Contribution à l’étude pétrographiques et minéralogiques des formations triasiques de l'Atlas saharien central et occidental (Algérie) et minéralisations associées

Abstract

The western (Ksour Mountains) and central (Djebel Amor and Ouled Nail mountains) parts of the Saharan Atlas are frequently affected by diapiric intrusions, composed of materials of presumed Triassic age. Some of these diapirs and associated magmatic rocks that have been very little studied in the past (diapirs of Zerigat, Ain el Harfi, Boualem, Kef el Melah, Krakda and Djebel Mouilah) are the object of this work. The use of remote sensing has shown the effectiveness of satellite image processing in the lithological discrimination of the different formations of the Saharan Atlas, including diapirs with Triassic materials. Petrographic, mineralogical and geochemical studies have shown the predominance of mafic magmatic rocks (dolerites and basalts), but also andesitic (case of Zerigat diapir), enclosed in an evaporite-richs (gypsum and halite) variegated clays. Mineralizations (iron oxides and sulphides) are sometimes associated with these magmatic rocks. More precise geochemical and geochronological studies are necessary to constrain the geodynamic context of the magmatic rocks emplacement in the Saharan Atlas.