The study area (Fig. 2), hereafter the ZGMR “Zgounder Mine Region” corresponds to the vicinity of the Zgounder Ag-Hg deposit, located 265 km east of Agadir, and 220 km west of Ouarzazate, along the southern flank of the Ouzellagh-Sirwa Salient in the Central Anti-Atlas Mountains (Ben-Tami et al., 2024). Detailed geological mapping across the ZGMR established the primary lithostratigraphic relationships (Fig. 2). The Ediacaran of the ZGMR (630–539 Ma) comprises: (i) the SG sedimentary successions and coeval magmatic rocks deposited 630 to 600 Ma (Errami et al., 2021; Abati et al., 2010); and (ii) large felsic plutons, subvolcanic formations, and coeval pyroclastic rocks, referred to as the OG (600–539 Ma; Thomas et al., 2002).

The oldest rocks in the study area belong to the SG: the northern, E–W-striking Tittalt Formation and the southern Imghi Formation (Fig. 2). The lowermost Tittalt Formation consists of basaltic and andesitic volcanic rocks associated with a gabbroic intrusion, bounded to the south by the Imghi Formation. The Imghi Formation features poorly graded, thick-bedded greywacke of stacked fine- to very fine-grained sandstone beds, and greyish-green, well-bedded, graded turbidites striking east and dipping steeply south at 70° (Fig. 2). Felsic magmatism is represented by the E–W-trending Tadmant rhyolite (Bou Salda Group; Thomas et al., 2002), forming the core of the area between the western Askaoun granodiorite and the eastern OG sequences (Fig. 2). Other subvolcanic activities include the E–W-trending rhyolitic dikes and plugs of the Assarrag suite (Thomas et al., 2002). Post-SG, post-Bou Salda magmatism includes the Askaoun granodiorite, intruding the western Imghi Formation, and the syn- to late-Ouarzazate Bou-Tazart granite (Amassine Suite; Thomas et al., 2002). To the east, the sub-horizontal volcano-sedimentary packages of the OG consist of laminated ignimbrites, ignimbritic rhyolites, andesites, and lapilli tuffs containing volcanic glass lenses. Associated mafic activity is recorded by an intermittent, fault-offset dolerite/diabase sill-like body (∼ 25 m surface width), parallel to the rhyolite-sediment contact (Fig. 2).

A total of 32 samples were collected from the Saghro and Ouarzazate groups for petrographic and geochemical analysis. For each sample, lithostratigraphic position, sample type, drill core name and depth, short description and analytical methods applied are reported in Table S1 in the Supplement. Three samples were selected for U-Pb geochronology: (i) a laminated, light-pink to brownish rhyolitic dike crosscutting the Tittalt Formation (Zg-106; 46 m long, 4–5 m thick; Fig. 2); (ii) a fine- to medium-grained, light grey granite (Zg-119) from drill hole ZG-20-21 at 555.30–568.50 m intruding the Imghi Formation; and (iii) a fine- to medium-grained greenish SG sandstone collected near the Zgounder Mine main entrance for detrital zircon analysis (Zg-132; Fig. 2) (Table S2).

Sample preparation for U-Pb zircon geochronology involved crushing, sieving to 50–250 µm, and weighing (1.4 kg for Zg-106; 1.5 kg for Zg-119; 2.3 kg for Zg-132) at the Département de Géologie, Faculté des Sciences, Université Ibn Zohr, Maroc. Samples were then shipped to the Geotop Research Center, Université du Québec à Montréal (UQAM), Canada. Analytical parameters are detailed in the Supplementary Data 1 file in the Supplement, following Horstwood et al. (2016). Ages of intrusive rocks are reported as weighted mean 206Pb/238U dates, calculated using the “exclude outliers” function in Isoplot R, and detrital zircon data as concordia dates. LA-ICP-MS U-Pb data are given in Table S2.

Fresh rock samples were collected for whole-rock geochemistry and Sm-Nd isotopes from outcrops (surface and underground), as well in various diamond drill holes from the ZGMR. Crushing and powdering were performed at the facilities of the Zgounder Millennium Silver Mining Company (ZMSM). Further analytical procedures are detailed in the Supplementary Data 1 file, and results are shown in Table S3.

Sm-Nd isotopic data from seven samples spanning the Ediacaran record of the Sirwa massif reveal petrogenetic processes and orogenic evolution of the Anti-Atlas belt (630–539 Ma) following Bou Azzer-Sirwa ophiolite accretion. Results are listed in Table 1.

Based on field relationships, an angular unconformity (Errami et al., 2009; Thomas et al., 2002) marks a significant sedimentary/magmatic gap between the 630–600 Ma SG and the overlaying 570–539 Ma OG (Errami et al., 2021). We used 620 Ma as a reference age for ϵNd analyses of SG samples (Zg-105, and Zg-108). They show narrow (143Nd/144Nd) 620 Ma ratios (∼ 0.512) and positive ϵNd620values of +3.2 and +4.6. Additionally, the TDM model ages (Fig. 8a) of 1.02 and 0.91 Ga exceed the individual maximum depositional ages of 630–600 Ma, and the crystallization ages of older to contemporaneous igneous intrusions found elsewhere in the Anti-Atlas belt, which fall within 640–580 Ma, (Errami et al., 2021; O'Connor et al., 2010; Liégeois et al., 2006; Gasquet et al., 2005; Mrini, 1993).

The OG rocks, calculated at 570 Ma, exhibit a mostly uniform distribution, with (143Nd/144Nd) values from 0.5118 to 0.5119. These ratios are close to, or slightly lower than, the Chondritic Uniform Reservoir (CHUR) values. (ϵNd570 = -0.8 to +1.1). Volcanic rocks show negative to near-zero ϵNd570 values: -0.8 (Tadmant rhyolite), +0.0 (OG rhyolite), and -0.3 (dolerite). Granitoids have ϵNd570 values of +0.0 and +1.1 for Zg-119 and Zg-09, respectively. TDM model ages for all samples range from 1.30 to 1.15 Ga (Fig. 8a). Overall, the distinct ϵNd(t) isotopic signatures for both groups are further supported by the negative correlation between ϵNd(t) values and SiO2 (Fig. 8b).

Further, to quantify the mixing proportions for the Saghro and Ouarzazate groups, this study employs a binary mixing model based on the equations of Faure (1986), following the computational approach detailed by Janoušek et al. (2016). In this model, the isotopic ratio of a mixture (IM) is defined as the mean of the isotopic ratios of two end-members (I1 and I2), weighted by their respective mass fractions and elemental concentrations. f1 represents the mass fraction of end-member 1 (where f1+f2=1), while C1, C2, and CM represent the elemental concentrations of the end-members and the resulting mixture, respectively. Mantle end-member 1 is defined by a metasomatized lithospheric source, with values of I1 = 0.512265, C1 = 13.27 ppm, and ϵNd620 = +8 from Errami et al. (2009), reflecting mantle enrichment by prior subduction processes. For crustal end-member 2, we used parameters from Ennih and Liégeois (2008) (I2 = 0.511472; C2 = 47 ppm; ϵNd620 = -16), representing the Paleoproterozoic basement of the WAC.

The mixing equations are defined as: IM=I1C1CMf1+I2C2CM(1-f1) where: 1CM=f1C1+(1-f1)C22f1=C2(IM-I2)C1I1-IM+C2(IM-I2)

Applying this mixing model reveals that SG rocks are characterized by a dominantly mantle origin: the andesite (Zg-108) and gabbro (Zg-105) yield high mantle-derived mass fractions (f1) of 88 % and 92 %, respectively, with minor crustal inputs (f2 ≈ 8 %–12 %). Conversely, the OG magmas have mantle mass fractions (f1) ranging from 75 % to 85 %. Moreover, the calculated crustal contribution (f2) increases from 15 % in granodiorite (Zg-09) to 25 % in rhyolite (Zg-117).

The SG and OG rocks exhibit chemical evolution consistent with fractional crystallization. General trends for major elements (e.g., Al2O3, CaO, and TiO2) show positive correlations with Mg# (Fig. 9a–c). Al2O3 contents decrease with decreasing Mg# suggesting plagioclase crystallization (Fig. 9a). CaO contents drop sharply as Mg# decreases below ∼ 40, indicating clinopyroxene or calcic plagioclase fractionation (Fig. 9b). TiO2 also decreases with decreasing Mg#, pointing to early crystallization of Fe-Ti oxides (e.g., ilmenite or titanomagnetite) (Fig. 9c).

On the A/CNK versus Mg# plot (Fig. 9d), the SG rocks are metaluminous (A/CNK < 1.0), while the OG felsic and plutonic rocks are peraluminous (A/CNK > 1.0). This shift to peraluminous compositions suggests melting of aluminum-rich material or fractionation of aluminum-poor minerals (e.g., hornblende, pyroxene) in the felsic rocks. In Fig. 9e, the SG rocks retain the highest Sr concentrations (∼ 200–350 ppm), indicating a more aluminum-enriched source or less plagioclase removal. This is supported by the absence of a negative Eu anomaly (Eu/Eu∗ = 0.89–1.28), reaching a positive value for gabbro Zg-105 (Eu/Eu∗ = 1.28), indicating limited plagioclase fractionation (Fig. 7a). In contrast, the OG rocks show a marked Sr decline from mafic volcanics through plutonics to felsic volcanics, indicating that plagioclase crystallization was the dominant driver of OG differentiation (Fig. 9e). This is corroborated by the prominent negative Eu anomaly in rhyolite Zg-106, while the absence of an Eu anomaly in dolerites suggests limited plagioclase involvement (Fig. 7c).

On the Th (ppm) versus Mg# plot (Fig. 9f), both the SG rocks and OG mafic volcanics show low Th concentrations (< 5 ppm), typical of mantle-derived melts. For the SG, however, Mg# values of 21.50 to 60.20 reflect early fractionation of ferromagnesian minerals, indicating the rocks are not derived from a primitive melt. For the OG, Th levels reach up to 32 ppm in felsic volcanics and plutonics, suggesting crustal melting or assimilation during magma ascent (Fig. 9f). The absence of a negative Eu anomaly in the SG rocks (Fig. 7a), despite the evolved nature of the magmas, likely reflects mixing between evolved basaltic magmas and more primitive magmas that lacked plagioclase fractionation. The OG felsic volcanics and plutonics show Sr and P depletion, consistent with plagioclase and apatite fractionation (Fig. 7d).

Eu/Eu∗ values versus Sr contents (ppm) show a clear positive correlation (Fig. 9g). Mafic rocks of the Saghro and the Ouarzazate groups have high Sr and Eu/Eu∗ values near 1.0, suggesting plagioclase accumulation consistent with their more primitive nature. In contrast, the OG felsic volcanics and plutonics show significantly lower Sr and Eu/Eu∗ values, indicating substantial plagioclase fractionation from the melt (Fig. 9g). Whole rock Zr/Sm versus Zr and Rb/Nb versus Rb correlations are as expected for a fractional crystallization process (Fig. 9h–i). A localized spike in Zr/Sm at high Zr contents (∼ 350 ppm) indicates late-stage mineralogical control, involving zircon or amphibole fractionation in the more evolved OG, distinct from the relatively stable ratios of most samples (Fig. 9h). This implies that the magmatic evolution of the SG and the OG rocks involved both fractional crystallization and progressive crustal contamination or a subduction-modified source (Fig. 9i).

The ϵNdi versus 147Sm/144Nd plot clearly distinguishes the SG from the OG rocks (Fig. 10a). The SG rocks show strongly positive ϵNdi values (+3.2 and +4.6), indicating a juvenile, depleted mantle origin with minimal crustal interaction. In contrast, the OG rocks, by contrast, cluster near or below the CHUR line (ϵNdi = -0.8 to +1.1), reflecting a hybrid source with significant reworking of older continental crust. Sample Zg-106 shares this near-zero isotopic signature, but its unusually high 147Sm/144Nd ratio (∼ 0.21) points to a distinct petrogenetic process, likely low degree of partial melting that fractionated REE without significantly altering the initial Nd isotopic composition of its source (Fig. 10a).

The SG and OG also show distinct geochemical fingerprints. For samples with Nb < 25 ppm (Fig. 10b), Nb/Ta ratios show a wide spread (∼ 3–15): OG plutonics decline sharply (∼ 3), indicating advanced fractional crystallization of ferromagnesian and accessory minerals, while SG mafic rocks maintain higher, stable ratios (∼ 10–15), consistent with more primitive melts. Although Nb and Ta typically behave as geochemical twins, they can fractionate during subduction (Hofmann et al., 1986). The OG rocks cluster below a Nb/Ta ratio of 14, well below the mantle value of 17.5 (Sun and McDonough, 1989) and close to the bulk continental crust value of ∼ 11 (Green, 1995), confirming a dominant crustal signature. This is further corroborated by an enrichment in LILEs, coupled with prominent negative Nb-Ta and Ti anomalies (Fig. 7d), consistent with subduction-related magmatism or recycling of metasomatized lithosphere (Ikenne et al., 2007). Finally, the OG rhyolite (Zg-106) displays a horizontal shift toward higher Nb at a fixed Nb/Ta ratio (∼ 9) (Fig. 10b), suggesting magma enrichment via a low degree partial melting from a source already characterized by a low Nb/Ta ratio and a pre-existing subduction-modified signature.

The SG and OG rocks show enrichment in LILEs and LREEs relative to HFSEs and HREEs. They also exhibit pronounced negative anomalies in Nb, Ta, and Ti (Fig. 7), suggesting subduction zone fluids influence (Wilson, 1989). For the OG rocks, this inherited geochemical signature is attributed to oceanic arc rocks previously subducted into the mantle (Toummite et al., 2013; Gasquet et al., 2008; Ikenne et al., 2007; Thomas et al., 2002).

Trace elements can clarify subduction input versus crustal contamination. In the Ba/Th versus La/Sm diagram (Fig. 10c), most samples display low Ba/Th and high, variable La/Sm ratios, favoring a dominant role for sediment melting process. A similar sediment melt signature is also observed for all samples in the Sr/Th versus La/Sm diagram (Fig. 10d). For the SG rocks, relatively high Sr/Th ratios are attributed to plagioclase accumulation. High La/Sm ratios further indicate a sediment-dominated influence, suggesting that slab pressure-temperature conditions were sufficient to trigger sediment melting (Labanieh et al., 2012). This melting process acted as the primary mechanism transferring the slab signature into the analyzed samples.

The whole-rock Sm-Nd isotope compositions of the Saghro and Ouarzazate groups suggest a heterogeneous magma source, reflected in the negative correlation between ϵNd(t) values and SiO2 (Fig. 8b). The SG maintains high ϵNd₍₆₂₀₎values (+3.2 and +4.6) even as silica increase, reinforcing a juvenile mantle source with minimal crustal input. The corresponding TDM model ages of 1.02 and 0.91 Ga further support a depleted mantle source. Within the OG, the decreasing trend in ϵNd570 = +1.1 to -0.8 with increasing SiO2 is a classic signature of Assimilation-Fractional Crystallization (AFC), whereby the cooling magma evolves toward a felsic composition while incorporating more evolved, negative ϵNd continental crust. Notably, TDM model ages clustering around 1.30 to 1.15 Ga indicate that the OG magmas were not purely mantle-derived, but involved significant recycling of much older basement (Mesoproterozoic and/or Paleoproterozoic).

The binary mixing model validates these isotopic trends. The SG rocks show a near-pristine mantle signature (f1 = 88 %–92 %). However, the increasing crustal contribution (f2) of the OG rocks, from 15 % in granodiorite (Zg-09) to 25 % in rhyolite (Zg-117), confirms a coupling between increasingly felsic compositions and higher crustal input. This 25 % contribution from an ancient Paleoproterozoic source (ϵNd620 = -16) represents a major contamination event, exerting a significant isotopic pull by shifting the ϵNd values of the samples to near zero. Normally, without recycling of this ancient basement, a purely mantle-derived magma at 570 Ma would be expected to show strongly positive values of +7 to +8. This hybridization is further supported by the TDM model ages of 1.30 to 1.15 Ga, proving the significant involvement of the underlying Eburnean WAC basement.

Previously, the SG basin was interpreted as consisting of distal, deep marine sediments equivalent to the platform series of the Tachdamt Group, formed during initial rifting associated with the Rodinia breakup (Thomas et al., 2002). However, recent zircon data from SG sediments in the Sirwa and Saghro inliers suggest deposition occurred following Bou Azzer-Sirwa ophiolite accretion, during the main Pan-African Orogeny (Abati et al., 2010; Errami et al., 2009; Liégeois et al., 2006). Furthermore, the tectonic setting of Ediacaran OG magmatism also remains debated, having been interpreted as: (i) post-collisional, linked to asthenospheric upwelling beneath the WAC during its metacratonic evolution (Gasquet et al., 2008, 2005; Liégeois et al., 2006; Thomas et al., 2002); (ii) subduction related (Walsh et al., 2012; Benziane, 2007; El Baghdadi et al., 2003); or (iii) linked to Iapetus Ocean opening, tied to the Ediacaran Central Iapetus Magmatic Province (CIMP; Youbi et al., 2020). Based on age and chemical similarities, this magmatism is also associated with the Avalonian-Cadomian marginal belt along the northwestern edge of Gondwana, constituting a major magmatic flare-up spanning roughly 590–540 Ma (Letsch et al., 2018; Tahiri et al., 2010; Linnemann et al., 2008).

For our samples, multi-elemental discrimination plots (Fig. 11a–f) provide a framework for deciphering the petrogenesis and tectonic transition of Ediacaran magmatic sequences in the Anti-Atlas. First, the SG basalts feature high Zr and relatively low Y concentrations, classifying them as within-plate basalts (WPB) (Fig. 11a) and indicating an extensional to transtensional setting. On the Th/Nb versus Ti/V diagram of Shervais (2022), these samples plot within the Continental Flood Basalts (CFB) field (Fig. 11b). Placed in the regional context of the Anti-Atlas, the geodynamic setting of the SG has been interpreted as an intracontinental rift evolving into either a mature back-arc basin (Errami et al., 2009; Fekkak et al., 2001) or a continental passive margin (Fekkak et al., 2002). This evolution is characterized by a transition from early, sediment-influenced tholeiites to more evolved magmatic suites, rather than a massive subaerial flood province. The calc-alkaline character for the SG mafic rocks (Fig. 6e) reflects Th enrichmentt, typical of subduction-influenced or crustally contaminated suites. This transitional character, exhibiting calc-alkaline affinity (Fig. 6e), yet within-plate (Fig. 11a) and continental tholeiites (Fig. 11e) character is interpreted as an early Ediacaran extensional phase, where advanced lithospheric thinning allowed asthenospheric decompression, triggering large-scale melting of the Sub-Continental Lithospheric Mantle (SCLM). In contrast, the younger OG volcanic and plutonic rocks plot at higher Th/Nb ratios (> 0.5), within the Upper Continental Crust (UCC) and Andean Arc fields, with extreme Th enrichment pointing to a regional thermal regime shift (Fig. 11b). This OG magmatism marks a massive crustal melting event, interpreted as a response to post-collisional lithospheric delamination and possible slab break-off. This process generated highly differentiated magmatic suites with wide variations in Ti/V ratios (Fig. 11b).

Furthermore, there is a clear lithospheric distinction between the SG and the OG rocks based on trace element enrichments. The SG mafic rocks follow the MORB-OIB array (Fig. 11c), indicating a magma source akin to enriched mid-ocean ridge basalt (E-MORB). This implies that primary magmas were derived via partial melting of an enriched lithospheric mantle carrying a fossil subduction signature from earlier Cryogenian cycles. Conversely, the younger OG volcanic and plutonic rocks show considerable crustal contamination. Their shift toward higher Th/Yb ratios reflects input of continental crust, or widespread tapping of a SCLM domain deeply metasomatized by subduction-related sediments (Fig. 11c). The SG rocks' lower Th/Nb ratios further suggest a more primitive, mantle-dominated source modified by an ancient subduction-preconditioned lithospheric root rather than an active deep-mantle plume head, clustering within the vertical Subduction Zone-Modified Lithospheric Mantle (SZLM) array, near the LCC (Lower Continental Crust) (Fig. 11d).

The OG rocks, in contrast, plot within the upper limits of the SZLM array, clustering within the IAB and CAB fields. This geochemical footprint may signify slab break-off, whereby crustal recycling or melting of the thickened lithospheric root was driven directly by the thermal anomaly of the upwelling asthenospheric mantle (Fig. 11d).

Ultimately, a coherent geodynamic transition emerges between both Saghro and Ouarzazate groups. On Fig. 11e, the SG mafic rocks cluster within the Continental Tholeiites (CT) field, adjacent to the Back-Arc Basin (BAB) domain. This position, combined with their calc-alkaline signature and within-plate character noted above, supports formation in an extensional continental setting. The proximity to the BAB field suggests that, while the crust was thinning, the magmatism retained a slight transitional character typical of a maturing continental rift or back-arc basin, with a distinct geochemical overprint from a pre-modified lithospheric root. The OG felsic and plutonic samples, meanwhile, plot decisively within the A2-type granite field, supporting a post-collisional origin (Fig. 11f). A2-type granites are considered to originate from partial melting of continental or underplated mafic crust, typically in extensional settings (Eby, 1992). In this context, crustal recycling was likely driven by the mechanical and thermal effects of lithospheric delamination and potential slab failure (Blein et al., 2023; Ougadire et al., 2023). This triggered rapid basin development and accumulation of the thick volcano-sedimentary sequences characteristic the OG, across the already rigid, fractured metacratonic margin of the WAC, providing preferential pathways for the rapid upward migration of deep-sourced magmas (Walsh et al., 2012, and references therein; Ennih and Liégeois, 2001, 2008; Gasquet et al., 2008).

At a regional scale, basaltic flows have been described as interbedded within the SG sediments of the Saghro massif (Errami et al., 2009; Fekkak et al., 2003, 2001). These flows exhibit diverse geochemical signatures. The basalts in Sidi Flah (SF) are of Initial Rift Tholeiites (IRT) and Ocean Island Basalts (OIB) character (Fekkak et al., 2001). In contrast, the Anou N'Izem basalts in the Boumalne (BO) inlier possess typical Mid-Ocean Ridge Basalt (MORB) signatures (Errami et al., 2009). U-Pb dating of detrital zircons from the SG in various inliers suggests this unit was deposited between 640–600 Ma across the entire Central-Eastern Anti-Atlas region (Errami et al., 2021; Abati et al., 2010).

In liaison, this geochemical variation within the SG likely reflects a single, continuous geodynamic event. Specifically, during the evolution of a back-arc basin, the earliest magmas often exhibit magmatic arc-like characteristics due to the proximity of the back-arc to the arc itself; as the back-arc matures and the magma source becomes further removed from the metasomatized mantle, magmas transition toward within-plate (OIB) and MORB-like signatures (Vasey et al., 2021; Saunders and Tarney, 1984). This interpretation is further supported by sediment geochemistry pointing toward a back-arc basin depositional environment (Ouguir et al., 1996). In the Anti-Atlas, this footprint is widely attributed to activation of a sub continental lithospheric mantle source, previously metasomatized during earlier Cryogenian Pan-African subduction, operating in tandem with distal stress fields from the emerging Cadomian orogenic system (Hefferan et al., 2014). As the basin matured and lithospheric extension advanced, the magma source increasingly tapped deeper, uncontaminated asthenospheric reservoirs, driving a compositional transition toward within-plate (OIB) and MORB-like signatures higher up the stratigraphy. Basaltic magmatism in the SG fits this evolutionary framework: the calc-alkaline basalts from the Sirwa inlier (Thomas et al., 2002; this study) represent the initial stages of back-arc formation, recording activation of this strongly metasomatized mantle source, whereas the IRT, OIB, and MORB-type basalts found higher in the stratigraphy indicate a more mature, extensional stage tapping deeper, uncontaminated asthenospheric reservoirs.

The thick volcano-sedimentary successions of the OG are dominated by silicic to intermediate high-K calc-alkaline to shoshonitic volcanism (Blein et al., 2014b; Toummite et al., 2013; Walsh et al., 2012; Gasquet et al., 2008, 2005; Benziane, 2007; Thomas et al., 2004; El Baghdadi et al., 2003). Based on our findings, and regional correlations with similar magmatism (see Table 1 in Hefferan et al. (2014), for reported precise ages from selected Anti-Atlas inliers), we attribute the OG rocks to a widespread post-collisional event, recognized across numerous inliers of the Anti-Atlas (Yajioui et al., 2020; Karaoui et al., 2015; Linnemann et al., 2014; Toummite et al., 2013; Walsh et al., 2012; Gasquet et al., 2005, 2004; Thomas et al., 2002). For the studied OG rocks, high Th/Nb ratios suggest that slab break-off induced a thermal pulse supplying heat to melt the Lower Continental Crust (LCC), with variable input from a metasomatized mantle wedge previously primed during an earlier subduction phase. Clustering near and above the Upper Continental Crust (UCC) field further indicates that lithospheric delamination supplied the necessary thermal energy to trigger widespread crustal melting, producing the high-K and shoshonitic signatures of the OG rocks (Bonin, 2004). This magmatism was coeval with a Silicic Large Igneous Province (SLIP) recognized across the Anti-Atlas (Ousbih et al., 2024, and references therein; Schulte et al., 2022).