strain shadow

strain shadow

[′strān ‚shad·ō]
(petrology)
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Inclusion-free or -poor zones may form in two general ways: 1) if growth is accompanied by dissolution and diffusion of unneeded material and or displacement of matrix insolubles, if present, and 2) by porphyroblast growth into fractures or openings at the interface between the porphyroblast and strain shadow.
Zoning is produced because growth along the porphyroblast margins that parallel foliation proceeds by matrix replacement and incorporation of inclusions whereas growth in the {001} sectors that are at a high angle to foliation involves syntaxial precipitation of biotite in dilating strain shadows, which generally precludes development of inclusions (Fig.
The clear zones form as a consequence of growth of the porphyroblast into voids created by separation of matrix from the porphyroblast in strain shadows and by the development of extension fractures in the middle of a grain, which yields clear zones at the ends and middle of the grain respectively.