stripes
Jebel Demik has a central stock of peralkaline quartz syenite containing sodic amphibole. This is enveloped in a ring of arfvedsonite granite. El Nadi (1980) was able to distinguish an inner ring of biotite microgranite which was not distinguished by Curtis and Brinkmann (1984) during their reconnaissance survey. A limited area of subalkaline syenite occurs on the northwestern margin. A number of microgranite dykes, which could be ring-dykes, cut the basement outcropping to the north of the complex.
BATYRMURZAEV, A.S., TROFIMOV, N.N., SHAKHPAZOV, I.M., AHMED, F., KHALIL, B.E., ZAKIEVA, F.S., GADZLIIEO, S.Z. and SLYMAEV, A.A. 1982. The absolute age of minerals in certain Sudanese provinces. In: Mobile belts and deposits. A collection of scientific papers, Academy of Sciences, Moscow. Patrice Lumumba University: 30-6. CURTIS, P. and BRINKMANN, K. 1985. The geology of younger intrusive alkali complexes in the southwestern Nuba Mountains, Sudan. Geologisches Jahrbuch, 63: 3-41.EL NADI, A.H. 1980. The geology of the Kheig El Kheil, Damik and Umm Dugo igneous complexes, Nuba Mountains, Sudan. M.Sc. thesis, University of Khartoum. (unpublished)
