%0 Journal Article
%T Pan-African Paleostresses and Reactivation of the Eburnean Basement Complex in Southeast Ghana (West Africa)
%A Mahaman Sani Tairou
%A Pascal Affaton
%A Solomon Anum
%A Thomas Jules Fleury
%J Journal of Geological Research
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/938927
%X 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¨C550 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. 1. Introduction Southeast Ghana is a geologically complex area (Figure 1). It includes three distinct structural domains [1¨C5] (1) the southeastern margin of the West african craton (WAC) consisting of Archean to Paleoproterozoic assemblages that underwent the Eburnean Orogeny ( 2 0 0 0 ¡À 2 0 0 £¿Ma); (2) the Neoproterozoic Volta Basin represented by its lower and middle megasequences (Bombouaka and Oti Supergroups); (3) the frontal structural units of the Pan-African Dahomeyide Orogenic Belt ( 6 0 0 ¡À 5 0 £¿Ma). Figure 1: Schematic geological map with the ¡°Stable Zone¡± (comprising the southeastern margin of the West african craton and its cover represented by the Volta Basin) and the Pan-African ¡°Mobile Zone¡± (i.e., the frontal structural units of the Pan-African Dahomeyide belt): 1 = Eburnean basement complex (WAC); 2 = Neoproterozoic to Paleozoic cover (Volta Basin); 3 = internal and external gneiss-migmatite units; 4 = kyanite bearing micaceous quartzites; 5 = basic and ultrabasic massifs of the suture zone; 6 = Atacora or Akwapim structural unit; 7 = Buem structural unit; 8 = Meso-Cenozoic cover of the Gulf of Guinea Basin; 9 = thrust contact; 10 = Kandi fault mylonitic zone; A-B = schematic section line (Figure 2). The sedimentary sequence in the Volta Basin rests unconformably on the Eburnean basement complex. This basement and its cover constitute the western ¡°Stable
%U http://www.hindawi.com/journals/jgr/2012/938927/