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Carbonatitic Lava from Fort Portal Area in Western Uganda

Naturevolume 192pages10641065 (1961) | Download Citation



IN an excellent paper Holmes1 quotes chemical analyses of two spectacular carbonated lavas, one from the Katwe region, the other from Kalyango volcano near Fort Portal. In earlier work, Holmes and Harwood2 described a similar carbonated lava from Lake Kyekora, also near Fort Portal. Present examination of a vesicular lava of high carbonate content poured out from Kalyango volcano shows close geochemical affinities with intrusive carbonatites. It must be emphasized that the lavas examined are fresh and unaltered and that the carbonated nature cannot be attributed to alteration after solidification. A proposed investigation of the numerous lavas in the Fort Portal field may elucidate the formation not only of the characteristic ultra-basic potassic volcanics of south-west Uganda and adjoining parts of the Congo, the petrogenesis of which Holmes has presented so admirably, but also the genesis of the carbonatites themselves.

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  1. 1

    Holmes A., Verh. Konink. Nederland. Geol. Mijnb. Genootschap, 16, 1 (1956).

  2. 2

    Holmes, A., and Harwood, F., Quart. J. Geol. Soc., 88, 369 (1932).

  3. 3

    Combe, A. D., Ann. Rep. Geol. Survey Uganda, 14 (1938).

  4. 4

    James, T. C., Rep. on Carbonatites and Rift Valleys in East Africa (Geol. Surv. Tanganyika, 1956).

  5. 5

    Combe, A. D., and Holmes, A., Trans. Roy. Soc. Edinburgh, 61, Pt. II, No. 14 (1945).

  6. 6

    Kranck, E. H., Bull. No. 19 (Geol. Surv. Newfoundland, 1939).

  7. 7

    von Knorring, O. (unpublished thesis, Geology Department, University of Helsinki, 1941).

  8. 8

    Higazy, R. A., Bull. Geol. Soc. Amer., 65, 39 (1954).

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  1. Research Institute of African Geology, Department of Geology, University of Leeds

  2. Mines and Geology Department, Nairobi, Kenya

    • C. G. B. DU BOIS


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