Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern Pyrenees

Open-system behaviour through fluid influx and melt loss can produce a variety of migmatite morphologies and mineral assemblages from the same protolith composition. This is shown by different types of granulite facies migmatite from the contact aureole of the Ceret gabbro-diorite stock in the Roc d...

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Autores: Aguilar Gil, Carmen María, Liesa Torre-Marín, Montserrat, Reche Estrada, Joan, Powell, R.
Formato: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2016
País:España
Recursos:Universidad de Barcelona
Repositorio:Dipòsit Digital de la UB
OAI Identifier:oai:diposit.ub.edu:2445/181649
Acesso em linha:https://hdl.handle.net/2445/181649
Access Level:acceso abierto
Palavra-chave:Petrologia
Geologia estructural
Pirineus Orientals (França)
Petrology
Structural geology
Pyrénées-Orientales (France)
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spelling Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern PyreneesAguilar Gil, Carmen MaríaLiesa Torre-Marín, MontserratReche Estrada, JoanPowell, R.PetrologiaGeologia estructuralPirineus Orientals (França)PetrologyStructural geologyPyrénées-Orientales (France)Open-system behaviour through fluid influx and melt loss can produce a variety of migmatite morphologies and mineral assemblages from the same protolith composition. This is shown by different types of granulite facies migmatite from the contact aureole of the Ceret gabbro-diorite stock in the Roc de Frausa Massif (eastern Pyrenees). Patch, stromatic and schollen migmatites are identified in the inner contact aureole, whereas schollen migmatites and residual melanosomes are found as xeno- liths inside the gabbro-diorite. Patch and schollen migmatites record D1 and D2 structures in folded melanosome and mostly preserve the high-T D2 in granular or weakly foliated leucosome. Stromatic migmatites and residual melanosomes only preserve D2. The assemblage quartz-garnet-biotite- sillimanite-cordierite K-feldspar-plagioclase is present in patch and schollen migmatites, whereas stromatic migmatites and residual melanosomes contain a sub-assemblage with no sillimanite and/or K-feldspar. A decrease in XFe (molar Fe/(Fe + Mg)) in garnet, biotite and cordierite is observed from patch migmatites through schollen and stromatic migmatites to residual melanosomes. Whole-rock compositions of patch, schollen and stromatic migmatites are similar to those of non-migmatitic rocks from the surrounding area. These metasedimentary rocks are interpreted as the protoliths of the migmatites. A decrease in the silica content of migmatites from 63 to 40 wt% SiO2 is accompa- nied by an increase in Al2O3 and MgO+FeO and by a depletion in alkalis. Thermodynamic modelling in the NCKFMASHTO system for the different types of migmatite provides peak metamorphic conditions ~7-8 kbar and 840 °C. A nearly isothermal decompression history down to 5.5 kbar was followed by isobaric cooling from 840 °C through 690 °C to lower temperatures. The preservation of granulite facies assemblages and the variation in mineral assemblages and chemical composition can be modelled by ongoing H2O-fluxed melting accompanied by melt loss. The fluids were probably released by the crystallizing gabbro-diorite, infiltrating the metasedimentary rocks and fluxing melting. Release of fluids and melt loss were probably favoured by coeval deformation (D2). The amount of melt remaining in the system varied considerably among the different types of migmatite. The whole-rock compositions of the samples, the modelled compositions of melts at the solidus at 5.5 kbar and the residues show a good correlation.John Wiley & Sons2016info:eu-repo/semantics/articleinfo:eu-repo/semantics/acceptedVersionapplication/pdfhttps://hdl.handle.net/2445/181649Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)reponame:Dipòsit Digital de la UBinstname:Universidad de BarcelonaInglésVersió postprint del document publicat a: https://doi.org/10.1111/jmg.12187Journal of Metamorphic Geology, 2016, vol. 34, num. 4, p. 379-400https://doi.org/10.1111/jmg.12187(c) John Wiley & Sons, 2016info:eu-repo/semantics/openAccessoai:diposit.ub.edu:2445/1816492026-05-27T06:46:51Z
dc.title.none.fl_str_mv Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern Pyrenees
title Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern Pyrenees
spellingShingle Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern Pyrenees
Aguilar Gil, Carmen María
Petrologia
Geologia estructural
Pirineus Orientals (França)
Petrology
Structural geology
Pyrénées-Orientales (France)
title_short Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern Pyrenees
title_full Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern Pyrenees
title_fullStr Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern Pyrenees
title_full_unstemmed Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern Pyrenees
title_sort Fluid-fluxed melting and melt loss in a syntectonic contact metamorphic aureole from the Variscan eastern Pyrenees
dc.creator.none.fl_str_mv Aguilar Gil, Carmen María
Liesa Torre-Marín, Montserrat
Reche Estrada, Joan
Powell, R.
author Aguilar Gil, Carmen María
author_facet Aguilar Gil, Carmen María
Liesa Torre-Marín, Montserrat
Reche Estrada, Joan
Powell, R.
author_role author
author2 Liesa Torre-Marín, Montserrat
Reche Estrada, Joan
Powell, R.
author2_role author
author
author
dc.subject.none.fl_str_mv Petrologia
Geologia estructural
Pirineus Orientals (França)
Petrology
Structural geology
Pyrénées-Orientales (France)
topic Petrologia
Geologia estructural
Pirineus Orientals (França)
Petrology
Structural geology
Pyrénées-Orientales (France)
description Open-system behaviour through fluid influx and melt loss can produce a variety of migmatite morphologies and mineral assemblages from the same protolith composition. This is shown by different types of granulite facies migmatite from the contact aureole of the Ceret gabbro-diorite stock in the Roc de Frausa Massif (eastern Pyrenees). Patch, stromatic and schollen migmatites are identified in the inner contact aureole, whereas schollen migmatites and residual melanosomes are found as xeno- liths inside the gabbro-diorite. Patch and schollen migmatites record D1 and D2 structures in folded melanosome and mostly preserve the high-T D2 in granular or weakly foliated leucosome. Stromatic migmatites and residual melanosomes only preserve D2. The assemblage quartz-garnet-biotite- sillimanite-cordierite K-feldspar-plagioclase is present in patch and schollen migmatites, whereas stromatic migmatites and residual melanosomes contain a sub-assemblage with no sillimanite and/or K-feldspar. A decrease in XFe (molar Fe/(Fe + Mg)) in garnet, biotite and cordierite is observed from patch migmatites through schollen and stromatic migmatites to residual melanosomes. Whole-rock compositions of patch, schollen and stromatic migmatites are similar to those of non-migmatitic rocks from the surrounding area. These metasedimentary rocks are interpreted as the protoliths of the migmatites. A decrease in the silica content of migmatites from 63 to 40 wt% SiO2 is accompa- nied by an increase in Al2O3 and MgO+FeO and by a depletion in alkalis. Thermodynamic modelling in the NCKFMASHTO system for the different types of migmatite provides peak metamorphic conditions ~7-8 kbar and 840 °C. A nearly isothermal decompression history down to 5.5 kbar was followed by isobaric cooling from 840 °C through 690 °C to lower temperatures. The preservation of granulite facies assemblages and the variation in mineral assemblages and chemical composition can be modelled by ongoing H2O-fluxed melting accompanied by melt loss. The fluids were probably released by the crystallizing gabbro-diorite, infiltrating the metasedimentary rocks and fluxing melting. Release of fluids and melt loss were probably favoured by coeval deformation (D2). The amount of melt remaining in the system varied considerably among the different types of migmatite. The whole-rock compositions of the samples, the modelled compositions of melts at the solidus at 5.5 kbar and the residues show a good correlation.
publishDate 2016
dc.date.none.fl_str_mv 2016
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
format article
status_str acceptedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/2445/181649
url https://hdl.handle.net/2445/181649
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv Versió postprint del document publicat a: https://doi.org/10.1111/jmg.12187
Journal of Metamorphic Geology, 2016, vol. 34, num. 4, p. 379-400
https://doi.org/10.1111/jmg.12187
dc.rights.none.fl_str_mv (c) John Wiley & Sons, 2016
info:eu-repo/semantics/openAccess
rights_invalid_str_mv (c) John Wiley & Sons, 2016
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv John Wiley & Sons
publisher.none.fl_str_mv John Wiley & Sons
dc.source.none.fl_str_mv Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)
reponame:Dipòsit Digital de la UB
instname:Universidad de Barcelona
instname_str Universidad de Barcelona
reponame_str Dipòsit Digital de la UB
collection Dipòsit Digital de la UB
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15.228081

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