Chromian spinels in the basalts from the Lisbon volcanic complex (portugal) and their petrogenetic implications

Detalhes bibliográficos
Autor(a) principal: d'Orey, F. L. C.
Data de Publicação: 2010
Outros Autores: Palacios, T.
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10362/3360
Resumo: Chromian spinels are common in the late Cretaceous alkali basalts of the Lisbon volcanic Complex in Portugal. They occur as unzoned inclusions in magnesian olivines of all basalt types and as large spectacularly zoned grains in the groundmass of porphyritic basalts. Microprobe analysis indicate complex cationic exchange in the groundmass zoned spinels due to simple peritectic reactions and in response to changing composition of the basalt liquid. The variation of cationic distribution in zoned chromian-Spinels, reflects very accurately the changing chemistry of the cooling silicate melt and the paragenetical relations of mineral oxides and silicates. Crystallization of initial chromian spinels occurred at T~1200°C and fO2~10-8.5 atm. earlier or contemporaneously with magnesian olivine. The titanomagnetite mantles of zoned chromian spinels crystallized at T~1200°C and much lower fO2.
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spelling Chromian spinels in the basalts from the Lisbon volcanic complex (portugal) and their petrogenetic implicationsChromiteFerritchromitBasaltLisbonPetrogenesisChromian spinels are common in the late Cretaceous alkali basalts of the Lisbon volcanic Complex in Portugal. They occur as unzoned inclusions in magnesian olivines of all basalt types and as large spectacularly zoned grains in the groundmass of porphyritic basalts. Microprobe analysis indicate complex cationic exchange in the groundmass zoned spinels due to simple peritectic reactions and in response to changing composition of the basalt liquid. The variation of cationic distribution in zoned chromian-Spinels, reflects very accurately the changing chemistry of the cooling silicate melt and the paragenetical relations of mineral oxides and silicates. Crystallization of initial chromian spinels occurred at T~1200°C and fO2~10-8.5 atm. earlier or contemporaneously with magnesian olivine. The titanomagnetite mantles of zoned chromian spinels crystallized at T~1200°C and much lower fO2.RUNd'Orey, F. L. C.Palacios, T.2010-04-19T08:26:05Z2010-04-182010-04-18T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10362/3360enginfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-07-10T15:23:10ZPortal AgregadorONG
dc.title.none.fl_str_mv Chromian spinels in the basalts from the Lisbon volcanic complex (portugal) and their petrogenetic implications
title Chromian spinels in the basalts from the Lisbon volcanic complex (portugal) and their petrogenetic implications
spellingShingle Chromian spinels in the basalts from the Lisbon volcanic complex (portugal) and their petrogenetic implications
d'Orey, F. L. C.
Chromite
Ferritchromit
Basalt
Lisbon
Petrogenesis
title_short Chromian spinels in the basalts from the Lisbon volcanic complex (portugal) and their petrogenetic implications
title_full Chromian spinels in the basalts from the Lisbon volcanic complex (portugal) and their petrogenetic implications
title_fullStr Chromian spinels in the basalts from the Lisbon volcanic complex (portugal) and their petrogenetic implications
title_full_unstemmed Chromian spinels in the basalts from the Lisbon volcanic complex (portugal) and their petrogenetic implications
title_sort Chromian spinels in the basalts from the Lisbon volcanic complex (portugal) and their petrogenetic implications
author d'Orey, F. L. C.
author_facet d'Orey, F. L. C.
Palacios, T.
author_role author
author2 Palacios, T.
author2_role author
dc.contributor.none.fl_str_mv RUN
dc.contributor.author.fl_str_mv d'Orey, F. L. C.
Palacios, T.
dc.subject.por.fl_str_mv Chromite
Ferritchromit
Basalt
Lisbon
Petrogenesis
topic Chromite
Ferritchromit
Basalt
Lisbon
Petrogenesis
description Chromian spinels are common in the late Cretaceous alkali basalts of the Lisbon volcanic Complex in Portugal. They occur as unzoned inclusions in magnesian olivines of all basalt types and as large spectacularly zoned grains in the groundmass of porphyritic basalts. Microprobe analysis indicate complex cationic exchange in the groundmass zoned spinels due to simple peritectic reactions and in response to changing composition of the basalt liquid. The variation of cationic distribution in zoned chromian-Spinels, reflects very accurately the changing chemistry of the cooling silicate melt and the paragenetical relations of mineral oxides and silicates. Crystallization of initial chromian spinels occurred at T~1200°C and fO2~10-8.5 atm. earlier or contemporaneously with magnesian olivine. The titanomagnetite mantles of zoned chromian spinels crystallized at T~1200°C and much lower fO2.
publishDate 2010
dc.date.none.fl_str_mv 2010-04-19T08:26:05Z
2010-04-18
2010-04-18T00:00:00Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
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status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10362/3360
url http://hdl.handle.net/10362/3360
dc.language.iso.fl_str_mv eng
language eng
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eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron:RCAAP
instname_str Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron_str RCAAP
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reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
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