X-Ray Study of Deformation Lamellae in Olivines of Ultramafic Rocks

G. A. Challis
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.

Mineralogical Magazine; June 1967 v. 36; no. 278; p. 195-203; DOI: 10.1180/minmag.1967.036.278.03
© 1967, The Mineralogical Society
Mineralogical Society (www.minersoc.org)