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Pre-Cambrian Perthosites in Nyasaland

Published online by Cambridge University Press:  01 May 2009

S. W. Morel
Affiliation:
c/o “Freeby”, The Green, Sidcup, Kent.

Abstract

Attention is drawn to the widespread occurrence of perthosite bodies in the Basement Complex of southern Nyasaland, and a description of these rocks is given.

It is suggested that these rocks represent a late stage in the differentiation of basaltic or andesitic magma which produced basic intrusives and volcanics and ultrabasic complexes in the late Pre-Cambrian. These were subsequently metamorphosed at a high grade. The nepheline-syenite gneisses of Port Herald and Tambani are believed to be related to the same series.

The remarkable similarities between the late Pre-Cambrian igneous history and that of the Karroo to Chilwa Series period is commented upon, and the occurrence of similar “ring structuress” in both series is described.

Type
Articles
Copyright
Copyright © Cambridge University Press 1961

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References

Ashley, B. E., 1951. The Geology of the Neno District. Ann. Rep. geol. Surv. Nyasaland, 45.Google Scholar
Bloomfield, K., 1952. The Geology of the Zomba area. Ann. Rep. geol. Surv. Nyasaland, 1516.Google Scholar
Bloomfield, K., 1958. The Geology of the Port Herald area. Bull. geol. Surv. Nyasaland, 9.Google Scholar
Cooper, W. G. G., 1946. The Geology of the Tambani corundum field. Ann. Rep. geol. Surv. Nyasaland, 16.Google Scholar
Cooper, W. G. G., 1952. The Geology of the Tambane-Salabidwe area. Ann. Rep. geol. Surv. Nyasaland, 46.Google Scholar
Dixey, F., Smith, W. Cambell, and Bisset, C. B., 1937. The Chilwa Series of southern Nyasaland. Bull. geol. Surv. Nyasaland, 5, (Revised 1955).Google Scholar
Garson, M. S., 1958. Chilwa Island. Geol. Surv. Nyasaland, Mem. 1.Google Scholar
Heier, K., 1955. The formation of feldspar perthites in highly metamorphic gneisses. Norsk. geol. Tidsskr., 35, 8791.Google Scholar
Michot, P., 1951. Essai sur la geologie de la catazone. Bull. Acad. Belg. Cl. Sci., 5th Sep., 37.Google Scholar
Morel, S. W., 1951. Chingali Ring Structure. Ann. Rep. geol. Surv. Nyasaland 67.Google Scholar
Morel, S. W., 1955. Biotitite in the Basement Complex of Southern Nyasaland. Geol. Mag. 92, 241254.CrossRefGoogle Scholar
Morel, S. W., 1957. The Ncheu Area. Unpublished report. Geol. Surv. Nyasaland.Google Scholar
Morel, S. W., 1958. The Geology of the Middle Shire area. Bull. geol. Surv. Nyasaland, 10.Google Scholar
Phemister, J. et al. , 1926. The geology of Strath Oykell and lower Loch Shin. Mem. geol. Surv. Scotland.Google Scholar
Savage, H. E. F., 1934. Blantyre Basic Rocks. Ann Rep. geol. Surv. Nyasaland 1522.Google Scholar
Stringer, K. V., Holt, D. N., and Groves, A. W., 1956. The Chambe Plateau Ring Complex of Nyasaland. Col. Geol. Min. Res. 6, 318.Google Scholar
Tilley, C. E., 1953. Age determinations of the nepheline-syenite-gneisses of Tambane district. Ann. Rep. geol. Surv. Nyasaland, 1516.Google Scholar