Petrologic modeling of chloritoid–glaucophane schists from the NW Iberian Massif

Two P–T pseudosections computed with Thermocalc and Perplex software for high-pressure pelitic Ceán Schists from the NWIberian Massif show that the paragenesis chloritoid+glaucophane, preserved as relict micro-inclusions in garnet porphyroblasts, is stable above 17–18 kbar, indicating a first stage...

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Detalles Bibliográficos
Autores: López Carmona, Alicia, Abati Gómez, Jacobo, Reche i Estrada, Juan
Tipo de recurso: artículo
Fecha de publicación:2010
País:España
Institución:Universidad Complutense de Madrid (UCM)
Repositorio:Docta Complutense
Idioma:inglés
OAI Identifier:oai:docta.ucm.es:20.500.14352/44174
Acceso en línea:https://hdl.handle.net/20.500.14352/44174
Access Level:acceso abierto
Palabra clave:552.3(460)
Malpica–Tui unit
High-pressure terranes
Blueschist
Glaucophane–chloritoid
P–T pseudosection
Petrología
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spelling Petrologic modeling of chloritoid–glaucophane schists from the NW Iberian MassifLópez Carmona, AliciaAbati Gómez, JacoboReche i Estrada, Juan552.3(460)Malpica–Tui unitHigh-pressure terranesBlueschistGlaucophane–chloritoidP–T pseudosectionPetrologíaTwo P–T pseudosections computed with Thermocalc and Perplex software for high-pressure pelitic Ceán Schists from the NWIberian Massif show that the paragenesis chloritoid+glaucophane, preserved as relict micro-inclusions in garnet porphyroblasts, is stable above 17–18 kbar, indicating a first stage of subduction with 65–70 km of burial. The subsequent growth of biotite and albite porphyroblasts, according to their stability fields in a MnNCKFMASH P–T phase diagram, indicates strong decompression accompanied by slight heating to reach a metamorphic peak at ∼500 °C. This mineral association, described in many subduction-related terranes around the world as one of the high-pressure indicators for metapelites, has not been reported previously in the NW Iberian Massif. The schists contains an initial high-pressure assemblage formed by chloritoid+garnet (Alm0.58 Prp00.03 Grs0.38 Sps0.09)±glaucophane+phengite (3.5–3.4Sip.f.u.)+paragonite+chlorite+epidote+rutile+ilmenite+quartz, preserved as micro-inclusions in garnet, chloritoid and albite porphyroblasts defining an S1 internal fabric. The matrix foliation (S2) additionally contains a high-pressure association formed by garnet (Alm0.68 Prp0.04 Grs0.25 Sps0.03)+ phengite (3.4–3.3Si p.f.u.)+paragonite+winchite+barroisite+hornblende+chloritoid+chlorite+ epidote+rutile+ilmenite+albite+quartz±biotite. An initial pseudosection calculated in the KFMASH system with Thermocalc 3.26 gives pressure estimates through Si-content in phengite barometry that are in agreement with conventional thermobarometry and Thermocalc average P–T calculations, but is unable to describe the full complexity of the mineral assemblages of the schists. For this reason, a more complete P–T pseudosection in the model system MnNCKFMASH was calculated with Perplex 07. This provides a reliable succession of mineral assemblages that are consistent with the petrographic observations and allows a mineralogical sequence to be set for each metamorphic event in the P–T evolution of the high-P pelitic Ceán Schists.Elsevier Science B. V., AmsterdamUniversidad Complutense de Madrid20102010-01-0120102010-01-01journal articlehttp://purl.org/coar/resource_type/c_6501info:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/20.500.14352/44174reponame:Docta Complutenseinstname:Universidad Complutense de Madrid (UCM)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2info:eu-repo/semantics/openAccessoai:docta.ucm.es:20.500.14352/441742026-06-02T12:44:21Z
dc.title.none.fl_str_mv Petrologic modeling of chloritoid–glaucophane schists from the NW Iberian Massif
title Petrologic modeling of chloritoid–glaucophane schists from the NW Iberian Massif
spellingShingle Petrologic modeling of chloritoid–glaucophane schists from the NW Iberian Massif
López Carmona, Alicia
552.3(460)
Malpica–Tui unit
High-pressure terranes
Blueschist
Glaucophane–chloritoid
P–T pseudosection
Petrología
title_short Petrologic modeling of chloritoid–glaucophane schists from the NW Iberian Massif
title_full Petrologic modeling of chloritoid–glaucophane schists from the NW Iberian Massif
title_fullStr Petrologic modeling of chloritoid–glaucophane schists from the NW Iberian Massif
title_full_unstemmed Petrologic modeling of chloritoid–glaucophane schists from the NW Iberian Massif
title_sort Petrologic modeling of chloritoid–glaucophane schists from the NW Iberian Massif
dc.creator.none.fl_str_mv López Carmona, Alicia
Abati Gómez, Jacobo
Reche i Estrada, Juan
author López Carmona, Alicia
author_facet López Carmona, Alicia
Abati Gómez, Jacobo
Reche i Estrada, Juan
author_role author
author2 Abati Gómez, Jacobo
Reche i Estrada, Juan
author2_role author
author
dc.contributor.none.fl_str_mv Universidad Complutense de Madrid
dc.subject.none.fl_str_mv 552.3(460)
Malpica–Tui unit
High-pressure terranes
Blueschist
Glaucophane–chloritoid
P–T pseudosection
Petrología
topic 552.3(460)
Malpica–Tui unit
High-pressure terranes
Blueschist
Glaucophane–chloritoid
P–T pseudosection
Petrología
description Two P–T pseudosections computed with Thermocalc and Perplex software for high-pressure pelitic Ceán Schists from the NWIberian Massif show that the paragenesis chloritoid+glaucophane, preserved as relict micro-inclusions in garnet porphyroblasts, is stable above 17–18 kbar, indicating a first stage of subduction with 65–70 km of burial. The subsequent growth of biotite and albite porphyroblasts, according to their stability fields in a MnNCKFMASH P–T phase diagram, indicates strong decompression accompanied by slight heating to reach a metamorphic peak at ∼500 °C. This mineral association, described in many subduction-related terranes around the world as one of the high-pressure indicators for metapelites, has not been reported previously in the NW Iberian Massif. The schists contains an initial high-pressure assemblage formed by chloritoid+garnet (Alm0.58 Prp00.03 Grs0.38 Sps0.09)±glaucophane+phengite (3.5–3.4Sip.f.u.)+paragonite+chlorite+epidote+rutile+ilmenite+quartz, preserved as micro-inclusions in garnet, chloritoid and albite porphyroblasts defining an S1 internal fabric. The matrix foliation (S2) additionally contains a high-pressure association formed by garnet (Alm0.68 Prp0.04 Grs0.25 Sps0.03)+ phengite (3.4–3.3Si p.f.u.)+paragonite+winchite+barroisite+hornblende+chloritoid+chlorite+ epidote+rutile+ilmenite+albite+quartz±biotite. An initial pseudosection calculated in the KFMASH system with Thermocalc 3.26 gives pressure estimates through Si-content in phengite barometry that are in agreement with conventional thermobarometry and Thermocalc average P–T calculations, but is unable to describe the full complexity of the mineral assemblages of the schists. For this reason, a more complete P–T pseudosection in the model system MnNCKFMASH was calculated with Perplex 07. This provides a reliable succession of mineral assemblages that are consistent with the petrographic observations and allows a mineralogical sequence to be set for each metamorphic event in the P–T evolution of the high-P pelitic Ceán Schists.
publishDate 2010
dc.date.none.fl_str_mv 2010
2010-01-01
2010
2010-01-01
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/20.500.14352/44174
url https://hdl.handle.net/20.500.14352/44174
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Elsevier Science B. V., Amsterdam
publisher.none.fl_str_mv Elsevier Science B. V., Amsterdam
dc.source.none.fl_str_mv reponame:Docta Complutense
instname:Universidad Complutense de Madrid (UCM)
instname_str Universidad Complutense de Madrid (UCM)
reponame_str Docta Complutense
collection Docta Complutense
repository.name.fl_str_mv
repository.mail.fl_str_mv
_version_ 1869408661527330816
score 15,300724

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