The northern part of the Moroccan meseta is characterized by a number of deposits or showings of tin and tungsten. They are spatially associated with the Hercynian granitic massifs.
The magmatic activity of the North-Mesetian basement is characterized by the establishment in the West and in the center of important granite intrusions: Zaër, Ment, Oulmès, of several pointings of lesser importance: Moulay Bouazza, Aouam, Oued Beht and massifs, still in a hypothetical state, such as the buried granite of Achemmèche (El Hammam). This magmatic activity has led to the establishment of stanno-wolfamiferous mineralization locally of economic importance.
This comparative study presents a synthesis of the stanno-wolframiferous occurrences of Hercynian Central Morocco. The study focused on the mineralization of five localities representing the main Sn-W mineralized districts of Central Hercynian Morocco (Oulmès, Zaër, Ment, El Hammam, and Aouam). The characteristics of each of these mineralized occurrences are described before establishing a comparative synthesis given by way of conclusion. It specifies the similarities and differences between the different granite stocks of Central Morocco by identifying the points of analogy and difference of the Sn-W mineralized sites of Hercynian Central Morocco.
In the district of EI Hammam and precisely in the sector of Ticht Ouguas and along the fault of Jbala, which materializes in this place the abnormal contact between the anticlinorium of Khouribga-Oulmès and the synclinorium of Fourhal-TeIt, the presence sulphides disseminated in the sediments, the discovery of a major gravimetric anomaly in these sectors and above all the recognition and description, for the first time, of volcanic pillow lavas (pillow lavas), prompted the undertaking of prospecting for sulphide deposits. In this sense, two cored boreholes (SCJB1, SCJB2) of a few hundred m were implanted in the valley of the Boutoukret wadi upstream of the mine, almost on the route of the Jbala fault.
The region of the Jbala fault has experienced multiple geological events, which can be summarized in two major stages. The first stage corresponds to Visean turbiditic sedimentation in an active context of synsedimentary tectonics, followed by a second stage which corresponds to a major deformation with a NE-SW structure (post-Visean event) materialized by the functioning of the inherited fault, a tourmalinization (introduction of boron probably in relation to a thermal flux of deep origin (placement of the Achemèche granite), shear under conditions of brittle deformation, and finally a placement of sulphides.
The petrographic and mineralogical study of a certain number of samples from these drillings supplemented with those of surface made it possible to recognize petrographic facies (1) of the sedimentary rocks corresponding to an alternation of limestone benches, sandstones and dark pelites having undergone slight metamorphism hardly exceeding the degree of greenschist, (2) igneous rocks: diorites, dolerites and pillow lavas probably similar to a keratophyre, and (3) sulphides present along the entire length of the boreholes. Depending on the arrangement and lithological nature of the formations that host these sulphides, several types have been distinguished: either disseminated (essentially pyrite and pyrrhotite) or in fine laminae predominantly pyritic, or polymetallic (pyrite, pyrrhotite, chalcopyrite and especially sphalerite) associated with carbonate levels, more or less skarnified and later in fissures parallel with the sulphides of the fluorite veins.