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Article

Geological and Geochemical Characterization of Variscan Pegmatites in the Sidi Bou Othmane District, Central Jebilet Province, Morocco

by
Amina Wafik
1,
Nouamane El Aouad
1,2,
Youssef Daafi
3,
Yousra Morsli
4,
Marouane Chniouar
1,
Rosalda Punturo
5,6,
Aida Maria Conte
6,
Daniela Guglietta
6,* and
Wissale Aba Sidi
1,2
1
DLGR Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech 40000, Morocco
2
Applied Geophysics, Water and Environment Laboratory, Faculty of Sciences and Technics, Sultan Moulay Slimane University, Béni Mellal 23000, Morocco
3
OCP Group, Bd Moulay Youssef, Youssoufia 46300, Morocco
4
Geosciences and Applications Laboratory, Faculty of Sciences Ben Msik, Casablanca 20670, Morocco
5
Department of Biological, Geological and Environmental Sciences, University of Catania, 95124 Catania, Italy
6
Institute of Environmental Geology and Geoengineering, National Research Council of Italy (CNR IGAG), Research Area of Rome 1, 00010 Rome, Italy
*
Author to whom correspondence should be addressed.
Geosciences 2024, 14(6), 144; https://doi.org/10.3390/geosciences14060144
Submission received: 20 December 2023 / Revised: 20 May 2024 / Accepted: 22 May 2024 / Published: 24 May 2024
(This article belongs to the Section Structural Geology and Tectonics)
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Abstract

:
The Sidi Bou Othmane (SBO) pegmatite district is situated in the Central Jebilet massif, Western Meseta domain, Morocco. The SBO district is hosted essentially in a volcano-sedimentary series composed of Late-Devonian Sarhlef shales. Pegmatite bodies crop out as dykes, which are oriented from N-S to E-W and are generally variably deformed with ductile and/or brittle structures with ante, syn- or post-kinematic criteria. Petrographic observations of pegmatite dykes show that feldspars (i.e., albite, microcline) are the most abundant mineral phases, followed by quartz and micas, with tourmaline and accessory minerals such as garnet, and zircon also featuring heavily, as well as secondary minerals such as clinochlore, sericite, and illite. The geochemical study of the SBO pegmatites indicates that they have mainly S-type granitic compositions, which are peraluminous granites with calc-alkalic affinities. The study of trace elements indicates that SBO pegmatites were formed in post-orogenic syn-collision context during the Variscan orogeny by the partial melting of argilliferous sediment. They can be ascribed to the muscovite-bearing pegmatite; moreover, they have good potential regarding ceramics. They also contain minerals, such as feldspar, which have been recently assessed as critical raw materials by the European Union.

1. Introduction

Pegmatite has been specified as an igneous rock of mostly granitic composition, featuring properties such as highly coarsened and generally variable crystals, an abundance of strongly directional graphitic or other skeletal crystal growth, and the prominent spatial zonation of mineral assemblages, including monomineralic zones [1,2,3,4].
Granitic pegmatites are the main host rocks for rare metal deposits, strategic minerals, and precious/semi-precious gems [5]. They are commonly interpreted as the end products of extreme fractional crystallization of granitic magmas. This fractionation promotes the increase in rare metals and volatiles in the residual melt, leading to mineralization in granitic pegmatites [6,7].
In Morocco, the granitic pegmatites hosted in Precambrian terrains are relatively the most studied [8,9,10,11,12,13,14,15,16,17]. The research on Variscan pegmatites, particularly those of the Jebilet Massif, dates back to some decades ago [18,19,20,21,22,23]. These studies focused on the crystallography of the phosphatic mineral phases and highlighted the presence of frequent monocrystalline ferrisicklerite nodules in the veins of Sidi Bou Othmane (SBO) pegmatites (Jebilet Massif).
Recently, Essaifi et al. [24] pointed out that the shear zones affecting the Tabouchent granodiorite allowed fluid flow on a regional scale, causing the metal zonation observed around the pluton from a proximal Cu-Au mineralization to a Ag-Pb-Zn-Au mineralization.
The Jebilet Massif represents a critical mining district characterized by various ore deposits (e.g., Draa Sfar VMS, Frag al Ma graphite field graphite, SBO district aplo-pegmatite). The SBO pegmatites and Bir Nhass have not been studied so far from a geological point of view despite the research carried out on the Jebilet Massif [25,26,27]. Detailed petrological and geochemical data, spatial distribution, and the relationships with surrounding rocks and deformation are still unclear.
This study aims to characterize and classify the petrographic and geochemical features of the SBO pegmatites and to identify the associated alteration.

2. Geological Setting

The study area is located at about 30 km to the north of Marrakesh (Morocco). It is geologically situated in the central unit of Jebilet in the Mestian domain (Figure 1) [26,28,29,30]. The geological framework of the studied region is characterized by a folded Variscan belt primarily consisting of Paleozoic basement formations. These basement rocks have undergone metamorphism, ranging from greenschist to amphibolite facies, and have been intruded by syn- to late-orogenic magmatic intrusions during the Variscan orogeny [31,32,33]. These formations are exposed below an undeformed cover of Mesozoic to Cenozoic strata.
The SBO area presents three main geological formations [29,34]:
  • A lower formation named the SBO formation, mainly consisting of sandstones, silty shale, and limestone;
  • A middle formation named the Kharrouba formation; formed essentially by turbidites, these two series are cut by numerous dykes (pegmatites, microdiorite, carbonates) and were formed during the Frasnian−Famennian extinction;
  • An upper formation (Visean) called the Teksim formation, which corresponds to a transgressive series deposited in a platform environment composed of shales, limestones, sandstones, and siltstones.
The field investigations show that 180 E-W dykes are secant on NS pegmatite dykes. Their thicknesses vary from a few centimeters to a few meters (30 cm to 8 m) and they have an extension of a few meters to a few hundred meters (1 m to 500 m). Successively, they underwent a deformation presented on the ground by boudinage, and strike-slip faults shifted their architectures.
Chopin et al. [35] propose two discernible magmatic pulses during the early Carboniferous and late Carboniferous to early Permian periods across the entire Meseta domain, refuting the previous notion of three distinct pulses. The U-Pb method gave ages of 350–330 Ma to the initial magmatic activity, coinciding with the Eovariscan phase and the formation of intracontinental basins throughout the Meseta. The subsequent magmatic pulse, ranging from 305 to 275 Ma, corresponds with the primary Variscan convergent events within the Meseta amidst a milieu of intracontinental orogeny. This phase is attributed to the collision between Gondwana and the European Variscan belt, marked by the closure of the Paleotethys Ocean propagator tip and succeeded by a direct collision with Laurussia. According to Bouloton et al. 1992 [25,36], the emplacement of these intrusions is accompanied by contact metamorphism in the hornfels facies. On the basis of the mineral assemblage in the metamorphic aureole, pressure conditions were estimated in the range of 2.2 kbar, which corresponds to a maximum depth of 8 km. Differently, the P-T conditions in which the pelitic basement was enclaved and equilibrated during magma ascent have been estimated at about 750 °C and 3.5 kbar (350  MPa) [36].
The Variscan collision event in the Meseta region occurs in two stages during the late Carboniferous to early Permian period. The late Carboniferous event follows the closure of the Rheic Ocean, and the magmatic activity coincides with syn-compressional deformation in neighboring regions, such as Iberia and Central Massif. This late Carboniferous event is followed by an early Permian collision between Gondwana and Laurussia, leading to enhanced late/post-orogenic magmatism in the Meseta region [35,36,37].
Indeed, the Carboniferous formation underwent a very intense deformation, showing that the Hercynian orogeny stretched out between 330–250 Ma [38]. This deformation results from a succession of tectonic events contemporary to the Hercynian and post-Hercynian orogeny.
Bordonaro [30] outlined five stages of deformation in the Central Jebilet, namely D0 through D4. D0 involved ante-schist deformation marked by large-scale E-W folds linked to syn-sedimentary strike-slip sheets. D1 exhibited syn-schistosity folding with an average N30 direction, transitioning to rectified axial planes from east to west, indicative of regional syn-metamorphism. D2 marked the peak of deformation and metamorphism featuring the folding and shearing of D1 structures. D3 showcased an N110 to N150 crenulation schistosity, featuring a slightly dipping axial plane towards the NE and localized thrusting towards the west. D4 manifested as two sets of conjugate N70 dextral and N135 sinistral strike-slip faults alongside observable zig-zag folds.
Therefore, Delchini et al. [26] reveal two distinct deformation phases shaping the Jebilet Massif from Late Carboniferous to Early Permian. Initially, superficial nappe emplacement, termed D1, induces NS shortening in the Central and Western Jebilet, with ambiguous kinematics being seen in the Eastern Jebilet. Subsequently, D2 involves continuous westward thrusting onto the Coastal Block via the WMSZ, causing significant NW-SE transpressional crustal shortening accompanied by HT-LP metamorphism. The absence of crustal stacking suggests a link between high-temperature metamorphism and post-rift thermal anomalies. As far as P/T metamorphic conditions, according to [26], temperature values vary between 474 ± 50 °C and 628 ± 50 °C, respectively. Moreover, an Early Triassic (ca. 240 ± 10 Ma) magmatic event in the Central Jebilet was responsible for emplacement of a quartz-monzodiorite dyke swarm [39].
These areas underwent a sub-meridian syn-schist folding phase, associated with epizonal metamorphism of the post-upper Visean age, followed by sub-parallel shearing at S1 [40,41]. However, there is also the existence of a peri-plutonic metamorphism that developed around granite intrusions. The brittle tectonics are marked mainly by the existence of directional faults generally from N70° to N90°, creating a sinistral strike-slip fault [42].

3. Materials and Methods

The field investigation did not produce a detailed geological mapping of the pegmatite dykes and structural measurements. At this end, the representative samples have been collected and petrographic observations have been carried out at the laboratories of the Faculty of Sciences of Semlalia, UCA, Marrakesh. Forty thin sections of fresh pegmatite samples have been prepared and used for minero-petrographic and geochemical investigations. Petrographic analyses have been carried out using a Zeiss Axiolab polarizing microscope. The sample database is set out in Table 1, showing the observed minerals and grain size.
Based on petrographic observations, 25 representative samples have been analyzed for major, trace, and rare earth elements, using inductively coupled plasma atomic emission spectrophotometry (ICP-AES). The major elements have been determined using a WD-XRF spectrometer equipped with five diffraction crystals, using fusion glasses made from a mixture of powdered sample and lithium tetraborate (Li2B4O7) in the ratio of 1.5. Calibration is based on 30 certified international standards. The trace and rare earth elements have been analyzed by ICP-MS Laser ablation with the following parameters: spot diameter = 90 μm; frequency = 10 Hz; energy density 20 J/cm2 in a helium ablation medium. The NIST glass reference material SRM 610 is used as the calibration standard. The analytical accuracy for ICP-MS analyses ranged from ±1–8%.

4. Results

4.1. Pegmatites Description

The SBO region is characterized by the abundance of pegmatite rocks forming veins and dykes around the area. The occurrence of pegmatite rocks suggests a shallow magma body [26,43,44,45]. Other magmatic products are present in the SBO region and are represented by microdiorite dykes posterior to the pegmatite veins and to the regional schistosity. Their emplacement is related to rifting during the opening of the Atlantic Ocean [26].
The SBO pegmatites crop out as dykes mainly oriented at N30° (N-S to NNE-SSW) with a sub-vertical dip (Figure 2).
These pegmatites are exclusively hosted in the Sarhlef Shale of the Upper Devonian age (Frasnian–Famennian), covering a large area of the Jebilet central unit [29]. They include an anoxic sedimentation in marine platform environment [45] of sandstone–pelite, sandstone and pelitic banks (Figure 3a), and at the top, the calcareous sedimentation (Figure 3b). In the study area, the host rock shows alternating levels of metapelite with andalusite and/or cordierite, as well as other unstained sandstone layers free of porphyroblast, ranging from centimeters to meters.
Alternatively, SBO pegmatites are mainly constituted by the association of quartz, albite, muscovite, and, sometimes, tourmaline and potassium-rich feldspar (Figure 4).
They are generally unzoned but different compared to some zoned pegmatites observed by Agard et al. [20]. Figure 5 shows the zonation, which is quite clear at a large and small scale. A general sequence of internal mineralogical zonation has been extracted from the border to the core (Figure 5):
  • The order zone represents a thin layer of a few millimeters in contact with the host rock. Their mineralogy is essentially the same as that of the wall zone;
  • The wall zone is formed by quartz and feldspar (mainly albite, muscovite, and tourmaline from a few millimeters to centimeters);
  • The intermediate zone is composed of quartz and feldspar. This unit is characterized by a large increase in the crystal size;
  • The inner zone (core) is the internal part of the pegmatitic bodies. It is essentially constituted by massive quartz and is mainly a monomineralic part.

4.2. Deformation and Metamorphism

The SBO study area is a part of the Central Jebilet and has undergone an intense tectonic deformation with at least four phases (D1, D2, D3, D4), which resulted in the almost total disappearance of early structures (the stratification S0) [46]. This is the major compressive phase of the Hercynian cycle, showing the Hercynian orogeny stretched out between 330–250 Ma [38]. The deformation allowed for the development of several structures, represented by the S1 schistosity, shear zones, boudins, and folds.
The analysis and study of these structures establish a chronology between the different phases of deformation as well as the possible relationship between these phases.

4.2.1. Schistosity

The S1 schistosity is clearly visible in all the facies by well-developed schistosity in the sandstone metapelites, and it is less tight in the carbonate metapelites. At the scale of the study area, the schistosity trajectories show a direction that varies from N0 to N35, with a dominance of the N20 direction and a dip ranging from 30° to 85° to the west. This schistosity is linked to a strong E-W compression.
Furthermore, in some places it is possible to observe an abrupt variation in the dip of the S1 schistosity towards the east, notably next to the pegmatite dykes. The directions of the S1 schistosity are almost N-S (between N0 and N20). The pole dip rosette shows a concentration of poles on the eastern side, which means that the S1 dips to the west (Figure 6).

4.2.2. Folding

The S1 trajectories show that there is, generally a great regularity in the direction and a dip of the planes of S1, with little variable direction from N0° to N30° and a variable dip (in the east, the dip is westward; in the western part of the study area, the dip is eastward).
These results show that the SBO formations have undergone folding (P) that goes with the flow schistosity (S1). The folds, ranging from a few millimeters to a few centimeters, affected the S1. This can be clearly seen in the strike of some pegmatite veins (Figure 7a). During the major deformation, the more competent levels (pegmatites) undergo boudinage (Figure 7b,c) along the planes of the schistosity, forming spindle-shaped crystallization tails at their edges (Figure 7d,e) and showing that the pegmatite setting is syn-deformation. It is also remarkable that the elongation of the small quartz veins intercalated in the schists and parallel to the deformation elongation axis X and perpendicular to the shortening axis Z (Figure 7f).
Tensile joints are evidence of the shearing that affected the Central Jebilet (Figure 7f). The cracks related to this major phase have an average direction of N10 to N15 and range from cm to dm in size. The filling of these tension joints is generally quartz, in response to the E-W shear.
The brittle tectonic is materialized by a fracturing that affects essentially the pegmatite dykes and the quartz veins, but it can also have an effect at the level of the sandstone bars in the form of diaclases. The microdiorite veins and the quartz-carbonate veins are included in fractures linked to these brittle tectonics.
In the study area, this tectonic is developed at a large extent, materialized essentially by decoupling. It is manifested by a lateral displacement of the magmatic veins (pegmatites, microdiorites), limestone bars, and quartz veins. These early quartz veins and the pegmatite veins are offset by faults of general direction N110 to N140.

4.3. Petrography

The petrographic analysis revealed that quartz, feldspar, plagioclase, muscovite, and tourmaline are common (Table 1) (Figure 8A–F), with some accessory minerals, such as zircon and garnet (Figure 7a), in the SBO rocks. Feldspar is the dominant mineral phase and albite is the most common feldspar. By modal analysis, albite constitutes most of the analyzed samples (>47 vol%) while microcline and anorthite are less than 3%. Albite presents deformation bands in the direction of elongation (Figure 8C–F). It appears in the form of elongated rod-like sections, with sharp cleavages parallel and perpendicular to the elongation of the mineral. This mineral is very altered in illite and sericite (Figure 8C–F).
After feldspar, quartz is the most abundant mineral in SBO pegmatites (Figure 8A–F). It is marked by patches of xenomorphic crystals, and it also occurs as inclusions in feldspar and muscovite. Also, other prominent criteria in quartz are the undulose extinction, chessboard patterns (Figure 8E), and triple points that indicate that the mineral underwent deformation.
Muscovite occurs as euhedral crystals, which are large elongated subautomorphic sheets or micaceous tablets with irregular contours (Figure 8A,E,F). In some cases, muscovite is deformed, showing undulose extinction. This mineral can be observed either as gigantic minerals (cm in size) or as small inclusions within plagioclase. Muscovite sometimes shows a preferential orientation along the schistosity plane. Among micas, biotite occurs with tiny crystals.
Tourmaline is usually found both as basal subhedral and elongated sections, and irregular fractures may occur (Figure 8B).
Among the accessory mineral phases, it is worth noting the occurrence of garnet in some specimens (Figure 8A). Garnet is very rich in muscovite and tourmaline inclusions. Zircon is also present in many specimens (Figure 8A,E).

4.4. Whole Rock Geochemistry

Major, minor, and trace element contents, including rare earth elements (REEs), have been used to highlight the distinct geochemical characteristics of rock types (Table 2, Table 3 and Table 4) and to make normative calculations (Table 5, Table 6 and Table 7).
The geochemical data of the SBO pegmatites samples show a wide range of major elements with silica (SiO2) contents ranging from 69.47 to 80.21 wt%. Al2O3 contents are generally high, ranging from 12.04 to 19.45 wt%; on the other hand, the other oxides are lower at Na2O ≤ 5.76; K2O ≤ 5.27 wt%; Fe2O3 ≤ 5.53, FeO ≤ 4.98 wt%; MgO ≤ 2.33 and TiO2 ≤ 0.77 wt%, CaO ≤ 3.86%, MnO ≤ 0.22 wt%, P2O5 ≤ 0.89 wt%. The Loss On Ignition (L.O.I.) shows values between 0.22 and 3.57 wt%. As far as the minor and trace elements analyzed from the pegmatite, Sr ranges between 38 and 164 ppm. The compatible elements show low to high concentrations, ranging from 0 to 25.50 ppm for Ni and from 25 to 231 ppm for Cr. In most samples, the low concentrations of these compatible elements suggest that the materials that formed the pegmatite are probably derived from a depleted source [47].
Zr values range from 6 to 66 ppm and are related to the accessory zircon, which is the main mineral phase in which this element is concentrated. Ba concentration varies from 9 to 551 ppm. The Ba is mainly detected in biotite and has a high affinity for potassium feldspar, in substitution to K [48]. Rb contents are relatively high, up to 1714 ppm; this element is generally incorporated in minerals such as biotite and potassium feldspar.
Furthermore, Ta and Nb contents range, respectively, from 0.8 to 4.2 ppm and 0 and 190 ppm. Li and Cs values comprise between 2.3 and 1893 ppm and 0.2 to 277 ppm, respectively. Sn values reach 415 ppm. The concentrations of Nb, Ta, Sn, and Cs are relatively high and indicate enrichment within these rocks. Li reaches the highest concentrations among trace elements. This can be explained by highly enriched sources.
The sum of the REEs concentrations of the SBO pegmatites range from 3.9 to 70 ppm, which is lower compared to the international range (250–270 ppm) of Cuney et al., 1987 [49]. The depletion of REEs has been attributed to various processes, including magmatic differentiation [50], hydrothermal leaching [51], and or a combination of both. The sum of light rare earth element (ƩLREE) and the sum of heavy rare earth element (ƩHREE) concentration values for the pegmatite samples vary within the range of 1.1–151 ppm and 0.6–13.30 ppm, respectively. Meanwhile, the La/Lu ratios range from 9 to 76. The spectra also show slight negative or positive Eu anomalies with Eu/Eu* values ranging from 0.2 to 3.2. These anomalies are related to plagioclase fractionation.
The major and minor elements are plotted into the Harker diagrams for oxides to determine their compatibility or relationship with silica. From the Harker diagram for oxides versus SiO2 (Figure 9), only Al2O3 shows a clear negative correlation with SiO2. As SiO2 increases, Al2O3, CaO, and FeOtot decrease, which would be related to tourmaline fractionation. Al2O3 and K2O decrease with increasing SiO2, which would be related to the formation of feldspars and muscovite. The dispersion of Na2O contents in the analyzed samples may be mainly related to their mobility. In fact, two groups of samples can be distinguished for the same SiO2 values, which would be related to the albite richness. The variation in P2O5 would be related to the late apatite fractionation.
On the other hand, trace elements show a strong dispersion (Figure 10). It is possible to observe a very weak negative correlation between silica and Rb, Sr, Y, and Zr; it is even less evident with Ba, Ce, La, and Ni.

5. Discussion

5.1. Geochemical Characteristics of the SBO Pegmatites

5.1.1. Major Elements

The geochemical analysis results have been plotted on a series of diagrams to determine the magmatic characteristics of SBO pegmatites. On the binary (Na2O + K2O) vs. SiO2 diagram of Middlemost et al. [51], all samples are plotted within the granite field (Figure 11a).
In the A/NK vs. A/CNK diagram [52], showing Al2O3/(Na2O + K2O) and Al2O3/(CaO + Na2O + K2O), respectively, all samples show ratios above 1, reflecting the excess of alumina over Ca, Na, and K. These rocks are therefore peraluminous (Figure 11b), and the aluminum richness is indeed reflected in the mineralogy by the presence of muscovite, together with feldspar, and tourmaline. It is also noted that excess of Al2O3 is found as a CIPW normative corundum in many pegmatite samples up to 12.8 wt% (Table 4).
The AFM diagram after Irvine [53], shows calc-alkaline series for SBO pegmatites (Figure 11c).
On the other hand, peraluminous granitic rocks, characterized by high Al contents relative to K, Na, and Ca, are assumed to be derived from the melting of supra-crustal metasedimentary rocks [53]. For Wilson [54] the peraluminous granites contain crustal or sedimentary material in their magma of origin. This result agrees with the results of the Al2O3/CaO + Na2O + K2O versus SiO2 diagram [55], to differentiate between S-type and I-type granites. The SBO pegmatites plot within the S-type granite field (Figure 11d). This type of granitoid implies that the parent magma (from which the pegmatites were formed) contained a large amount of sedimentary or crustal material. This suggests that the SBO pegmatites are derived from the partial melting of the Paleozoic metasedimentary rocks, even though a Precambrian source (not cropping out) is not excluded [23].
Geosciences 14 00144 g011
Figure 11. (a) Classification diagrams of (SBO) pegmatite TAS diagram (Total Alkalis versus Silica after Middlemost et al. [51]; (b) classification diagrams. A/NK versus A/CNK diagram after Maniar et al. [52]; (c) AFM diagram after Irvine et al. [53]; (d) classification diagrams. Al2O3/CaO + Na2O + K2O versus SiO2 after White et al. and Chappell et al. [56,57] (e) SBO pegmatite plotted in the Rb-Ba-Sr ternary diagram, after El Bouseily et al. [58].
Figure 11. (a) Classification diagrams of (SBO) pegmatite TAS diagram (Total Alkalis versus Silica after Middlemost et al. [51]; (b) classification diagrams. A/NK versus A/CNK diagram after Maniar et al. [52]; (c) AFM diagram after Irvine et al. [53]; (d) classification diagrams. Al2O3/CaO + Na2O + K2O versus SiO2 after White et al. and Chappell et al. [56,57] (e) SBO pegmatite plotted in the Rb-Ba-Sr ternary diagram, after El Bouseily et al. [58].
Geosciences 14 00144 g011

5.1.2. Minor and Trace Elements

As far as the minor and trace elements, Rb, Sr, and Ba have been plotted in the ternary diagram Rb-Sr-Ba proposed by El Bouseily et al. [58], revealing that the SBO pegmatites occupy the field of strongly differentiated granites (Figure 11e). Some samples also show a relative enrichment in Sr compared to their Ba content. According to El Bouseily et al. [58], Rb, Sr, Ba are monitors of the degree of magmatic differentiation.
In the geodynamic diagram, Rb vs. Nb + Y (proposed by Pearce et al. [59]), pegmatites are plotted in syn-collisional granite, with an exception for volcanic-arc granites (VAG) and within-plate granites (WPG) (Figure 12a). This finding aligns with the Nb vs. Y diagram results after Pearce et al. [59] and Pearce [60], as shown in Figure 12b. There are some deviations observed for within-plate granites (WPG). Similarly, the Rb vs. Yb + Ta diagram shows that all samples are categorized as syn-collisional granite, with a few exceptions being classified as volcanic-arc granites (VAG), as illustrated in (Figure 12c). Additionally, the Ta vs. Yb diagram, following Pearce et al. [58], and the Rb vs. Y/Nb diagram by Pearce et al. [60], further support that all samples have a syn-collisional granite affinity, as demonstrated in Figure 12d.
In the diagram after Batchelor et al. [61] (R1 = 4Si-11(Na + K)-2(Fe + Ti) versus R2 = 6Ca + 2Mg + Al), the SBO pegmatites fall in syn-collisional to post-orogenic for the granite pegmatite field (Figure 12) in syn- collisional (Figure 13).
The trace element data related to SBO pegmatites samples have been normalized to the upper crust [63]. The multielement diagram (Figure 13) shows strong to moderate positive anomalies in Rb, U, Sr, Sm, and Tm. They sometimes indicate a slight negative anomaly in Nb, Ce, Nd, Zr, and Ti. The negative Nb anomaly represents the role played by magmatic contamination from the continental crust in developing the regional rocks. Negative Nb anomalies are typical of continental crust, while negative Nb and Zr anomalies indicate a calc-alkaline affinity [64].
Negative Ce anomalies are typical of certain orogenic rocks, which Hole et al. [63] and White et al. [64] attribute to an imprint of subducted sediments. However, the quantitative aspect seems to restrict this hypothesis. Ben Othman et al. [65] suggest that the relative Ce deficiency in some orogenic rocks may reflect the specific behavior of this element concerning other REEs during the fluid−rock interactions that take place at subduction zones.
Negative Nb-Ta anomalies and the relative deficit of Nb and Ta compared to light REEs are typical features of rocks associated with subduction zones [65,66]. Some authors attribute this Nb and Ta deficit to selective trapping of these elements by stable titanium mineral phases in the hydrated, high-pressure, high-temperature conditions prevailing at subduction zones [66,67,68,69].
Contrary to a widely held view in the literature, Zr and Hf elements do not show a systematic deficit concerning REEs in orogenic rocks [66]. In this type of representation, positive Zr and Hf anomalies are expressed by ordinate values greater than 1, while negative anomalies are expressed by values less than 1. Thus, orogenic rocks do indeed show both positive and negative Zr and Hf anomalies. In the SBO pegmatite spider diagram, Zr and Hf display negative anomalies.
The spider diagram of the SBO pegmatites shows a good correlation with the patterns for the collision granites calcalkaline type [59]. Some distinctive characteristics are the high contents of Rb in many of the patterns from the syn-collision granites and the very low contents of Ce and Zr.
The REEs of the SBO pegmatites were normalized to the chondrites of McDonough et al. [70]. The similarity of the rare-earth pattern of the multielement (Figure 14b) suggests a common source for their magmas. The patterns show a relatively weak enrichment in LREEs compared to HREEs. They sometimes show a negative Eu anomaly; at other times, they show a positive Eu anomaly. The pattern of REE spectra agrees with the petrographic observations; for example, the presence of plagioclases is expressed on the REEs spectra with a positive Eu anomaly. The samples show an average enrichment in LREEs. The patterns highlight a good correlation between the REEs distribution and the Eu anomaly. Thus, samples with a positive Eu anomaly have a slightly higher REE concentration.

5.2. Hydrothermal Alteration and Metasomatism

In addition to providing information on the physicochemical conditions of the system, the distribution of trace elements and EARs in the SBO pegmatites revealed important information on the rock/fluid interaction (Figure 15). Due to the dissolution or replacement of primary and accessory minerals and the consequent development of new mineral phases, virtually all trace elements were mobilized during hydrothermal alteration, and the petrographic study indeed confirms these changes. Moreover, the different types of hydrothermal alteration that affected these pegmatites can also be characterized using several geochemical diagrams proposed in the literature. The diagram of Stemprok [71] using the normative composition Qz-Ab-Or allows us to determine the sodic, potassic, silicic, and greisen alterations. The pegmatite samples are distributed in fields indicating silicification and greisinization, respectively (Figure 15).
These results are confirmed by microscopic observations where the occurrence of quartz and the quartz−muscovite association from the transformation of minerals of the primary paragenesis is evident. However, additional samples display considerable Na2O levels and tend to albite composition. Albitization occurs during sodium metasomatism when Na+ substitutes for K+ and Ca2+ in pre-existing feldspars. The silicification leads to an increase in SiO2 at the expense of the other major oxides and is followed by an increase in a few trace elements, including Zr, Ba, and Rb. The K2O vs. Na2O diagram of Cuney et al. [48] shows that these pegmatites are affected by mainly clay sodic and potassic alterations (Figure 15c).
Moreover, the argillic alteration is the most dominant and marked (Figure 15b) according to the ternary diagrams Al2O3 − (Na2O + CaO) − K2O and Al2O3 − (Na2O + K2O) − (Fe2O3t + MnO + MgO) and of Meyer and at., [73].
The action of hydrothermal fluids was intense and generalized to all the pegmatitic bodies as suggested by Fransolet [12] and confirmed by Fontan [23].

5.3. Classification

The current schemes used to classify pegmatites are varied as well as numerous. Several authors have proposed different classification schemes based on the typical and auxiliary minerals of the pegmatite, on the P-T conditions of its emplacement, and, more recently, on its geochemistry [23,26,74,75]. However, the classification of pegmatites by Ginsburg et al. [76] has had a significant influence on contemporary methods of pegmatite classification. This classification groups the pegmatites according to their depth of emplacement, association with metamorphism, and relationship to granitic plutons. The currently used taxonomy of pegmatites has the support of researchers and is known as the revision of Černy [77,78]. Its classification is based on a combination of minor element concentration and metamorphic grade at depth of emplacement. The four main classes or types are identified as follows: (1) Abysal (AB) is the high-grade temperature (700–800 °C), high to low pressure (4–9 kbar) and depth ≥ 11 km; (2) Muscovite (MSC) is a lower temperature (580–650 °C) high pressure (5–8 kbar) and depth (7–11 km); (3) Rare-Element (REL) is a low temperature (500–650 °C) and pressure (2–4 kbar) and depth (3.5–7 km); (4) Miarolitic (MI) is a shallow level 500–650 °C at low temperature (≤500 °C) and pressure (1–2 kbar) and depth (1.5–3.5 km).
The SBO pegmatite study highlights that these rocks are essentially composed of large crystals of feldspar, quartz, muscovite and (occasionally) tourmaline. They are hosted exclusively in schists, and no outcrops of granite have been observed in this area. Moreover, the geochemical results of these rocks indicate that they do not present any significant enrichment and that they are poor in REEs; however, on the other hand, they are quite famous for their content in ceramic minerals [20]. These characteristics allow us to classify the SBO pegmatites in the class of muscovite pegmatites. According to Černy [77], the latter are rarely mineralized but can produce feldspars and muscovite. They are of metamorphic origin, characterized by high-pressure metamorphism, hosted in almandine and kyanite schists, and they may contain Th, U, Nb, Ta, Zr, Ti [7,78]. Direct anatexis is thought to be the origin of first-drop rare-element mineralised pegmatites [79] and could also explain the diversity of magmatic fractionation observed in each type of pegmatite [79]. The crustal anatexis model was suggested in the 1970s [80,81,82,83,84] to justify the extent of pegmatite fields compared with that of granitic plutons [85]. It has also been used to justify (i) the absence of granite related to LCT pegmatite fields, (ii) the diachronism between granites and pegmatites [85], and (iii) the lack of continuity of magmatic fractionation between granites and the most differentiated pegmatites [86,87]. Furthermore, the diversity of mineralization and geochemical signatures associated with the pegmatite complex is mainly linked to the P-T conditions of regional metamorphism rather than to the fractional crystallization of granitic bodies during their crystallization [88].

5.4. Origin of SBO Pegmatites

The most widely accepted model for the genesis of pegmatites in the 1970s and 1980s was fractional crystallization of a granitic fluid. However, it is becoming accepted that they can be formed by metamorphic rock anatexis [88]. Considering the different models proposed that simplify the formation and mineralization of pegmatites, the following two final models have been proposed for pegmatite formation: the continuous crystallization and the fractional dissolution [89].
According to Shmakin et al. [90], Gorlov [91], and Sokolov et al. [92], pegmatites of the muscovite class are produced directly by partial melting or by a very limited level of differentiation of anchiautochthonic palingenitic granites [78,92,93,94]. This suggests that SBO pegmatites resulted from the partial melting of the argillaceous metasedimentary rock of Sarhlef shist during Varsican subduction and shortening. This corroborates the geodynamic models proposed to explain the evolution of the Meseta from Upper Devonian to Lower Permian. The eastward subduction of the Rheic Ocean, leading to the formation of fore- and back-arc basins in the Mesetian block between the 420 and 330 Ma models [40,95,96], corroborates the Evolution model of the Meseta during the Carboniferous proposed by Essaifi et al. [97], which involves westward subduction followed by a slab breakoff, leading to upwelling of hot asthenospheric currents and eroding the litho-sphere.

6. Conclusions and Final Remarks

The SBO Variscan pegmatite crop out as dykes mainly oriented N30° (N-S to NNE-SSW) with sub-vertical dip. The field investigations show that E-W dykes are secant on NS pegmatite dykes. Their thicknesses vary from centimeters to meters (30 cm to 8 m), and they have extensions ranging from 1 m to 500 m. These dykes underwent a deformation presented on the ground by boudinage, and strike-slip faults shifted their architectures.
SBO pegmatites are observed within the metamorphic rocks of the Sarlef series. They are clearly delimited bodies, which are mainly zoned and rarely homogeneous. They are never isolated; rather, they are in a group of several dykes which are organized in clusters. SBO pegmatites show clearly tectonic control and are syn- or tardi-orogenic, have a calco-alkalic affinity, and are composed of S-type granite. Using the mineralogy and the geochemistry, these pegmatites fall into a very strongly differentiated granite field. Their geochemical features are compatible with their petrographic and mineralogical characteristics. They are mainly constituted by quartz, albite, muscovite, and tourmaline, with minor amounts of microcline and illite and accessories such as garnet, apatite, and zircon. These characteristics allow us to classify the SBO pegmatites in the class of muscovite pegmatites. The classification of the SBO pegmatites within this class indicates that they do not present any significant enrichment in REEs. They are probably the products of the partial melting of pelitic metasedimentary rock of Sarhlef during Varsican shortening between 330 and 280–275 Ma, even though a contribution of older formations is not excluded.
Finally, in the frame of the shift to green technologies, it is worth noting that, apart from some accessory minerals of interest that are hosted in pegmatite-type deposits, some main occurring minerals, such as feldspars and quartz, are increasingly required for the production and storage of renewable (green) energy to supply the green and sustainable societies of the future [88]. For instance, feldspars have been recently assessed by the European Commission as being critical raw materials (CRMs) (https://single-market-economy.ec.europa.eu/publications/study-critical-raw-materials-eu-2023-final-report_en (accessed on 31 October 2023)).
Therefore, in the frame of the current global trend, the SBO pegmatite may constitute an important resource to be considered in greater detail.

Author Contributions

Conceptualization, A.W.; methodology, A.W.; software, N.E.A., Y.M. and M.C.; validation, A.W., Y.M. and M.C.; formal analysis, A.W.; investigation, A.W., M.C. and W.A.S.; resources, A.W.; data curation, A.W., M.C. and W.A.S.; writing—original draft preparation, A.W., Y.M., R.P., D.G. and A.M.C.; writing—review and editing, A.W., R.P., D.G. and A.M.C.; visualization, A.W.; supervision, A.W.; project administration, A.W.; funding acquisition, Y.D. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The data is included in the article.

Acknowledgments

We acknowledge Reminex, Managem Group for ICP-MS analysis.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. (a) Localization of the Jebilet Massif in the Variscan of Morocco; (b) geological context of the Variscan Jebilet Massif, showing the location of the SBO study area (modified from Huvelin) [28]; (c) synthetic lithostratigraphic column of the SBO area in the Jebilet Massif modified after Bordonaro [30], Delchini [26], Lazreq et al. [29].
Figure 1. (a) Localization of the Jebilet Massif in the Variscan of Morocco; (b) geological context of the Variscan Jebilet Massif, showing the location of the SBO study area (modified from Huvelin) [28]; (c) synthetic lithostratigraphic column of the SBO area in the Jebilet Massif modified after Bordonaro [30], Delchini [26], Lazreq et al. [29].
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Figure 2. Simplified geological map showing the distribution of the pegmatites within the Sidi Bou Othmane area.
Figure 2. Simplified geological map showing the distribution of the pegmatites within the Sidi Bou Othmane area.
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Figure 3. (a) The host rock shows alternating between metapelite and sandstone; (b) the calcareous levels at the top (S0 is stratification and S1 is schistosity).
Figure 3. (a) The host rock shows alternating between metapelite and sandstone; (b) the calcareous levels at the top (S0 is stratification and S1 is schistosity).
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Figure 4. The mineralogy of a pegmatite vein (A) with tourmaline (Turm), quartz (QZ) and feldspar (Fld); (B) with muscovite (Ms), quartz (QZ) and K-feldspar (K-Fld).
Figure 4. The mineralogy of a pegmatite vein (A) with tourmaline (Turm), quartz (QZ) and feldspar (Fld); (B) with muscovite (Ms), quartz (QZ) and K-feldspar (K-Fld).
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Figure 5. Field picture shows the zonation that has been observed in the pegmatite in SBO area.
Figure 5. Field picture shows the zonation that has been observed in the pegmatite in SBO area.
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Figure 6. Structural features measured at the scale of (a) the outcrop directional rose diagram of the schistosity and (b) the pole dip of fold stereoplot.
Figure 6. Structural features measured at the scale of (a) the outcrop directional rose diagram of the schistosity and (b) the pole dip of fold stereoplot.
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Figure 7. Field pictures showing (a) S1 schistosity folding, (b,c) boudinaged pegmatite dykes, (d) diaclases; (e) pegmatite boudinaged dike, (f) tension jointsin a pegmatite dyke (P: Pegmatite; S1: Schistosity).
Figure 7. Field pictures showing (a) S1 schistosity folding, (b,c) boudinaged pegmatite dykes, (d) diaclases; (e) pegmatite boudinaged dike, (f) tension jointsin a pegmatite dyke (P: Pegmatite; S1: Schistosity).
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Figure 8. Photomicrographs showing (A) large muscovite (Ms), albite (Ab) and quartz (Qz) crystals, garnet (Gr) and zircon (Zr); (B) large quartz with tourmaline (Tur); (C,D) sheared area with plagioclase (Pl), quartz (Qz) and muscovite (Ms); (E,F) large patches of cataclastic plagioclase (Pl) (albite Ab) with and quartz (Qz), and muscovite (Ms).
Figure 8. Photomicrographs showing (A) large muscovite (Ms), albite (Ab) and quartz (Qz) crystals, garnet (Gr) and zircon (Zr); (B) large quartz with tourmaline (Tur); (C,D) sheared area with plagioclase (Pl), quartz (Qz) and muscovite (Ms); (E,F) large patches of cataclastic plagioclase (Pl) (albite Ab) with and quartz (Qz), and muscovite (Ms).
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Figure 9. Binary variation diagrams showing major elements versus SiO2 (wt%) of SBO pegmatites.
Figure 9. Binary variation diagrams showing major elements versus SiO2 (wt%) of SBO pegmatites.
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Figure 10. Binary variation diagrams showing trace elements versus SiO2 (wt%) of SBO pegmatites.
Figure 10. Binary variation diagrams showing trace elements versus SiO2 (wt%) of SBO pegmatites.
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Figure 12. Tectonic discrimination diagrams for SBO pegmatites compositions. (a) Rb vs. Y+ Nb diagram; (b) Nb vs. Y diagram, after Pearce et al. [59] and Pearce [60]; (c) Rb versus Yb + Ta; (d) Ta versus Yb, after Pearce et al. [58]. Tectonic fields are ocean-ridge granites (ORG); syn-collisional granites (syn-COLG); volcanic-arc granites (VAG) and within-plate granites (WPG). The SBO pegmatites show syn-collisional granite affinity.
Figure 12. Tectonic discrimination diagrams for SBO pegmatites compositions. (a) Rb vs. Y+ Nb diagram; (b) Nb vs. Y diagram, after Pearce et al. [59] and Pearce [60]; (c) Rb versus Yb + Ta; (d) Ta versus Yb, after Pearce et al. [58]. Tectonic fields are ocean-ridge granites (ORG); syn-collisional granites (syn-COLG); volcanic-arc granites (VAG) and within-plate granites (WPG). The SBO pegmatites show syn-collisional granite affinity.
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Figure 13. Discrimination geodynamic diagram [59,62] R1 = 4Si-11 (Na + K) −2(Fe + Ti) versus R2 = 6Ca + 2Mg + Al. The SBO pegmatites show syn-collisional and post-orogenic affinity.
Figure 13. Discrimination geodynamic diagram [59,62] R1 = 4Si-11 (Na + K) −2(Fe + Ti) versus R2 = 6Ca + 2Mg + Al. The SBO pegmatites show syn-collisional and post-orogenic affinity.
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Figure 14. Multielement spider and REEs normalization diagrams explaining magma source and differentiation: (a) Upper Continental Crust spider plot normalized and (b) REE chondrite spider plot after McDonough et al. [70].
Figure 14. Multielement spider and REEs normalization diagrams explaining magma source and differentiation: (a) Upper Continental Crust spider plot normalized and (b) REE chondrite spider plot after McDonough et al. [70].
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Figure 15. (a) Ternary diagrams showing Normative Qz-Ab-Or ternary diagram [71]; (b) bivariate K2O − Na2O variation diagram [49]; (c) Al2O3 − (Na2O + K2O) − (Fe2O3 t +MnO + MgO) ternary diagram showing alteration type [72].
Figure 15. (a) Ternary diagrams showing Normative Qz-Ab-Or ternary diagram [71]; (b) bivariate K2O − Na2O variation diagram [49]; (c) Al2O3 − (Na2O + K2O) − (Fe2O3 t +MnO + MgO) ternary diagram showing alteration type [72].
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Table 1. Sampling database reporting, for each selected rock specimen, the mineralogical content and the average grain size.
Table 1. Sampling database reporting, for each selected rock specimen, the mineralogical content and the average grain size.
Sample ReferencesMineralogical Content (Accessory Minerals)Grain Size
SBO.01Quartz, Muscovite, Feldspar (apatite, zircon)<3.5 cm
SBO.02Quartz, Muscovite, Feldspar (apatite, zircon)<1.5 cm
SBO.03Quartz, Muscovite, Feldspar (apatite, zircon)<1 cm
SBO.04Quartz, Feldspar, Tourmaline, Muscovite (apatite, zircon)1–3 cm
SBO.05Quartz, Feldspar, Muscovite (apatite, zircon)0.5 cm–3.5 cm
SBO.06Quartz, Feldspar, Muscovite (apatite, zircon)1–3 cm
SBO.07Quartz, Feldspar, Muscovite (apatite, zircon)<0.5 cm
SBO.08Quartz, Feldspar, Tourmaline, Muscovite (apatite, zircon)<4.5 cm
SBO.09Quartz, Feldspar, Muscovite, Tourmaline (apatite, zircon)<1.5 cm
SBO.10Quartz, Muscovite, Feldspar (apatite, zircon)<2.5 cm
SBO.11Quartz, Muscovite, Feldspar (apatite, zircon)0.5–1.5 cm
SBO.12Quartz, Feldspar, Muscovite (apatite, zircon)<3 cm
SBO.13Muscovite, Feldspar, Quartz (apatite, zircon)<1.5 cm
SBO.14Quartz, Feldspar, Muscovite, Tourmaline (apatite, zircon)0.5–3.5 cm
SBO.15Quartz, Muscovite, Feldspar, Tourmaline (apatite, zircon)1–5 cm
SBO.16Quartz, Feldspar, Muscovite, Tourmaline (apatite, zircon)2–4.5 cm
SBO.17Quartz, Muscovite, Feldspar, Tourmaline (apatite, zircon)2–10 cm
SBO.18Quartz, Feldspar, Muscovite (apatite, zircon)1–4.5 cm
SBO.19Quartz, Muscovite (apatite, zircon)<2.5 cm
SBO.20Quartz, Feldspar, Muscovite (apatite, zircon)<3 cm
SBO.21Quartz, Feldspar, Muscovite (apatite, zircon)<2.5
SBO.22Quartz, Feldspar, Muscovite (apatite, zircon)<3 cm
SBO.23Quartz, Muscovite, Feldspar (apatite, zircon)<1.5 cm
SBO.24Quartz, Feldspar, Muscovite (apatite, zircon)<0.3 cm
SBO.25Feldspar, Muscovite, Quartz (apatite, zircon)<0.9 cm
Table 2. Major elements (wt%) of SBO pegmatite dykes. b.d.: Below detection limits.
Table 2. Major elements (wt%) of SBO pegmatite dykes. b.d.: Below detection limits.
SampleSiO2Al2O3Fe2O3FeOtotCaOMgOK2OMnOTiO2P2O5Na2OSO3
SBO-0177.0414.30.480.4320.25b.d.2.130.030.010.194.050.61
SBO-0274.8414.840.370.333<0.10b.d.1.970.040.010.625.640.57
SBO-0373.0515.520.880.7920.740.103.90.070.010.583.740.63
SBO-0478.9413.31.261.1340.290.1220.050.020.132.050.63
SBO-0577.5214.030.740.6660.27b.d.3.70.030.010.160.900.65
SBO-0672.5116.110.990.8910.72b.d.3.770.070.010.603.820.62
SBO-0774.0616.24<0.10b.d0.21b.d.1.30.020.010.146.630.63
SBO-0874.8415.720.750.6750.53b.d.3.550.170.020.360.960.60
SBO-0975.4115.250.950.8550.50b.d.3.520.140.020.290.440.60
SBO-1076.4714.081.020.9180.540.13.830.070.040.360.160.62
SBO-1172.8215.630.340.3060.73b.d.3.230.100.010.765.100.69
SBO-1273.616.510.50.450.29b.d.5.270.030.010.230.240.61
SBO-1371.0919.45<0.10b.d0.33b.d.4.960.020.010.150.330.68
SBO-1473.5717.460.230.2070.18b.d.4.500.020.010.120.550.70
SBO-1577.0713.940.220.1980.3b.d.0.710.030.010.385.760.62
SBO-1674.9714.080.60.541.27b.d.1.930.140.010.894.230.62
SBO-1769.9118.710.970.8731.140.163.970.030.070.80.420.63
SBO-1872.0417.450.390.3510.70b.d.2.520.070.020.593.730.60
SBO-1972.617.930.70.630.37b.d4.000.040.020.230.720.64
SBO-2074.7914.680.820.7380.62b.d2.040.220.010.884.260.66
SBO-2180.2112.040.640.5760.49v0.420.180.010.214.940.61
SBO-2274.8314.664.213.7890.460.100.350.090.030.253.840.71
SBO-2369.4718.291.391.2511.110.633.120.080.220.410.360.51
SBO-2474.4716.062.352.1150.430.230.810.050.030.204.410.65
SBO-2574.0515.91.621.4580.56b.d1.780.050.010.244.020.61
SBO-2676.0115.591.161.0440.31b.d1.380.040.010.214.110.63
Table 3. Minor, minor trace, and rare earth elements of SBO pegmatite dykes. Contents are expressed as ppm., n.d. = not detected.
Table 3. Minor, minor trace, and rare earth elements of SBO pegmatite dykes. Contents are expressed as ppm., n.d. = not detected.
SampleTiKAsPBaBeBiCdCoCrCuLiMoNbNiPbRbSbScSeSn
SBO-0159.95145172829.1629.36.315.84.8n.d.108.39.31436.114.66.7n.d.333.331.37n.d.22.7
SBO-0259.95142872705.6822.710.414.11.9n.d.355.698.7n.d.37.8n.d.n.d.359.92.25.7n.d.44.3
SBO-0359.95183932531.12101.85.412.22.3n.d.1166.4141.71.944.11.1n.d.759.510.55.9n.d.28
SBO-04119.9024277567.3217.14.34.50.9n.d.57.97130.6n.d.n.d.11.5n.d.338.5n.d.6.2n.d.27
SBO-0559.9517974698.2435.56.4201.9n.d.176.68208.91.346.7<0.1n.d.1201n.d.5.2n.d.107.4
SBO-0659.951801012618.492.15.218.52.8n.d.111.34.7128.4n.d.43.7n.d.n.d.716.6n.d.5.62.927.9
SBO-0759.9512887610.9624.85.515.41.247.390.49.3193.44.53.79.5n.d.44654.64.431.4
SBO-08119.90275571571.0458.74.622.21.5n.d.39.23.5170.53.8n.d.2.4n.d.408.71.46.6n.d.27.1
SBO-09119.90275461265.5634.73.9n.d.1.7n.d.174.25.1155.1n.d.12.110.8n.d.435.99.77.1n.d.24.3
SBO-10239.80481621571.0451.13.6n.d.2.6n.d.48.25.7191.6n.d.9.8<0.1n.d.471.114.27.5n.d.41.5
SBO-1159.951692053316.6413.46.8n.d.5n.d.38.56.9140.47.120.89.8n.d.847.4n.d.5.6n.d.14.2
SBO-1259.951112721003.72151.97.820.61.6n.d.374.3 2.844.23.7n.d.868.210.55.2n.d.50.4
SBO-1359.951105209654.633.2818.55.9200.383.78.7153.77.249.619n.d.1571<0.14<0.1102.6
SBO-1459.95196201523.6846.74.913.85.217.2158.68.339.4n.d.74.616.9n.d.1466n.d.40.971.2
SBO-1559.951151091658.3222.73.321.52.1n.d.164.2819.310.719010.216.7272.816.74.8n.d.19.8
SBO-1659.951411153883.9626.98.60.92.9n.d.34.37.6247.92.636.19.3n.d.70056.2551.4
SBO-17419.65784463491.2154.33.9n.d.0.6n.d.50.16.4119.31.333.420.9n.d.585.81.94.83.962.9
SBO-18119.90254652574.7646.97.99.51n.d.132.83.438.81.28.525.5n.d.385.2n.d.3.6n.d.26.5
SBO-19119.90285661003.7283.99.4n.d.2.5n.d.504.271.2n.d.35.20.2n.d.842.521.15.2n.d.41.6
SBO-2059.95143423840.3216.54.513.53.9n.d.38.74.1141.7n.d.21.71.17.7716.612.15.9n.d.22.4
SBO-2159.9519112916.44103.8n.d.2.5n.d.145.13.316.9n.d.n.d.16.4n.d.28.615.16.621.40.6
SBO-22179.8537345109120.83.618.38.9n.d.231.111.544.3 13.7n.d.11.8n.d.72.4n.d.5.9n.d.6
SBO-231.318.922661381789.24551.510n.d.2.7n.d.59.38.218931.14812.2n.d.171439.614.5415.7
SBO-24179.85317122872.818.63.3212.9n.d.206.823.636.30.7<0.118.7n.d.84.99n.d.6.1n.d.2.5
SBO-2559.951381211047.3612.73.7112.945.851.97.674.75.47.319.7n.d.248.416.77.1n.d.16.8
SBO-2659.9512932916.449.14.516.40.5n.d.145.85.6176.64.91<0.1n.d. 9.45.2n.d.20.3
Table 4. Minor, minor trace and rare earth elements of SBO pegmatite dykes. Contents are expressed as ppm., n.d. = not detected. (continued).
Table 4. Minor, minor trace and rare earth elements of SBO pegmatite dykes. Contents are expressed as ppm., n.d. = not detected. (continued).
SampleSnSrThUVYZnZrLaCePrNdSmEuGdTbDyHoErTmYbLuPFCl
SBO-0122.751.40.51.12.10.649.69.111.30.30.80.60.10.400.20.10.10.10.10.10.96465.3
SBO-0244.385.31.3430.839.417.71.21.90.30.90.700.500.30.10.10.10.10.11.01310.2
SBO-0328135.71.31.53269.213.71.11.80.41.60.90.30.80.10.50.10.20.10.20.10.93443.1
SBO-042739.80.70.55.70.836.89.411.50.30.80.600.500.20.10.20.10.10.11.08819.8
SBO-05107.490.80.81.21.30.938.311.41.21.20.30.90.70.10.60.10.50.10.20.10.10.11.49886.3
SBO-0627.9126.51.31.62.51.96212.71.12.10.41.60.90.30.80.10.70.10.20.10.20.10.82576.1
SBO-0731.450.70.50.11.70.519.16.20.80.90.20.70.60.10.400.20.10.10.10.10.10.72310.2
SBO-0827.150.41.85.14.2532.9171.73.50.61.810.20.90.210.20.50.20.70.11.64731.2
SBO-0924.3440.81.64.11.939.111.91.12.10.41.10.70.20.60.10.50.10.30.10.30.11.94775.5
SBO-1041.544.71.43.53.93.549.317.91.63.10.51.60.90.10.80.10.70.20.40.20.60.11.76753.3
SBO-1114.21310.71.63.20.859.215.80.91.10.30.70.60.10.500.20.10.10.10.10.10.67421
SBO-1250.453.40.81.52.80.930.417.711.40.30.80.60.20.500.30.10.20.10.10.12.36531.8
SBO-13102.648.60.51.35.10.759.566.80.910.20.70.60.10.400.20.10.10.10.10.12.47265.9
SBO-1471.266.80.61.73.20.714.837.50.70.60.20.60.60.10.400.20.10.10.10.10.12.31332.3
SBO-1519.880.33.31.60.82.62213.71.43.10.52.11.10.210.10.70.10.30.10.20.10.66841.9
SBO-1651.486.21.12.52.83.9109.615.42.33.70.62.61.40.91.50.20.80.10.30.10.20.11.54398.8
SBO-1762.975.91.21.314.12.625.710.62.95.80.831.10.70.90.10.60.20.40.10.30.12.34797.6
SBO-1826.594.73.63.35.45.924.413.62.23.80.62.31.50.31.60.31.60.20.40.10.30.11.74841.9
SBO-1941.652.71.70.83.91.325.78.71.21.50.310.70.20.60.10.40.10.20.10.10.12.07598.2
SBO-2022.4116.81.110.92.21.2206.8250.91.10.30.80.600.500.30.10.20.10.20.10.9288
SBO-210.638.11.39.2<0.15.61420.324.10.61.9100.90.110.30.60.21.10.20.22310.2
SBO-22669.31.52.75.82.5117.417.51.52.30.41.30.90.10.70.10.60.10.30.10.40.10.39332.3
SBO-23415.7164.35.51.363.98.7107.233.115.2293.412.52.61.22.50.31.80.410.20.90.23.57398.8
SBO-242.540.50.81.23.21.766.918.21.630.51.50.80.10.60.10.30.10.20.10.30.10.4310.2
SBO-2516.850.73.72.26.31.352.915.91.55.30.51.610.10.70.10.40.10.20.10.40.11.12709
SBO-2620.348.11.10.51.40.841.57.70.81.30.20.70.600.500.20.10.10.10.10.10.76753.3
Table 5. CIPW norm Holacher calculation for Sidi Bou Othmane pegmatites.
Table 5. CIPW norm Holacher calculation for Sidi Bou Othmane pegmatites.
Minerals Weight %SBO-01SBO-02SBO-03SBO-04SBO-05SBO-06SBO-07SBO-08SBO-09SBO-10SBO-11SBO-12SBO-13SBO-14
Quartz52.0954.3833.7752.4245.2245.6953.2351.7836.4538.8436.3633.2444.6947.60
Plagioclase0.000.2038.6328.5232.2435.360.0038.8643.9927.5231.3052.1331.7233.06
Orthoclase29.3129.3119.092.0711.4112.5931.142.4811.6423.0518.447.6812.064.79
Corundum14.0812.034.628.625.634.2410.813.854.165.958.314.676.278.76
Hypersthene0.020.200.283.600.730.410.440.841.350.800.920.111.072.30
Ilmenite0.020.020.020.060.020.020.020.020.020.020.420.040.020.06
Magnetite0.000.330.496.100.870.700.720.930.541.152.020.001.193.41
Apatite0.350.281.760.582.060.440.530.491.441.340.950.322.040.46
Zircon0.010.010.000.000.000.000.000.000.000.000.000.000.000.00
Chromite0.000.030.010.040.010.030.010.030.010.030.010.010.010.01
Anhydrite1.160.000.000.000.000.000.000.000.000.000.000.000.000.00
Na2SO40.001.241.221.261.101.081.081.081.011.120.901.121.171.15
Total97.0498.0399.89103.2799.29100.5697.98100.36100.6199.8299.6399.32100.24101.60
Fe3+/(Total Fe) in rock0.049.649.750.050.050.150.049.836.549.050.00.049.949.9
Ca/(Ca + Na) in rock100.015.37.36.214.214.840.05.20.00.014.11.77.40.6
Ca/(Ca + Na) in plagioclase0.065.20.02.21.513.70.02.60.00.09.10.30.00.0
Differentiation Index81.483.991.583.088.993.684.493.192.189.486.193.188.585.5
Calculated density. g/cc2.762.742.682.842.712.692.742.692.692.702.752.672.722.79
Calculated liquid density2.372.362.362.442.372.362.362.352.362.372.412.362.372.40
Calculated viscosity. dry12.412.810.29.911.712.212.813.811.010.89.110.811.510.6
Calculated viscosity. wet9.08.97.37.37.98.38.98.67.77.77.17.77.97.7
Estimated liquidus temp.783755791802746726750665755779853763755784
Estimated H2O content4.134.454.043.914.534.764.495.434.424.173.324.344.434.10
Table 6. CIPW norm Holacher calculation for Sidi Bou Othmane pegmatites. (continued).
Table 6. CIPW norm Holacher calculation for Sidi Bou Othmane pegmatites. (continued).
Minerals Weight %SBO-15SBO-16SBO-17SBO-18SBO-19SBO-20SBO-21SBO-22SBO-23SBO-24SBO-25SBO-26SBO-28SBO-27
Quartz45.7047.5961.2760.6261.2543.5557.8361.1053.9043.2238.0442.0720.9597.68
Plagioclase30.6130.8413.813.680.0044.684.520.950.360.0027.7528.2639.540.00
Orthoclase10.5210.5211.8221.8722.634.2020.9820.8023.469.3523.6416.3724.290.00
Corundum7.927.638.359.259.934.4910.9411.2614.340.008.147.620.080.00
Hypersthene1.410.991.470.631.150.210.890.421.130.000.610.919.230.00
Ilmenite0.020.020.040.020.080.020.040.040.130.570.040.021.460.02
Magnetite2.351.681.831.071.480.321.091.231.410.001.011.448.020.00
Apatite0.560.490.300.370.830.880.830.671.850.000.531.390.440.09
Zircon0.000.000.000.000.000.000.000.000.000.000.000.000.010.00
Chromite0.010.030.010.040.010.030.010.040.010.000.010.030.010.00
Anhydrite0.000.000.000.000.180.000.000.300.241.060.000.000.000.00
Na2SO41.081.121.121.150.911.101.060.750.870.001.141.100.280.00
Total100.18100.91100.0298.7098.4599.4898.1997.5697.7098.56100.9199.21104.3198.16
Fe3+/(Total Fe) in rock50.050.145.849.849.949.750.260.550.150.150.050.050.00.0
Mg/(Mg + Total Fe) in rock0.00.00.00.08.80.00.00.014.10.00.00.029.40.0
Mg/(Mg + Fe2+) in rock0.00.00.00.016.20.00.00.024.70.00.00.045.50.0
Mg/(Mg + Fe2+) in silicates0.00.00.00.026.60.00.00.041.80.00.00.069.00.0
Ca/(Ca + Na) in rock5.64.07.314.265.12.823.438.660.09.45.29.444.7100.0
Ca/(Ca + Na) in plagioclase1.80.64.08.30.00.06.80.00.00.01.30.044.70.0
Differentiation IndexI would avoid this part. otherwise, we explain the software in a detailed manner86.889.086.986.283.992.483.382.977.785.789.486.784.897.7
Calculated density. g/cc2.752.732.752.742.762.682.762.762.802.732.722.732.822.65
Calculated liquid density2.392.372.362.352.372.352.372.362.402.372.382.382.532.23
Calculated viscosity. dry11.011.714.214.514.212.613.314.111.011.010.110.65.225.6
Calculated viscosity. wet7.88.19.19.39.28.39.09.38.28.07.57.74.65.9
Estimated liquidus temp.775749683691703707733713819 8117891002303
Estimated H2O content4.204.495.235.165.024.974.684.903.71 3.794.041.767.65
Table 7. CIPW norm calculation for SBO pegmatites from maximum to minimum Na2O contents.
Table 7. CIPW norm calculation for SBO pegmatites from maximum to minimum Na2O contents.
SBO-PG7SBO-PG12
Q30.567.0
A7.77.7
P56.22
F0.00.0
Total100100
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Wafik, A.; El Aouad, N.; Daafi, Y.; Morsli, Y.; Chniouar, M.; Punturo, R.; Conte, A.M.; Guglietta, D.; Aba Sidi, W. Geological and Geochemical Characterization of Variscan Pegmatites in the Sidi Bou Othmane District, Central Jebilet Province, Morocco. Geosciences 2024, 14, 144. https://doi.org/10.3390/geosciences14060144

AMA Style

Wafik A, El Aouad N, Daafi Y, Morsli Y, Chniouar M, Punturo R, Conte AM, Guglietta D, Aba Sidi W. Geological and Geochemical Characterization of Variscan Pegmatites in the Sidi Bou Othmane District, Central Jebilet Province, Morocco. Geosciences. 2024; 14(6):144. https://doi.org/10.3390/geosciences14060144

Chicago/Turabian Style

Wafik, Amina, Nouamane El Aouad, Youssef Daafi, Yousra Morsli, Marouane Chniouar, Rosalda Punturo, Aida Maria Conte, Daniela Guglietta, and Wissale Aba Sidi. 2024. "Geological and Geochemical Characterization of Variscan Pegmatites in the Sidi Bou Othmane District, Central Jebilet Province, Morocco" Geosciences 14, no. 6: 144. https://doi.org/10.3390/geosciences14060144

APA Style

Wafik, A., El Aouad, N., Daafi, Y., Morsli, Y., Chniouar, M., Punturo, R., Conte, A. M., Guglietta, D., & Aba Sidi, W. (2024). Geological and Geochemical Characterization of Variscan Pegmatites in the Sidi Bou Othmane District, Central Jebilet Province, Morocco. Geosciences, 14(6), 144. https://doi.org/10.3390/geosciences14060144

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