Petrological implications of some corona structures

W. L. Griffin*, K. S. Heier

*Corresponding author for this work

Research output: Contribution to journalArticle

99 Citations (Scopus)

Abstract

Reactions between olivine and plagioclase, and between pyroxenes and plagioclase, commonly produce corona assemblages of lower volume and entropy. These coronas imply that assemblages representative of intermediate-and high-pressure granulite facies, and of eclogite facies (emphacite + garnet), can be produced by the cooling of dry olivine + plagioclase and pyroxene + plagioclase assemblages from igneous temperatures within the continental crust. They further imply that eclogite is a stable assemblage within the deeper parts of the continental crust; this in turn requires that dP/dT > 0 for the equilibrium curves for the relevant reactions. The general relations between T and rates of nucleation, growth and diffusion suggest that these coronas will only be formed in relatively deep-seated rocks (P > 6 kb ?). The formation of such coronasby regional or contact metamorphism, or by metasomatism, is unlikely; they are best regarded as retrograde features.

Original languageEnglish
Pages (from-to)315-335
Number of pages21
JournalLithos
Volume6
Issue number4
DOIs
Publication statusPublished - 1973
Externally publishedYes

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