Chemistry of minerals from the Azegour skarn deposits, western High Atlas, Morocco
Résumé
The Azegour Cu-Mo deposit, located on the north side of the High Atlas, occurs in lower Cambrian volcanic and
sedimentary rocks. The mineralization of this deposit is directly associated with skarns, developed on carbonate bars
during the intrusion of the calc-alkaline hyperaluminous granite of Azegour. The type of the hydrothermal
transformations recorded in the carbonated bars is controlled by the lithological nature of the protolith and is closely
confining with the volcanic and volcano clastic levels.
Five paragenetic stages of skarn formation and ore deposition can at least be described: Stage I: clinopyroxene;
stage II: wollastonite ± vesuvianite; stage III: garnet; stage IV: quartz ± potassium feldspar ± calcite ± sulphides ±
molybdenite ± cassiterite ± scheelite ± fluorite ± accessory minerals (apatite, zircon, titanite) and stage V:
amphibole ± calcite ± chlorite ± muscovite ± epidote ± sulphides. Two mineralizations stages are identified. The
first stage observed in volcanic and volcano clastic rocks in contact with the dolomitic marble is previous to the
metamorphic and structural events and consists essentially of sulphides and sulfo-arsenides (Cu, Pb, Zn, As and Ag).
The second stage of mineralization (Mo, W and Sn) is observed in the skarn from marble of granitic metamorphic
aureole.