Alkaline Rocks and Carbonatites of the World

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Limmo

stripes

Occurrence number: 
054-00-020
Country: 
Ethiopia
Location: 
Longitude: 40.1, Latitude: 12.62

The Limmo granite intrusion covers about 60 km2, has a faulted western margin and is overlain in the southeast by basaltic flows of the Dabayra volcanic centre. The granite is highly variable in texture with all gradations from miarolitic to granophyric. Quartz may be abundant or, in more syenitic facies, less so. The mafic minerals, which generally comprise about 5% by volume, are interstitial with a blue sodic amphibole the most abundant, but in some facies the amphibole is hastingsitic and accompanied by biotite; hedenbergite and fayalite may also occur.

Age: 
K-Ar determinations gave 23.3(0.6 and 22.8(.6 Ma.
References: 
BLACK, R., REX, D.C. and SHACKLETON, R.M. 1972. Sur la decouverte en Afar (Ethiopie) d'un granite hyperalcalin Miocene: le massif de Limmo. Comptes Rendus des Seances de l'Academie des Sciences. Paris, 274D: 1453-6.
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