Dang-Patou area is situated in the East region of Cameroon precisely Lom and Djerem Division and Betare-Oya District. Betare Oya is underlain by a series of granitic rocks, including granodiorite and tonalite, that are locally cut by systems of gold-bearing quartz veins (Figure 1) [1][2]. This zone can be reached through Mararaba from Betare-Oya or Mabele through Beka-Guiwang. It is also accessed by following the 271 km road from Meidougou (Figure 2). The metallotectic

Figure 1. Geological map of Cameroon, modified [2].

Figure 2. Location map of Dang-Patou (a) East region; (b) Lom and Djerem division, Betare-Oya district; (c) Betare-Oya district; (d) study zone.

context of an auriferous zone refers to the metallogenic factors that contribute to the formation and distribution of gold deposits and crucial for exploration [3]. These ore-forming processes are identified from existing literature about the mineralization system [4]-[6] and spatially using GIS analysis to predict mineral potential in the study region. Mineral deposit locations for hard rock gold mineralization were extracted from the GERM mineral deposit database [7]. Alluvial or eluvial gold deposits can have various sources, and involves studying the processes that led to the mineralization of the gold [8]. The primary Au ore is hosted in the biotite and muscovite granite and occurs mostly as structurally controlled (veins, veinlets and stockwork) and locally disseminated ore. The structure of mineralization gold, the mineral assemblage, the host rock composition, and the geodynamic setting of Adamawa region and particularly around Meiganga area are presented [9]. Several geological criteria for gold mineralization were compiled from different references [10]-[14] that appear to be suitable for this area, such as Banded Iron Formation (BIF), Quartz veins, Major Faults, and Dykes. These gold deposits are typically found in river beds, flood plains and other areas where water flow has transported and concentrated gold particles from their primary sources. Satellite remote sensing images have been widely and successfully used for mineral exploration since the launch of Landsat in 1972 [15][16]. Many ore deposits have been recognized using satellite imagery [17]-[19]. This paper provides further information on the location of potential mineralization zones of the Dang-Patou area using field data and remote sensing techniques to identify mineral resources. Moreover, it presents the lithologic types of the study area and uses the simple image processing methods to do the geological mapping of gold deposits and other mineralization. This includes the mineralogy, structural geology, and remote sensing data recording information based on material composition and the analysis of many geological features essential for the gold exploration.

The eastern region of Cameroon is characterized by significant gold mining activities. The most dominant area of shearing is situated along the contact between undated high-grade migmatitic gneisses and schists, and the eastern edge of the Lom Belt defined by the Betare-Oya Shear Zone [20]. Some veins cut the Neoproterozoic metavolcanic-metasedimentary rocks, undated older metamorphic rocks, and the Pan-African plutonic rocks, but other auriferous veins occur along the contact between rock layers [21]-[24] and [25]. The rocks of the Lower Lom Belt can be grouped into three categories based on their structure and mineralogy, with gold occurring in all three types of rock, ranging from the edges to the middle of the belt. Veins are most commonly composed of hydrothermal minerals such as quartz, carbonates, chlorite, muscovite, sulfides, and/or tellurides [26]. These include chlorite-sericite schist, which is linked to the edges of the ductile to brittle shear zones and includes the Betare-Oya Shear Zone. The chlorite-sericite schists are strongly deformed, with interbedded quartz veins displaying pinch-and-swell and shearing features, which appear to represent Riedel structures related to the main shear zone. The schistosity generally has a high to moderate northwesterly dip. The mineralogical composition of the schist is dominated by quartz, ilmenite, rutile, zircon, pyrite, muscovite, sericite, and staurolite. Garnet, magnetite/hematite, and graphite have also been identified in this region. The Betare Oya area is part of the Neoproterozoic (700 - 1100 Ma) volcano-sedimentary formations of Cameroon or schist belts, which are also known as the Lower Lom series. These rock formations can be found on top of the Pan-African basement, which is made up of migmatite and granitic to orthogneissic, biotite-rich rocks. These rock formations are found in the NE-SW trending shear zones as part of the Central African and Cameroon shear zone [27]. The Betare Oya gold field is found within a major shear zone that represents extensions along the Sanaga fault line. This structure is found in the valleys formed when rock blocks are moved along faults and bears a resemblance to other basins that have been formed by rock blocks moving along faults [28]. It is hypothesized that the basin was filled with eroded and transported materials from N30E-N40-E striking gold-bearing quartz veins [29][30] and slightly changed quartzites and granitoids.

The structural geology and tectonic setting of hydrothermal gold deposits are critical factors in understanding their genesis and guiding exploration strategies. In gold exploitation, geologic fractures play a crucial role in the formation and concentration of gold deposits. They act as pathways for gold-bearing fluids and also as structural traps for gold accumulation. The lithology of the study area is traversed by several fractures trending from N-S to E-W. Fractures ranging from centimeters to meters were observed in several outcrops in our zone of study. The major direction of fractures observed is N53˚E (Figure 8(a)). The area’s fractures show that the NE-SW is the dominant structural direction. The veinlets and veins are fracture zones strongly stained with small rounded grains distributed throughout, with their size between 2 and 5 cm (Figure 8(b)). A defining characteristic of these deposits is pronounced structural control on mineralization.

Figure 8. (a) Fractures observed on rocks, (b) veins intruded in the gneiss.

The map below (Figure 9) is an assemblage of all the relevant information obtained during data collection, treatment, and interpretation. From this map, we can notice lineaments aligned with the hydrographic network and the presence of mineral indices (iron oxide, clay, and ferrous minerals) in zones of high density, confirming what was observed in the field. The area is made up of very low, low, moderate, high, and very high concentrations of lineaments. The very low concentration areas are in grey, low areas in cadet blue, moderate areas in yellow, high areas in orange, and very high areas in red, respectively. Some points correspond to old mining sites, while others correspond to points where villagers conduct small-scale artisanal mining. Already exploited zones or zones under exploitation can be seen in red, and zones not yet under exploitation in black. The geological map (Figure 9) shows that lineaments are highly concentrated on undifferentiated gneisses, as well as mineralization, explaining the traces of eluvial gold found in the field.

Images enhancing hydrothermally altered rocks using band ratios with distinctive reflection features were produced. This corresponds directly to minerals associated with this alteration and represents the surface expression of auriferous deposits. Areas with abundant iron oxide-bearing minerals (formula B4/B2), ferrous mineral indices (formula B6/B5), and clay minerals (formula B7/B5) were found using the ratio of Landsat 8 OLI band 4 over band 2. The band ratio is used to differentiate altered rocks from unaltered rocks. Using Sabin’s ratio, we combined these three 4/2, 7/5, and 6/7 as RGB for lithological mapping.

Figure 9. Potential mineralization map of the Dan Patou area showing lineament density, hydrographic network, and mineral indices.

Macroscopic and microscopic analyses were conducted on plutonic igneous rocks (granites) and metamorphic rocks (gneisses) in the Dand Patou area. Several light-colored, fine-grained intrusive bodies were identified, comprising both granite and gneiss. These two facies are generally distinguishable in the field, including biotite gneiss and muscovite gneiss, though minor outcrops exhibit ambiguous similarities that may have led to misclassification. The fresh granite exhibits a gray coloration and contains rounded to ovoid phenocrysts of gray K-feldspar (up to 2 cm across) with a medium-grained matrix of quartz, orthoclase, and microperthite.

The application of field, remote sensing data, and strategic prospection is a successful approach in mineral exploration and the research of mineral resources. This approach is done through the study of rock samples, their mineralogical properties, and the treatment and interpretation of remote sensing data [39]. The rocks from the study zone are rich in quartz, and some outcrops even display several quartz veins. Classification of quartz textures in epithermal vein systems has been presented by many researchers many years ago [40][41]. Recent studies have noted that quartz textures in epithermal gold veins can provide evidence about mineralization processes [42]. The presence of a quartz vein can indicate the potential of an area to host mineralization in the surrounding rocks [42]. Folding and foliation are important geological structures that play a crucial role in the formation, concentration, and distribution of gold deposits. Folding and foliation are often associated with regional metamorphism, which can result in changes in rock composition and mineral assemblages.

Microscopic observations show that biotite and muscovite can be observed together in the same rock. Biotite in the alteration zone was altered to chlorite, and K-feldspar was altered to sericite by the sericitization process, which is the result of a mineral crystallization process that occurs in hydrous magma conditions in the liquid phase [43][44]. The occurrence of microcline and perthite in granites and gneisses may be linked to the low temperature of metamorphism and suggests that the regional metamorphism of Adamawa has been weak in this locality.

The occurrence of quartz veins and fractures in the studied rocks indicates that during the ascent of the magma that was emplaced in the hypabyssal subsurface, the crust became domed, and fractures developed, thus providing channels for magmatic hydrothermal fluids to migrate. Gneisses from the study area are deformed and display folds and foliation, testifying to the subsequent tectonic activities along the Betaré-Oya fault. Mineral accumulation was identified in thin sections by the presence of opaque minerals, which mostly consist of heavy metals like gold, chromium, and iron, suggesting the sources of eluvial gold deposits. In the thin sections, the presence of opaque minerals included in quartz may suggest magmatic mineralization or enrichment of the rock in metallic minerals such as pyrite, chalcopyrite, and gold, which have been observed macroscopically in the rock samples from the study area. The presence of quartz veins and intrusions is a strong indicator of the post-magmatic processes responsible for mineralizing fluids. The presence of a quartz vein can indicate several important geological characteristics, such as hydrothermal activity, which generally leads to mineral concentration. These veins are excellent exploration targets and structural controls of mineralization [43]. The epigenetic nature of the quartz veins observed in this zone reflects a complex geological history encompassing hydrothermal fluid circulation, brittle deformation (fracturing and faulting), pressure-temperature fluctuations, and metasomatism.

Figure 12.Geological map of the potential mineralization zone of Dang Patou.

A lineament map was the main icon used to correlate lithological formations and mineralization zones. It shows that the area has many fractures (contacts) that can be linked to the presence of mineralization zones in this area, since the exploitation carried out is from the primary source formed by the in-situ weathering of the bedrock. The identification of mineralization zones through lineaments is due to the fact that lineaments result from tectonic activities where there is an unusual accumulation of useful minerals [44]. Lineaments are generally considered as favorable zones of mineralization due to the presence of post-magmatic fluids [45]. The accumulation of useful materials in lineaments is due to constant alteration and transportation of heavy minerals by post-magmatic fluids. Post-magmatic fluids transport minerals along lineaments, and the surrounding rocks are subjected to intense alteration, hence liberating heavy minerals which arrive at the surface. Major faults and fractures that might hold minerals and have mining potential were recognized by the high lineament density [46]. The presence of an epigenetic quartz vein in granite is indicative of a complex geological history involving the circulation of hydrothermal fluids, fracturing and faulting, and pressure and temperature changes. These veins are used as pathways for mineral-rich fluids, suggesting a potential for mineral deposits within the surrounding rocks. The distribution of lineaments, particularly their intersections, has been utilized to elucidate and predict the spatial localization of magmatic and hydrothermal mineralization as documented by [47][48]. A combination of indirect Landsat images and geological information has been used to define lineaments in Dang Patou. The relationship between these lineaments and mineralization is explored with a strong control on the gold distribution. The use of lineament intersection relationships for mineral exploration gains increased validity when defined through a multi-technique approach, such as the integration of remote sensing and geological methods. The applicability of this approach can be evaluated by incorporating known metallogenic information, which can be a guide to identify the favorable structural settings of gold deposits in the Dang Patou geological context. The geological map presented in Figure 12 synthesizes all pertinent information derived from data collection, processing, and interpretation. Areas are color-coded to represent varying concentration levels. Very low concentrations are depicted in grey, low concentrations in cadet blue, moderate concentrations in yellow, high concentrations in orange, and very high concentrations in red.

The use of field data and remote sensing techniques in the study of the metallotectic context of Dang-Patou has proven to be a valuable approach in delimiting potential mineralization zones. The combination of data processing and fieldwork provided the geological and structural features, leading to a better understanding of identified potential gold mineralization. The field data documented herein confirm that the mineralization zone and related veins represent a structurally controlled gold-bearing quartz vein system. This approach has not only helped identify areas with high mineralization potential but also allowed for the identification of key geological controls and structures that influence the distribution of gold deposits. The petrographic characteristics and satellite minerals (pyrite, blende, chalcopyrite) and pedologic profile show different types of gold deposits (dissemination, vein, and placer). The fieldwork (petrography and structural geology) shows the potential mineralization map, which corresponds to very high, high, and moderate concentrations respectively circled in red and black. Gold exploration in the Dang-Patou is supported by the presence of two spatially associated plutonic rocks and metamorphic rocks affected by post-magmatism processes through the presence of veins and quartz veins generally accompanied by mineralizing fluids. This temporal constraint is necessary to distinguish epigenetic mineralization features from post-mineralization structures and alteration. The occurrence of pyrite, blende, and chalcopyrite in the quartz veins constitutes an indicator for researching the eluvial gold and suggests the significant role of hydrothermal fluids in the gold deposits. The combination of the geological data and the lineament map shows that the lineaments are highly concentrated on undifferentiated gneisses. This is confirmed by the presence of eluvial gold grains on some gneiss samples in the study area. The structural control of quartz veins and hydrothermal alteration, and alteration assemblages comprising mainly Bt, Qte ± Au, Pyr, indicate that the mineralization is classified as hypozonal orogenic gold class of Au deposit.

Ntoumbé Mama contributed to the conceptualization, fieldwork, methodology, mapping, analysis, and writing of the article. Ntieche Benjamin participated in elaborating the methodology, mapping, and the revision of the manuscript, Mounjouohou Aziz, Amaya Adama, Nchare Mominou, and Dang Vanisa, Guihdama Dagwai contributed to mineral observation, interpretation, and reviewing the manuscript, NGounouno Ismaïla was involved in constructing the methodology, review, and analysis. All authors have read and agreed to publish this version of the manuscript.

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.