Alkaline Rocks and Carbonatites of the World

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Taghouaji (Tarouadji)

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Occurrence number: 
121-00-019
Country: 
Niger
Location: 
Longitude: 8.5, Latitude: 17.2

The approximately circular, 16x20 km Taghouaji complex is composed essentially of granites with biotite granites covering 28% and rings of sodic amphibole and aegirine granites extending over 72% of the area. Fabries and Rocci (1965) distinguish the following mineral associations: quartz-microcline-albite-aegirine-hastingsite; quartz-perthite-aegirine-hastingsite-arfvedsonite-aenigmatite; quartz-perthite-hastingsite; quartz-perthite-riebeckite-biotite; quartz-perthite-biotite; quartz-albite-microcline-biotite and quartz-biotite, the last in greisens. They give full accounts of these minerals, including much chemical data and, using these data, discuss the petrogenesis of the rocks. Extensive suites of accessory minerals have been identified (Perez and Rocci, 1985) including, in the peralkaline granites, monazite, bastnasite-synchysite, chevkinite, wiikite, Nb-rich titanite, RE silicates, pyrochlore, fergusonite, niobo-titanates, xenotime, fluorite and fluocerite; in the biotite granites typical accessories include fluorite, columbite, thorite, topaz, zircon and anatase. Perez and Rocci (1985) consider crystallization of the Taghouadji complex in terms of these minerals and fluid interactions. Perez et al. (1990) describe Be and Zn mineralization in veins and breccias in biotite granites and identified genthelvite, beryl, bertrandite, willemite, Zn-berthierine and sphalerite.

Age: 
A whole-rock Rb-Sr isochron gave 401(5 Ma (Karche and Vachette, 1978).
References: 
FABRIES, J. and ROCCI, G. 1965. Le massif granitique du Tarraouadji (Republique du Niger). Etude et signification petrogenetique des principaux mineraux. Bulletin de la Société Francaise de Mineralogie et de Cristallographie, 88: 319-40.KARCHE, J.-P. and VACHETTE, M. 1978. Age et migration de l'activité magmatique dans les complexes paléozoïques du Niger. Consequences. Bulletin de la Société Géologique de France, 20: 941-53.PEREZ, J.B. and ROCCI, G. 1985. Fluid interaction during the crystallisation of granites in the Taghouaji ring complex (Air, Niger): textures, paragenesis of rock forming and accessory minerals. 13th Colloquium of African Geology, St. Andrews. International Center for Training and Exchanges in the Geosciences. Occasional Publication, 1985/3: 305.PEREZ, J.-B., DUSAUSOY, Y., BABKINE, J. and PAGEL, M. 1990. Mn zonation and fluid inclusions in genthelvite from the Taghouaji complex (Air Mountains, Niger). American Mineralogist, 75: 909-14.
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