Contribution of X-Ray Diffraction in the Identification of Crystalline Phases of the Mineralization Hosted in the Mesozoic Cover of the Tazzeka Hercynian Massif – Maghrawa Region - Morocco of X-Ray Diffraction in the Identification of Crystalline Phases of the in the

Geological Research and prospection, mining exploration, remote sensing, geochemical methods, and geophysical technologies could improve the effectiveness and productivity of mineral exploration and ore identification. The application of these kinds of technologies presents the key factor of the future mining discoveries across the world. In this paper, we present the case study that consists to the use of geological investigation, remote sensing and geochemical studies in order of describing and determinizing the mineral fraction occurred in the Liasic series of Tazekka that manifests as carbonates cover of the Hercynean basement of the eastern Mesetean domain of Morocco. In fact, the followed procedure assigns the handling of remote sensing maps related to the area study, where we focus the hydrothermal alteration whichever allows the determination of selective and representative sample stations. Note that the collected samples were subjected for two kind of geochemical analysis, when the first consists to the determination of mineral tenors using Inductive Coupled Plasma (ICP), and the second corresponds to the examination of samples by powder X-Ray Diffraction (XRD) methods in order to provide useful information about sample composition in terms of quantification of crystalline phases and content. In this work, we make in evidence the existence of remarkable mineralization of base and precious metals. These results may present an economic discovery in term of the potentiality of the Liasic cover of Tazekka for the mining exploration.


Introduction
The Zone study is located into northeast of the Hercynean basement of Tazekka massif, based in the northeast end of the Middle Atlas of Morocco, and especially in the Mesozoic cover that outcrops SW of Taza (Fig. 1). In the Tazekka, the mineralization occurs in the Hercynean massif, as veins, and stratiform in the Liasic cover [2][3][4]. The basement, appears as a lower Ordovician epimetamorphic schists, surmounted by volcano sedimentary complex dated Upper Visean-Namurian [5][6][7].
Note that magmatic rocks as kind of granite and microdiorite, are generally enclosed by an aureole of contact metamorphism [8].
The Mesozoic formations are represented by Triassic and Liassic rocks (Fig. 1), resting in discordance on the hercynean basement [9]. The Triassic serie starts with two formations of red argillites separated by a volcanic formation [3]. The lower and upper Triassic argillites show a huge hydraulic fracturing. The Lower Lias assigns three formations where the lowest consists of fine, massive, and dark dolomites [4].
The middle, presents a series of dolomitic breccias, laminated dolomites and crystalline dolomites, and the upper formation consists of pale grey, fine-grained limestone and dark grey limestone with oolitic and bioclastic intervals [3]. The Middle Lias consists of a series of interbedded limestones and marls, however, the Upper Lias-Aalenian and Lower Bajocian are generally marly [3]. In the Middle Atlas Causse domain, there's an unconformity between the lower Lias and upper formations of the center and upper Lias. The Liassic platform of the Tazekka contains some Pb-Zn and Fe deposits, whose distribution is controlled by paleogeography and structure. The mineralization is found along the basin margin and it is related to dolomitization [10,11]. It shows a straight paragenesis, essentially based sphalerite and galena, with small amounts of pyrite and chalcopyrite. Sulfides occur in places and commonly form massive aggregates hosted by both hydrothermal dolomite and saddle dolomite [12,13]. The deposits are globally stratiform (Ain Hallouf, Ben Zerhla, Ain Tarselt, Ain Khebbab and Bou Khalifa) or open-space filling (Sidi Abdellah), and are located along the borders of grabens formed within the Middle Atlas Causse domain during the major Middle Atlas Toarcian-Bathonian tectonic event [9,14,15]. The presence of breccias, layered sediments and fragments confirms the karstic character of the mineralization. In the Lias cover, the mineralization seems to be occurred during two phases: first, the Carixian and so the Toarcian (Auajjar, 1994). Indeed, and based on all these arguments already cited, it appears that the major part of the mineralization detected in the Mesozoic Tazekka cover is stratiform, hosting Pb-Zn ores, that take an MVT form [16,17]. However, because it is clear that the geological and geodynamical contexts of the area is remarkable in term of mining wealth, we notice that the area is yet unrecognized in terms of mineral exploration and geological prospecting and research.
In this work, we will focus in a first order the lower liasic brecciated dolomitic zones [18] dated hettangian, which may contain some showings of base or precious metal mineralization, and which may give us an idea about the close relation between these mineralization and the buried Hercynian basement, which is granitized, metamorphosed and mineralized (Pb, Zn, Sb, Ag, Au, Sn, W, Fe…..) [19].

Methods & Characterization
In this paper, we have based our work on the spatial mapping of hydrothermal alterations in the Maghrawa area via remote sensing [20,21] (Fig. 2). Indeed, it is on the basis of this mapping that we have targeted the potential zones in terms of hydrothermal alteration. We carried out selective sampling of breccea, from which five samples were taken and designed for Geochemical and petrographic analyses.
All the samples were analyzed using inductively coupled plasma analytical techniques for measuring the levels of inorganic elements in the samples (ICP: Inductive Coupled Plasma) [22,23]. To ensure an optimal characterization, all the samples were analyzed using inductively coupled plasma analytical technics for measuring the levels of inorganic elements in the samples, while XRD (X-Ray Diffraction) [24] patterns were obtained from X'Pert High Score Report using Cu Kα (λ=1.54178 Å), 2θ mode was used to scan all the samples in the range of 30° ~ 60° with the step of 0.02° and the stay time is 2~3 s. Finally, to investigate the surface and morphology of the samples, Scanning Electron Microscopy (SEM) analyses were carried out on a FEI Quanta 200 microscope. Each sample is placed on a copper grid covered with a very thin layer of amorphous carbon (20 to 30 nm of thickness

ICP Analysis
According to the result of the ICP analysis, we note that no occurrence of (Pb) mineralization were detected in all samples, however the (Zn) (Cu) and (Fe) are present as clues of low concentration (0.018 -8%), except of SS04 which shows a high tenor of Zn (36%) and Iron (≈2%).
We note that this sample is taken from Ain Aouda region located in the north part of the zone study where an old mine of zinc as kind of strata manifested, and for that reason we conclude and suggest that the existence of high tenors of (Zn) and (Fe) is related to some extension of the principal ore body of Ain Aouda.
For the precious metals, we note the existence considerable (Ag) concentration (2-4 ppm) associated to some gold mineralization (1-7ppm). For the (Sb) we note an average of 282 ppm, with 34 ppm of (W) and 164.6 ppm of (Sn).
Based on the geological context/geochemical content, we investigate the crystalline phases and structures of the five samples, by using the techniques of crystallographic analysis by X-ray diffraction.

Structural Properties of SS01
X-ray diffraction (XRD) patterns were used to investigate the phases and structures of our five extracted samples. The XRD pattern of the as-prepared sample SS01 (Fig. 3A) revealed the existence of four phases, calcite, manganocolumbite, tetrahedrite and freibergite.
Furthermore, the diffraction peaks of freibergite (Ag,Cu,Fe) 12 (Sb,As) 4 S 13 could be indexed to the cubic crystalline phase (space group I -4 3 m) with the lattice constants a = b = c = 10.4920 Å and (α = β = γ = 90°), compatible with the standard already described in the literature, i.e. JCPDS 96-901-2611 [28]. Note that no peaks of any other phases or impurities were detected in the spectra, which mean that the sample SS01 is mainly composed of calcite, manganocolumbite, tetrahedrite and freibergite. The diagram in (Fig. 3B) present an estimation of mineral percentage's calculated using the crystal impact software ´´Match Phase Analysis´´ which indicates respectively 44,1% of calcite, 27,7% of manganocolumbite, 14,2% of tetrahedrite and 14% of freibergite.
Hence, no peaks of any other phases or impurities were detected in the spectra, which mean that the sample SS03 is composed of calcite, tin (II) halide sulphates, barium iron selenide, tetrahedrite and zinc germanium ± barite. The diagram in (Fig. 5B) presents an estimation of these element`s percentage calculated using the software Match Phase Analysis, where the obtained percentage was found to be respectively (65.4%), (14.9%), (6.2%), (5.1%), (5%) and (3.3%).
Hence, no peaks of any other phases or impurities were detected in the spectra, which mean that the sample SS05 is mainly composed of Calcite, Iron (II) Iodide, Niobium Sulphate, Theoparacelsite, Silver antimony telluride, Germanium Antimony Telluride, Dicesium Potassium Manganese and Sodium Nitrate.

Structural Interpretation
Note that the average crystallite size of the five extracted samples was calculated by using Scherrer's formula [50]: Where (d) is the average crystallite size, K is a dimensionless shape factor, with a value close to unity, called the Scherrer constant. The shape factor has a typical value of about 0.89, but varies with the actual shape of the crystallite, λ is the wavelength of X-ray source used in XRD (λ = 0.15418 nm), β is the full width at half the maximum intensity (FWHM) and θ is the diffraction angle in degrees.
In addition, the typical panoramic SEM images presented in (Fig. 8) Obviously shows smaller microparticles in all samples with a non-uniform size distribution confirming the existence of numerous phases in each sample. Furthermore, the overall products, compositions, crystalline phases, space groups, lattice parameters, densities and cristalite sizes are summarized in the Table 2.

Conclusion
In this paper, we realized a series of field and laboratory studies in order of determining, sampling and analyzing five sample rocks that were taken from the carbonates liasic cover of Tazekka paleozoic inlier, located in the noth eastern part of Middle Atlas domain of Morocco.
According to the result of ICP analysis of these five samples, we note that no occurrences of (Pb) mineralization were detected, however the (Zn) (Cu) and (Fe) are present as clues of low concentration (0.018 -8%), except of SS04 which shows a high tenor of Zn (36%) and Iron (≈2%). We mark that this sample is taken from Ain Aouda where an old mine of zinc as kind of strata is manifested, and for that reason we conclude and purpose that the existence of high tenors of (Zn) and (Fe) may be related to some extension of the principal ore body of Ain Aouda. For the precious metals, we note the existence considerable (Ag) concentration (2-4 ppm) associated to some gold mineralization (1-7ppm). For the (Sb) we note an average of 282 ppm, with 34 ppm of (W) and 164.6 ppm of (Sn).
Taking into account the results of the ICP and XDR analysis, in this work, we highlight the presence of metalliferous concentrations in the five samples taken from the dolomitic breccias of the lower Lias in the MAGHRAWA region. These concentrations concern base metals whose (Fe), (Pb) and (Zn) manifest as sulphate form, associated with supergeneous copper. On the other hand, we note that the precious metal including (Ag), (Au), and (Sb) are well developed and depends to the surface condition chemistry. It should be noted that other elements such as (Sn) have been detected in trace amounts.
In fact, the setting up of these metalliferous occurrences in the Mesozoic Liassic cover presents in a first-hand a concrete case of the evolution of the mineralization which is rich in Fe-Pb-Zn-Cu-Ag-Sb-Sn-W..., from the deep Hercynian basement up to its Liassic platform cover, and present in a second hand a new opportunity to conduct deep studies in terms of petrography, metallogeny, geophysics, and all disciplines of geology allowing the understanding of the distribution of these mineralization, and more precisely those of (Ag), (Au), (Sb), (Sn) which present new potential prospects for precious metals in the Tazekka Liassic cover.