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X-ray study of deformation lamellae in olivines of ultramafic rocks

Published online by Cambridge University Press:  14 March 2018

G. A. Challis*
Affiliation:
New Zealand Geological Survey, Lower Hutt, New Zealand

Summary

Olivine crystals showing {100} deformation lamellae between crossed polars show spots streaked out transversely to 00l layer lines in X-ray oscillation photographs. Compositional inhomogeneity is ruled out by optics and electron microprobe analysis. Structurally controlled gliding on {100} (plane of greatest atom density) in the direction [001] (close-packing direction) is deduced on analogy with deformed metals. Mechanism of lamella formation is discussed in terms of superincumbent load; but it is concluded that pressures due to crystal growth are mainly responsible.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1967

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