The Pan-African Trans-Saharan Belt in the Hoggar Shield (Algeria, Mali, Niger): A Review

Abstract

The Pan-African belt of central northwest Africa is part of the Transaharan belt (Cahen et al. 1984) and has been interpreted by Black et al. (1979) and Caby et al. (1981) as a collision belt formed during a Wilson cycle. The Tilemsi suture zone separates the stable West African Craton (passive margin) from the mobile belt (active margin). Pan-African deformation and metamorphism affected the whole Hoggar shield from the Tilemsi region at least to the 8°30′E lineament and is recognized on a 1000-km-wide area (Fig. 1). Actually, the Transaharan belt appears as a complex assemblage of NS trending geological domains which have undergone different evolutions. Large areas are still poorly known and several interpretations have been proposed for some others. In this review paper, I will present the geological evolution of each domain and discuss these different interpretations. Correlations of these domains with the Togo-Benin belt and with the Nigerian shield have been proposed by several authors (Bessoles and Trompette 1980; Caby et al. 1981; Ajibade et al. 1987; Caby, in press).