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The orthoenstatite to clinoenstatite transformation by shearing and reversion by annealing: Mechanism and potential applications

Contributions to Mineralogy and Petrology

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,
DOI: 10.1007/BF00378000

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Abstract

Clinoenstatite (CE) was produced by deforming single-crystal specimens of ortho-enstatite (OE) in several different sorta of experiments. Examination with light and trans-mission electron microscopes shows that the transformation is coherent and involves a macroscopic shear on (100) [001] through an angle of 12.8??1.3 ??, in good agreement with the theoretically expected value of 13.3 ??, and that the transformation is accomplished by glide on (100) of partial dislocations with b= 0.83[001]. Structural analysis provides further insight into the transformation mechanism. Reversion occurs in specimens annealed under a variety of conditions, and thin lamellae of CE in unconstrained, low-strain specimens recover their original shape during transformation back to OE. Our experiments and thermodynamic estimates both suggest that the equilibrium transition temperature is raised roughly 300 ?? C per kilobar of shear stress on (100) [001]. This provides the basis of a method by which it may be possible to determine the magnitude as well as the orientation of the principal stresses that produce CE in nature during deformation of enstatite-bearing rocks. ?? 1975 Springer-Verlag.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The orthoenstatite to clinoenstatite transformation by shearing and reversion by annealing: Mechanism and potential applications
Series title:
Contributions to Mineralogy and Petrology
DOI:
10.1007/BF00378000
Volume
52
Issue:
1
Year Published:
1975
Language:
English
Publisher:
Springer-Verlag
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Contributions to Mineralogy and Petrology
First page:
29
Last page:
55