Department of Geology, University of Kuwait, P.O. Box: 5969, Safat, 13060, Kuwait
Department of Earth sciences, the Open University, Milton Keynes, England, and National Environment Research Council, Istope Geology Centre, 64 Grays Inn Road, London, UK.
ABSTRACT
A dyke composed of natural glass was discovered during a student mapping exercise in 1980 at Sabaloka, Sudan, and is the only known occurrence of this rock type in the Younger Granite Association of Sudan. We show the glass to have a peraluminous rhyolite composition similar to lavas in the nearby Sabaloka Complex. but a K-Ar whole-rock determination gave an end-Cretaceous age (69.6 f 2.0 Ma), considerably younger than ages determined on the Sabaloka Complex to the west and the Sileitat-Es-Sufr Complex to the south. The dyke, and the northeast felsite swarm to which it belongs, may mark a previously unrecorded episode in the long history of anorogenic igneous activity at Sabaloka.