Organization of drainage networks from space imagery in the Tanezrouft plateau (Western Sahara) : implications for recent intracratonic deformations

Analyses of satellite images (Landsat TM, SPOT and SAR ERS-1) of the Tanezrouft Plateau (Sahara) together with observations in the field have provided evidence of palaeo-drainage networks and intracratonic tectonic activity. The central network was a large braided system which collected waters from the western Hoggar in the Holocene. This network is connected northwesterly with Wadi Mouilah, the Reggan topographic depression and Sebkha Meqerghane. It is affected by conjugate northwest- and northeast-striking recent faults which reactivate older faults related to the north-south-trending Pan-African suture zone. The southern network comprises the wadis Tamanrasset, El Djouf and El Djouf his. They formerly constituted a large system running from southeast to northwest, captured and turning south in western Tanezrouft. This wadi system is presently cut into two parts as a result of recent tectonic deformations, i.e. uplift affecting the western border of the Tanezrouft plateau and north-striking faults paralleling the Pan-African suture zone.