Alkaline Rocks and Carbonatites of the World

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Occurrence number: 
Longitude: 36.22, Latitude: -3.3

This 7x6 km volcanic cone has a core of nephelinitic and ijolitic agglomerates and tuffs with a thin covering of nephelinitic and phonolitic lavas. Ejected blocks in the agglomerates are commonly nephelinite or phonolite, but ijolite, melteigite and nepheline syenite also occur. There are four rock analyses, including trace element and Sr, Nd and Pb isotope data, and a nepheline analysis, in Paslick et al. (1995 and 1996).

K-Ar on nephelinite gave 1.03(0.04 and 0.91(0.03 Ma (Evans et al., 1971).
DAWSON, J.B. and PICKERING, R. 1964. Monduli. Geological Survey of Tanganyika, Quarter Degree Sheet, 54.EVANS, A.L., FAIRHEAD, J.D. and MITCHELL, J.G. 1971. Potassium-argon ages from the volcanic province of northern Tanzania. Nature, Physical Science, 229: 19-20.PASLICK, C., HALLIDAY, A.N., JAMES, D. and DAWSON, J.B. 1995. Enrichment of the continental lithosphere by OIB melts: isotopic evidence from the volcanic province of northern Tanzania. Earth and Planetary Science Letters, 130: 109-26.PASLICK, C., HALLIDAY, A.N., JAMES, D. and DAWSON, J.B. 1996. Indirect crustal contamination: evidence from isotopic and chemical disequilibrium in minerals from alkali basalts and nephelinites from northern Tanzania. Contributions to Mineralogy and Petrology, 125: 277-92.
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