Possible primary sources of diamond in the North African diamondiferous province

Abstract

Abstract The Eglab shield is the easternmost part of the Reguibat rise, which belongs to the West African craton (WAC). It corresponds to the amalgamation of the Yetti and Eglab Palaeoproterozoic domains. These domains are separated by a mega-shear zone called the ‘Yetti–Eglab Junction’ where fieldwork has led to the discovery of kimberlite indicator minerals but no diamond. In the southwestern part of this zone, an outcrop of Archaean basement and a komatiitic–picritic dyke had been recognized. Within the Eglab shield, deep-seated lithospheric faults control emplacement of alkaline complexes, and of small circular structures made up of mafic, ultramafic and silica-undersaturated rocks. These structural zones are characterized by widespread development of dyke swarms and repeated reactivations of earlier Eburnean trends from the Neoproterozoic to Mesozoic. Accordingly, they are sites of high magmatic permeability and crustal weakness. In this study, we summarize all known earlier and newly obtained structural, geophysical, geological and geochemical data on this area. They indicate that the ‘Yetti–Eglab Junction’ has good possibilities for the finding of kimberlite or/and other diamondiferous rocks. The features of the Eglab shield provide a possible explanation for the enigmatic sources of the diamond-bearing Reggane placer deposit located at the boundary of the WAC.