Abstract
Karroo (Triassic-Jurassic) sediments and lavas occupy a N.N.E.-trending trough known as the Tuli Syncline 230 km in length by 45 km wide along the southern margin of Rhodesia. The structure is fault bounded, especially on the north, and comprises a sequence of gently inward dipping lava flows cut by numerous E-W and N.N.E. striking dolerite dykes. The igneous rocks have been subdivided on the basis of mineralogy and chemistry into a stratigraphic sequence of limburgites near the base, olivine basalts and upper augite-plagio-clase-phyric basalts. In addition, rare shoshonite and absarokite types occur. Twentyfour new silicate analyses are comparable to those from rocks in the neighbouring Nuanetsi Province of Rhodesia, and show strong affinities to the northern province Karroo basalts of southern Africa as defined by Cox,McDonald andHornung (1967).
Similar content being viewed by others
References
Con, K. G., Johnson, R. L., Monkman, L. J., Stillman, C. J., Vail, J. R., andWood, D. N., 1965,The geology of the Nuanetsi Igneous Province. Phil. Trans. Royal Soc. Lond., Ser. A. 257, pp. 71–218.
—————, andNornung, G., 1966,The petrology of the Karroo basalts of Basutoland. Amer. Mineralogist, 51, pp. 1414–1432.
—————, andHornung, G., 1967,Geochemical and petrographic provinces in the Karroo basalts of southern Africa. Amer. Mineralogist, 52, pp. 1451–1474.
Green, D. 1966.The Karroo System in Bechnanaland. Bull. Geol. Surv. Bechuanaland, 2, 74 pp.
Holmes, A., andHarwood, H. E., 1937,The volcanic area of Bufumbira. Part II: The petrology of the volcanic field of Bufumbira, South-west Uganda. Mem. Geol. Surv. Uganda, 3, 300 pp.
Iddings, J. P., 1895,Absarokite-shoshonite-banakite series. J. Geol., 3, pp. 935–959.
Jamieson, B. G., 1966,Evidence on the evolution of basaltic magma at elevated pressures. Nature, London, 212, 5059, pp. 243–246.
Mason, R., 1965,Geology of the Macloutsie area. Records Geol. Surv. Bechuanaland 1961–1962, pp. 25–42.
Moeyneun, A. J. C., 1903,The sedimentary deposits of Southern Rhodesia. Quart. J. Geol. Soc. Lond., 59, pp. 266–291.
Monkman, L. J., 1961,The geology of the Maose-Malibangwe river basins, with special reference to the Stormberg rhyolitic volcanicity of Southern Rhodesia. Ph. D. thesis, Leeds University.
Poldervaart, A., 1951,Karroo dolerites and basalts of the Bechuanaland Protectorate. Geol. Surv. Bechuanaland, unpublished report.
Vail, J. R., 1968,The southern extension of the East African Rift System and related igneous activity. Geol. Rdsch., 57, 2, pp. 601–614.
Van Breemen, O., Dodson, M. H., andVail, J. R., 1966,Isotopic age measurements on the Limpopo orogenic belt, southern Africa. Earth and Planet. Sci. Letters, 1, pp. 401–406.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Vail, J.R., Hornung, G. & Cox, K.G. Karroo basalts of the Tuli Syncline, Rhodesia. Bull Volcanol 33, 398–418 (1969). https://doi.org/10.1007/BF02596517
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02596517