Discovery of a late precambrian volcanic ring-complex at Jebel Abu Nahl,Bayouda Desert,Northern Sudan

A photogeologic study of Jebel Abu Nahl in the Bayouda Desert reveals that it is a Late Precambrian ring-complex, larger and more intricate than the three ring-complexes already known from the Northern Sudan. Like the latter, the Abu Nahl complex must have formed as a result of near-surface volcanic activities whereby extrusion of mainly acid lavas and tuffusites and the emplacement of high-level granites were accompanied by repeated subsidence of surface or near-surface blocks along arcuate ring-faults.