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7026465 
Journal Article 
Structural and gold mineralizing evolution of the world-class orogenic Mana district, Burkina Faso: Multiple mineralizing events over 150 million years 
Augustin, J; Gaboury, D; Crevier, M; , 
2017 
1 
Ore Geology Reviews
ISSN: 0169-1368
EISSN: 1872-7360 
ELSEVIER SCIENCE BV 
AMSTERDAM 
981-1012 
WOS:000418978300054 
The Mana district, located in the northern part of the Birimian Hounde greenstone belt in western Burkina Faso, is a world-class Paleoproterozoic orogenic gold district (similar to 8 Moz) including five gold deposits (Fofina, Nyafe, Siou, Wona-Kona and Yaho). These deposits are located in specific lithostratigraphic domains, and gold is controlled by various structural features. Deposit- and regional-scale mapping, intrusion age and geochemistry, as well as airborne aero-magnetic and electrical resistivity geophysical data, were used to decipher the tectonic evolution of each gold deposit and the district. Five deformational and four gold mineralizing events were recognized.The first deformation event (D1(MD): E-W oriented shortening) affected the metamorphosed volcanic and sedimentary rocks of the Lower Birimian group. This early deformation episode was correlated with the formation of gently N-plunging folds (F-1MD) and N-S-striking thrusts faults coeval with emplacement of the pre- to synkinematic Wona-Kona and Siou plutons dated at similar to 2172 Ma, under greenschist facies metamorphism. The quartz-carbonate veins (V-1MD) at Fofina and Siou formed during D-1MD at Eoeburnean time, manifesting the first gold event at approximately similar to 2172 Ma.The following deformation event (D2(MD): E-W oriented extension) is associated with the deposition of the Upper Birimian group (Mana basin) overlying the Lower Birimian group. The geometry of the Mana basin is controlled by the Mana and Maoula shear zones. The Tarkwaian-type rock formation overlying the Upper Birimian group, controlled by the Wona-Kona and Siou shear zones, is constrained at the end of D2(MD) or at the beginning of the D3(MD) event with a maximum deposition age at similar to 2113 Ma.The third deformation event (D3(MD): E-W to WNW-ESE transpression) affected the entire supracrustal rock. Such event is correlated with the formation of map-scale F-3MD folds and dextral shear zones during the Eburnean orogeny (similar to 2113-2090 Ma). A second gold mineralizing event occurred during D3(MD) and is manifested by quartz-carbonate veins (V-3MD) and disseminated sulfides at the Yaho, Fofina and Nyafe and possibly Wona-Kona deposits.The fourth deformation event (D4(MD): NNW-SSE transpression) is correlated with sinistral shearing along the major transcurrent faults and the development of asymmetric NNE-striking folds (F-4MD) associated with vertical fold axes. Syn-D4(MD) mineralization is characterized mainly by a strong silicification (Si-4MD) with disseminated pyrite and arsenopyrite along the Wona-Kona shear zone and by tiny quartz-carbonate veinlets (V-4MD). This event is considered the main gold-bearing-event in the western margin of the Mana district.The fifth and last deformation event (D5(MD)) is brittle in character and was responsible for the formation of E-W subvertical crenulation cleavages and reverse faults under overall N-S shortening. This late deformation event is tentatively associated with a last gold event recorded as free gold associated with muscovite in brittle fractures developed in competent orebodies at the Wona-Kona and Siou deposits. This event could be as young as similar to 2022 Ma, the age obtained from Ar-Ar datation of muscovite-schists at the Wona-Kona deposit.Our main contribution is that we decipher multiple gold mineralizing events at the district scale based on deposit- and regional-scale mapping. It is interpreted that gold was introduced as early as similar to 2172 Ma and possibly as late as similar to 2022 Ma during at least 3 or even 4 shortening tectonic events in a timeframe not yet recognized at the district scale for all the Birimian belts.