Projet de fin d'études Master Yassir
YASSIR ALAOUI MRANI2022, Etude lithologique et métallographique du gisement polymétallique de Draa Sfar Nord (Jebilet Centrale, Maroc)
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Abstract
The Moroccan Hercynian province has a rich metalliferous potential with deposits of metals of major economic interest, as is the case for the Draa Sfar mine, which is a polymetallic deposit of the VMS type with Pb-Zn-Cu, subdivided into three blocks: the southern block, the central block, and the northern block. The core holes studied were in the latter block. The Draa Sfar North polymetallic deposit is a small, massive sulphide horizon hosted in a volcano sedimentary formation. During the Hercynian orogeny, the Draa Sfar sector was deformed and metamorphosed, which generated shear structures, folding and a network of faults, responsible for the current morphology of the deposit. Considering the depletion of the Hajjar deposit and the exploitation of the mineral resources of the central and southern block of the Draa Sfar mine, this study will focus on the exploration of new resources in the northern part of the deposit not yet exploited: the North Block of Draa Sfar. The lithostratigraphic study of the Draa Sfar North sector showed that the dark sandstone metapelites of Dinantian age (Middle Mississippian) are the most abundant and thickest followed by the carbonate metapelites of Namurian age. These metapelites are oriented along the direction of regional deformation (the S1 schistosity). The carbonate sandstone metapelites are in the form of levels or lenses where the whole has been attributed to the Sarhlef series. The sulphide mineralization of Draa Sfar North deposit (Sidi M'Barek) contains several types: disseminated, banded, massive and fissural. It consists of two major mineralized lenses, one copper-bearing and the other zinc-bearing, which is essentially formed of pyrrhotite, chalcopyrite, sphalerite, pyrite and arsenopyrite with a quartz and carbonate gangue. The geochemical and petrographic study of the samples collected at the level of drill holes of Draa Sfar North showed the intensity and the degree of the hydrothermal alteration which affected the surrounding rocks, the mineralization, and the distribution of its metallic elements. This alteration is reflected by strong chloritization, sericitization and oxidation. This has masked all the sedimentary figures and the indications of the polarity of this sector.
