Gourougou stratovolcano dominates the landscape near Nador city (Figure 1 & Figure 2). This well-preserved stratovolcano and its satellites (9 - 5.4 Ma) are considered the largest volcanic complex in the northeast Morocco. The volcano is of about 12 km diameter and 900 m of elevation and consists mainly of intermediate lava flows. The massif’s central part is mostly formed by calc-alkaline and shoshonitic Miocene volcanic rocks (rhyolites, dacites and andesites) in addition to local interstratified volcanoclastic layers with basin sediments [10] and few granodioritic intrusions close to the main volcanic area (Beni Bou Ifrour). In this volcanic field, three areas were studied, Amejjaou and Selouane areas surround the Gourougou stratovolcano from the west and the south, respectively, and Terkaa area is located in the south of the volcanic complex.

Amejjaou volcanic area is located around 12 km in the west of Gourougou’s main eruptive centre (Figure 1 & Figure 3) and is crossed by the Nador-Amejjaou village national road. The rocks in both sides of the roads are strongly altered.

Selouane volcanic area is made of two small hills, located 5 km in the southeast of Selouane village, approximately 13 km south of Nador city (Figure 1). Selouane’s volcanic rocks are well preserved and very hard to break (Figure 3).

Terkaa volcanic area is located in the southeast of Gourougou’s main eruptive centre (Figure 1) and the south of the Terkaa charqiya district. It consists of a large basalt quarry (Figure 4(a)), under current exploitation. The upper volcanic level is vesicular and the vesicles are sometimes filled with marls and calcite.

In contrast to Ain Zohra volcanic complex, described in the literature [43], hardly seen in the field, Saka’s outcrops are well visible and easily accessible (Figure 4(b)). Saka volcanic outcrops are located in the north of Guercif city and northeast of the village of Saka. The volcanic area is made of a small hill crosscut by a normal fault oriented NE-SW (Figure 4(b)). The rocks are strongly altered and show great similarity with Selouane’s volcanic facies.

Tassatfacht is located south of Saka outcrop and consists of greyish basaltic rocks occurring as small blocs and volcanic scree topping the sedimentary levels below (Figure 4(c)).

Guilliz volcanic area is represented as an alignment of volcanic centres, 24 km northeast of Guercif city (located between Fez and Oujda) (Figure 1). It consists of two main volcanos (Guilliz Elkbir “big” and Guilliz Essghir “small”) and few smaller satellites.

The age and the composition of the magmatic flows of Guilliz are similar to those of Gourougou [2]; the evolution goes from more acidic term, calc-alkaline and shoshonitic composition to an under-saturated term of a younger age. The magmatic eruptions occurred within the Neogene Guercif Basin is considered as the eastern continuation of the Riffian foredeep, before getting separated by the late Neogene uplift of the diaper of Tazzeka and it overlies the Jurassic half-grabens of the Middle Atlas [31].

Guilliz Elkbir is the main massif of Guilliz volcanic area and is almost 3 km large; it consists of several felsic outcrops, frequently bearing enclaves and presents irregular forms (Figure 4(d)) and sometimes a peculiar shape of domes.

Guilliz Essghir is located in the south of Guilliz Elkbir and it consists of several basaltic flows, some of them are of a great size, while others are thinner and crosscut other volcanic rocks (Figure 4(e)).

This volcanic field crops out in a desertic zone, located in the east of Saka and Guilliz and surrounded by quaternary alluviums from the Tertiary basins (Figure 1). The closest geological units to the area are those of the eastern foreland.

Elghassoul volcanic field is presented by two facies; the first is strongly altered, has a greenish colour and exhibits different structures (pillow lava, stratification (N125), and imbrication); the second is less altered and shows no preferential structure (Figure 4(f)).

Ezzerga volcanic area outcrops mainly in the valley and is represented by pyroclastic tuffs and lava flows. The rocks are rounded, brecciated, random and compact (Figure 4(g)).

Oujda region is a collapsing ditch wedged between the Horsts chain to the south and the Beni Snassen chain to the north (Figure 1). This depression was submitted to an intense alkaline volcanic activity which ranging from the upper Neogene (6.2 Ma) to the early Quaternary (1.5 Ma). This depression with about 3.5 to 4 km of diameter is filled with volcanic and volcano-clastic formations deposited in a collapsed area 230 meters deep [44] [45]. This activity also conceals the effects of a phreatomagmatic activity, associated to typical volcanic rocks such as tephrites [6]. The four volcanic areas of Oujda studied within this work are Jorf Lakhdar, Oujda Oujda, Oued Lakram and Semara (Figure 1).

Oujda Jorf Lakhdar volcanic area is located in the northwest of Oujda city centre and the outcrop show three different volcanic levels (Figure 5). The lowest level is made of spectacular huge volcanic columns, the rocks have a greyish colour and they are well preserved (Figure 5(a) & Figure 7(b)). The second volcanic level consists of vesicular facies (Figure 5(c)), this volcanic level is generally surrounded by marls (Figure 5(d)). The third level has the same composition of the first level but the columns are smaller (Figure 5(f)).

Oujda-Oujda and Oujda Oued Lakram volcanic areas are small outcrops directly observed on the road named “La Rocade” and they exhibit a variety of structures such as cracks, fractures, breaks (Figure 6(a)), secondary alteration minerals filling (Figure 6(b) & Figure 7(c)) and spheroidal weathering (Figure 6(f) & Figure 7(g)). Oujda Oued Lakram volcanic rocks are more altered and deformed than those of Oujda Oujda’s outcrop (Figure 6(e)).

Oujda Semara volcanic area corresponds to an old basalt quarry and is located in the southwest of Oujda city. It is a big outcrop near the national road N17. It consists of three volcanic levels (Figure 7); in the middle, it takes a shape of small columns (Figure 7(a)), topped by tephrites (Figure 7(b)) and topping the lowest level, mostly massif and strongly crosscut by breaks and faults (Figures 7(c)-(e)).

In this volcanic field and as our study is focused mainly on Plio-quaternary volcanic activity, three volcanic outcrops were sampled and studied: Terkaa, Selouane and Amejjaou.

Terkaa is made for the major part of basaltic trachy-andesites (Figure 8). They are porphyric with a very fine-grained groundmass. The phenocrysts assemblage consists of Cpx (Augite) (Figures 8(a)-(c) & Figure 9(a)) + Ol (Figure 8(b)) + Amp (Oxy-Hbl) + Pl (zoned) (Figure 9(b)) + Idd (Figure 8(b)) + Mt (Figure 8(d)), with few small crysts of KF (Figure 8(a)).

Amejaou is made of basanites, basalts and trachy-andesites (Figure 8). They are generally porphyric and exhibit a phenocrysts assemblage of Bt (deformed) (Figures 8(a) & Figure 9(d)) + Amp (oxy-Hbl) (Figure 8(b)) + Pl (An = 50 - 60, Andesine, frequently zoned) (Figure 8(c) & Figure 9(e)) + KF + Cpx (fractured Aegyrinic augite and augite) (Figure 8(d) & Figure 9(c)) + Lm + Mt inclusions (Figure 8(d)). They show a fine-grained groundmass, sometimes blurry with few microliths (Figure 8).

Selouane is made of basaltic trachy-andesites. They are porphyric with a fine-grained groundmass and present a phenocrysts assemblage of Pl (zoned) + Ol + Idd + Bt + KF + Mt (Figure 8(d)).

Saka outcrop is well preserved and is mainly formed by basalts and trachy-andesites. Both facies have a porphyric microlithic texture. Microliths occupy the most of basaltic rocks’ mineral content and they generally consist of Pl (Figure 10(a)). They also exhibit a phenocryst assemblage of Cpx (Augite) and OPx (Figures 10(b)-(d)) + Ol + Idd (Figure 10(d)) + Pl (Figure 10(e)) + Mt, while the trachy-andesites show the same mineral assemblage excluding Ol and adding + KF phenocrysts.

Tassatfacht volcanic rocks consist of basanites. They are porphyric and exhibit a fine-grained groundmass. The phenocryst assemblage consists of zoned Cpx (Mg-rich) (Figure 9(f)) + Ol + Idd + Pl (Figure 10(f)) + Mt (Table 1).

Located in the North of Guercif, two different volcanic activities were recorded. The most recent activity crops out in Guilliz Essghir, while Guilliz Elkbir is mainly dominated by the older (Miocene) volcanic activity, except for few random eruptions.

Guilliz Essghir is made of alkali basalts, basaltic trachy-andesites and basanites. They are microlithic porphyric with a phenocryst assemblage of Pl (Figure 11(a)), frequently zoned (labradorite-andesine) and exhibiting different mineral inclusions (Sph + Mt + Idd) + Cpx (Figure 9(h); Figure 11(b); Figure 11(d) & Figure 11(e)) + Lim + Ol (Figure 9(I); Figure 11(c) & Figure 11(f)) + KF (Figure 11(e)), with an abundance of secondary minerals (Zeo + Cal) (Figure 11).

Guilliz Elkbir consists of trachy-andesites. They are porphyric with a fine-grained groundmass (Figure 11(a) & Figure 11(b)) and show a phenocryst assemblage of KF (zoned) (Figure 11(a) & Figure 11(c)) + Cpx (Augite and Aegyrinic Augites) (Figure 11(c) & Figure 11(d)) + Oxy-Hbl (Figure 9(k) & Figure 11(e)) + Opx (Figure 11(f)) + Lim + Mt + Cal (Figure 9(j) & Figure 11(b)).

Elghassoul and Ezzerga volcanic outcrops are made of alkali basalts. They are porphyric with a fine-grained groundmass (Figure 12(a) & Figure 12(b)). The phenocryst assemblage consists of Ol + Idd (Figure 12(a)) + Cpx (Augite) (Figure 9(g) & Figure 12(c)) + Pl (zoned) + KF + Mt + Cal + Zeo (Figure 12(d)). However, they represent some mineralogical differences: basaltic rocks of Elghassoul show phenocrysts of Opx (Figure 12(e)) and secondary minerals of zeolites and calcite, while Ezzerga basalts exhibit phenocrysts of Oxy-Hbl (Figure 12(b)) with a microlithic groundmass (Figure 12(f)).

Oujda volcanic areas considered in this study are all located in the east, northeast and northwest of the city. Jorf Lakhdar outcrop is made of basaltic trachy-andesites, basalts and basanites. Four different facies have been identified, the first level is porphyric with a fine-grained to microlithic groundmass while the other levels show only few phenocrysts with dominance of the fine-grained groundmass. The first volcanic level shows a phenocryst assemblage of Ol (Figure 13(a)) + Idd (Figure 13(b)) + Pl (Figure 13(c)) + Oxy-Hbl (Figure 9(l); Figure 9(n) & Figure 13(d)) + Cpx (Figure 9(m) & Figure 13(e)) + Mt + KF with a secondary alteration of Calcite (Figure 13(f)). The second volcanic level is rather microlithic with only KF and Mt crysts. The third volcanic level exhibits a phenocryst assemblage of rare Ol + Idd + KF + Mt, with zeolite and calcite secondary minerals (Figure 9(o) & Figure 13(f)). The fourth level (the uppermost) shows a poor phenocryst assemblage of Cpx + Lm + Idd + Pl + KF + Mt.

Semara outcrops are made of basanites and tephrites, three different levels are presented in the field. The lowest level exhibit a porphyric aphanitic texture (Figure 13(a)) with a phenocryst assemblage of Oxy-Hbl (Figure 9(p) & Figure 13(b)) + Ol (Figure 13(c)) + Cpx (Figure 13(d)) + Idd (Figure 13(e)) + Pl + Mt, with

the same secondary minerals of Zeolites and Calcites (Figure 13(b)). The level in the middle shows less phenocrysts, mainly consisting of Cpx + KF + Leu (Figure 9(q)) + Mt, with Pl showing traces of the magma mixing process (Figure 13(f)). The third level shows a fine-grained groundmass with rare small phenocrysts of Pl + Idd + Mt.

Oued Lakram and Oujda-Oujda volcanic fields outcrop in both sides of the road taken from the West of Oujda to Guenfouda in the South. Oued Lakram area mainly consists of alkali basalts with intensely altered intrusions. They are porphyric with a fine-grained groundmass and exhibit a phenocryst assemblage of zoned Ol (Figure 13(a)) + Idd + Pl (mostly oriented and intersected) (Figure 9(r) & Figure 13(a) & Figure 13(b)) + Cpx (Figure 13(b)) + Lim + Bt (as relics) + Mt + KF + Oxy-Hbl (Figure 13(c)). Secondary minerals are of Zeolites and Calcite. The oxidized volcanic intrusion consists of altered porphyric basalts with few phenocrysts of Ol + Idd + KF + Pl + Mt.

Oujda-Oujda outcrop is made of basanites and tephrites; it presents different local volcanological and deformation structures (e.g. radial form and frequent fracturing lineaments). They are porphyric with a fine-grained groundmass. They show a phenocryst assemblage of pyroxenes with rare Opx (Figure 13(a)) and Cpx + oxy-Hbl (Figure 13(b)), surrounded by a thick ferric rim (Figure 9(s)) and exhibiting Idd inclusions (Figure 13(c)) + KF + Pl in addition to secondary Carbonates mineral.

The clinopyroxenes are generally Mg-rich, Ca and Ti content is highly relevant in the sampled phenocrysts. However, sometimes they exhibit a high content of Fe. Overall samples, plagioclase is Ca-rich and olivine is Mg-rich. Oxy-hbl show high contents of Mg, Fe, Ti and K (Table 1).

Analyzed rock samples display slight to moderate alteration effects, as reflected in their loss on ignition (LOI) values, ranging mainly between 0.34 and 3.05 wt% (Table 1) and in their petrographic assemblages.

Petrographic observations indicate that all the samples exhibit a replacement of olivine with iddingsite suggesting an oxidizing environment during the alteration

processes (Figures 11-13). Vesicles and fractures in studied samples are filled with secondary minerals, mainly calcite and zeolite, probably resulting from the circulation of hot hydrothermal fluids. In alkali systems, zeolites in vesicles dissolve with decreasing temperature, and F.K. precipitates.

To constrain the nature of the main alteration phases present in these rocks, analysis by Raman Spectroscopy of basaltic rocks from Oujda Semara and Guilliz Essghir show that the main hydrothermal alteration is a-clay type, followed by mica-type, oxides, carbonates and sulfates minerals (Table 4). Abundant minerals such as calcite, zeolite (Analcime) were also observed in thins sections. Calcite is observed in basalts and pyroclastic tuffs due to the high porosity in the lava (Figure 12 and Figure 13). The argillic alteration is characterized by the presence of montmorillonite, palygorskite, stilpnomelane and ferrimontmorillonite, eventually accompanied by low-temperature zeolites (Table 4).

The mica-type zone develops up to temperatures of 160˚C, above which mont-morillonite becomes unstable. Montmorillonite is a dioctahedral smectite that

usually occurs in argillic alteration facies and it is a typical product of hydrolysis reactions using silicate phases (Pl, F.K, Px, Ol, volcanic glass), generally at temperature below 160˚C (Figure 14). Kaolinite is a very common dioctahedral alteration mineral that we find in superficial geothermal zones and it is the first alteration clay mineral to form but it is not considered as a good thermal indicator, unlike the montmorillonite, systematically present in every hydrothermal setting. Both minerals generally indicate a low temperature domain and less frequently even medium temperature (i.e. Montmorillonite in Philippines [48]).

Sepiolite and palygorskite alteration minerals are mainly recorded in mafic and ultramafic rocks of oceanic crust. They generally reflect a hydrothermal temperature below 160˚C (Figure 14) and are locally found in argillic alteration facies [49]). Although they are not totally phyllic minerals, they are usually referred to as phyllosilicate s.l. [50]. Palygorskite might also be an indicator of a temperature close to 200˚C [51].

Saponite and Vermiculite are tetrahedral smectites; the former is frequently identified within high temperature hydrothermal zones (propylitic facies) of active geothermal systems [52]. While the latter is substantially is typically found in argillic hydrothermal alteration facies. Kaolinite is a mineral of intermediate argillic alteration facies and can rarely occur in developed argillic facies [53]. Its significance lays on indicating relatively low fluid temperature (<110˚C) (Figure 14).

The presence of jarosite indicates the probable presence of shallow sulphides. The occurrence of kaolinite and jarosite might indicate a boundary between oxidized and reduced materials and hence, point to acid-sulphate conditions surrounding the sulphides [54].

As the hydrothermal alteration minerals are quite various and exhibit large compositional variation, we believe that more than one hydrothermal fluid is implicated in the alteration process after the volcanic activity volcanic setup. Alteration minerals can be classified based on temperature range in two classes into two classes: a high temperature hydrothermal fluid of and a medium to low temperature thermal fluid. The first is responsible of the precipitation of oxides and sulphates, while the latter has controlled the clay, micas and calcite alteration.

Given this range of variations in the LOI values, we recalculated the major-element oxides to total 100% on a volatile-free basis before using these compositions in classification geochemical diagrams. In the TAS classification diagram of [55], the volcanic rock samples plot in the basalts, basanites, basaltic trachy-andesites, trachy-andesites and tephrites fields (Figure 15). In the TAS diagram, all the samples are plot in between alkaline-subalkaline separating line of [56]. Basaltic trachy-andesites (samples MR-7, MR-20, MR-39 and MR-40) contain SiO₂ (51.7 - 53.19 wt%), and K₂O + Na₂O (6.17 - 8.07 wt%). Basalts (samples MR-9, MR-16, MR-18, MR-36, MR-44 and MR-45) contain SiO₂ (45.09 - 47.09 wt%), and K₂O + Na₂O (3.75 - 4.77 wt%). Basanites (samples MR-13, MR-19, MR-31, MR-34 and MR-41) contain SiO₂ (42.26 - 44.72 wt%), and K₂O + Na₂O (3.38 - 5.68 wt%). The tephrite sample (MR-28) contain SiO₂ (44.72 wt%), and K₂O + Na₂O (7.4 wt%). Finally, the most felsic facies of trachy-andesites (samples MR-12, MR-42 and MR-46) containing SiO₂ (58.97 - 59.96 wt%), and K₂O + Na₂O (6.36 - 8.34 wt%). Except for samples MR-20, MR-39, MR-40, MR-42 and MR-46 who show a negative Na₂O/K₂O values, all the samples have a sodic affinity.

To summarize, the studied volcanic outcrops consist only on mafic rocks (basalts, basanites and tephrites) as for example Oujda-Oujda and Tassatchaft, others as Terkaa, only by intermediate rocks while other volcanic field exhibit rocks spanning from mafic to felsic rocks as for example Amejjaou and Guiliz Esghir and Jorf Lakhder. Saka volcanic field is formed only by trachy-andesite.

The multiple plot of SiO₂ vs. other major elements diagrams depict the following trends (Figure 16) basaltic trachy-andesite samples show high Al₂O₃ and

K₂O contents and MgO, CaO and TiO₂ low contents. The P₂O₅ and Na₂O contents decrease significantly with increasing SiO₂ content in relation with the crystallization of the apatite; 2) Trachy-andesite samples have lower contents of TiO₂, MgO and CaO than the basaltic trachy-andesites and higher contents of Al₂O₃ and K₂O, while the content of Na₂O and P₂O₅ are quite close in both facies (excepting MR-12 that has a very high Na₂O content; 3) basalts have high Al₂O₃, MgO, Na₂O and CaO contents, but low K₂O, TiO₂ and P₂O₅ contents. The negative correlation between CaO and SiO₂ contents in these samples correlates with the fractional crystallization of clinopyroxene and plagioclase; 4) basanites have high contents of TiO₂, MgO, CaO, Na₂O and P₂O₅ but low Al₂O₃ and K₂O contents, in these samples, the P₂O₅ and Na₂O content decreases towards the less saturated samples.

Rare earth elements patterns for the studied volcanic rock show the same pattern, an enrichment in LREEs and a depletion in MREEs and HREEs (Figure 17), which is consistent with the general OIB pattern [57].

All the samples exhibit a positive anomaly of Nd, Dy and Tm and a negative

anomaly of Ho and Er. Chondrite-normalized rare earth elements (REE) diagrams show a negative anomaly of Sm, well recorded in Guilliz Essghir samples and of Gd in Jorf Lakhdar, Terkaa and Amejjaou samples. Three samples (MR-12, MR-39 and MR-41) exhibit a very low (Eu/Eu*) of 0.84 - 0.85 while the others show a slight negative and positive Eu anomalies (Eu/Eu* = 0.91 - 1.38). (Ce/Ce*) anomalies are almost steady, with values ranging between (0.86 and 1.01), the ratio values indicates a small interference of oxidation at an early stage. (La/Lu)N and (La/Sm)N ratios are 7.27 - 28.54 and 2.44 - 4.95, respectively (Table 3). They are higher in basanites and tephrite samples, suggesting a late-stage of fractional crystallization from parent magma. (La/Yb)N, (Gd/Yb)N and (La/Gd)N ratios

are 5.29 - 24.5, 1.13 - 2.68 and 2.94 - 16.6, respectively, these values suggest the enrichment of LREE compared to MREE and HREE (Figure 17).

Basalts and basanites show a wide range of concentrations of incompatible elements. Basalts generally have low Zr and Y contents, excepting one sample makes the exception (MR-36) which is very different from other basaltic samples, they also show a low content of Cr, except for two samples (MR-16 and MR-18). Unlike the basalts, basanites show a high content of Zr and Rb, except for one sample (MR-13) which exhibit the lowest content of Rb (Figure 18). Basaltic trachy-andesites show low Ni and Cr contents and high Rb contents (excepting the sample MR-20), they show also low Zr and Y contents (excepting sample MR-7). Trachy-andesites samples show close compositions in Zr, Ba and Rb, however, Ni, Cr and Y content is very low, except for one sample (MR-12), where Y content is notably high. Tephrite sample shows low Ni, Zr, Rb and Cr contents and high Ba and Y contents. The highest concentrations of large-ion lithophile elements (LILEs) such as Rb and Ba, and high-field-strength elements (HFSEs) such as Nb and Zr are those corresponding to Oujda area (Amejjaou and Oujda-Oujda) (Figure 17 & Figure 18).

The Circum Mediterranean Anorogenic Cenozoic Igneous province (CiMACI) refers to the Tertiary anorogenic magmatism, reported widely from the Mediterranean area. Previous studies revealed a common sub-lithospheric mantle source component beneath most of the regions where the anorogenic magmatism has been identified and studied (Figure 19); this source is also referred to as

the Common Mantle Reservoir (CMR). P and S wave velocity anomalies revealed by different seismic tomography studies beneath CiMACI province and suggest the presence of mantle plumes and diapiric upwellings. CiMACI igneous activity may occur either in extensive settings or in compressive phases as it took place in France along old suture zones affected by Cenozoic rifting and in Turkey in a hinterland position above active or fossil subduction zones. Hence, the term anorogenic cannot be used as an exact synonym of “intra-plate” and the term orogenic cannot be used as synonym of “subduction-related”, as both terms are open to encompass a variety of geochemical compositions, unnecessarily related to a contemporaneous geodynamic event [42].

CiMACI rocks are generally effusive and are under-saturated to saturated (SiO₂ between 45 and 57 wt%), they are frequently sodic (Na₂O/K₂O between 1.4 - 5) and rarely CaO-rich [4] [63] [64] [65] [66]. The most primitive mafic rocks are under-saturated and alkali-rich (Na₂O + K₂O between 3 and 10 wt%). The main recorded subalkaline lithologies are the basaltic andesites, andesites, picritic basalts, dacites and rhyolites. While the identified alkali rocks are tephrites, tephri-phonolites, leucitites and hauynophyres [67].

Cenozoic magmatic activity in NW Africa is mostly represented by volcanic rocks characterized by a temporal sequence from orogenic products (Miocene Calc-alkaline to high-K Calc-alkaline and Shoshonites) to anorogenic compositions (Plio-quaternary Na₂O-rich Alkaline). The anorogenic products generally show typical trace element patterns of magmas emplaced in intraplate settings, such as negative K anomalies, peaks at HFSE (Nb-Ta-Hf-Zr), enrichment of LILE (Cs, Ba, Sr) over HFSE and depletion of Rb [42]. Volcanic rocks with intermediate geochemical affinities between orogenic and anorogenic compositions occur in many areas (e.g., Spain, France, Algeria, Morocco, Turkey) and are undoubtedly related to the interaction between anorogenic sub-lithospheric melts and orogenic subcontinental lithospheric mantle [6] [8].

The geodynamic model of [42] points to a partially melted sub-lithospheric mantle, resulting from different geodynamic settings related to lithospheric extension, and compression, including continental collision and orogenic collapse, contemporaneous subduction, slab roll-back and slab-window formation.

Three models can be proposed to explain the presence of the post-collisional volcanic activity during the Plio-quaternary in NE of Morocco, taking in consideration the regional geodynamic settings within the neighbouring regions. Two of them were previously suggested for NE of Morocco by [6] [8].

The first model investigates the difference in geochemical characteristics of rocks close in age and petrography occurring within the same area. The aim is to explain the temporal transition from an orogenic igneous activity to an anorogenic magmatic activity, e.g., in Maghrebian Africa, Pannonian Basin and Turkey (e.g. [6] [7]). It consists of an adiabatic decompression causing partial melting of the asthenosphere as the mantle beneath the slab rises through the slab-window created by the break-off of the subducted slab (Figure 20(a)).

The second was proposed by [8] for continental margins of South Iberia and NW of Africa. It suggests that the igneous activity is structurally related to a subduction system. It involves slab rollback or simple lithospheric delamination and steepening of subducted oceanic lithosphere. Those elements contribute in the transport of mantle flow to the surface by creating low-pressures zones

(Figure 20(b)). This model stands perfectly with geophysical data (earthquake hypocentres’ locations and velocity anomalies) suggesting the presence of a thin wedge-shaped layer (20 - 40 km) with asthenospheric material beneath SE of Spain and NE of Morocco [68] [69].

The third model was proposed to explain the magmatic activity of Veneto Volcanic Province and the north of Pannonian Basin [1] [70] in northern Italy and Central Europe, respectively (Figure 20(c)). It consists of a channelized plume sourcing probably for the lower mantle and laterally extending in the asthenosphere, feeding volcanic areas with magmatic flow through the weak zones all along the Mediterranean and beneath the North-African crust during the late Miocene to Quaternary. It also invokes the first model to explain the drastic change in geochemistry of volcanic rocks present within the same areas and are closest in age. This model covers a variety of aspects, represented within this study, including the similarities between the different volcanic provinces, discussed previously, petrographic characteristics and the geochemical evolution of volcanic rocks of NE of Morocco.

In northeastern Morocco, the main magmatic source during late Miocene (Pliocene) changed from a subduction-modified subcontinental lithosphere to a plume-contaminated sublithospheric source. Indeed, some of the silica-saturated samples in Gourougou and Guilliz do not show the expected enrichment and depletion in some FMEs (Fluid-Mobile Elements) (e.g. Th, U, K and Pb) and display large ranges in these elements’ ratios, which values indicate a source between OIB and subduction zone lavas. Some alkali under-saturated samples show silent depletion and enrichment in some FMEs (e.g. Th, U, K and Pb). Such behaviour suggests a binary mixing of magmas from different sources, including a shallow mantle wedge, enriched by melts and fluids from subducted oceanic lithosphere beneath the Alboran Basin; a metasomatically enriched subcontinental mantle lithosphere and an upwelling plume-contaminated asthenosphere beneath the south of Iberia and northwest of Africa [6] (Figure 21).

This change can be observed in the Gourougou stratovolcanic area, in a progressive temporal and geochemical evolution marked by decreasing influence of subduction related component and increasing effect of intraplate-related component.

Petrographic data and geochemical analysis of volcanic rocks from NE of Morocco’s Plio-quaternary volcanic fields show the dominance of Na-rich basaltic rocks (basanites, basalts, tephrites and basaltic trachy-andesites), followed by the trachy-andesites. Major and trace element compositions exhibit an enrichment of LILE over HFSE, with high content of Mg and show similar pattern of Oceanic Island Basalts (OIB). The identification and characterization of hydrothermal alteration facies and minerals help us get a better understanding of hydrothermal and geothermal systems, induce thermal parameters and deduce water/rock interaction processes such as the temperature and pH, which will be the main perspective of related studies. We believe that involved hydrothermal fluids in volcanic rocks of NE of Morocco must be at least two different fluids, a low temperature fluid and a high temperature fluid.

Plio-quaternary alkaline volcanic activity, as an anorogenic magmatic province shares many similarities with neighboring anorogenic magmatic areas (e.g. Spain, Algeria, and Morocco), referred as CiMACI province developed along the Mediterranean area. Comparison of different anorogenic magmatic fields within the global model highlighted a great resemblance that supports the idea of areas having a common source beneath the lithosphere. Indeed, inspired from [1], a new model is suggested for the NE of Morocco’ recent volcanic province, involving channelized mantle plume along sub-lithospheric weak zones and a slab-window.