Contribution à l'étude pétrographique et gitologique de la serpentinite de l'Oued Madagh -Oranie, Algérie-

Abstract

The occurrence of serpentinites in the Oued Madagh area has long been known, but very few studies have been devoted to these rocks. The serpentinite massif crop out as tectonic lenses pinched in Paleozoic formations. Petrographical and mineralogical studies reveal the existence of a mineralogical assemblages of high-grade metamorphism (Chrysotile - Antigorite) and three serpentinization stages, no relics of primary minerals have been observed. The occurrence of bastites indicate the serpentinization of pyroxenes, whereas the presence of metamorphic olivine resulted from the breakdown of antigorite indicates a HP-HT conditions. A preliminary geochemical study suggests an origin from an abyssal peridotites, and a harzburgite as a protolith of the Serpentinites of Oued Madagh. Metallogenic study of these rocks shows the existence of magnetite-sulphides vein mineralization remobilized from an already disseminated of these minerals in the rocks. Our metallogenic investigations did not reveal an interesting mineralization in the Oued Madagh serpentinites