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dc.contributor.authorHughes, HSR
dc.contributor.authorMcDonald, I
dc.contributor.authorGoodenough, KM
dc.contributor.authorCiborowski, TJR
dc.contributor.authorKerr, AC
dc.contributor.authorDavies, JHFL
dc.contributor.authorSelby, D
dc.date.accessioned2018-02-28T10:27:46Z
dc.date.issued2014-09
dc.description.abstractThe Lewisian Gneiss Complex of NW Scotland represents the eastern margin of the North Atlantic Craton. It comprises mid-late Archaean tonalite-trondhjemite-granodiorite gneisses that were metamorphosed and deformed during the Late-Archaeanand Palaeoproterozoic.Amajor swarmofmafic-ultramafic dykes, the Scourie Dyke Swarm, was intruded at ca. 2.4–2.3 Ga during a period of extension that can be correlated across the North Atlantic Craton. The majority of dykes are doleritic, with volumetrically minor picrite and olivine gabbro suites. New major and trace element geochemical data and Re-Os isotopes indicate that the Scourie Dyke Swarm was not solely derived from a ‘typical’ asthenospheric mantle source region. The geochemical signatures ofthe dykes show significant negative Nb, Ta and Ti anomalies, coupled with enrichmentin Th, Light Rare Earth Elements and other large ion lithophile elements. These features cannot be reproduced by simple contamination of asthenospheric sources with Lewisian granulite-facies crust. Instead they are a feature of the mantle source that produced the Scourie Dykes and may have developed during Archaean subduction episodes. Spinel lherzolite mantle xenoliths from the Isle of Lewis offer directinsightinto the lithospheric mantle below this region. They display similar geochemical‘enrichments’ and ‘depletions’ observed inthe Scourie Dykes and the magma source is thus considered to reside primarily in the sub-continental lithospheric mantle (SCLM), with some potential contribution from asthenospheric melts. Platinum Group Element geochemistry and trace element modelling indicate that the dolerite dykes were formed by moderate (<15%) partial melting of the source, whilst higher degrees of partial melting led to the formation of picritic and olivine gabbro suites. Magma production was triggered by significant crustal and lithospheric extension, causing both asthenospheric and substantial lithospheric melting.en_GB
dc.description.sponsorshipHSRH would like to acknowledge the financial support of the Natural Environment Research Council (NERC) for funding this work which has been undertaken as part of her PhD (studentship NE/J50029X/1)en_GB
dc.identifier.citationVol. 250, pp. 97 - 126en_GB
dc.identifier.doi10.1016/j.precamres.2014.05.026
dc.identifier.urihttp://hdl.handle.net/10871/31736
dc.language.isoenen_GB
dc.publisherElsevieren_GB
dc.rights© 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).en_GB
dc.subjectScourie Dykeen_GB
dc.subjectLewisianen_GB
dc.subjectLithospheric mantleen_GB
dc.subjectMantle xenolithsen_GB
dc.subjectMetasomatismen_GB
dc.subjectPGEen_GB
dc.titleEnriched lithospheric mantle keel below the Scottish margin of the North Atlantic Craton: Evidence from the Palaeoproterozoic Scourie Dyke Swarm and mantle xenolithsen_GB
dc.typeArticleen_GB
dc.date.available2018-02-28T10:27:46Z
dc.identifier.issn0301-9268
exeter.article-numberCen_GB
dc.descriptionThis is the final version of the article. Available from the publisher via the DOI in this record.en_GB
dc.identifier.journalPrecambrian Researchen_GB


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