stripes
The Moro Hills rise 450 m above the surrounding plain and consist of a northwards progressing intrusive sequence principally of syenites. Jebel Umm Dorein and Jebel Abu Hashim are much smaller nearby intrusions. Precambrian basement granitic gneisses outcrop at a number of places around the hills. The syenites contain a little quartz, perthite, clinopyroxene and amphibole, with fayalite also sometimes present. A small area of peralkaline quartz syenite and a rather larger area of peralkaline granite are also present. Jebel Umm Dorein consists of an outer zone of syenite and an inner one of feldsparphyric syenite containing xenoliths. The small occurrence of Jebel Abu Hashim consists of a series of syenites that appear to form ring features; one peralkaline quartz syenite forms an almost complete ring. The innermost area is of volcanic rocks including trachybasalt, trachyte and rhyolite breccia.
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.
