stripes
A central granite ring complex about 10 km in diameter lies within a zone of about 25x20 km containing peralkaline rhyolites and rhyolitic dykes. The central complex comprises numerous arcuate, concentric, vertical sheets of medium- to fine-grained biotite and biotite-amphibole peralkaline granite and aplitic granite. In the west and north gneisses of the Kurmut Series lie in slices between the granite sheets. In the central part of the complex a roof facies of granite and basement gneisses are intimately fused with much veining and brecciation and development of a pegmatitic facies of the granite. Feldspathization and fusion of basement blocks has produced hybrid biotite granites and diorites. Among the peralkaline rhyolite dykes are varieties containing spherulites of sodic amphibole or pyroxene.
BARTH, H. and MEINHOLD, K.-D. 1979. Mineral prospecting in the Bayuda Desert. Part 1, Volume A. Investigation of mineral potential. Technical Report Sudanese-German Exploration Project. Hannover (Bundesanstalt fur Geowissenschaften und Rohstoffe). 336 pp. (unpublished) BARTH, H., BESANG, C., LENZ, H. and MEINHOLD, K.-D. 1983. Results of petrological investigations and Rb/Sr age determinations on the non-orogenic igneous ring-complexes in the Bayuda Desert, Sudan. Geologisches Jahrbuch, 51: 1-34.