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Article: Petrogenetic significance of chromian spinels from the Sudbury Igneous Complex, Ontario, Canada

TitlePetrogenetic significance of chromian spinels from the Sudbury Igneous Complex, Ontario, Canada
Authors
KeywordsEarth sciences
Issue Date1997
PublisherN R C Research Press. The Journal's web site is located at http://www.nrc.ca/cgi-bin/cisti/journals/rp/rp2_desc_e?cjes
Citation
Canadian Journal Of Earth Sciences, 1997, v. 34 n. 10, p. 1405-1419 How to Cite?
AbstractChromian spinels occur in mafic-ultramafic inclusions in the Sublayer of the Sudbury Igneous Complex (SIC) as well as in mafic-ultramafic rocks in the immediate footwall of the Sublayer. The host rocks are pyroxenite and melanorite with minor dunite, harzburgite, and melatroctolite. As common accessory phases in these rocks, the chromian spinels display euhedral or subhedral forms and are included in olivine and orthopyroxene. Chromian spinel grains generally have ilmenite lamellae and contain abundant inclusions (zircon, olivine, diopside, plagioclase, biotite, and sulfide). All the chromian spinels have similar trace element abundances and are rich in TiO2 (0.5-15 wt.%). They have constant Cr# (100Cr/(Cr + Al)) (55-70) and exhibit a continuum in composition that traverses the normal fields of spinels in a Al-(Fe3+ + 2Ti)-Cr triangular diagram. This continuum extends to that of the composition of chromian magnetite in the host norite matrix to the mafic -ultramafic inclusions. This continuum in composition of the spinels suggests that the noritic matrix to the Sublayer formed from the same magma as the inclusions. A positive correlation between the Cr and Al contents of the spinels was probably produced by dilution of these elements by Fe3+ contributed, perhaps, by a plagioclase-saturated melt. Zircon inclusions in a chromian spinel grain reflect incorporation of crustal, felsic materials into the magma before crystallization of chromian spinel. The chemical characteristics and mineral inclusions of the spinels suggest that the Sublayer formed in response to magma mixing. It is suggested that subsequent to the formation of the crustal melt, mantle-derived high-Mg magmas mixed vigourously with this and generated the magmatic sulfides that eventually formed the Ni - Cu - platinum-group elements sulfide ore deposits. Some of the early crystallization products of the high-Mg magma settled to the chamber floor, where they partially mixed with the crustal melt and formed the mafic - ultramafic inclusions and footwall complexes.
Persistent Identifierhttp://hdl.handle.net/10722/42674
ISSN
2015 Impact Factor: 1.19
2015 SCImago Journal Rankings: 0.811
References

 

DC FieldValueLanguage
dc.contributor.authorZhou, MFen_HK
dc.contributor.authorLightfoot, PCen_HK
dc.contributor.authorKeays, RRen_HK
dc.contributor.authorMoore, MLen_HK
dc.contributor.authorMorrison, GGen_HK
dc.date.accessioned2007-03-23T04:29:38Z-
dc.date.available2007-03-23T04:29:38Z-
dc.date.issued1997en_HK
dc.identifier.citationCanadian Journal Of Earth Sciences, 1997, v. 34 n. 10, p. 1405-1419en_HK
dc.identifier.issn0008-4077en_HK
dc.identifier.urihttp://hdl.handle.net/10722/42674-
dc.description.abstractChromian spinels occur in mafic-ultramafic inclusions in the Sublayer of the Sudbury Igneous Complex (SIC) as well as in mafic-ultramafic rocks in the immediate footwall of the Sublayer. The host rocks are pyroxenite and melanorite with minor dunite, harzburgite, and melatroctolite. As common accessory phases in these rocks, the chromian spinels display euhedral or subhedral forms and are included in olivine and orthopyroxene. Chromian spinel grains generally have ilmenite lamellae and contain abundant inclusions (zircon, olivine, diopside, plagioclase, biotite, and sulfide). All the chromian spinels have similar trace element abundances and are rich in TiO2 (0.5-15 wt.%). They have constant Cr# (100Cr/(Cr + Al)) (55-70) and exhibit a continuum in composition that traverses the normal fields of spinels in a Al-(Fe3+ + 2Ti)-Cr triangular diagram. This continuum extends to that of the composition of chromian magnetite in the host norite matrix to the mafic -ultramafic inclusions. This continuum in composition of the spinels suggests that the noritic matrix to the Sublayer formed from the same magma as the inclusions. A positive correlation between the Cr and Al contents of the spinels was probably produced by dilution of these elements by Fe3+ contributed, perhaps, by a plagioclase-saturated melt. Zircon inclusions in a chromian spinel grain reflect incorporation of crustal, felsic materials into the magma before crystallization of chromian spinel. The chemical characteristics and mineral inclusions of the spinels suggest that the Sublayer formed in response to magma mixing. It is suggested that subsequent to the formation of the crustal melt, mantle-derived high-Mg magmas mixed vigourously with this and generated the magmatic sulfides that eventually formed the Ni - Cu - platinum-group elements sulfide ore deposits. Some of the early crystallization products of the high-Mg magma settled to the chamber floor, where they partially mixed with the crustal melt and formed the mafic - ultramafic inclusions and footwall complexes.en_HK
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dc.format.mimetypeapplication/pdf-
dc.format.mimetypeapplication/msword-
dc.languageengen_HK
dc.publisherN R C Research Press. The Journal's web site is located at http://www.nrc.ca/cgi-bin/cisti/journals/rp/rp2_desc_e?cjesen_HK
dc.relation.ispartofCanadian Journal of Earth Sciencesen_HK
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.rightsCanadian Journal of Earth Sciences. Copyright © N R C Research Press.en_HK
dc.subjectEarth sciencesen_HK
dc.titlePetrogenetic significance of chromian spinels from the Sudbury Igneous Complex, Ontario, Canadaen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0008-4077&volume=34&issue=10&spage=1405&epage=1419&date=1997&atitle=Petrogenetic+significance+of+chromian+spinels+from+the+Sudbury+Igneous+Complex,+Ontario,+Canadaen_HK
dc.identifier.emailZhou, MF:mfzhou@hkucc.hku.hken_HK
dc.identifier.authorityZhou, MF=rp00844en_HK
dc.description.naturepublished_or_final_versionen_HK
dc.identifier.scopuseid_2-s2.0-0031411242en_HK
dc.identifier.hkuros35600-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0031411242&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume34en_HK
dc.identifier.issue10en_HK
dc.identifier.spage1405en_HK
dc.identifier.epage1419en_HK
dc.publisher.placeCanadaen_HK
dc.identifier.scopusauthoridZhou, MF=7403506005en_HK
dc.identifier.scopusauthoridLightfoot, PC=7102963749en_HK
dc.identifier.scopusauthoridKeays, RR=7005122208en_HK
dc.identifier.scopusauthoridMoore, ML=7404470488en_HK
dc.identifier.scopusauthoridMorrison, GG=7201786352en_HK

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