Abstract:The West African region has long been known for its gold endowment and gold production. Apart from the last 20 to 30 years, this production was largely derived from informal artisanal workings covering large areas of West Africa. For a period of over a thousand years until 1500 AD, West Africa was the world's most important supplier of gold, much of which formed part of the trans-Sahara trade with the Arab world, whose monetary system was based on gold. Artisanal gold mining is still widespread across West Afr… Show more
“…Gold-bearing quartz veins are associated with sulphides and oxides minerals and would be from hydrothermal related to magmatism. The existence of several structures favourable to mineralisation proves that it is possible to discover gold deposits through research focused on their geological and metallogenic contexts, which is in agreement with Robertson and Peters (2016); which showed Bénin is located close to big gold deposits in Ghana and Burkina Faso (Figure 6). There is a reason to believe that the mineralisation potential could extend into Bénin as similar-aged rocks to those hosting big deposits in West Africa appear to extend into the country.…”
Section: Discussionsupporting
confidence: 83%
“…There is a reason to believe that the mineralisation potential could extend into Bénin as similar-aged rocks to those hosting big deposits in West Africa appear to extend into the country. Figure 6 Generalised geological and structural map of the West African Craton showing the distribution of gold mines, deposits and occurrences (Robertson and Peters 2016). …”
Section: Discussionmentioning
confidence: 99%
“…The Pan-African Belt of West Africa has long been known for its gold endowment and gold production, with informal artisanal mining having taken place for centuries (Robertson and Peters 2016). In Benin, gold occurs both as primary mineralisation and secondary mineralisation (alluvial deposits; Chermette 1938Chermette , 1939Chermette and Olori-Togbé 1966;Kriatov et al 1980Kriatov et al , 1995Yessoufou 1991).…”
Gold in Benin occurs as primary and alluvial forms in various deposits and occurrences. The mineralisation has a regional distribution covering, in particular, the Atacora area (Natitingou) and the regions of Bembèrèkè, Djougou and Dunkassa which are between the 9th and 11th parallel north. The data collected during previous work allow us to recognise the main style of primary gold as being quartz-vein hosted. This style occurs principally in quartzite, mica schist, schist and amphibolite lithologies, outcropping in the criss-crossing of the faults and the rugged relief. The mineralised veins are milky, deformed and gold is associated with sulphides and tourmaline. In these veins, gold exhibits three forms: free native metal, tellurides, and combined or included in sulphides. These gold-bearing quartz veins would proceed from hydrothermal solutions related to granitic mass. Classical characteristics available about the primary gold mineralisation in Bénin are inadequate to better clarify its geodynamic context. However, it has some similarities with deposits of the Precambrian terranes in adjacent countries (Pourra deposit in Burkina Faso and Kalana deposit in Mali) which are characterised by epigenetic gold deposits in Precambrian metamorphic terranes. Also, the vein gold of Bénin are mostly located in Precambrian metamorphosed sedimentary and volcanic formations ; these could also have the epigenetic disseminated gold style like in some West African deposits (Ashanti deposit).
“…Gold-bearing quartz veins are associated with sulphides and oxides minerals and would be from hydrothermal related to magmatism. The existence of several structures favourable to mineralisation proves that it is possible to discover gold deposits through research focused on their geological and metallogenic contexts, which is in agreement with Robertson and Peters (2016); which showed Bénin is located close to big gold deposits in Ghana and Burkina Faso (Figure 6). There is a reason to believe that the mineralisation potential could extend into Bénin as similar-aged rocks to those hosting big deposits in West Africa appear to extend into the country.…”
Section: Discussionsupporting
confidence: 83%
“…There is a reason to believe that the mineralisation potential could extend into Bénin as similar-aged rocks to those hosting big deposits in West Africa appear to extend into the country. Figure 6 Generalised geological and structural map of the West African Craton showing the distribution of gold mines, deposits and occurrences (Robertson and Peters 2016). …”
Section: Discussionmentioning
confidence: 99%
“…The Pan-African Belt of West Africa has long been known for its gold endowment and gold production, with informal artisanal mining having taken place for centuries (Robertson and Peters 2016). In Benin, gold occurs both as primary mineralisation and secondary mineralisation (alluvial deposits; Chermette 1938Chermette , 1939Chermette and Olori-Togbé 1966;Kriatov et al 1980Kriatov et al , 1995Yessoufou 1991).…”
Gold in Benin occurs as primary and alluvial forms in various deposits and occurrences. The mineralisation has a regional distribution covering, in particular, the Atacora area (Natitingou) and the regions of Bembèrèkè, Djougou and Dunkassa which are between the 9th and 11th parallel north. The data collected during previous work allow us to recognise the main style of primary gold as being quartz-vein hosted. This style occurs principally in quartzite, mica schist, schist and amphibolite lithologies, outcropping in the criss-crossing of the faults and the rugged relief. The mineralised veins are milky, deformed and gold is associated with sulphides and tourmaline. In these veins, gold exhibits three forms: free native metal, tellurides, and combined or included in sulphides. These gold-bearing quartz veins would proceed from hydrothermal solutions related to granitic mass. Classical characteristics available about the primary gold mineralisation in Bénin are inadequate to better clarify its geodynamic context. However, it has some similarities with deposits of the Precambrian terranes in adjacent countries (Pourra deposit in Burkina Faso and Kalana deposit in Mali) which are characterised by epigenetic gold deposits in Precambrian metamorphic terranes. Also, the vein gold of Bénin are mostly located in Precambrian metamorphosed sedimentary and volcanic formations ; these could also have the epigenetic disseminated gold style like in some West African deposits (Ashanti deposit).
“…La teneur de coupure permettant la séparation entre la minéralisation et l'encaissant varie selon les exploitations minières et en fonction du contexte géologique. Elle est de l'ordre de 0,3 g/t pour la mine de Samira au Niger, 0,74 g/t à Siguiri en Guinée (Lebrun et al, 2017) 0,60 g/t à Morila au Mali et 0,98 à Bamboré au Burkina Faso (Robertson and Peters, 2016). Comparées à ces teneurs de coupure, les valeurs obtenues dans le Sud Maradi, variant de 0.005 à 0.017 g/t, indiquent que toutes les formations de socle sont très faiblement minéralisées.…”
Section: Indices D'or Dans Les Formations De Socle (Indices Primaires)unclassified
Le socle du Sud Maradi (Sud Niger) correspond à l’extrémité Nord du bouclier Bénino-Nigérian, appartenant à la zone mobile panafricaine à l’Est du Craton Ouest-Africain. Cette étude apporte une modeste contribution dans la caractérisation géochimique des minéralisations aurifères de cette province métallogénique panafricaine. A cet effet, l’approche méthodologique mise en oeuvre associe le dosage géochimique de l’or par absorption atomique (Au Fire Assay/AA) pour les roches saines, et la séparation des pépites d’or par l’utilisation de la table à secousse pour les altérites du socle et les sédiments (placers et paléoplacers). Les analyses géochimiques ont mis en évidence l’existence de deux types de minéralisations: primaires et secondaires. Les minéralisations primaires de l’or sont à l’état disséminé (faibles teneurs de 0.005 à 0.017 g/t) mais des teneurs relativement plus élevées (0.006 à 0.017 g/t) ont été enregistrées au voisinage des zones de cisaillement du socle. Tandis que la minéralisation secondaire, mise en évidence dans les altérites du socle, dans les alluvions (placers) et dans les grès du Crétacé (paléoplacers) présentent des teneurs en or plus élevées (5 à 30 g/t), dépassant largement les teneurs des minéralisations primaires observées dans les roches saines du socle. Ce grand écart de teneurs s’explique par un fort lessivage du socle, qui aurait permis une reconcentration de l’or dans les sédiments.
The South Maradi (South Niger) basement corresponds to the northeastern part of the Benin-Nigerian Shield, belonging to the Pan-African mobile zone, which is located to the east of the West African Craton. This study brings a modest contribution to the geochemical characterization of gold mineralization in this Pan-African metallogenic province. For this purpose, the methodological approach implemented combines the geochemical determination of gold contents by atomic absorption (Au Fire Assay/AA) for basement rocks and physical separation of gold specks by using the vibrating table process for basement alterites and sediments (placers and paleoplacers). The obtained results showed two types of gold mineralization: primary and secondary. Primary gold mineralization is in a disseminated state (low contents of 0.005 to 0.017 g / t) but relatively the higher values (0.006 to 0.017 g / t) were recorded near the basement shear zones. While the secondary gold mineralization, highlighted in basement alterites, alluvium (placers) and Cretaceous sandstones (paleoplacers) present higher gold contents (5 to 30 g / t) than primary gold contents observed in basement rocks. This large difference in values can be explained by a strong alteration of the basement, which would have allowed a reconcentration of the gold in the sediments.
“…West Africa is currently the largest Paleoproterozoic gold-producing region in the world with an annual gold production of ca. 250 t (Béziat et al 2008;Markwitz et al 2016;Robertson and Peters 2016;Goldfarb et al 2017). The majority of gold deposits are closely located to major first-order tectonic structures such as the Markoye shear zone (MSZ, Fig.…”
Section: Paleoproterozoic Gold Metallogeny Of the Baoulé-mossi Domainmentioning
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