Lee, AL orcid.org/0000-0003-0067-9183, Torvela, T orcid.org/0000-0003-1539-8755, Lloyd, GE orcid.org/0000-0002-7859-2486 et al. (1 more author) (2018) Melt organisation and strain partitioning in the lower crust. Journal of Structural Geology, 113. pp. 188-199. ISSN 0191-8141
Abstract
Partial melts can form as a result of crustal thickening due to orogenesis. Even small melt fractions weaken the crust, so that partially molten volumes should accumulate significant amounts of strain. However, relatively little is known of how strain partitions in partial melts, and how effective the melt expulsion processes from the partially molten crust are. Using examples from the Western Gneiss Region (WGR), Norway, we consider a case of co-existing migmatites and shear zones. Field, image analysis, and microanalytical methods allow (semi)quantification of melt volume, rock mineralogy and mineral chemistry, and microstructures. Integration of these analyses implies effective syn-melt strain partitioning and subsequent freezing of both the shear zone and migmatite texture. We propose a mechanism that allows i) syn-melt strain localisation at an outcrop scale through stress-driven melt organisation, resulting in significant relative competence differences in a partially molten rock volume; and ii) formation of fine-grained rocks at outcrop that is entirely or mostly syn-melt, without subsequent mylonitic shearing in the solid-state. Syn-melt shear zones that have not acted as effective melt transport channels and/or that have not accumulated post-melt deformation may be more common than conventionally assumed.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 Elsevier Ltd. This is an author produced version of a paper published in Journal of Structural Geology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Melt; Migmatite; Shear zone; Microstructures; Strain; Western Gneiss Region |
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) The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Institute for Applied Geosciences (IAG) (Leeds) |
Funding Information: | Funder Grant number NERC NE/K008803/1 NERC NE/M000044/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 24 May 2018 08:35 |
Last Modified: | 01 Jul 2019 16:25 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.jsg.2018.05.016 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:131173 |