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Archean tectonics in the sangmelima granite-greenstone terrains, Ntem Complex (NW Congo craton), southern Cameroon.

par Akame, Joseph ;Owona, Sébastien;Hublet, Geneviève ;Debaille, Vinciane
Référence Journal of African earth sciences, 168, page (103872)
Publication Publié, 2020-08

Article révisé par les pairs

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Résumé :

Structural study of in the Sangmelima granite-greenstone terrains (SGB) provide a new overview of the evolution of the Ntem Complex (South Cameroon), the northwestern part of the Congo Craton. The regional deformation is marked by a strong steep dips foliation and steeply plunging mineral-stretching. D1-related structures are folding and shearing by a D2 deformation that is synchronous with extraction granitic dykes. D1–D2 structures were developed during regional E-W sub-horizontal shortening under ductile conditions associated with steeply dipping principal stretching in a transpressive regime, progressive strain localization along strike-slip shear zones. Syn-D1 mineral assemblages and high strain microstructures suggest that ductile deformation D1 occurred under high-grade metamorphic conditions, whereas D2 microstructures suggest a brittle deformation. The strain patterns in the SGB recorded a long-lasting Archean tectonic history within the Archean Ntem Complex (ca. 2.83–2.72Ga). Finally, some Archean structures were reactivated during a brittle deformation (D3), likely during the Eburnean event.