Alkaline Rocks and Carbonatites of the World

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Almi Guenfalabo (Gwenfalabo, Halmi)

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Occurrence number: 
030-00-013
Country: 
Cameroon
Location: 
Longitude: 12.42, Latitude: 7.77

This is a large complex, with a diameter of nearly 20 km, comprising both plutonic and extrusive volcanic rocks. Few details on the volcanic rocks are available but according to Guiraudie (1955) and Ngonge and Nsifa (1990) they include Ne-normative basanitoids, basalts, rhyolites, peralkaline trachytes and pantellerites. The plutonic rocks comprise an early suite of gabbro, monzonite and granite which was followed by a syenite-granite porphyry suite (Derruelle et al., 1991). In the more evolved granites sodic amphibole and aegirine are the principal mafic minerals.

References: 
DERUELLE, B., MOREAU, C., NKOUMBOU, C., KAMBOU, R., LISSOM, J., NJONFANG, E., GHOGOMU, R.T. and NONO, A. 1991. The Cameroon Line: a review. In A.B. Kampunzu and R.T. Lubala (eds), Magmatism in extensional structural settings. 274-327. Springer-Verlag, Berlin.GUIRAUDIE, C. 1955. Notice explicative sur la feuille Ngaoundéré-Ouest. Carte Geologique de Reconnaissance à l'échelle du 1/500,000. (O42). Paris.NGONGE, E.D. and NSIFA, E.N. 1990. Geochemistry of the Guenfalabo anorogenic complex (a volcano-plutonic complex along the “Cameroon Line”). Occasional Publication, International Center for Training and Exchanges in the Geosciences, 1990/20: 400. (Abstract)
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