PAN-AFRICAN DISPLACED TERRANES IN THE TUAREG SHIELD (CENTRAL SAHARA)

Concepts developed in the recently published model of the Air region ( eastern Tuareg shield; Niger, Africa) as a college of three displaced terranes integrated in a single geodynamic model lead us to propose a terrane map of the Tuareg shield (500 000 km2). The 23 terranes recogn ized have their own lithological, metamorphic, magmatic, and tectonic characteristics and are separated by subvertical strike-slip megashear zones that can be traced for hundreds of kilometres, or by major thru st fronts. Some of these boundaries have ophiolitic assemblages or mol assic deposits. The Tuareg shield was shaped and partly accreted durin g the Pan-African orogeny (750-550 Ma), but not as a homogeneous body.