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Textural patterns at porphyroblast margins and their use in determining the time relations of deformation and crystallization

Published online by Cambridge University Press:  01 May 2009

C. C. Ferguson
Affiliation:
Department of Geology, University of NottinghamNottingham, NG7 2RD
B. Harte
Affiliation:
Grant Institute of Geology, University of Edinburgh, EdinburghScotland

Summary

Textural patterns characteristic of supposed pre-, post- and to a lesser extent syn-tectonic porphyroblasts are reviewed. Difficulties of interpretation arise where an Si (internal schistosity) is absent, and Se (external schistosity) behaviour adjacent to porphyroblast margins is the only available criterion; examples may be found showing truncation of Se by pre-Se porphyroblasts. Truncation and/or deflection textures are not by themselves sufficient criteria for determining the time relations of particular phases of deformation and crystallization.

Type
Articles
Copyright
Copyright © Cambridge University Press 1975

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