Alkaline Rocks and Carbonatites of the World

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

Hadjer El Khamis (Hadjer El Hamis) And Hadjer Bigli

stripes

Occurrence number: 
033-00-004
Country: 
Chad
Location: 
Longitude: 14.92, Latitude: 12.75
Carbonatite: 
No

Hadjer el Hamis and Hadjer Bigli comprise several rocky pinnacles close to the southern shore of Lake Chad and immediately east of the Chari river; they are up to about 100 m high. The rocks are principally comendites and probably extrusive. They are glassy with phenocrysts of quartz, sanidine, magnetite, aegirine and sodic amphibole, which is generally arfvedsonite but sometimes with a little riebeckite. Facies with spherulitic and micrographic textures also occur. A whole rock analysis is given by Garde (1911).

References: 
BARBEAU, J. 1956. Notice explicative sur la Feuille Fort-Lamy. Carte Géologique de Reconnaissance à l'échelle de 1.1,000,000. Gouvernement General de l'Afrique Equatoriale Française.GARDE, G. 1911. Déscription géologique des regions situées entre le Niger et le Tchad. Thesis, University of Clermont-Ferrand. A. Hermann et Fils, Paris. 284 pp.GENTIL, L. 1904. Sur l'existence de roches alcalines dans le centre Africain. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences, Paris, 139: 413-5.
Location: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith