High level igneous emplacements in the Red Sea Hills,Sudan

Over one hundred non-orogenic ring complexes comprising various proportions of granites, gabbros, syenites and some carbonatites occur in a belt 250 km wide by 700 km N-S in eastern Sudan. The intrusions and related dyke swarms cut Precambrian gneisses, greenschist assemblages, batholithic granites and late acid effusives and appear to be early Palaeozoic and late Mesozoic in age. Structural alignments are rare but the complexes cluster along old interplate suture zones. Tin, tungsten and molybdenum mineralization is known in Egyptian ring complexes, and is to be expected in this newly recognized province.