Petrographical and geochemical characteristics of the ultramafic rocks of Zalm, Central Arabian Shield, Saudi Arabia

The Jabal Zalm ultramafic complex (Precambrian) is part of the Nabitah suture zone and forms a belt striking northwest. The ultramafic rocks within the complex are highly deformed and have been completely altered to serpentinite. Petrographic study conducted on the serpentinite mineral textures and crystal shapes indicates that they may have been derived from olivine, orthopyroxene, clinopyroxene and/or hornblende respectively. Chromite is present within the serpentinite in the form of disseminations, small lenses and pods. Chemical analysis of serpentinite rock samples showed elevated concentrations of Cr, Ni and Mn. The maximum values for Cr, Ni and Mn are 5000ppm, 3000 ppm and 3000 ppm respectively. Field and laboratory studies indicate that the area may have a good potential for chromium and nickel mineralization. (author)