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Differing Powers of Crystal Nucleation as a Factor Producing Diversity in Layered Igneous Intrusions

Published online by Cambridge University Press:  01 May 2009

L. R. Wager
Affiliation:
Department of Geology and Mineralogy, University Museum, Oxford.

Abstract

To account for a type of rhythmic unit found in the Bushveld complex of South Africa and probably in other layered intrusions, a hypothesis is put forward dependent on the different powers of crystal nucleation from supersaturated magma. It is suggested, for example, that the three common primary precipitate minerals, chromite, bronzite, and bytownite nucleated in this order which is probably dependent on the differing complexity of their crystal structures and that the common rhythmic unit, beginning with chromitite, passing upwards into bronzitite and ending with a bytownite-rich rock is the result of these crystals accumulating successively at the bottom'of the liquid.

Type
Articles
Copyright
Copyright © Cambridge University Press 1959

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