Prediction of Buried Cobalt-Bearing Arsenides Using Ionic Leach Geochemistry in the Bou Azzer-El Graara Inlier (Central Anti-Atlas, Morocco): Implications for Mineral Exploration

Abstract

The Aghbar-Bou Azzer East mining district (ABED) is located between the Bou Azzer East and Aghbar deposits. It is an area of approximately 7 km long towards ENE–WSW and 2 km wide towards N–S. In this barren area, volcano-sedimentary rocks are attributed to the Ouarzazate group outcrop (Ediacarian age): they are composed of volcanic rocks (ignimbrite, andesite, rhyolite, dacite, etc.) covered by the Adoudou detritic formation in angular unconformity. Given the absence of serpentinite outcrops, exploration investigation in this area has been very limited. This paper aims to use ionic leach geochemistry (on samples of soil) to detect the presence of Co-bearing arsenides above hidden ore deposits in this unexplored area of the Bou Azzer inlier. In addition, a detailed structural analysis allowed the identification of four families of faults and fractures with or without filling. Three directional major fault systems of several kilometers in length and variable orientation in both the Cryogenian basement and the Ediacaran cover have been identified: (i) ENE–WSW, (ii) NE–SW, and (iii) NW–SE. Several geochemical anomalies for Co, As, Ni, Ag, and Cu are aligned along three main directions, including NE–SW, NW–SE, and ENE–WSW. They are particularly well-defined in the western zone but are only minor in the central and eastern zones. Some of these anomalies correlate with the primary structural features observed in the studied area. These trends are consistent with those known under mining exploitation in nearby ore deposits, supporting the potential for similar mineralization in the ABED. Based on structural analysis and ionic leach geochemistry, drilling programs were conducted in the study area, confirming the continuity of serpentinites at depth beneath the Ediacaran cover and the presence of Co–Fe-bearing arsenide ores. This validates the ionic geochemistry technique as a reliable method for exploring buried ore deposits.

1. Introduction

Cobalt (Co) has recently been classified as a critical metal due to its growing importance in metallurgical alloys and modern energy storage technologies, particularly as a key component in rechargeable lithium-ion batteries [1]. Worldwide, cobalt occurs in several deposit types, of which the most important source is the stratiform sediment- hosted Cu–Co deposits in the Katangan Basin, hosting the Central African Copperbelt stretching across Zambia and the Democratic Republic of Congo [2,3,4], and the Ni–Co laterite deposits in New Caledonia, Cameroon, and Brazil [5]. Additionally, magmatic Ni–Cu–Co-bearing sulfide deposits are linked to mafic–ultramafic intrusions in many deposits of Sudbury in Canada and Norilsk in Russia [6,7]. About 98% of cobalt is mined as a by-product of the exploitation of the Cu- and Ni-bearing sulfide or oxide ore deposits [1].

The worldwide increase in demand and production of Co, Ni, and Cr has led to a search for alternative, time- and cost-effective prospecting methods. It has become increasingly common for miners to drill through 100 m or more of overburden in search of hidden mineral deposits. However, conventional exploration over vast areas is constrained by the inefficiency of traditional geochemical techniques in covered areas as well as the high costs associated with extensive drilling programs and the use of geophysics. Ion leach geochemistry remains an effective and affordable exploration technique for identifying surface metal anomalies that indicate mineralization at depth.

Several migration processes have been proposed to explain the origin of geochemical anomalies observed above mineralized zones. Some theories, such as the ascending migration of metals attached to carrier gases [8,9], the presence of “fast ions” exceeding chemical diffusion [10], or ionic migration under an electrochemical field [11,12,13], are considered unlikely or possible only in arid environments [14]. Cameron et al. [15] argue that simple advective flow can explain the geochemical anomalies at the surface, provided the cover is highly fractured. After an earthquake, a study of buried porphyry deposits in northern Chile yielded promising results [15]. Additionally, numerous studies confirm that fractures strongly facilitate the migration of metals from the orebodies to the surface [15,16,17,18,19]. The strongest anomalies are often found near large faults. For example, Amex Exploration [20] tested this method in the Perron area during a regional exploration program in 2023. This program confirmed the structural control of gold geochemical anomalies, leading to the identification of several new targets. It also revealed a strong anomalous response along the N110 corridor, which controls the emplacement of gold mineralization in the Perron area [20].

Unlike most cobalt deposits worldwide, the Bou Azzer deposits are unique, as they represent the only known deposits where cobalt is mined as the primary ore. The polymetallic deposits of the Aghbar-Bou Azzer East district are located in the central Anti-Atlas and are associated with the Major Anti-Atlas Fault trending ESE–WSW (MAAF) [21,22]. These deposits belong to the As–Co–Ni–Fe–Au–Ag mining district, which is linked to the Bou Azzer-El Graara ophiolitic complex. The geological framework comprises a Cryogenian basement made up of gneisses, amphibolites, serpentinized harzburgites [23,24], quartz diorites, and a volcano-sedimentary sequence of rhyolites, ignimbrites, dacites, and reworked microconglomerates. These Neoproterozoic formations are uncomfortably overlain by volcanic and volcano-sedimentary rocks of the Ediacaran, as well as by Lower Cambrian carbonates (Adoudou Formation) [22,25,26,27,28,29,30].

The Bou Azzer mining district has undergone significant brittle and ductile tectonics, which have influenced the localization and migration of mineralization. Therefore, applying geochemical methods, such as ionic leach geochemistry, in this district is supported by a detailed fracturing study to better understand the structural controls on mineralization. The objective of this study is to use this new geochemical technique to predict the presence of Co-bearing arsenides above hidden ore deposits in the unexplored area of the Bou Azzer inlier. The focal point of this exploration program was to define target areas for drilling to discover polymetallic deposits, with the subsidiary intention of detecting multi-element signatures that could potentially indicate other commodities characterizing a larger mineralizing system in depth.

2. Geological Setting

The Bou Azzer inlier, located in the central part of the Anti-Atlas belt, formed during the major Pan-African orogeny phase as a consequence of the collision between the West African Craton (WAC) and a hypothetical island arc to the North [23,31,32,33,34,35,36,37] (Figure 1). The oldest terranes in the southern part of the Bou Azzer inlier are divided into two groups, the Tachdamt-Bleïda and Tazegzaout groups. The first one corresponds to a passive margin formed during the Tonian to the Early Cryogenian and has recently been reinterpreted as comprising two distinct formations [38,39]. The second formation consists of orthogneiss, metagabbro, schists, and pegmatite, with ages ranging from 770 to 700 Ma, using the U-Pb in the orthogneiss and metagabbro [33,40,41,42]. The Tichibanine Ben Lgrad group, located in the northeast part of the Bou Azzer inlier, also has an age between ~761 and ~767 Ma [41] and comprises metagreywackes, arc-related basalts, andesites, rhyolites, and tuffs [43]. The most important Cryogenian terranes correspond to the ophiolite sequence of the Bou Azzer Group [24,31], which includes serpentinized mantle peridotites, sheeted submarine pillow basalts, and locally, a varied set of partly metamorphosed sedimentary rocks. This ophiolite sequence is intruded by diorite, quartz-diorite, and monzodiorite attributed to the Ousdrat unit and dated between 640 and 660 Ma [30,41,42,44]. This unit would be contemporaneous with the obduction of the oceanic crust responsible for the Bou-Azzer and Sirwa ophiolites.

The Ediacaran terranes are divided into three groups. (1) The Tiddiline Group, overlying the Bou Azzer Group, is composed of terrigenous sedimentary rocks (siltstone and conglomerate) locally interstratified with pyroclastic deposits (606 ± 5 Ma) [41]. (2) The Ouarzazate group is made up of andesite, dacite, and rhyolite flows (dated between 567 ± 5 Ma and 566 ± 4 Ma [41] interstratified with polymictic breccia, polygenic conglomerates, and arkosic sandstones. (3) The intrusive magmatic Bou Lbarod Group, including the Bleïda granodiorite (559 ± 4 Ma) [30,41,45], which was generated during the post-collisional metacratonic evolution of the northern edge of the West African craton [30]. A Lower Cambrian carbonate-dominated sedimentary series (Adoudou and Lie-de-vin formations) [25], unconformably overlies the Neoproterozoic formations and has been dated at 541 ± 6 Ma [41].

The Bou Azzer-El Graara inlier is well known for its Co–As–Ni arsenides mineralization, which is also associated with low significance Au and Ag occurrences. The Bou Azzer ore deposits occur along the Anti-Atlas Major Fault (AAMF) in connection with the serpentinite bodies. From west to east, the principal Co–Ni deposits include Méchoui, Taghouni, Filon 7/5, Bou Azzer East, Aghbar, Tamdrost, Agoudal, and Aït Ahmane. Ore mineralization took place in the late Devonian–Carboniferous [27,46,47,48,49,50]. The ore formation model involves a contribution of the basement, quartz diorite, and the serpentinite sequence [48,51]. The study of fluid inclusions reveals the high salinity of the mineralizing fluids, with a weight percentage (NaCl + CaCl₂) ranging between 25 and 30%. The isotopic composition of sulfur in pyrite and chalcopyrite ranges from −6.2 to +4.9, while the oxygen isotopic data in the carbonates range from −2.9 to +1.4%. The formation temperature varies between 150 and 277 °C under a pressure of 550 bars [52]. Recent models predict a mixing between NaCl-dominated saline brines enriched in As, probably originating from a felsic magmatic source and meteoric waters enriched in Ca and S after interaction with buried evaporite and carbonate horizons [46,53,54,55]. It is now widely recognized that the mineralizing fluid circulated along the reactivated Neoproterozoic faults and joints between serpentinites and their adjacent rocks [48,55]. These mineralized fluids captured As, Co, and Au in the regional adjacent rocks and Co, Ni, Fe, and PGE in the serpentinites [46,48,53,54,55,56] and deposited Ni and Ni–Co ores in the fault-related open spaces along the contact between serpentinites and adjacent rocks [48,51,56,57]. Subsequently, infiltration of hydrothermal fluids caused the alteration and partial dissolution of serpentinites [51,56,57,58,59], resulting in the precipitation of Co–Fe arsenide ores along the intra-serpentinite fault zones [51,56].

Figure 1. (a) Geological map of the Anti-Atlas belt with its location on the northern edge of the West African Craton (After [60]). (b) Geological map of the Bou Azzer-El Graara inlier (adapted and compiled from [61,62]).

Figure 1. (a) Geological map of the Anti-Atlas belt with its location on the northern edge of the West African Craton (After [60]). (b) Geological map of the Bou Azzer-El Graara inlier (adapted and compiled from [61,62]).

The study area is located between the Bou Azzer East and Aghbar deposits (Figure 1b). It is an area of about 7 km in the ENE-WSW direction and 2 km in the N–S direction. In this area, no serpentinites, gabbros, or quartz diorite of Cryogenian age are exposed. Only volcanic and volcano-sedimentary rocks attributed to the Ouarzazate Group are exposed, overlain unconformably by Lower Cambrian sandstone and carbonate beds (Adoudou Formation) intercalated with trachyte-andesite lava flows of the Jbel Boho Formation (Figure 2). The Ouarzazate group has been the subject of several petrographic and geochemical studies [28,63,64,65,66,67,68]. As noted above, this group is made up of volcanic rocks (here dominated by rhyolites, dacites, and ignimbrites, compared to basic lavas) [63,69]. U–Pb dating of ignimbrite and rhyolite zircons from the Ouarzazate series yielded ages ranging from ~545 to ~567 Ma. [28,70]. The whole formations are intersected by faults and NE–SW and E–W vein swarms of quartz and quartz-carbonate associated with iron and/or manganese oxides.

3. Sampling and Analytical Methods

3.1. Petrographic Investigations

A sample campaign was carried out to collect rock samples from different outcrops and diamond drill cores. Forty thin sections were prepared at the Research Center and Development of Reminex (Managem Group, Marrakech, Morocco) for petrographic and mineralogical studies using a transmitted- and reflected-light polarized microscope (Optika B-1000). These forty thin sections were also studied using STEM and EDX detectors of the Philips_XL30 scanning electron microscope at the Reminex Center (Managem Group, Morocco). SEM operating conditions were accelerating voltage of 20 kV, beam current of 20 nA and count times of 20 s.

3.2. Ionic Leach Sampling

The ionic leaching geochemistry technique is particularly well-suited for detecting buried ore deposits. It enables the identification of metal ions in soils and sediments derived from deep mineralization transported to unconsolidated surface materials through geochemical processes (diffusion, electromigration, osmosis, etc.) [72]. This method is widely used to delineate buried mineralization associated with polymetallic assemblages linked to specific lithological groups, ore types, hydrothermal alteration, and/or fracturing.

In the Aghbar-Bou Azzer East area, a total of 1704 soil samples and 296 QA/QC (including blanks and duplicates) were collected for ionic leaching analysis. The sampling grid dimension was designed based on major structures within the serpentinite massif. In the central grid, samples were collected using a grid of 100 × 50 m, with profiles spaced 100 m apart and sampling stations 50 m apart. In the western zone near the Bou Azzer East mine, the grid was tightened to 50 × 50 m due to the outcrop of serpentinite massif and an interesting geophysical signature potentially linked to the eastern extension of the buried serpentinite massif ([73]; unpublished). During the sampling campaign, organic horizons, undecomposed matter, and any potential cultural debris were excluded to ensure sample integrity. Approximately 120 g of soil was collected for each sample and placed in a ‘snap seal’ plastic bag, which was then double-bagged with an identical sealed bag. To avoid cross-contamination, sampling equipment was thoroughly cleaned between collections by removing residues from the previous sample and flushing it with soil from the new sampling site.

Analyses were conducted at the ALS Global Laboratory in Loughrea, Ireland, using the analytical code ME-MS23TM package. This technique, referred to as ‘ionic’ geochemical analysis, employs an innovative partial extraction method designed to minimize the attack on the substrate or matrix materials while selectively extracting a range of elements of interest. For surface samples, this approach uses complexing agents to selectively extract and stabilize ionic species from soil, stream, and organic-rich sediments in the leachant solution. The samples were processed as collected in isolated, purpose-built facilities under strict protocols to eliminate contamination and prevent sample loss. Sodium cyanide leaching, enhanced with chelating agents such as amino-carboxylic acids, polyethylenediamines, or thiol acids, was employed to improve the leaching efficiency. The leachate was buffered to an alkaline pH of 8.5, maintaining high stability of the cyanide complex at this pH, thereby creating a low-interference matrix suitable for aspiration. The leachant solution was introduced directly to the ICP-MS instrument using advanced sample introduction technology. This enabled ultralow sub-ppb detection limits (

Table 1. Main statistical variables characteristic of the elements considered and the ICP-MS detection limit.

ppb	Co	As	Ni	Ag	Au	Cu	Mo	Ce	Cd	Pb	Se	Th	U
Median	19.40	22.60	192.00	15.15	1.00	1460.00	78.75	0.70	4.40	1.80	10.00	0.06	0.29
Average	33.46	55.29	232.01	16.35	1.28	1535.98	117.15	0.88	4.77	2.16	11.87	0.08	0.39
Minimum	0.70	1.80	13.00	1.30	0.12	95.00	6.40	0.05	0.40	0.05	2.00	0.01	0.03
First quartile	9.00	11.10	102.00	11.90	0.65	1090.00	49.90	0.40	3.00	1.00	8.00	0.03	0.17
Third quartile	39.90	55.30	320.00	19.00	1.56	1880.00	139.00	1.10	6.20	2.90	14.00	0.10	0.48
Maximum	933.00	1240.00	1340.00	191.00	20.70	12,450.00	1220.00	6.80	23.80	30.50	93.00	0.93	5.42
Standard deviation	45.83	95.64	169.82	9.08	1.08	720.21	110.38	0.67	2.51	1.86	6.89	0.08	0.40
Variance	2098.83	9141.37	28821.81	82.32	1.17	518,402.29	12,176.30	0.45	6.28	3.45	47.38	0.01	0.16
Detection limit	0.30	0.30	1.00	0.05	0.01	1.00	0.20	0.05	0.05	0.10	0.04	0.01	0.03

), routinely achieving ‘natural background’ levels and enhancing the ‘signal-to-noise’ ratio. This increased sensitivity helps detect subtle but significant responses related to mineralization, geology, and alteration, which can be diagnostic of various mineral systems. The Ionic Leach™ package offers the detection of 61 elements, providing comprehensive geochemical insights [74].

This study focuses on the mineral exploration of Co-, Ni-, As-, and Fe-bearing arsenides, along with their associated precious and base metals. Based on previous mineral paragenesis, mineralogical and geochemical studies, we present results for selected elements, including Co, As, Ni, Au, Ag, Cu, Mo, Ce, Cd, Pb, Se, U, and Th (Table 1).

To better quantify anomalies, element populations were segmented into distinct groups, and background values were calculated for each. The anomaly-to-background (A/B) ratios were then determined, allowing for the assessment of anomaly intensity across elements and sampling sites. This approach facilitates direct comparison of geochemical responses regardless of the element’s absolute concentration levels. The outputs include geochemical maps of elemental concentrations, A/B ratio maps, and multi-element indices, all of which were further processed and visualized using Surfer 15 and ArcGIS (10.8) software to enhance interpretation and spatial understanding.

3.3. Structural Controls

To investigate the relationship between the geological structures and the distribution of ionic geochemical anomalies, structural analysis was performed using the ArcPad mobile 10.2 application installed on Trimble tablets and handheld computers. The field microcomputers are equipped with GPS, allowing for the accurate collection of satellite-positioning data and precise surveying of the geologist’s position in the field. Structural measurements (fault, fracture, and vein) are recorded as strike and dip, following the right-hand rule for dip direction. Data processing and analysis were conducted using the Dips (5.103) software from Rocscience.

4. Results

4.1. Structural Analysis

This study draws upon multiple datasets from various sources, encompassing (i) the kinematic behavior of tectonic structures at multiple scales, (ii) the internal textures observed within veins, (iii) geological cross-sections, and (iv) relative chronology of structures.

Structural analyses identified three generations of faults and fractures (Figure 3). The faults of several kilometers in length with variable orientation occur in both the Cryogenian basement and the Ediacaran cover (Figure 4). They belong to the following directional systems: (i) the ENE–WSW family; (ii) the NE–SW family; and (iii) the NW–SE family.

• ENE–WSW system: This fault system forms the boundary of the major lithological units (serpentinites, volcanic rocks) of the Ouarzazate group and quartz diorites. The faults of this system are generally strike-slip faults, often sinistral, and most of them are filled with quartz, carbonate, and iron oxide veins (Figure 5F) with a variable thickness ranging from a few centimeters to a few meters. This system of faults runs parallel to the major Anti-Atlas fault and was formed in earlier Pan-African phases [31,63]. In addition, these faults affect the volcano-detrital series of the Ouarzazate group and the Adoudounian series. This fault system comprises three major striking faults ranging from N 85° to N 95°: the Major North Fault (FMN), the Major Center Fault (FMC), and the Major South Fault (FMS), as shown in Figure 4 and Figure 5F.

The Major North Fault (FMN) is oriented from N 85 to N 95. It crosscuts the Adoudounian cover on the surface. Still, it is assumed that the northern limit of the serpentinite massif is at depth (based on unpublished geophysical data from Geotech and field mapping of this fault). The FMN extends to the central Bou Azzer mine. The Central Major Fault (FMC) can reach a width of ten meters in place. This fault is the western extension of vein 2, which is exploited at Bou Azzer. The filling is composed of quartz-carbonate in nature and may be without filling or hematite in other places. In the study area, the FMC corresponds to the contact between the Ouarzazate volcano-detrital series and the Adoudounian cover. The Major South Fault (FMS) stretches for around twenty kilometers from Aghbar. This fault crosscuts the Cryogenian basement and the Early Cambrian cover (Adoudou Fm.). It is divided into several branches, filled either with quartz and hematite or without filling.

• The NE–SW system is the most abundant Bou Azzer East area. It includes sinistral strike-slip faults oriented from N 40 to N 70 associated with the Pan-African tectonic, which caused NW–SE directed extension during the Ediacaran [63] and which is responsible for the division of the Cryogenian terrain into horsts and grabens (Figure 5A–C). A local and very limited compressive system has been mentioned in the district, generally represented by reverse faults at different scales (Figure 5D,E,G). The NE–SW system is similar to the various strike-slip faults with a sinistral component mapped in the underlying metamorphic basement. These faults control the sedimentation of the Ouarzazate Group series by functioning as normal faults with a strong sinistral strike-slip component [63].

This system includes two main faults titled FM1 and FM2 (Figure 4 and Figure 5F). These faults extend for several kilometers and can be up to 1.7 m thick. The fill is primarily composed of quartz-carbonate and hematite. Structural measurements taken on FM1 clearly indicate normal sinistral strike-slip motion.

• The NW–SE system is poorly represented in the study area. The fault and tension gashes dimensions are not more than several meters, and they are generally centimetric.

The N–S fault, which is rarely documented, crosscuts all the other fault systems mentioned above, including the Adoudou Formation. These faults are filled with quartz, quartz-hematite, and, less commonly, quartz-carbonate.

A structural analysis of the Aghbar-Bou Azzer East mining district has shown that it is controlled globally by ENE–WSW and NE–SW trending faults with or without filling. The mineralogical composition of the fault filling consists of quartz, hematite, manganese minerals, and/or carbonates. All these structures show similarities with other structures in the Bou Azzer district, where cobalt arsenide mineralization has been mined [51,53].

4.2. Ionic Leach Geochemistry

The geochemical results and statistical analysis show three metal categories: Co-arsenides, base, and precious metals. According to the mineralogy and mineral chemistry of the sample material, several elements can be used as proximity indicators of Co-bearing arsenides. These pathfinder elements can be applied in prospection for metal anomalies for the prospection and recognition of the anomalous targets. The structural control of cobalt-bearing mineralization has been extensively documented by numerous authors [51,53,75,76]. In the ABED area, the observed structures, particularly veins-oriented NE–SW and from ENE–WSW to E–W exhibit significant analogies with those found in currently exploited or developing deposits. The integration of structural data with the identified geochemical anomalies, therefore, delineates prospective targets for forthcoming drilling campaigns.

The statistical analysis of the 1704 ionic leach samples reveals significant differences between medians and averages, indicating a strong asymmetry in the distribution of several chemical elements (Table 1). This skewness results from anomalously high values caused by the presence of highly enriched mineralization, particularly in Co-, Ni-, and Fe-arsenides, sulfo-arsenides, and Cu- and Mo-bearing sulfides. These anomalies significantly influence the overall distribution and dispersion of the data. Moreover, Table 1 also highlights a wide range of Co contents, from 933 to 0.7 ppb, with an average of 34 ppb and a variance of 2099. The high values (“signal to natural background noise” ratios) are encouraging; indeed, only 25% of the population studied had a strong Co anomaly, while the 75% quartile showed very low values of 39.9 ppb (Table 1). As and Ni show, respectively, maximum levels of 1240 and 1340 ppb and minimum levels of 1.80 and 13 ppb, with an average of 30 and 38 ppb, which are relatively high, as is Co. In the Bou Azzer mining district, it is well known that Co and Ni are elements that are always associated with As.

The correlation matrix is shown in

Table 2. Pearson correlation coefficient matrix. (r: correlation coefficient).

Correlation	Co	As	Ni	Ag	Au	Mo	Cr	Cu	Th	Ce	Pb	Se	U
Co	1
As	0.59	1
Ni	0.49	0.16	1
Ag	0.39	0.28	0.23	1
Au	0.28	0.3	0.1	0.46	1
Mo	0.44	0.38	0.34	0.18	0.2	1
Cr	−0.13	−0.089	−0.29	0.031	0.12	0.04	1
Cu	0.34	0.2	0.44	0.48	0.27	0.3	−0.072	1
Th	0.22	0.087	0.44	0.021	−0.11	0.0015	−0.24	0.13	1
Ce	0.35	0.17	0.43	0.065	−0.11	0.011	−0.27	0.11	0.63	1
Pb	0.43	0.31	0.24	0.21	−0.037	0.045	−0.16	0.22	0.31	0.43	1
Se	0.33	0.12	0.54	0.22	0.12	0.48	0.04	0.29	0.17	0.17	0.074	1
U	0.64	0.54	0.33	0.049	0.14	0.22	0.37	0.34	0.18	0.61	0.69	0.13	1

, highlighting pairs of elements with varying degrees of correlation: Co–As (r = 0.59), Co–U (r = 0,64), As–U (r = 0,54), Ni–Co (r = 0.49), Ag–Cu (r = 0.48), Se–Ni (r = 0.54), Mo–Se (r = 0.48), Th-Ce (r = 0.63), and Pb–Ce (r = 0.43). The strong correlation between Co and As reflects their close association in cobalt minerals, particularly cobalt arsenides. In contrast, Co exhibits weak correlations with Pb, Ce, Th, Ag, Se, and Cu, suggesting that cobalt-bearing minerals are probably independent of these elements in this setting, suggesting that these elements reside predominantly in separate mineral phases or geochemical domains.

There is very weak correlation between As and Ni, unlike in the Bou Azzer mining district, where nickel-bearing minerals are always expressed as arsenides (nickeline, rammelsbergite, gersdorffite, etc.) [46,58]. These two elements should show a strong correlation. The characteristics of the soil analyzed can influence the relationship between As and Ni; its pH can influence the mobility and distribution of nickel independently of As [77].

Statistical analyses have shown strong correlations between the Co–As, –-Se, Cu–Ag, and Mo–Se element pairs; these correlations will be used to generate anomaly maps. A statistical analysis was conducted (see table in Supplementary Materials) to determine the anomaly thresholds (using Tukey’s method) for each of the analyzed elements. The established thresholds are as follows: cobalt (Co) = 113.8 ppb, arsenic (As) = 110.3 ppb, uranium (U) = 0.94 ppb, nickel (Ni) = 646.12 ppb, selenium (Se) = 28 ppb, thorium (Th) = 0.18 ppb, molybdenum (Mo) = 342 ppb, copper (Cu) = 3114.62 ppb, chromium (Cr) = 11 ppb, gold (Au) = 2.93 ppb, and silver (Ag) = 32.2 ppb.

4.3. Geochemical Analysis Results

The interpretation of geochemical data is divided into two categories: the mono-element and the bi-element treatments.

4.3.1. Mono-Elements

Using the kriging method, the geochemical interpretation of the chemical analyses is given in Figure 6 and Figure 7. These geochemical maps reveal the presence of several positive anomalies of Co, As, Ni, and U. According to the anomaly thresholds for each of the analyzed elements (table of thresholds in Supplementary Materials), these elements are the main chemical elements that characterize the ore mineralization in Bou Azzer. As shown in the mono-element maps (Figure 6 and Figure 7), several distinct anomalies have been recognized in the studied area. The western side of the survey is more anomalous, with occasional peaks in the central area. However, the structural features described above are visible in the eastern and central parts of the map. Areas where certain geochemical anomalies coincide with NE–SW- or ENE–WSW-trending structures represent strategic drilling targets, likely to reveal the presence of mineralization buried beneath these anomalies (e.g., FM1, FMS, and FM2).

4.3.2. Bi-Element Analysis

To find the relationships between the main chemical elements controlling the genesis of economic mineralization, the statistical analysis distinguished several metal categories: Co, As, Ni, Se, U, Cu, and Ag. Using the previous studies on the mineralogical and mineral chemistry of the cobalt mineralization of Bou Azzer [31,48,55,57,75,78,79,80,81,82,83,84], several elements are intimately associated. These chemical pathfinder elements can be used as couples (Co–As, Ni–Se, Cu–Ag, etc.) to create geochemical anomaly maps that will form the basis of subsequent exploration.

The element associations have been generally limited to indices (pairs) having two elements or more. Usually, metal zonation is common and can be attributed to a number of sources (mineralization, alteration, geology, and structural pathways). Incorporating too many elements expands the anomaly but reduces the resolution [72].

• Co–As

The geochemical analysis of soil samples shows a highly heterogeneous distribution of Co and As (Figure 8A). The highest concentrations (above 30 ppb) are found particularly in the northwestern part of the district (near to the Bou Azzer East mine). A few anomalies are also noted in the central and extreme eastern part of the district, near the Aghbar cobalt deposit. Several anomalies cited above are distributed along N–S, E–W, and NE–SW alignments.

Although geochemical anomalies do not always correspond to indications of mineralization, the high concentrations measured in the western part of the district deserve particular attention. In addition, geochemical analysis of volcanic rocks from the Ouarzazate group in the Bou Azzer East-Aghbar area reveals that Co and As contents are, respectively, lower than 120.8 ppm and 71 ppm. The highest value of Co and As in these volcanic rocks (example: 0.19 At% Co and 2.66 At% As) is due to the presence of arsenide minerals disseminated in the volcanic rocks.

• Ni–Se

The anomalies defined by the Ni–Se element pair (Figure 8B) are spatially associated with those of the Co–As pair. The highest concentrations are always found in the central and western sectors of the district. This distribution could correspond to a metallic zonation in the mineralizing system, as seen in the Bou Azzer deposits [31,75,84].

Base and Precious Metals (Cu-Ag)

Cu and Ag display a good spatial correlation (r = 0.48, Table 2), which allows for the definition of clear anomalous zones. The tightest anomalies are concentrated in the northwestern corner (Figure 8C), and a wider, more diffuse zone appears in the southwestern part of the district. These anomalous zones exhibit E–W and NE–SW orientations identical to the directions identified on the Ni–Se and Co–As anomalous maps. Geochemical anomalies of Cu–Ag correspond harmonically to Ni–Se distributions and overlap moderately with Co–As anomalies.

The distribution of several geochemical anomalies for Co, As, and Ni in the Aghbar-Bou Azzer East district is organized along three main directions: NE–SW, NW–SE, and E–W. They are particularly concentrated in the western zone, with minor anomalies in the central and eastern zones. One of the main objectives of this study is to guide drilling operations in the ABED area, which is entirely covered by a continuous Early Cambrian cover (Adoudou Fm.). The integration of geochemical anomalies with the structural map has allowed the identification of several drilling exploration targets, particularly in the western part of the area, towards the Bou Azzer East mine.

4.4. Drill Core Logging

Building on previous geological studies conducted in the Bou Azzer district [31,48,51,63,75] as well as valuable insights gained from ongoing mining operations and the current study, a targeted core drilling campaign was recently initiated in the study area. The objectives are to verify the continuity of the serpentinite massif beneath the Ediacaran cover, to investigate geochemical anomalies identified in the geochemical maps (Figure 8), particularly those aligned with NE–SW, E–W, and ENE–WSW structural trends, and to assess the potential of ionic leach geochemistry. Additionally, the campaign aims to develop a preliminary geological model for the area, which lies between two deposits with distinct genetic models (the Aghbar and Bou Azzer East mines). To support these research goals, a preliminary investigation combining petrographic and ore mineralogical analyses was carried out on drill cores, including newly intersected mineralized zones identified for the first time in the ABED sector.

4.4.1. Petrography

In the Bou Azzer East-Aghbar area, the Cryogenian terrains, which do not outcrop at the surface, consist of serpentinite and quartz diorite identified solely through drill core sampling. Serpentinite in the area occurs as dark green, fine-grained rocks resulting from the alteration of primary minerals such as olivine and pyroxene. This serpentinite is mainly composed of chrysotile and antigorite (XRD data), with minor lizardite (Figure 9A) it is partly dispersed by calcite, dolomite, magnetite, and asbestos (Figure 9A,B). The quartz diorite texture evolves from coarse-grained in the central part of the intrusion to micro-grained at the edges. This rock is composed of zoned plagioclase phenocrysts of biotite, amphibole, and quartz (Figure 9C,D). The plagioclase is altered into albite, sericite, and epidote, while biotite and amphibole are altered into chlorite (Figure 9C,D). The contact between serpentinite and quartz diorite was defined by rodingite resulting from retrograde metamorphism of serpentinite. In addition, these rocks are intruded by micro-gabbro dikes transformed into amphibolite (Figure 9E) [22,25,31,85,86,87].

The Ouarzazate Group in the ABED area rests unconformably on the Cryogenian serpentinite and quartz diorite. It is characterized by a series of sandstone and sandstone-conglomerate layers interstratified with ignimbrites, dacitic, rhyolitic, and andesitic tuffs (Figure 9E–H). Rhyolite facies show a porphyritic texture with large quartz grains (Figure 9F), while dacite and andesite have a porphyritic texture (Figure 9H). These volcano-sedimentary rocks are overlain with an angular unconformity by carbonates attributed to Adoudou Formation of the Taroudant Group.

4.4.2. Ore Mineralogy

Diamond drill cores carried out by the Managem Group (2021–2022), confirmed for the first time the presence of Co–Fe-bearing arsenide ores in the studied area (Figure 10 and Figure 11). The core drilling intersected a brecciated intra-diorite veins and veinlets are filled with arsenides and sulfides associated with quartz and carbonates gangue. Remarkably hydrothermal alterations are recognizable and are comprising chlorite, epidote, gray quartz, carbonates and iron oxides. The contact between quartz diorite and volcano-sedimentary rocks form the Ouarzazate group is marked by the presence of iron arsenide along a brecciated, fractured zone with intense hydrothermal alteration.

The As-bearing minerals are commonly represented by löllingite and skutterudite (Figure 10B–D and Figure 11). Löllingite is the abundant diarsenides and occurs as millimeter-sized rosettes (50–100 µm), often affected by micro-fractures. Bi minerals are included in löllingite rosettes, which can also occur as spindle-shaped crystals. EDX analysis of arsenides shows an As content of about 58.75 wt.%, while the Co, Ni, and Fe contents are 4.41 wt.%, 4.07 wt.%, and 23.87 wt.%, respectively (

Table 3. Analysis of minerals from Fe-Co ores in the studied area (Lo: löllingite, Asp: arsenopyrite).

	S (wt.%)	As (wt.%)	Fe (wt.%)	Co (wt.%)	Ni (wt.%)	Total
Lo	1.07	76.37	22.55			100
Asp	17.11	52.92	29.97			100
Lo		76.67	16.68	6.65		100

).

Skutterudite is less abundant in the studied samples. This Ni-rich tri-arsenide mineral often occurs as massive, millimeter-sized patches or as micrometer to millimeter-sized idiomorphic crystals.

Arsenopyrite is a unique sulfo-arsenide mineral identified in the area, and it occurs as automorphic crystals or as aggregates of isolated crystals.

Sulfide (Figure 11) minerals are represented by chalcopyrite, pyrite, and molybdenite. Chalcopyrite is the most abundant and occurs as automorphic crystals or as xenomorphic patches ranging from micrometric to millimetric in size. It generally fills fractures. Pyrite typically appears in veins or is disseminated throughout the quartz diorite and serpentinites. Molybdenite occurs in millimeter-sized clusters within chlorite and fills late-stage microfractures.

SEM investigations reveal the presence of native Bi in minor amounts appearing in close association with arsenides. Hematite has been observed in the majority of veins in the district, while magnetite is frequently observed in serpentinites.

It is important to note that the data obtained from the drilling campaign remains limited, as the borehole deviated from its intended target. As a result, the quantity of mineralized material recovered was insufficient to fully carry out all the planned analyses. This limitation is further compounded by the operational context of the study, which was conducted within an industrial framework, where access to core samples is often restricted due to ongoing exploitation priorities and company constraints.

5. Discussion

5.1. Structural Features

The Bou Azzer mining district is located in the central Anti-Atlas at the northern boundary of the West African Craton, where the Bou Azzer inlier crops out along the major Anti-Atlas Fault. Previous structural analyses [88,89,90,91] identified four major tectonic phases in the ABED area. The first phase is a compressive event oriented at N 30°, referred to as the B2 Pan-African compressive phase [89], forming major faults trending from N 85° to N 110°, which mark the contact between key lithological units, such as Ouarzazate volcanic formations, serpentinites, and quartz diorite [89]. The second phase corresponds to a WNW–ESE distensive syn-volcanic event, which developed early normal faults trending from N 45° to N 80° (NE–SW fault system) and filled with quartz, hematite, carbonates, and cobalt arsenides at depth, consistent with the Ediacaran syn-volcanic distension reported by [63]. While [92] argue that NE–SW structures primarily affect the Ouarzazate Group without cutting the so-called Adoudounian formations, some NE–SW structures in the ABED area are observed to cut across both. The third phase is a compressive NW–SE trending regime, likely Hercynian, which formed tension gashes along NW–SE orientations [90]. The fourth and final phase is a NNW–SSE compressive event, resulting in the development of NNW–SSE and N–S fault systems, with tension gashes filled by quartz, hematite, and carbonates. This sequence highlights the complex structural history of the ABED area, shaped by successive tectonic events.

In the Bou Azzer district, the orebodies exhibit three main stages of mineral deposition [53,54]. (1) The first stage includes a pre-arsenide assemblage marked by the association of chlorite, quartz, and minor muscovite and calcite. (2) The second is an arsenide ore stage, which is subdivided into three mineral assemblages: Ni-rich arsenide minerals, Co–Ni-rich arsenide minerals, and Co–Fe-rich arsenide minerals (e.g., [31,48,51,54,55,56,58]. (3) The third is a post-arsenide ore stage, which is characterized by the precipitation of sulfides associated with late-stage quartz and calcite. Metals and minerals such as gold, silver, molybdenite, bismuth, bismuthinite, brannerite, uraninite, and sphalerite are locally abundant in some deposits (Bou Azzer East, Méchoui, Filon 7/5, Aït Ahmane, etc.; [23,31,79,83]). However, their contents and distribution are too irregular to be of economic interest. The metal zonation revealed by the ionic geochemical study is common and can be attributed to various processes related to hydrothermal activity, weathering alteration, and other factors.

5.2. Ionic Leach Geochemistry Versus Conventional Geochemistry

The ionic leach geochemistry technique is now routinely used in exploration strategies. In Morocco, this method was first applied in the Bou Azzer inlier in 2021 for a cobalt project. In 2022, the Managem group tested this technique in Bleida district for copper and in Imiter for silver (Ag) exploration. A comparison of ionic leach geochemistry surveys with conventional geochemical surveys across various mineralization styles and settings reveals some key differences. In some areas, ionic leach geochemistry shows a recognizable contrast, while conventional methods may show either poor or no anomalies, particularly in regions with deep weathering or mature overburden. Such situations are common for more chemically mobile elements like Zn, Cd, Co, and Ni [14]. Often, ionic leach geochemistry produces sharper, higher-contrast anomalies that more directly overlie the mineralized zones compared to conventional techniques (Figure 12). In some cases, the broader conventional geochemical anomalies are displaced. However, ionic leach geochemistry anomalies are less likely to be affected by lateral surface transport for two reasons [14]: (i) they are continuously converted to bound metal, causing a decrease in the proportion of the total metal over time and distance from the source; (ii) Being mobile, rainfall can flush back into the soil profile. In the case of buried, low-grade, or disseminated mineralizations, as well as areas with active mechanical transport (such as in mobile dunes and lacustrine environments), conventional geochemical techniques may fail to provide a recognizable surface anomaly if the detection limits of the instruments are inadequate. However, with the advancement of analytical techniques, the ionic leach geochemistry method can help resolve some of these challenges. Due to its ability to detect mobile metal ions released by mineralization before their fixation in the soil, ionic leach geochemistry is particularly effective in accurately locating deeply buried primary mineralization (Figure 12). This method offers a significant advantage over conventional geochemical techniques, which generally highlight anomalous zones without precisely identifying the source or depth of the mineral deposit.

According to Bradshaw [93], the complexity of geochemical processes involved in the fixation of metallic ions within the subsurface soil horizons cannot be explained by a single mechanism. However, the work of Amedjoe [94] highlights the potential for vertical migration of mobile metallic ions (including Ni, Co, As, Cu, Pb, Au, etc.) toward the surface, thereby enabling their detection during sampling campaigns. The elevated anomalous responses observed particularly in proximity to NE–SW and from ENE–WSW to E–W oriented structures likely indicate significant subsurface metal concentrations, which may be associated with an underlying gold deposit.

Mann [95] proposed a new conceptual model for the formation of soil geochemical anomalies. The model suggests a dynamic equilibrium between bound and unbound metals in the soil horizons. Three processes are outlined for the formation of geochemical anomalies: (i) the emission of unbound metals into the soil layer, which occur through gaseous transport, hydromorphic alteration of mineralized rocks, or a combination of both; (ii) the creation of bound metals from unbound metals during soil development; and (iii) the lateral dispersion of bound metals, which may be related to gravitational processes (such as fluvial or aeolian transport). In contrast, Bradshaw [93] proposes that the geochemical anomalies form through the incorporation of metals from a mineral concentration into a soil developed by the alteration of bedrock. According to Bradshaw [93], metals in soils are generally weakly bound, which contrasts with the interpretation of Mann [14], who argued that initial alteration fluids containing unbound metals are located near the source, with the bound form of the metals being mechanically dispersed.

However, in the ABED area, several geochemical anomalies identified for the Co–As, Ni–Se, and Cu–Ag pairs (Figure 8) coincide with three orientations (NE–SW, E–W, and NW–SE). This spatial distribution pattern indicates that fracturing likely plays a critical role in controlling the surface dispersion of metal ions, as suggested by Cameron [15]. In arid and semi-arid environments, such as the Anti-Atlas region, the mobility and migration of chemical elements through geological formations are primarily governed by the presence and orientation of fractures and faults, which act as conduits for geochemical transport. In some cases, there is no clear spatial relationship between the anomalies, which can be explained by the mechanical transport of elements or by the porosity of the bedrock, which may allow the migration of metallic elements to the soil.

The most prominent geochemical anomalies are primarily concentrated in the central and western parts of the district, which are also characterized by a high density of fractures associated with the previously defined FM1, FM2, and FMS systems (Figure 7 and Figure 8). This correlation suggests that the transfer of metals from the deep ore deposits to the surface may be controlled by fracturing. Furthermore, these anomalies are typically discontinuous and especially pronounced at fracture junctions (tectonic nodes) (Figure 12). These tectonic locations represent potential targets for a subsequent survey program.

5.3. Drilling Validation

In the Bou Azzer district, Co–As–Ni arsenide ores are associated with serpentinites from the ophiolitic sequence. To evaluate the ionic leach geochemistry anomalies, oriented core drilling was conducted, guided by interpreted structural data and the spatial distribution of ion geochemical anomalies (Figure 13). Recent geophysical interpretations from the airborne survey data revealed the significant magnetic and electromagnetic signatures at depth [96].

The study conducted in the ABED area has demonstrated the effectiveness of ionic geochemistry as a tool for exploring buried ore deposits. A number of geochemical anomalies show a significant correlation with a fault network-oriented NE–SW, from ENE–WSW to E–W, and N–S structural orientations known to play a major role in controlling mineralization at the district scale. This relationship is further supported by detailed structural analysis, which reveals a highly tectonized area traversed by several major fault systems. In particular, the faults are oriented along NE-SW and ENE–WSW directions. The Co–As–Ni ore bodies can be classified into two types based on their morphologies. The first one, known as “contact-type ore”, consists of flame-shaped bodies, flat lenses, and pocket-like masses, ranging from ENE–WSW to WNW–ESE, located at the contacts between serpentinites and adjacent rocks such as quartz diorite or, locally, gabbros, younger volcanic, and sedimentary rocks from the Ouarzazate Group [31,51,53,75,76,97]. The second type, called “crosscutting-type ore”, occurs as veins ranging from N–S to NE–SW that intersect the contact between serpentinites and adjacent rocks (quartz diorite, gabbro, younger volcanic rocks from the Ouarzazate group), which shows the economic ore decrease further away from this contact [51,53,75,76,98]. The fracturing analysis carried out for this study reveals the same directions as those previously known throughout the Bou Azzer inlier and in the Bou Azzer-East mine. All converging lines of evidence indicate that areas simultaneously characterized by significant geochemical anomalies, proximity to well-defined tectonic structures, and the presence of serpentinite are particularly favorable for the concentration of cobaltiferous mineralization. In this context, it appears relevant to prioritize the implementation of exploratory drilling at the intersections of geochemical anomalies and NE–SW- or ENE–WSW-oriented structures. Special attention should be given to contact zones between serpentinite units and the surrounding host formations, where fracturing may have played a key role in facilitating the circulation and concentration of mineralizing fluids (contact-type setting). The geochemical anomaly maps, combined with structural data presented in Figure 8, highlight several targets that meet all the favorable criteria for the presence of buried mineralization. These include anomalies associated with NE–SW-oriented structures (FM1 and FM2), as well as others located in the northwestern area and in the northeastern zone near the Aghbar mine.

To investigate these anomalies, a program of oriented diamond drilling has been initiated. The first drill hole was designed to intersect the contact between the FM1 structure and the serpentinite beneath a geochemical anomaly that coincides with the FM1 quartz-carbonate-filled vein. The second drill hole targeted a junction zone involving FM1, FMC, and the serpentinite, also located beneath a surface geochemical anomaly.

As a result, the exploration drilling carried out by the Managem Group confirmed the presence of mantle rocks at depths ranging from 500 to 1000 m below the surface. The oriented drill core in the studied area intersected quartz diorite intrusions and serpentinite bodies. These serpentinites exhibit an average orientation of N100° (ESE–WNW) with a dip of 70° on the southern flank and 72° on the northern flank. Multiple traces of Co–As–Ni mineralization were detected along the contact between serpentinites-quartz diorite, and volcano-sedimentary rocks from the Ouarzazate Group. Therefore, in the ABED area, Co–As–Ni ore is located along the contact between serpentinites and adjacent rocks at a depth of approximately 1100 m (contact-type ore). Quartz- and carbonate veins-trending NE–SW (crosscutting-type ore) emanate from this contact and are already exposed at the surface. Brecciated intra-diorite faults were filled with cobalt arsenide minerals, chalcopyrite, and molybdenite, accompanied by quartz and carbonates gangue. The formation of these faults was associated with an alteration process characterized by the presence of chlorite, epidote, silica, carbonate, and iron oxides. The contact zone between quartz diorite and volcano-sedimentary rocks from the Ouarzazate Group was marked by the presence of iron arsenide within a brecciated and fractured zone exhibiting intense hydrothermal alteration (Figure 10).

The diamond drill core confirmed, for the first time, the presence of Co–As–Ni ores in the ABED area. This also validated several ionic geochemistry anomalies and supported the geological and exploration models for the region (Figure 13).

5.4. Mineral Paragenesis

As stated earlier, this study represents the first instance of intersecting cobalt-bearing mineralization in the ABED area. These mineralizations occur either in disseminated form within brecciated zones in quartz diorites or as centimeter-thick veins of calcite and quartz. However, the limited extent of mineralization intercepted by the diamond drill cores, which are not yet representative of the entire deposit, given the early exploration stage, restricts a comprehensive assessment of the deposit. As a result, the current analysis is primarily based on macroscopic observations of the drill core and petrographic examination of polished sections, aimed at characterizing the textural relationships among the various mineral phases encountered.

Previous studies on the Bou Azzer mining district [54,75,99,100] generally agree on a paragenetic sequence of the mineralization that begins with arsenides, followed by sulfo-arsenides, and finally sulfides.

In the ABED area, the textural relationships between the mineralization and the gangue result from several stages of paragenesis, marked by crosscutting, brecciation, and overgrowths. Stage I is characterized by the appearance of skutterudite I and disseminated löllingite I. Stage II is marked by the crystallization of löllingite II and skutterudite II in calcite and quartz veins. Stage III involves the appearance of arsenopyrite, which contains löllingite minerals, and arsenopyrite is the sulfo-arsenides observed to date in the ABED area. Stage IV marks the deposition of sulfur minerals, including chalcopyrite, pyrite, and molybdenite, which are associated with forming carbonates and chlorite in veins. The late-stage V corresponds to the formation of iron and manganese oxides. Additionally, gold has been observed in the form of micro-veinlets, while supergene alteration minerals, such as erythrite, heterogenite, and annabergite, have not been recognized in the study area. This paragenetic sequence and the associated mineral assemblages provide key insights into the mineralization processes and serve as a foundation for further exploration in the ABED area.

Primary ore mineralogy observed in diamond drill cores reveals that veins and veinlets cutting the quartz diorite are filled with arsenide and sulfide minerals, along with calcite and chlorite. The mineral assemblage includes löllingite, Co-rich skutterudite (CoAs3), chalcopyrite, and Cu–Mo-bearing sulfides. Löllingite is also present within intense hydrothermal alteration zones along the contact between quartz diorite and volcano-sedimentary rocks from the Ouarzazate Group. In the studied area, the initial occurrence of ore mineralization in quartz diorite could be related to the crosscutting ore type, as described in other ore deposits by Tourneur [51]. Ore minerals found at the contact between quartz diorite and volcano-sedimentary rocks may suggest a contact-type ore, although its morphology remains under question. This could be related to the contact type ores as described by Tourneur [51] in nearby ore deposits. Ore minerals’ assemblages found in the Bou Azzer East-Aghbar area are typically described as disseminated within serpentinites [51,56]. However, the serpentinite samples were observed in proximity to the intense hydrothermal alteration zones, necessitating further investigation through deeper drilling to assess the relationship between this ore mineralogy and the serpentinite massif.

Based on the detailed paragenetic sequence of Co–Ni–Fe-bearing arsenide ores from the Bou Azzer mining district [48,53,54], the ore minerals recognized in the Bou Azzer East-Aghbar area can be associated with Fe–Co–rich ores and the late epithermal stage. Diarsenide minerals are related to löllingite from the Fe–Co-rich ores and are often found in association with Fe-rich skutterudite. The late ore stage was marked by the precipitation of sulfides such as chalcopyrite, pyrite, and molybdenite, associated with late-stage quartz and calcite formation.

6. Conclusions

By integrating structural mapping, ionic leach geochemical investigation, and comprehensive mineralogical characterization, this study provides critical insights that enhance the understanding and strategic targeting of mineralization at the Aghbar-Bou Azzer East deposit (ABED). The main conclusions are as follows:

• In the ABED area, a thick layer of volcanic rocks (rhyolite, dacite, ignimbrite, etc.) is interstratified with chaotic breccia and polygenic conglomerate outcrops. These volcano-sedimentary rocks belong to the Ouarzazate Group and they are overlain by the Adoudou Formation through an angular unconformity.
• The area is intersected by three family of faults and fractures: (i) the ENE–WSW family; (ii) the NE–SW family; and (iii) the NW–SE family, some of which are filled by quartz and quartz-carbonate gangues containing iron and/or manganese oxides. These fault systems are similar to those hosting mineralized in neighboring deposits.
• Multiple geochemical anomalies of Co, As, Ni, Ag, U, and Cu follow the main structural trends (NE–SW, NW–SE, and E–W). These anomalies are most prominent on the western side of the study area, with more subdued signatures in the central and eastern sectors.
• The integration of geochemical anomalies with structural data has enabled the identification of high-priority targets for the exploration of concealed ore bodies. Within the Bou Azzer inlier, several areas, particularly those analogous to the ABED zone located east of Aghbar toward Aït Ahmane, warrant the implementation of ionic leach geochemical surveys. Such efforts would be especially valuable in regions lacking surface exposures of serpentinized rocks.
• Due to its ability to detect mobile metal ions released by mineralization before fixation in the soil, the ionic leach geochemical method provides a precise tool for locating deeply buried mineralization.
• Diamond Drilling and structural mapping results confirm the continuity of the serpentinite massif beneath the Ediacarian volcano-sedimentary deposits. The core study also highlighted the presence of Co–Fe-bearing arsenides for the first time in this area.