Deep mixing of mantle melts beneath continental flood basalt provinces : Constraints from olivine-hosted melt inclusions in primitive magmas

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dc.contributor University of Helsinki, Finnish Museum of Natural History en
dc.contributor.author Jennings, Eleanor S.
dc.contributor.author Gibson, Sally A.
dc.contributor.author Maclennan, John
dc.contributor.author Heinonen, Jussi S.
dc.date.accessioned 2017-02-10T14:39:01Z
dc.date.available 2017-02-10T14:39:01Z
dc.date.issued 2017-01-01
dc.identifier.citation Jennings , E S , Gibson , S A , Maclennan , J & Heinonen , J S 2017 , ' Deep mixing of mantle melts beneath continental flood basalt provinces : Constraints from olivine-hosted melt inclusions in primitive magmas ' , Geochimica et Cosmochimica Acta , vol. 196 , pp. 36-57 . https://doi.org/10.1016/j.gca.2016.09.015 en
dc.identifier.issn 0016-7037
dc.identifier.other PURE: 68243307
dc.identifier.other PURE UUID: 346317a5-2897-413e-80df-bfd4285368f4
dc.identifier.other WOS: 000390959200003
dc.identifier.other Scopus: 84991229619
dc.identifier.uri http://hdl.handle.net/10138/175084
dc.description.abstract We present major and trace element compositions of 154 re-homogenised olivine-hosted melt inclusions found in primitive rocks (picrites and ferropicrites) from the Mesozoic Paraná–Etendeka and Karoo Continental Flood Basalt (CFB) provinces. The major element compositions of the melt inclusions, especially their Fe/Mg ratios, are variable and erratic, and attributed to the re-homogenisation process during sample preparation. In contrast, the trace element compositions of both the picrite and ferropicrite olivine-hosted melt inclusions are remarkably uniform and closely reflect those of the host whole-rocks, except in a small subset affected by hydrothermal alteration. The Paraná–Etendeka picrites and ferropicrites are petrogenetically related to the more evolved and voluminous flood basalts, and so we propose that compositional homogeneity at the melt inclusion scale implies that the CFB parental mantle melts were well mixed prior to extensive crystallisation. The incompatible trace element homogeneity of olivine-hosted melt inclusions in Paraná–Etendeka and Karoo primitive magmatic rocks has also been identified in other CFB provinces and contrasts with findings from studies of basalts from mid-ocean ridges (e.g. Iceland and FAMOUS on the Mid Atlantic Ridge), where heterogeneity of incompatible trace elements in olivine-hosted melt inclusions is more pronounced. We suggest that the low variability in incompatible trace element contents of olivine-hosted melt inclusions in near-primitive CFB rocks, and also ocean island basalts associated with moderately thick lithosphere (e.g. Hawaii, Galápagos, Samoa), may reflect mixing along their longer transport pathways during ascent and/or a temperature contrast between the liquidus and the liquid when it arrives in the crust. These thermal paths promote mixing of mantle melts prior to their entrapment by growing olivine crystals in crustal magma chambers. Olivine-hosted melt inclusions of ferropicrites from the Paraná–Etendeka and Karoo CFB have the least variable compositions of all global melt inclusion suites, which may be a function of their unusually deep origin and low viscosity. en
dc.format.extent 22
dc.language.iso eng
dc.relation.ispartof Geochimica et Cosmochimica Acta
dc.rights en
dc.subject 1171 Geosciences en
dc.title Deep mixing of mantle melts beneath continental flood basalt provinces : Constraints from olivine-hosted melt inclusions in primitive magmas en
dc.title.alternative Vaipan sulien sekoittuminen syvällä laakiobasalttiprovinssien alla: Rajoituksia primitiivisten magmojen oliviinin sulasulkeumista en
dc.type Article
dc.description.version Peer reviewed
dc.identifier.doi https://doi.org/10.1016/j.gca.2016.09.015
dc.type.uri info:eu-repo/semantics/other
dc.type.uri info:eu-repo/semantics/publishedVersion
dc.contributor.pbl
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