stripes
The eastern half of this complex includes a partial ring-dyke of peralkaline quartz syenite containing sodic amphibole and aegirine. Within the ring-dyke is an area of volcanic rocks that are interpreted as remnants of the roof of the syenite unit. The volcanics are generally felsic types including ignimbrite and trachyte. The western half of the complex consists of three units younging westwards. The first and third are peralkaline quartz syenites, the second a peralkaline granite. Within the granite in one area are lenses and small dykes giving high scintillometer readings. These are composed of quartz, alkali feldspar, iron oxides, fluorite and zircon and in one sample finely disseminated bastnasite.
CURTIS, P. and BRINKMANN, K. 1985. The geology of younger intrusive alkali complexes in the southwestern Nuba Mountains, Sudan. Geologisches Jahrbuch, 63: 3-41.