Genetic implications of the Ain Sedma iron mineralization, NE Algeria

Purpose. To reconstruct the geological evolution of the Ain Sedma magnetite lodes, located in NE Algeria. Methodology. The petrographic and elemental composition of the ores were determined using energy dispersive spectroscopy and elemental mapping whilst oxygen isotope ratios were measured on rock samples and high purity mineral separates from the Ain Sedma iron. Findings. Petrographic observations show massive texture, spherulitic lamellae, skeletal growths, dendritic branching, and rare vesicular crystals. Major constituents are iron oxides with quartz being the most dominant gangue mineral. Oxygen isotope analysis for both host rock and iron ores gave 18O values ranging from 19.1 to 22.5 ‰ V-SMOW and 15.9 to 20.3 ‰ V-SMOW, respectively. These results support the involvement of an 18O-rich and Fe- rich component in the genesis of the host rock and the associated mineralization. Originality. The present study is the first to combine geochemical data and petrographic observations to establish the genesis processes the mineralization and the host rock have passed through, from the beginning of partial melting until magma eruption. Practical value. These results are the first geochemical analysis delivered in the area which focuses mainly on the genetic model of the host rock and the mineralization as well as their mutual relationships.