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Article: Noble metal abundances of late Archean (2.7 Ga) accretion-related shoshonitic lamprophyres, Superior Province, Canada

TitleNoble metal abundances of late Archean (2.7 Ga) accretion-related shoshonitic lamprophyres, Superior Province, Canada
Authors
Issue Date1995
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/gca
Citation
Geochimica Et Cosmochimica Acta, 1995, v. 59 n. 1, p. 47-57 How to Cite?
AbstractShoshonitic magmatism occurred in transpressive geodynamic settings within the Superior Province during the diachronous accretion of allochthonous subprovinces over 2720 to 2680 Ma, which culminated in stabilization of this Archean craton. The dikes are interpreted to have formed from low degrees of partial melting of depleted mantle metasomatically enriched in LILE and LREE during a prior subduction-accretion event. Selenium contents of the dikes range from 50-130 ppb, and S from 150-1000 ppm, with S/Se ratios of 1150-18,000, signifying open-system behaviour of S during autometasomatic and late hydrothermal alteration. Based on the Se contents, and assuming magmatic S Se ratios of ∼ 5,000, primary S contents of the alkaline magmas were undersaturated at ∼ 650 ppm. MgO and Ni are correlated, and Ir (<0.02-0.24 ppb) and Rh (0.02-0.32 ppb) also decrease with lower MgO. Platinum (0.15-5.8 ppb) and Pd (0.48-4.8 ppb) abundances are systematically greater than averages for MORB, but less than contents of 11 ppb and 15 ppb, respectively, for boninites. Primitive mantle normalized patterns are smooth, except at Ru and Au; Pt Ir ratios tend to increase in more evolved dikes because of decreased abundances of Ir. Platinum, paladium, and gold do not correlate with La Yb in least altered dikes, interpreted to imply that mantle metasomatism responsible for enrichment of the source did not contribute Pt, Pd, or Au. During evolution of the shoshonitic magmas, olivine ± pyroxene controlled Ir concentrations and probably Rh. Platinum and palladium correlate with Ti, implying that these PGE were controlled by Timagnetite fractionation. © 1995.
Persistent Identifierhttp://hdl.handle.net/10722/150968
ISSN
2015 Impact Factor: 4.315
2015 SCImago Journal Rankings: 3.016

 

DC FieldValueLanguage
dc.contributor.authorWyman, Den_US
dc.contributor.authorKerrich, Ren_US
dc.contributor.authorSun, Men_US
dc.date.accessioned2012-06-26T06:15:21Z-
dc.date.available2012-06-26T06:15:21Z-
dc.date.issued1995en_US
dc.identifier.citationGeochimica Et Cosmochimica Acta, 1995, v. 59 n. 1, p. 47-57en_US
dc.identifier.issn0016-7037en_US
dc.identifier.urihttp://hdl.handle.net/10722/150968-
dc.description.abstractShoshonitic magmatism occurred in transpressive geodynamic settings within the Superior Province during the diachronous accretion of allochthonous subprovinces over 2720 to 2680 Ma, which culminated in stabilization of this Archean craton. The dikes are interpreted to have formed from low degrees of partial melting of depleted mantle metasomatically enriched in LILE and LREE during a prior subduction-accretion event. Selenium contents of the dikes range from 50-130 ppb, and S from 150-1000 ppm, with S/Se ratios of 1150-18,000, signifying open-system behaviour of S during autometasomatic and late hydrothermal alteration. Based on the Se contents, and assuming magmatic S Se ratios of ∼ 5,000, primary S contents of the alkaline magmas were undersaturated at ∼ 650 ppm. MgO and Ni are correlated, and Ir (<0.02-0.24 ppb) and Rh (0.02-0.32 ppb) also decrease with lower MgO. Platinum (0.15-5.8 ppb) and Pd (0.48-4.8 ppb) abundances are systematically greater than averages for MORB, but less than contents of 11 ppb and 15 ppb, respectively, for boninites. Primitive mantle normalized patterns are smooth, except at Ru and Au; Pt Ir ratios tend to increase in more evolved dikes because of decreased abundances of Ir. Platinum, paladium, and gold do not correlate with La Yb in least altered dikes, interpreted to imply that mantle metasomatism responsible for enrichment of the source did not contribute Pt, Pd, or Au. During evolution of the shoshonitic magmas, olivine ± pyroxene controlled Ir concentrations and probably Rh. Platinum and palladium correlate with Ti, implying that these PGE were controlled by Timagnetite fractionation. © 1995.en_US
dc.languageengen_US
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/gcaen_US
dc.relation.ispartofGeochimica et Cosmochimica Actaen_US
dc.titleNoble metal abundances of late Archean (2.7 Ga) accretion-related shoshonitic lamprophyres, Superior Province, Canadaen_US
dc.typeArticleen_US
dc.identifier.emailSun, M:minsun@hku.hken_US
dc.identifier.authoritySun, M=rp00780en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.scopuseid_2-s2.0-0028870960en_US
dc.identifier.hkuros998-
dc.identifier.volume59en_US
dc.identifier.issue1en_US
dc.identifier.spage47en_US
dc.identifier.epage57en_US
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridWyman, D=7006471092en_US
dc.identifier.scopusauthoridKerrich, R=7005649319en_US
dc.identifier.scopusauthoridSun, M=25932315800en_US

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