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Significance of the Radiometric Ages of the Nchanga and Lusaka Granites, Northern Rhodesia

Published online by Cambridge University Press:  01 May 2009

A. R. Drysdall  and
P. Garrard
A. R. Drysdall
Affiliation:
Geological Survey Department, P.O. Box RW.135, Ridgway, Lusaka, Northern Rhodesia.
P. Garrard
Affiliation:
Geological Survey Department, P.O. Box RW.135, Ridgway, Lusaka, Northern Rhodesia.
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Abstract

The similarity between the “whole-rock” ages of the Nchanga and Lusaka granites, 755 m.y. and 725 m.y. respectively, is misleading. The field evidence indicates that the Lusaka granite, although syntectonic, intrudes Katanga metasediments, whereas the Nchanga granite is overlain unconformably by basal Katanga conglomerate and arkose. The age of the Lusaka granite thus sets a younger limit to the age of the Katanga metasediments of the Central Province and dates the waning phases of the Lufilian orogeny. The radiometric age of the Nchanga red granite is too young for a pre-Katanga intrusive, and it is suggested that it has been modified by subsequent metasomatism.

Type
Articles
Information
Geological Magazine , Volume 101 , Issue 2 , 17 April 1964 , pp. 161 - 168
Copyright
Copyright © Cambridge University Press 1964

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References

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