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Exsolution of Ca-clinopyroxene from orthopyroxene aided by deformation

Physics and Chemistry of Minerals

By:
,
DOI: 10.1007/BF00308225

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Abstract

Monoclinic calcium-poor shear-transformation lamellae and calcium-rich exsolution lamellae occur parallel to (100) in orthopyroxene. The formation of both structures from an orthopyroxene host involves a shear on (100) parallel to [001], with additional cation exchange in the exsolution case. The shear transformation involves a macroscopic simple shear angle of 13.3?? (shear strain of 0.236) and produces a specific a-axis orientation with respect to the sense of shear; we have found that this orientation dominates in exsolution lamellae in kinked orthopyroxene, where the sense of shear is known. In undeformed orthopyroxene, there is generally no preferred sense of orientation of the monoclinic a axes. We advance a specific model for exsolution involving nucleation and growth by shear transformation combined with cation exchange, thus circumventing the classical nucleation barrier and permitting exsolution at lower solute supersaturations. ?? 1981 Springer-Verlag.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Exsolution of Ca-clinopyroxene from orthopyroxene aided by deformation
Series title:
Physics and Chemistry of Minerals
DOI:
10.1007/BF00308225
Volume
7
Issue:
3
Year Published:
1981
Language:
English
Publisher location:
Springer-Verlag
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
105
Last page:
109
Number of Pages:
5