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Size-graded layering in the Imilik gabbro, East Greenland

Published online by Cambridge University Press:  01 May 2009

P. E. Brown  and
D. G. Farmer
P. E. Brown
Affiliation:
Department of Geology, University of Sheffield, Mappin Street, St George's Square, Sheffield, S1 3JD
D. G. Farmer
Affiliation:
Department of Geology, University of Sheffield, Mappin Street, St George's Square, Sheffield, S1 3JD
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Summary

Rhythmic layering in which the layers grade from coarse base to finer top is described in a plagioclase—pyroxene—olivine gabbro. The medium sizes of the various cumulus minerals at each level have significantly different settling velocities. Variation in the proportions of the cumulus minerals accompanies the size grading. It is shown that these characteristics can reasonably be accounted for if hydrodynamic factors exerted the main control, over-riding any chemical effects.

Type
Articles
Information
Geological Magazine , Volume 108 , Issue 6 , November 1971 , pp. 465 - 476
Copyright
Copyright © Cambridge University Press 1971

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