West Africa | Distribution of the 23 major gold belts in West Africa
Gold deposits in West Africa are widely distributed in space, with obvious clustered distribution characteristics. They are mainly concentrated in the Leo Shield area within the West African Craton, and are sporadically exposed in other areas. Based on the mineralization geological conditions, spatial distribution characteristics and other factors, West African gold deposits are divided into 23 major IV-level mineralization sub-zones.
1. Location of the Kaigudou gold mine sub-zone (Ⅳ-1): Mainly located in the Kaigudou structural window, the main part is located at the border between Senegal and Mali. Geological characteristics: A large area of Birim metamorphic volcanic rocks are developed, and later intrusive rocks are interspersed among them. The lithology includes metamorphic basalt, andesite, dacite, a small amount of rhyolite and associated volcanic sedimentary rock series. Two obvious north-northeast strike-slip shear structures are developed, which control the output of gold. Ore deposit type: Mainly orogenic gold deposits. Typical deposits: Mali: Super-large Sadiola gold mine (241 t). Senegal: Sabodala gold mine (146 t), Massawa gold mine (113 t).
Division of gold metallogenic belts in West Africa
2. Keneba gold mine sub-zone (IV-2) Location: It straddles Mali and Senegal, is located on the east side of the Kégudou belt, and belongs to the Kégudou-Kénema tectonic window. Geological characteristics: The lithology is mainly composed of sedimentary rocks (limestone, dolomite marble, sandstone, schist and marl) and intermediate-acidic magmatic rock series. Affected by the near north-south strike-slip fault, it has undergone a certain degree of metamorphism [15]. Ore deposit type: It is mainly orogenic, accompanied by a small amount of skarn. Typical deposits: Mali: Loulo gold mine (404 t), Fekola gold mine (221 t). 3. Siguiri gold mine sub-zone (IV-3) Location: The main part is located in northeastern Guinea, close to Mali. Geological characteristics: A large number of Paleoproterozoic Birim Group greenstone belts are developed. Ore deposit type: It is mainly orogenic, accompanied by a small amount of placer. Typical deposits: Siguiri gold mine (291 t), Lefa gold mine (135 t), T-rik gold mine (61.6 t)
3. Siguiri gold mine sub-zone (Ⅳ-3) Location: The main part is located in northeastern Guinea, close to Mali. Geological characteristics: A large number of Paleoproterozoic Birim Group greenstone belts are developed. Deposit type: Mainly orogenic gold deposits, accompanied by a small amount of placer deposits. Typical deposits: Siguiri gold mine (291 t), Lefa gold mine (135 t), T-rik gold mine (61.6 t)
Distribution of gold reserves in West African gold-producing countries (a) and histogram of gold ore grade (b)
4. Kobada-Kanara gold deposit sub-zone (Ⅳ-4) Location: Located in southwestern Mali, bordering Guinea. Geological characteristics: Affected by the Eburnean orogeny (2.0~1.8 Ga), a large number of Birim rock series and associated granites developed. It is distributed in a narrow strip, and a shallow metamorphic greenschist phase combination is developed. Ore deposit type: Mainly orogenic and alluvial placer type. Typical deposits: Kalana gold mine (109.5 t), Kobada gold mine (72.5 t), Kodieran gold mine (52.4 t)
A simplified diagram of the main Precambrian shields in West Africa
5. Morila-Sayama gold deposit sub-zone (Ⅳ-5) Location: Located in the southeast of Mali, bordering Burkina Faso and Côte d'Ivoire. Geological characteristics: A large area of Paleoproterozoic Birim Group metamorphic volcanic-sedimentary rocks are developed, characterized by typical greenstone belts. Ore deposit types: Mainly orogenic and alluvial sand types. Typical deposits: Syama gold mine (257 t), Tabakarole gold mine (18.5 t), Fatou gold mine (19 t), Morila gold mine (6.8 t)
6. Wahgnion-Seguela gold deposit sub-zone (IV-6) Location: Mainly located in the north of Côte d'Ivoire, across the southwestern part of Burkina Faso. Geological characteristics: Affected by the Ebonyi orogeny, a series of NNE-trending structures and metavolcanic sedimentary rocks of the Birim Group developed. Ore deposit types: Mainly orogenic and skarn types. Typical deposits: Wahgnion gold mine (81.2 t), Tangon gold mine (77.8 t), Seguela gold mine (32.3 t)
7. Boli-Doropo gold deposit sub-belt (IV-7) Location: The main part is located in the central and western part of Burkina Faso, extending in a near northeast direction, across parts of Côte d'Ivoire and Ghana. Geological characteristics: A large area of Paleoproterozoic Birim Group metavolcanic-sedimentary rock formation (greenstone belt) and associated intrusive rocks are exposed. There are many near northeast strike-slip faults. Deposit type: Mainly orogenic, closely related to the strike-slip extension after the Ebonian orogeny, with a small amount of skarn type and alluvial placer type. Typical deposits: Burkina Faso: Houde gold mine (153 t), Mana gold mine (152.6 t), Bouly gold mine (148.1 t), Gaoua gold mine (105.3 t). Cote d'Ivoire: Doropo gold mine (108.2 t), Batie West gold mine (101.2 t). Ghana: Wa-Lawra gold mine (86.1 t).
8. Inata-Tapakou gold mine sub-zone (IV-8) Location: Located in the northeast of Burkina Faso, the regional tectonic line is distributed in a NW direction. Geological characteristics: It is a strike-slip extension structure formed during the Ebonian orogeny, with a large number of Paleoproterozoic Birim rock series and granites. Ore deposit type: Mainly orogenic, followed by skarn. Typical deposits: Essakane gold mine (171.4 t), Inata gold mine (137.2 t), Tapakou gold mine (34.9 t).
9. Korui-Koaka gold mine sub-zone (IV-9) Location: Located in the northeast of Burkina Faso, it is distributed in a near NE direction, consistent with the direction of the regional tectonic line. Geological characteristics: Paleoproterozoic Birim rock group is developed, accompanied by a large number of granite intrusions. Ore deposit type: Mainly orogenic gold deposits, followed by skarn and alluvial placer types. Typical deposits: Kiaka gold mine (195.3 t), Bomboré gold mine (191.7 t), Kouri gold mine (43.5 t).
10. Nandini-Boungou gold mine sub-zone (IV-10) Location: It spans southern Burkina Faso and northeastern Ghana and is controlled by the same tectonic line. Geological characteristics: Paleoproterozoic Birim Group metavolcanic sedimentary rocks are developed, interspersed with a large amount of granite. Ore deposit type: It is mainly orogenic gold deposits, closely related to the Ebonian orogeny, followed by skarn type. Typical deposits: Namdini gold mine (217.4 t), Boungou gold mine (56.8 t), Youga gold mine (50.1 t).
11. Bole-Buyi gold mine sub-zone (IV-11) Location: It is mainly located in central Ghana and is controlled by near north-south strike-slip faults. Geological characteristics: It develops Birim Group metavolcanic sedimentary rocks and a small amount of granite. The deposits are produced in the Birim greenstone belt. Ore deposit type: It is mainly orogenic gold deposits, with a small scale. Typical deposits: Tinga gold mine (7.3 t), Bole gold mine (5 t), Bui gold mine (4.4 t).
12. Safwe gold mine sub-belt (Ⅳ-12) Location: Mainly located in western Ghana, extending to the Afima area of Côte d'Ivoire, and extending in a north-northeast direction. Geological characteristics: The deposits are produced in the Birim metavolcanic sedimentary rocks and granites, or in the skarn belt. Deposit types: Mainly orogenic gold deposits, followed by skarn, conglomerate, and alluvial placer types. Typical deposits (one of the main gold mine belts in Ghana): Ahafo gold mine (475.9 t), Asanko gold mine (120.1 t), Bibiani gold mine (77.8 t), Afema gold mine (61.9 t).
13. Ashanti Gold Mineral Sub-Belt (Ⅳ-13) Location: The most famous gold mineral belt in Ghana, extending in a NNE-NE direction. Geological features: Developed Birim volcanic sedimentary rocks and the overlying Tarkwa Group (molasse formation conglomerate). Ore deposit types: Mainly orogenic gold deposits, followed by conglomerate gold deposits (Tarkwa conglomerate type), with a small amount of skarn type and alluvial placer type. Typical deposits (huge scale): Obuasi gold mine (965.9 t), Wassa gold mine (348.8 t), Tarkwa gold mine (339.4 t), Iduapriem gold mine (192.2 t), Damang gold mine (184.1 t), Akyem gold mine (110.4 t)
14. Yaouré-Bonikro gold mine sub-zone (IV-14) Location: Located in the central part of Côte d'Ivoire. Geological characteristics: Paleoproterozoic Birim rocks and large areas of granites are developed, and the northeast-trending structure is formed under the influence of the Ebonian orogeny. Ore deposit type: Mainly orogenic gold deposits, followed by skarn type. Typical deposits: Yaouré gold mine (116.8 t), Bonikro gold mine (37.3 t), Agnéby gold mine (17.3 t).
15. Abuja-Tupou gold mine sub-zone (IV-15) Location: Located in the west of Côte d'Ivoire, extending to the east of Liberia, with tectonic lines extending in a northeast direction. Geological characteristics: Birim Group metamorphic volcanic-sedimentary rocks and granite intrusions are developed, and Archean high-grade gneiss is exposed locally. Deposit type: mainly orogenic gold deposits, with a small amount of alluvial placer deposits (manually mined by local people). Typical deposits: Abujar gold mine (nearly 100 tons), Topo gold mine, etc.
16. Putu Mountain-Dugbe Gold Mineral Sub-Belt (IV-16) Location: Located in the eastern part of Liberia, extending in a northeast direction, belonging to the Leo Shield. Geological characteristics: Paleoproterozoic Birimite System metavolcanic-sedimentary rocks (greenstone belt) are developed, affected by the Ebonian orogeny, and are metamorphic in low greenschist phase-high amphibolite phase. Dube shear zone and Juazon shear zone are developed in the area, and gold mines are mostly produced around the shear zone. Ore deposit type: Mainly orogenic gold deposits, followed by alluvial placer type (smaller scale). Typical deposit: Dugbe gold mine (resource volume 110 t).
17. Iti-Sestos Gold Mineral Sub-Belt (IV-17) Location: Extending from the west of Côte d'Ivoire to the north-central part of Liberia, extending in a northeast direction, belonging to the Man Shield. Geological characteristics: Mainly Paleoproterozoic Birim rock system, with the development of Cestos shear zone (crustal vertical tectonic zone, with mineralization potential comparable to the Ashanti gold belt). Deposit type: Mainly orogenic gold deposits, followed by skarn type and alluvial placer type. Typical deposits: Kobada Mt, Innis gold mine (Liberia); Ity gold mine (Cote d'Ivoire).
18. Kokoya gold deposit sub-zone (IV-18) Location: Located in central Liberia, belonging to the Maen Shield. Geological characteristics: Archean granite-quartz diorite gneiss and overlying metavolcanic-sedimentary rocks are developed, controlled by the northeast shear zone. Mineralization may be related to the Neoarchean Liberian tectonic thermal event (~2800 Ma). Deposit type: Mainly orogenic gold deposits. Typical deposit: Kokoya gold mine (15.5 t)
19. Zorovo-Bea Mount Gold Mineral Sub-Belt (IV-19) Location: Located in the northwest of Liberia, extending to Simandou, Guinea, consistent with the northeast tectonic line. Geological characteristics: Archean Man Shield granodiorite gneiss, banded iron formation (BIF), basic-ultramassic schists are developed. Ore deposit types: mainly orogenic and alluvial placer types. Typical deposits: Bea Mount gold mine (68.7 t); Ndabrama gold mine (18.3 t), Weju gold mine (5.6 t).
20. Sula Mountain-Kegari Gold Mineral Sub-Belt (IV-20) Location: Located in the north-central part of Sierra Leone, with Archean Man Shield metamorphic basement and Quaternary cover exposed. Geological characteristics: The basement is the Middle Archean mixed granite and the Neoarchean greenstone belt (clastic metamorphic rock + intermediate-basic magmatic rock). Deposit type: orogenic gold deposits in greenstone belts are dominant, followed by alluvial placer deposits. Typical deposits: Sonfon gold mine (131.4 t); Baomahun gold mine (86.5 t).
21. Tasiast-Guelb Moghrein gold mine sub-zone (IV-21) Location: located in western Mauritania, belonging to the Reguibaté shield, and extending in a northwest direction. Geological characteristics: Archean crystalline gneiss and overlying metamorphic sedimentary rocks and mafic volcanic rocks are developed. Deposit type: including orogenic type and IOCG type (iron oxide copper gold type). Typical deposits: Tasiast gold mine (303.9 t); Guelb Moghrein gold mine (15.0 t).
22. Chegar gold deposit sub-zone (IV-22) Location: Located in southern Mauritania, bordering Senegal. Geological characteristics: Developed Paleoproterozoic Birim Group metavolcanic-sedimentary rocks and Mesozoic-Cenozoic sedimentary rocks, transformed by Pan-African tectonic movements. Ore deposit type: Mainly orogenic gold deposits. Typical deposits: Chegar gold mine, Ouaoua gold mine
23. Mandingo Hill gold deposit subzone (IV-23) Location: Located on the coast of Liberia, extending in a NWW direction, consistent with the Pan-African active belt-Rockled tectonic belt. Geological characteristics: Archean granite gneiss, greenstone belts and basic intrusive rocks are developed, and the mineralization age is questionable (Archean or Pan-African). Deposit type: Mainly orogenic, followed by alluvial placer type. Typical deposits: Gold Coast gold mine (44.5 t); Mandingo Hill gold mine
