Microstructures and late-stage magmatic processes in layered mafic intrusions: symplectites from the Sept Iles Intusion, Quebec, Canda

Holness, M. B. and Keevil, H. and Namur, O. (2020) Microstructures and late-stage magmatic processes in layered mafic intrusions: symplectites from the Sept Iles Intusion, Quebec, Canda. Journal of Petrology. ISSN Print ISSN 0022-3530 - Online ISSN 1460-2415 (In Press)

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Abstract

Replacive symplectites (vermicular intergrowths of two or more minerals) are an important feature of layered igneous intrusions, recording evidence of late-stage reactions between interstitial liquid and crystals. They are common throughout the Layered Series of the 564 Ma Sept Iles layered intrusion in Quebec, Canada, and fall into three types: oxy-symplectites, ‘Type I’ symplectites, and ‘Type II’ symplectites. Oxy-symplectites are comprised of magnetite and orthopyroxene, nucleate on olivine primocrysts, and form via the reaction Olivine + O2  Orthopyroxene + Magnetite; Type I symplectites (of which there are 3 distinct categories) are comprised of anorthitic plagioclase with pyroxene, amphibole, or olivine vermicules, grow from primocryst oxide grains, and replace primary plagioclase; and Type II symplectites (of which there are 2 distinct categories) are comprised of anorthitic plagioclase with orthopyroxene ± amphibole vermicules, grow from primocryst olivine.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA76
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
08 - Green Open Access
Journal or Publication Title: Journal of Petrology
Depositing User: Sarah Humbert
Date Deposited: 09 Jul 2020 21:36
Last Modified: 09 Jul 2020 21:36
URI: http://eprints.esc.cam.ac.uk/id/eprint/4818

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