandy-carbonate levels. In this study, feld observations and mineralogical analyses combined with geochemical and oxygen isotopic data were used to determine the origin of the mineralizing fuid and the source of mineralization. The results indicate that the iron ore of Chaabet El Bellout is of medium quality resulting following two main phases: frst, the replacement of Cretaceous carbonates by ankerite and siderite, followed by the alteration of iron oxides (hematite and magnetite), then, a deposit of high temperature sulfdes, sulfosalts, and sulfates (pyrrhotite, pyrite, chalcopyrite, gray copper, and barite) in a fractured zone. However, the contribution of magmatic fuids cannot be excluded, as some samples reveal high V-Mo-Ni and Zn contents and a negative isotopic signature (-0.6‰ VSMOW) diferent from the rest of samples that all indicate positive values (0.6 to 1.6‰ VSMOW), suggesting the participation of metasomatic saline fuids interacting with marine carbonate levels deposited in the Cretaceous and Triassic formations.