Alkaline Rocks and Carbonatites of the World

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Silaia (Silai, Gabal Salai)


Occurrence number: 
Longitude: 34.87, Latitude: 24.05

Peralkaline syenites and granites form a conspicuous hill 1.5 km in diameter, and there are a number of small stocks, of similar composition, to the southeast. The granites contain about 10% biotite together with aegirine-augite and sodic amphibole. Xenoliths of country rock are abundant in the outer part of the main intrusion. There are some aplitic dykes.

A Rb-Sr isochron on four rocks gave 221±12 Ma (Hashad and El Reedy, 1979).
EL RAMLY, M.F., BUDANOV, V.I. and HUSSEIN, A.A.A. 1971. The alkaline rocks of south-eastern Egypt. Geological Survey of Egypt, Paper, 53: 1-111.HASHAD, A.H. and EL REEDY, M.W.M. 1979. Geochronology of the anorogenic alkalic rocks, South Eastern desert, Egypt. Annals of the Geological Survey of Egypt, 9: 81-101.
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