The Terceira Rift, Azores: a melt inclusion study of submarine lavas
Autor(a) principal: | |
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Data de Publicação: | 2012 |
Outros Autores: | , , , , |
Tipo de documento: | Artigo de conferência |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10174/7420 |
Resumo: | The Azores plateau, a bathymetric high, is seated on an anomalous mantle domain located in the Azores Triple Junction where the American, EUR and AFR lithospheric plates meet. The cause for these anomalies is controversial but many authors consider the presence of an anomalously hot/wet enriched mantle probably supplied by a plume [3]. The origin, size and present location of the plume is under debate but an area near Terceira is the favoured plume centre [2]. The Terceira Rift (TR) defines the EUR/AFR plate boundary of the Azores triple junction. The TR is a 550 km long, generally ESE trending line of volcanic massifs along the axis (e.g. São Miguel, D. João de Castro, Terceira and Graciosa) alternating with deep basins (e.g. Hirondelle basin) interpreted as volcanically unfilled rift valley segments [3]. Vesicular, porphyritic basalts were sampled along the Terceira Rift during Portuguese scientific cruises (EMEPC 2007-2009). Initial studies focused on the adjacent areas Don João de Castro - DJC (submarine volcano) and Hirondelle - Hir (basin). Major and trace element data of phenocrysts (olivine, clinopyroxene, plagioclase), groundmass and exposed melt inclusions found in these vesicular lavas depict only slight differences between the two sites. DJC samples depict higher Fo and Mg# in olivine and clinopyroxene, respectively. Chondrite-normalized REE data indicate that groundmass material is LREE-enriched in both Hir and DJC lavas. Exposed melt inclusions (MI) show similar REE patterns compared to their hosts. Clinopyroxene in both sites display L-MREE enriched, HREE depleted sinusoidal patterns. MI were found in olivine, clinopyroxene and plagioclase phenocrysts. MI are glassy to completely opaque and devitrified, with one or more bubbles, and sulfide globules (SG). SG are spherical, depict two-phase lamellar intergrowths of Fe-Ni and Cu-Fe phases, and are ubiquitous in DJC and Hir lava samples. Some lavas display SG within clinopyroxene-hosted MI and dispersed in the groundmass. Preliminary data suggest that lavas found in these areas of the Terceira Rift were sulfur-saturated in different stages of their evolution; during early fractionation and prior to eruption. The geochemistry of melt inclusion will contribute to the understanding of mantle source, melting and mixing processes in the Terceira Rift, Azores. |
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The Terceira Rift, Azores: a melt inclusion study of submarine lavasTerceira RiftMelt inclusionsAzoresThe Azores plateau, a bathymetric high, is seated on an anomalous mantle domain located in the Azores Triple Junction where the American, EUR and AFR lithospheric plates meet. The cause for these anomalies is controversial but many authors consider the presence of an anomalously hot/wet enriched mantle probably supplied by a plume [3]. The origin, size and present location of the plume is under debate but an area near Terceira is the favoured plume centre [2]. The Terceira Rift (TR) defines the EUR/AFR plate boundary of the Azores triple junction. The TR is a 550 km long, generally ESE trending line of volcanic massifs along the axis (e.g. São Miguel, D. João de Castro, Terceira and Graciosa) alternating with deep basins (e.g. Hirondelle basin) interpreted as volcanically unfilled rift valley segments [3]. Vesicular, porphyritic basalts were sampled along the Terceira Rift during Portuguese scientific cruises (EMEPC 2007-2009). Initial studies focused on the adjacent areas Don João de Castro - DJC (submarine volcano) and Hirondelle - Hir (basin). Major and trace element data of phenocrysts (olivine, clinopyroxene, plagioclase), groundmass and exposed melt inclusions found in these vesicular lavas depict only slight differences between the two sites. DJC samples depict higher Fo and Mg# in olivine and clinopyroxene, respectively. Chondrite-normalized REE data indicate that groundmass material is LREE-enriched in both Hir and DJC lavas. Exposed melt inclusions (MI) show similar REE patterns compared to their hosts. Clinopyroxene in both sites display L-MREE enriched, HREE depleted sinusoidal patterns. MI were found in olivine, clinopyroxene and plagioclase phenocrysts. MI are glassy to completely opaque and devitrified, with one or more bubbles, and sulfide globules (SG). SG are spherical, depict two-phase lamellar intergrowths of Fe-Ni and Cu-Fe phases, and are ubiquitous in DJC and Hir lava samples. Some lavas display SG within clinopyroxene-hosted MI and dispersed in the groundmass. Preliminary data suggest that lavas found in these areas of the Terceira Rift were sulfur-saturated in different stages of their evolution; during early fractionation and prior to eruption. The geochemistry of melt inclusion will contribute to the understanding of mantle source, melting and mixing processes in the Terceira Rift, Azores.Geochemical Society2013-01-17T18:00:37Z2013-01-172012-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/conferenceObjecthttp://hdl.handle.net/10174/7420http://hdl.handle.net/10174/7420engsimnaonaoafamarques@fc.ul.ptscottsd@geology.utoronto.capedro@uevora.ptpconceicao@emepc-portugal.orgnuno.lourenco@ipma.ptcarlos.rosa@lneg.pt247Marques, FilipaScott, SteveMadureira, PedroConceição, PatríciaLourenço, NunoRosa, Carlosinfo: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:RCAAP2024-01-03T18:47:40Zoai:dspace.uevora.pt:10174/7420Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T01:01:57.931327Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
The Terceira Rift, Azores: a melt inclusion study of submarine lavas |
title |
The Terceira Rift, Azores: a melt inclusion study of submarine lavas |
spellingShingle |
The Terceira Rift, Azores: a melt inclusion study of submarine lavas Marques, Filipa Terceira Rift Melt inclusions Azores |
title_short |
The Terceira Rift, Azores: a melt inclusion study of submarine lavas |
title_full |
The Terceira Rift, Azores: a melt inclusion study of submarine lavas |
title_fullStr |
The Terceira Rift, Azores: a melt inclusion study of submarine lavas |
title_full_unstemmed |
The Terceira Rift, Azores: a melt inclusion study of submarine lavas |
title_sort |
The Terceira Rift, Azores: a melt inclusion study of submarine lavas |
author |
Marques, Filipa |
author_facet |
Marques, Filipa Scott, Steve Madureira, Pedro Conceição, Patrícia Lourenço, Nuno Rosa, Carlos |
author_role |
author |
author2 |
Scott, Steve Madureira, Pedro Conceição, Patrícia Lourenço, Nuno Rosa, Carlos |
author2_role |
author author author author author |
dc.contributor.author.fl_str_mv |
Marques, Filipa Scott, Steve Madureira, Pedro Conceição, Patrícia Lourenço, Nuno Rosa, Carlos |
dc.subject.por.fl_str_mv |
Terceira Rift Melt inclusions Azores |
topic |
Terceira Rift Melt inclusions Azores |
description |
The Azores plateau, a bathymetric high, is seated on an anomalous mantle domain located in the Azores Triple Junction where the American, EUR and AFR lithospheric plates meet. The cause for these anomalies is controversial but many authors consider the presence of an anomalously hot/wet enriched mantle probably supplied by a plume [3]. The origin, size and present location of the plume is under debate but an area near Terceira is the favoured plume centre [2]. The Terceira Rift (TR) defines the EUR/AFR plate boundary of the Azores triple junction. The TR is a 550 km long, generally ESE trending line of volcanic massifs along the axis (e.g. São Miguel, D. João de Castro, Terceira and Graciosa) alternating with deep basins (e.g. Hirondelle basin) interpreted as volcanically unfilled rift valley segments [3]. Vesicular, porphyritic basalts were sampled along the Terceira Rift during Portuguese scientific cruises (EMEPC 2007-2009). Initial studies focused on the adjacent areas Don João de Castro - DJC (submarine volcano) and Hirondelle - Hir (basin). Major and trace element data of phenocrysts (olivine, clinopyroxene, plagioclase), groundmass and exposed melt inclusions found in these vesicular lavas depict only slight differences between the two sites. DJC samples depict higher Fo and Mg# in olivine and clinopyroxene, respectively. Chondrite-normalized REE data indicate that groundmass material is LREE-enriched in both Hir and DJC lavas. Exposed melt inclusions (MI) show similar REE patterns compared to their hosts. Clinopyroxene in both sites display L-MREE enriched, HREE depleted sinusoidal patterns. MI were found in olivine, clinopyroxene and plagioclase phenocrysts. MI are glassy to completely opaque and devitrified, with one or more bubbles, and sulfide globules (SG). SG are spherical, depict two-phase lamellar intergrowths of Fe-Ni and Cu-Fe phases, and are ubiquitous in DJC and Hir lava samples. Some lavas display SG within clinopyroxene-hosted MI and dispersed in the groundmass. Preliminary data suggest that lavas found in these areas of the Terceira Rift were sulfur-saturated in different stages of their evolution; during early fractionation and prior to eruption. The geochemistry of melt inclusion will contribute to the understanding of mantle source, melting and mixing processes in the Terceira Rift, Azores. |
publishDate |
2012 |
dc.date.none.fl_str_mv |
2012-01-01T00:00:00Z 2013-01-17T18:00:37Z 2013-01-17 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/conferenceObject |
format |
conferenceObject |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10174/7420 http://hdl.handle.net/10174/7420 |
url |
http://hdl.handle.net/10174/7420 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
sim nao nao afamarques@fc.ul.pt scottsd@geology.utoronto.ca pedro@uevora.pt pconceicao@emepc-portugal.org nuno.lourenco@ipma.pt carlos.rosa@lneg.pt 247 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.publisher.none.fl_str_mv |
Geochemical Society |
publisher.none.fl_str_mv |
Geochemical Society |
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 |
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Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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RCAAP |
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RCAAP |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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