Alkaline Rocks and Carbonatites of the World

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Hossere Poli

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Occurrence number: 
029-00-010
Country: 
Cameroon
Location: 
Longitude: 13.27, Latitude: 8.47

The upstanding, circular 1 km diameter Poli complex consists of an outer ring of gabbro, an intermediate ring of granite and a core of andesites which form a cap to the hill. The granites are predominantly biotite types but riebeckite has been reported (Lasserre, 1966).

Age: 
A Rb-Sr determination on a whole rock gave 54(22 Ma and determinations on biotite 33(5 and 38(4 Ma (Lasserre, 1966). A Rb-Sr isochron age of 39.2(2 Ma was obtained by Lasserre (1978); K-Ar on K-feldspar gave 31(1 Ma (Cantagrel et al. , 1978).
References: 
CANTAGREL, J.-M., JAMOND, C. and LASSERE, M. 1978. Le magmatisme alcalin de la ligne du Cameroun au Tertiaire inférieur: données géochronologiques K/Ar. Bulletin de la Société Géologique de France Compte Rendu Sommaire des Seances, 20: 300-3.LASSERRE, M. 1966. Confirmation de l'existence d'une série de granites Tertaires au Cameroun (Afrique équatoriale). Bulletin du Bureau de Recherches Géologiques et Minières. Paris 3: 141-8.LASSERRE, M. 1978. Mise au point sur les granitoides dits "ultimes" du Cameroun: gisement, pétrographie et géochronologie. Bulletin du Bureau de Recherches Géologiques et Minières. Paris, IV: 143-59.
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