Abstract

A model for the formation of rnetamorphic aureoles beneath ophiolite complexes is proposed on the basis of evidence from the St. Anthony Complex of northwestern Newfoundland. This complex consists of peridotite underlain by high-grade amphibolites, epidote amphibolites, greenschists, and undeformed volcanic rocks. A rnetamorphic profile through the St. Anthony Complex shows a steep thermal gradient, a change in metamorphic pressure from 7–10 kb near the peridotite contact to 2 kb at the base of the aureole, and a variation in protoliths from gabbros through tholeiitic and alkaline basalts to sedimentary rocks. This evidence suggests that the aureole formed by the accretion of oceanic rocks to the base of an overriding ophiolite sheet during its displacement from the oceanic lithosphere.

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