Contrasting types of bladed olivine in ultramafic rocks from the Archean of Labrador

Exceptionally coarse grained, interlocking olivine crystals up to 1 m long occur in small lenticular ultramafic bodies within the Nain Province of Labrador. The ultramafic rocks occur in association with Archean gneisses that vary in metamorphic grade from amphibolile fades to granulite facies. Some...

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Bibliographic Details
Published in:Canadian Journal of Earth Sciences
Main Authors: Collerson, Kenneth D., Jesseau, C. Wayne, Bridgwater, David
Format: Article in Journal/Newspaper
Language:English
Published: Canadian Science Publishing 1976
Subjects:
Online Access:http://dx.doi.org/10.1139/e76-045
http://www.nrcresearchpress.com/doi/pdf/10.1139/e76-045
Description
Summary:Exceptionally coarse grained, interlocking olivine crystals up to 1 m long occur in small lenticular ultramafic bodies within the Nain Province of Labrador. The ultramafic rocks occur in association with Archean gneisses that vary in metamorphic grade from amphibolile fades to granulite facies. Some of the interlocking textures (i.e. near Hopedale) are interpreted as relict cumulate or harrisitic growths, mimicked by olivine regrowlh during metamorphism and preserved in structurally isotropic enclaves in their host rocks. Others (e.g. near Saglek) are regarded as solely of metamorphic origin. None of the olivine growths resemble spinifex textures reported in Archean ultramafic rocks elsewhere.