Cr-Ni-PGE Mineralization and Serpentinization of Peridotites in Beni Bousera Massif (Internal Rif, Morocco)

Abstract

The Beni Bousera ultramafic massif outcrops at the base of the internal zones of the Alpine Rif belt of northern Morocco. It is characterized with the presence of two types of magmatic ores (i) chromite and Ni arsenides, associated with orthopyroxene and cordierite (Cr-Ni ores), and (ii) Fe-Ni-Cu sulfide mineralization, containing variable amounts of graphite and chromite associated with phlogopite, clinopyroxene and plagioclase (S-G ores). The Cr-Ni and S-G ores endured High-T alterations related to injection of leucogranite dykes, producing Ni and Co rich in chromite from Cr-Ni ores; and low-T alteration, due mainly to serpentinization/weathering process. The latter resulted in the serpentinization phenomenon of peridotites, followed by carbonation, along with the leaching of the Ni-arsenides and sulfides, giving rise to Ni-rich silicates in the Cr-Ni ores, and Fe-rich silicates in the S-G ores.