Pan-African Paleostresses and Reactivation of the Eburnean Basement Complex in Southeast Ghana (West Africa)

Mahaman Sani Tairou (1) , Pascal Affaton (2) , Solomon Anum (3) , Jules Fleury (2)

1 Departement de Geologie, Faculte des Sciences, Universite de Lome, BP 1515, Lome, Togo
2 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
3 Geological Survey Department, Koforidua Eastern Region, P.O. Box 672, Koforidua, Ghana

This faulting tectonics analysis concerns the southernmost segment of the Dahomeyide Orogen and the West-African craton eastern margin in southeast Ghana. The analysis of strike-slip faults in the frontal units of the Dahomeyide Belt indicates that four distinct compressive events (NE-SW, ENE-WSW to E-W, ESE-WNW to SE-NW and SE-NW to SSE-NNW) originated the juxtaposition of the Pan-African Mobile Zone and the West-African craton. These paleostress systems define a clockwise rotation of the compressional axis during the structuring of the Dahomeyide Orogen (650–550 Ma). The SE-NW and SSE-NNW to N-S compressional axes in the cratonic domain and its cover (Volta Basin) suggest that the reactivation of the eastern edge of the West African craton is coeval with the last stages of the Pan-African tectogenesis in southeast Ghana. An extensional episode expressed as late normal faulting is also recorded in this study. This E-W to SE-NW extension, which is particular to the southernmost part of the Dahomeyide Belt, appears to be post-Pan-African. This extension probably contributed to the formation of a major Jurassic rifting zone that originated the Central Atlantic and the Benue Trough.

Mots clés: pan-african paleostress; reactivation; eburnean basement complex; ghana

Domaines: Tectonique

Mahaman Sani Tairou, Pascal Affaton, Solomon Anum, Jules Fleury. Pan-African Paleostresses and Reactivation of the Eburnean Basement Complex in Southeast Ghana (West Africa). Journal of Geological Research, 2012, 2012, ⟨10.1155/2012/938927⟩. ⟨hal-01258644⟩