Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences

Nigrub El Tahtani (Gabal Nigrub El Tahtani)


Occurrence number: 
Longitude: 35.02, Latitude: 23.02

This intrusion of peralkaline syenite and granite forms a ridge 3.5 km in length and is intruded into Precambrian metavolcanics, schists and granodiorites. Volcanic rocks, including trachytic agglomerates and tuffs, latites and rhyolites are preserved as infaulted wedges and as roof remnants to the syenite. Dykes of solvsbergite and bostonite are numerous in the country rocks and include radial and curving dykes, the latter being interpreted as ring-dykes. Rock analyses will be found in El Ramly et al. (1971) and El Reedy and El Sokkary (1982).

An Rb-Sr determination on peralkaline granite gave 139.7±9 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.EL REEDY, M.W. and EL SOKKARY, A.A. 1982. Contribution to the geochemistry of some ring complexes in the South Eastern desert of Egypt. Acta Geologica. Academiae Scientiarum Hungaricae, 25: 349-64.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.
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith