Alkaline Rocks and Carbonatites of the World

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Junguru

stripes

Occurrence number: 
122-00-024
Country: 
Nigeria
Location: 
Longitude: 9.33, Latitude: 10.4

This rather small occurrence consists of an approximately circular, 3 km-diameter biotite granite, an earlier concentric arfvedsonite granite along its southern margin, and an overlapping system of cone sheets and radial dykes. The arfvedsonite granite consists of perthite and a little albite, quartz, prisms of amphibole, minor biotite, abundant astrophyllite and accessory fluorite and zircon. Apart from mica the biotite granite also contains a little hornblende and fluorite is a widespread accessory. The system of cone sheets and dykes extends all around the intrusion and comprises a perthite-quartz porphyry with minute prisms and films of a blue sodic amphibole in the matrix.

References: 
BUCHANAN, M.S., MACLEOD, W.N., TURNER, D.C., BERRIDGE, N.G. and BLACK, R. 1971. The geology of the Jos Plateau. Volume 2, Younger granite complexes. Bulletin, Geological Survey of Nigeria, 32: 1-159.
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