Enrichment of 18O in the mantle sources of the Antarctic portion of the Karoo large igneous province

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dc.contributor University of Helsinki, Department of Geosciences and Geography en
dc.contributor University of Helsinki, Finnish Museum of Natural History en
dc.contributor.author Heinonen, Jussi S.
dc.contributor.author Luttinen, Arto V.
dc.contributor.author Whitehouse, M.J.
dc.date.accessioned 2018-03-29T07:21:01Z
dc.date.available 2018-03-29T07:21:01Z
dc.date.issued 2018-03
dc.identifier.citation Heinonen , J S , Luttinen , A V & Whitehouse , M J 2018 , ' Enrichment of 18 O in the mantle sources of the Antarctic portion of the Karoo large igneous province ' , Contributions to Mineralogy and Petrology , vol. 173 , no. 3 , 21 . https://doi.org/10.1007/s00410-018-1447-4 en
dc.identifier.issn 0010-7999
dc.identifier.other PURE: 98620668
dc.identifier.other PURE UUID: 60c7ba7a-7e16-4919-b32d-d17b3f67fecf
dc.identifier.other WOS: 000427307200003
dc.identifier.other Scopus: 85042436904
dc.identifier.other ORCID: /0000-0002-3129-0392/work/67131645
dc.identifier.uri http://hdl.handle.net/10138/233825
dc.description.abstract Karoo continental flood basalt (CFB) province is known for its highly variable trace element and isotopic composition, often attributed to the involvement of continental lithospheric sources. Here, we report oxygen isotopic compositions measured with secondary ion mass spectrometry for hand-picked olivine phenocrysts from similar to 190 to 180 Ma CFBs and intrusive rocks from Vestfjella, western Dronning Maud Land, that form an Antarctic extension of the Karoo province. The Vestfjella lavas exhibit heterogeneous trace element and radiogenic isotope compositions (e.g., epsilon(Nd) from -16 to +2 at 180 Ma) and the involvement of continental lithospheric mantle and/or crust in their petrogenesis has previously been suggested. Importantly, our sample set also includes rare primitive dikes that have been derived from depleted asthenospheric mantle sources (epsilon(Nd) up to + 8 at 180 Ma). The majority of the oxygen isotopic compositions of the olivines from these dike rocks (delta O-18 = 4.4-5.2%; Fo = 78-92 mol%) are also compatible with such sources. The olivine phenocrysts in the lavas, however, are characterized by notably higher delta O-18 (6.2-7.5%; Fo = 70-88 mol%); and one of the dike samples gives intermediate compositions (5.2-6.1%, Fo = 83-87 mol%) between the other dikes and the CFBs. The oxygen isotopic compositions do not correlate with radiogenic isotope compositions susceptible to crustal assimilation (Sr, Nd, and Pb) or with geochemical indicators of pyroxene-rich mantle sources. Instead, delta O-18 correlates positively with enrichments in large-ion lithophile elements (especially K) and Os-187. We suggest that the oxygen isotopic compositions of the Vestfjella CFB olivines primarily record large-scale subduction-related metasomatism of the sub-Gondwanan mantle (base of the lithosphere or deeper) prior to Karoo magmatism. The overall influence of such sources to Karoo magmatism is not known, but, in addition to continental lithosphere, they may be responsible for some of the geochemical heterogeneity observed in the CFBs. en
dc.format.extent 21
dc.language.iso eng
dc.relation.ispartof Contributions to Mineralogy and Petrology
dc.rights en
dc.subject 1171 Geosciences en
dc.subject CONTINENTAL FLOOD BASALTS en
dc.subject LARGE IGNEOUS PROVINCE en
dc.subject mantle en
dc.subject CONTAMINATION en
dc.subject OXYGEN ISOTOPES en
dc.subject Karoo en
dc.subject Antarctica en
dc.subject olivine en
dc.subject metasomatism en
dc.subject Oxygen isotopes en
dc.subject Continental flood basalt en
dc.subject Large igneous province en
dc.subject Karoo en
dc.subject Antarctica en
dc.subject Olivine en
dc.subject Mantle en
dc.subject Metasomatism en
dc.subject DRONNING-MAUD-LAND en
dc.subject TRACE-ELEMENT COMPOSITION en
dc.subject OXYGEN-ISOTOPE EVIDENCE en
dc.subject FLOOD-BASALT PROVINCE en
dc.subject OCEAN ISLAND BASALTS en
dc.subject SUB-ARC MANTLE en
dc.subject CONTINENTAL BASALTS en
dc.subject EAST ANTARCTICA en
dc.subject RECYCLED CRUST en
dc.subject TECTONIC DISCRIMINATION en
dc.title Enrichment of 18O in the mantle sources of the Antarctic portion of the Karoo large igneous province en
dc.title.alternative 18O-rikastuminen Karoon suuren magmaprovinssin antarktisen osan vaippalähteissä en
dc.type Article
dc.description.version Peer reviewed
dc.identifier.doi https://doi.org/10.1007/s00410-018-1447-4
dc.type.uri info:eu-repo/semantics/other
dc.type.uri info:eu-repo/semantics/acceptedVersion
dc.contributor.pbl
dc.contributor.pbl
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