Alkaline Rocks and Carbonatites of the World

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Sutumi

stripes

Occurrence number: 
122-00-027
Country: 
Nigeria
Location: 
Longitude: 9.3, Latitude: 10.2

Sutumi is a volcanic plug in which most of the plug materials have been displaced by later intrusions of granite. Rhyolites and agglomerates form screens between the granite and the basement rocks at several places around the plug. Coarser, recrystallised areas of rhyolite contain small phenocrysts of quartz and perthite with mafic streaks of poikilitic amphibole and biotite and accessory fluorite. Xenoliths of rhyolite occur in the granites which contain euhedral hornblende, sometimes with a rim of a blue-green amphibole, and biotite. Two minor intrusions of biotite granite complete the igneous events.

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