1. Gold concentration during polyphase deformation: Insights from Boulanger Project, French Guiana.
- Author
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Lacroix, Brice, Lahondes, Dennis, Hainque, Pierre-Jean, Le Goff, Etienne, Fournier, Dominique, Hauteville, Alix, Gourcerol, Blandine, Eglinger, Aurélien, and Andre-Mayer, Anne-Sylvie
- Subjects
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INCRUSTATIONS , *GREENSTONE belts , *VEINS (Geology) , *ORES , *DATA analysis - Abstract
The Boulanger gold deposit is hosted within the Rhyacian greenstone belts from the Guiana shield located within the North Guiana Through, French Guiana. The Boulanger deposit is characterized by a complex polyphase deformation and mineralization history involving a coaxial shortening phase, D 1 , followed by a transcurrent deformation event, D 2. The main ore bodies consist of a series of quartz-tourmaline-pyrite-carbonate extension and shear veins in response to NNE-SSW shortening event (D 1), and adjacent altered host-rocks. The proximal alteration bordering the vein system is characterized by pyrite-tourmaline (main ore assemblage). This shortening event is followed by transcurrent deformation, D 2. Locally, D 2 is expressed by the formation of N020-030 narrow zones (F 2 axial trace) along which D 1 structures are reoriented. The structural analysis performed on both S 1/0 foliation and on geophysical data interpretation highlights the presence of Type-1 interference patterns. These zones are associated with significant gold enrichment and the presence of a new ore assemblage dominated by pyrrhotite-pyrite. Quantitative structural analysis approach, based on measured foliations (S 1/0) and gold grade demonstrates that D 2 -related folding is associated with important gold endowment. These findings suggest that the characterization of the exact fold interference pattern is fundamental for the targeting of favorable enriched zones at the deposit scale. • The Boulanger deposit is hosted within the Rhyacian greenstone belts from the Guiana shield. • The deposit is characterized by a complex polyphase deformation and mineralization history involving two deformation stages. • The main ore bodies consist of quartz-tourmaline-pyrite extension and shear vein system. • D 1 Quartz-tourmaline-pyrite vein system formed in response to NNE-SSW compressive event. • D 2 is expressed by the formation of N020-030 narrow zones (F 2 axial trace) along which D 1 structures are reoriented. • D 2 zones are associated with significant gold enrichment and the apparition of pyrrhotite-pyrite ore assemblage. • Structural analysis and geophysical data interpretation both highlight the presence of Type-1 interference, patterns. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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