In Morocco, the antimony indices and deposits are divided into three regions: Central Morocco which contains the majority of the indices, the Rif, the Tazekka and Tamlelt massifs. These mineralizations are mainly hosted in Paleozoic terrains, sometimes near outcrops of Hercynian granites outside their aureole of contact metamorphism. They are in most cases in the form of stibine with fracture filling. Antimony deposits are vein-like and belong to several morphological types: deposits of large fractures opposing those of small fractures to which a particular type can be attributed, including that of cracks, and stratiform deposits with mineralization disseminated within the rock sedimentary host.
The pattern of distribution of antimoniferous mineralization in Central Morocco clearly shows their dependence on granite massifs. Lithological control is a key trap for the distribution of mineralization. The preferential alignment of these mineralizations is generally following the major fractures including two tectonic axes of NE-SW direction (Smala-Achemeche; Pays Zaïan-Haut Oued Beht), with a high frequency in the vicinity of the Carboniferous terrains and those of the pre-Carboniferous basement which constitutes the essential element of the search for new mineralized zones. In fact, it is the hearts of the anticlines as well as their flanks that are the best mineralized. Brittle tectonics played an essential role either at the local level of the deposit, or at the regional level of faulted anticlinal folds in determining the distribution of antimoniferous mineralization in the various massifs. The age of emplacement of antimoniferous mineralization is similar to the different massifs having been deposited at the end of the Hercynian orogeny.
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.
The central Jebilets located to the south west of the Moroccan meseta represent a metalliferous province containing numerous deposits and massive sulphide index, of which the Koudiat Aïcha deposit is one of them.
This last enclosed in the series of Saghlef attributed to the upper visean. It is predominantly pyrrhotite, contains minerals of the base metals such as sphalerite, galena, chalcopyrite, arsenopyrite and some traces of stannite. The orebody is enclosed in argillites interspersed with gabbroic magmatic sills at the footwall and hanging wall of the mineralization. It is materialized on the surface by the development of a gossan with iron oxides and hydroxides (hematite, magnetite, goethite, limonite, malachite ...), and shows an NS orientation according to the direction of the orebody.
This study intersted with the search for distinctive criteria between gossan assigned to mineralization of economic interest in relation to massive sulphide and those developed on iron deposits or other non-economic iron indices near the sector of Koudiat Aïcha. This approach has made it possible to identify criteria that make it possible to distinguish the gossan of products directly from polymetallic base metal mineralization. The elements analyzed, such as Ag, As, Bi and Sn, in addition to the elements searched, made it possible to identify the gossan directly assigned to the Koudiat Aïcha deposit and to pinpoint its location.
The results obtained are in good agreement with the data of the magnetic and gravimetric studies realized in carried out around the area of Koudiat Aïcha deposit. These results can be applied to all the ferruginous indices near the sector of Koudiat Aïcha in the Central Jebilet, see its extrapolation towards all the Hercynian lands.
The central Jebilets located to the southwest of the Moroccan meseta represent a massive VMS province whose Draa sfar deposit is one of them. The latter predominantly pyrrhotite, contains minerals of the base metals, enclosed in the Saghlef series attributed to the higher visean. The area of Draa sfar is materialized on the surface by the development of gossan with oxides and hydroxides of iron (hematite, goethite, limonite, malachite ...), and shows an orientation NS in the direction of the ore body. The analyzed elements such as Ag, As, Bi, Sn and Te in addition to the desired base metals, made it possible to identify the gossan directly linked to the Draa sfar deposit, and to clearly identify its location. They can be used as a guide to prospecting for gossan and these results can be applied to all gossan around the Draa Sfar area in the central Jebilets and its extrapolation to all Hercynian terrains.
The central Jebilets are occupied by the Saghlef series attributed to the upper Visean, are materialized by a predominance of the gossans, some of which directly cover massive sulphide predominantly pyrrhotite. These gossan with oxides and hydroxides of iron can be distinguished from East to West in three main plurikilometric axes sub-parallel to the meridian direction. The present study is concerned with the interpretation of geochemical data covering all Central Jebilets gossans. The analyzed elements such as Ag, As, Bi, Sn, Mo and Te, in addition to the base metals researched, made it possible to classify these gossans into three classes: 1) very promising class contains the Draa sfar and Koudiat Aïcha deposits, 2) moderately promising class includes the Kettra deposit and Ben Slimane and Lachach indices, 3) and the least promising class contains the rest of the sites. These chemical elements can be used as a basic prospecting guide for gossan in Central Jebilets province and extrapolate these results to all Hercynian lands.