Karst forms, underground circulation and feeding of the lakes with carbonate deposits of the basin of Taoudenni, Malian Sahara

The lake basin of Taoudenni presents two principal Holocene lakes, the one is salted (Taoudenni) the second is carbonated (Haijad). The complexity of the aquifers and the presence of geological calcareous and evaporitic series explain these differences. The carbonate deposits of the Haijad lake (8300 BP-4500 BP) show that it is feed by karst springs. On the back slope of the namurian limestones some karst forms are observed: lapiez, dolines, dry valleys. An aquifer feed come to the Hoggar, across the Tanezrouft seems very problematic.Original Abstract: La cuvette de Taoudenni compte deux principaux lacs holocenes, l'un sale (Taoudenni) et l'autre carbonate (Haijad). La complexite des aquiferes et des series geologiques carboniferes calcaires et evaporitiques expliquent ces differences, le lac d'Haijad (8300 BP-4500 BP) etait alimente par des sources kars- tiques, les depots carbonates en temoignent. Sur le revers substructural des calcaires du Namurien, des modeles karstiques s'observent: lapiez, dolines, vallees seches. En revanche, une alimentation lointaine, depuis le Hoggar, a travers le Tanezrouft, paratt problematique.