Stuart, CA, Meek, U, Daczko, NR et al. (2 more authors) (2018) Chemical Signatures of Melt–Rock Interaction in the Root of a Magmatic Arc. Journal of Petrology, 59 (2). pp. 321-340. ISSN 0022-3530
Abstract
Identification of melt–rock interaction during melt flux through crustal rocks is limited to field relationships and microstructural evidence, with little consideration given to characterising the geochemical signatures of this process. We examine the mineral and whole-rock geochemistry of four distinct styles of melt–rock interaction during melt flux through the Pembroke Granulite, a gabbroic gneiss from the Fiordland magmatic arc root, New Zealand. Spatial distribution, time-integrated flux of melt and stress field vary between each melt flux style. Whole-rock metasomatism is not detected in three of the four melt flux styles. The mineral assemblage and major element mineral composition in modified rocks are dictated by inferred P–T conditions, as in sub-solidus metamorphic systems, and time-integrated volumes of melt flux. Heterogeneous mineral major and trace element compositions are linked to low time-integrated volumes of melt flux, which inhibits widespread modification and equilibration. Amphibole and clinozoisite in modified rocks have igneous-like REE patterns, formed by growth and/or recrystallisation in the presence of melt and large equilibration volumes provided by the grain boundary network of melt. Heterogeneities in mineral REE compositions are linked to localisation of melt flux by deformation and resulting smaller equilibration volumes and/or variation in the composition of the fluxing melt. When combined with microstructural evidence for the former presence of melt, the presence of igneous-like mineral REE chemical signatures in a metamorphic rock are proposed as powerful indicators of melt–rock interaction during melt flux.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | (c) The Author(s) 2018. Published by Oxford University Press. All rights reserved. This is a pre-copyedited, author-produced version of an article accepted for publication in Journal of Petrology following peer review. The version of record is available online at: https://doi.org/10.1093/petrology/egy029. |
Keywords: | amphibolite; hydration; lower crust; melt–rock interaction; porous melt flow |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 19 Sep 2018 12:20 |
Last Modified: | 10 Mar 2019 01:38 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | 10.1093/petrology/egy029 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:135919 |