stripes
Jebel Erba stands as a striking topographic feature rising to 1200 m above the surrounding plain. It comprises two distinct ring intrusions Erbab, which is 19x13 km, and Saluweb 4.5 km in diameter (Elnour, 1990). Erbab comprises concentric rings of (1) an outer coarse-grained granite, (2) a horseshoe-shaped intrusion of quartz monzonite, monzonite and monzo-gabbro, which is cut by dykes of microgranite, (3) a fine- to medium-grained leucogranite and (4) a central plug of coarse-grained granite. The Saluweb ring intrusion consists of (1) an outer ring of alkali feldspar porphyritic trachyte and syenite, (2) a semicircular fine- to medium-grained granite and (3) a circular core of coarse-grained alkali feldspar granite. These rocks are characterised by the presence of aegirine, aegirine-augite, arfvedsonite and biotite.
ELNOUR, A.E. 1990. The Jebel Erba ring complex, NE Sudan. 15th Colloquium of African Geology, University of Nancy, Abstracts. International Center for Training and Exchanges in the Geosciences, Occasional Publication 1990/20: 398.HOHNDORF, A., MEINHOLD, K-D. and VAIL, J.R. 1994. Geochronology of anorogenic igneous complexes in the Sudan: isotopic investigations in North Kordofan, the Nubian Desert and the Red Sea Hills. Journal of African Earth Sciences, 19: 3-15.