Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina

Autores
Aliani, Paola; Ntaflos, Theodoros; Bjerg, Ernesto Alfredo
Año de publicación
2009
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Peridotite mantle xenoliths collected north of Gobernador Gregores, Patagonia, affected by cryptic and modal metasomatism bear melt pockets of unusually large size. Melt pockets consist of second generation olivine (ol2), clinopyroxene (cpx2) and spinel (sp2) ± relict amphibole (amph) immersed in a yellowish vesicular glass matrix. Amphibole breakdown was responsible for melt pocket generation as suggested by textural evidence and proved by consistent mass-balance calculations: amph → cpx2 + ol2 + sp2 + melt. Composition of calculated amphibole in amphibole-free melt pockets is very similar to that measured in amphibole-bearing melt pockets from the same xenolith, i.e. amphibole was consumed in the melt pocket generation process. In melt pockets devoid of relict amphibole, mass-balance calculations show remarkable differences between the calculated amphibole and the measured amphibole compositions in melt pockets from the same xenolith. The participation of minor proportions of a consumed reactant phase could be a reasonable explanation. In some samples the calculated phase proportion of glass is in excess compared to modal estimations based on backscattered electron images, probably because a portion of the generated melt was able to migrate out of the melt pockets. Compositional inhomogeneity of cpx2 and variable Ti Kd in cpx2 vs. glass in the same melt pocket reflect fast nucleation and growth and disequilibrium crystallisation, respectively. This and the difference between forsterite content in calculated equilibrium olivine and second generation olivine, suggest that mineral equilibrium was inhibited by rapid quenching of melt pockets.
Fil: Aliani, Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina
Fil: Ntaflos, Theodoros. Universidad de Viena; Austria
Fil: Bjerg, Ernesto Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina
Materia
Amphibole Breakdown
Mass Balance
Melt Pockets
Mineral And Glass Chemistry
Patagonia
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/77154
Acceder
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oai_identifier_str oai:ri.conicet.gov.ar:11336/77154
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repository_id_str 3498
network_name_str CONICET Digital (CONICET)
spelling Origin of melt pockets in mantle xenoliths from southern Patagonia, ArgentinaAliani, PaolaNtaflos, TheodorosBjerg, Ernesto AlfredoAmphibole BreakdownMass BalanceMelt PocketsMineral And Glass ChemistryPatagoniahttps://purl.org/becyt/ford/1.5https://purl.org/becyt/ford/1Peridotite mantle xenoliths collected north of Gobernador Gregores, Patagonia, affected by cryptic and modal metasomatism bear melt pockets of unusually large size. Melt pockets consist of second generation olivine (ol2), clinopyroxene (cpx2) and spinel (sp2) ± relict amphibole (amph) immersed in a yellowish vesicular glass matrix. Amphibole breakdown was responsible for melt pocket generation as suggested by textural evidence and proved by consistent mass-balance calculations: amph → cpx2 + ol2 + sp2 + melt. Composition of calculated amphibole in amphibole-free melt pockets is very similar to that measured in amphibole-bearing melt pockets from the same xenolith, i.e. amphibole was consumed in the melt pocket generation process. In melt pockets devoid of relict amphibole, mass-balance calculations show remarkable differences between the calculated amphibole and the measured amphibole compositions in melt pockets from the same xenolith. The participation of minor proportions of a consumed reactant phase could be a reasonable explanation. In some samples the calculated phase proportion of glass is in excess compared to modal estimations based on backscattered electron images, probably because a portion of the generated melt was able to migrate out of the melt pockets. Compositional inhomogeneity of cpx2 and variable Ti Kd in cpx2 vs. glass in the same melt pocket reflect fast nucleation and growth and disequilibrium crystallisation, respectively. This and the difference between forsterite content in calculated equilibrium olivine and second generation olivine, suggest that mineral equilibrium was inhibited by rapid quenching of melt pockets.Fil: Aliani, Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; ArgentinaFil: Ntaflos, Theodoros. Universidad de Viena; AustriaFil: Bjerg, Ernesto Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; ArgentinaPergamon-Elsevier Science Ltd2009-12info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/77154Aliani, Paola; Ntaflos, Theodoros; Bjerg, Ernesto Alfredo; Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina; Pergamon-Elsevier Science Ltd; Journal of South American Earth Sciences; 28; 4; 12-2009; 419-4280895-9811CONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/doi/10.1016/j.jsames.2009.04.009info:eu-repo/semantics/altIdentifier/url/https://www.sciencedirect.com/science/article/pii/S0895981109000601info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-29T09:33:09Zoai:ri.conicet.gov.ar:11336/77154instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-29 09:33:09.972CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina
title Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina
spellingShingle Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina
Aliani, Paola
Amphibole Breakdown
Mass Balance
Melt Pockets
Mineral And Glass Chemistry
Patagonia
title_short Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina
title_full Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina
title_fullStr Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina
title_full_unstemmed Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina
title_sort Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina
dc.creator.none.fl_str_mv Aliani, Paola
Ntaflos, Theodoros
Bjerg, Ernesto Alfredo
author Aliani, Paola
author_facet Aliani, Paola
Ntaflos, Theodoros
Bjerg, Ernesto Alfredo
author_role author
author2 Ntaflos, Theodoros
Bjerg, Ernesto Alfredo
author2_role author
author
dc.subject.none.fl_str_mv Amphibole Breakdown
Mass Balance
Melt Pockets
Mineral And Glass Chemistry
Patagonia
topic Amphibole Breakdown
Mass Balance
Melt Pockets
Mineral And Glass Chemistry
Patagonia
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.5
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv Peridotite mantle xenoliths collected north of Gobernador Gregores, Patagonia, affected by cryptic and modal metasomatism bear melt pockets of unusually large size. Melt pockets consist of second generation olivine (ol2), clinopyroxene (cpx2) and spinel (sp2) ± relict amphibole (amph) immersed in a yellowish vesicular glass matrix. Amphibole breakdown was responsible for melt pocket generation as suggested by textural evidence and proved by consistent mass-balance calculations: amph → cpx2 + ol2 + sp2 + melt. Composition of calculated amphibole in amphibole-free melt pockets is very similar to that measured in amphibole-bearing melt pockets from the same xenolith, i.e. amphibole was consumed in the melt pocket generation process. In melt pockets devoid of relict amphibole, mass-balance calculations show remarkable differences between the calculated amphibole and the measured amphibole compositions in melt pockets from the same xenolith. The participation of minor proportions of a consumed reactant phase could be a reasonable explanation. In some samples the calculated phase proportion of glass is in excess compared to modal estimations based on backscattered electron images, probably because a portion of the generated melt was able to migrate out of the melt pockets. Compositional inhomogeneity of cpx2 and variable Ti Kd in cpx2 vs. glass in the same melt pocket reflect fast nucleation and growth and disequilibrium crystallisation, respectively. This and the difference between forsterite content in calculated equilibrium olivine and second generation olivine, suggest that mineral equilibrium was inhibited by rapid quenching of melt pockets.
Fil: Aliani, Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina
Fil: Ntaflos, Theodoros. Universidad de Viena; Austria
Fil: Bjerg, Ernesto Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina
description Peridotite mantle xenoliths collected north of Gobernador Gregores, Patagonia, affected by cryptic and modal metasomatism bear melt pockets of unusually large size. Melt pockets consist of second generation olivine (ol2), clinopyroxene (cpx2) and spinel (sp2) ± relict amphibole (amph) immersed in a yellowish vesicular glass matrix. Amphibole breakdown was responsible for melt pocket generation as suggested by textural evidence and proved by consistent mass-balance calculations: amph → cpx2 + ol2 + sp2 + melt. Composition of calculated amphibole in amphibole-free melt pockets is very similar to that measured in amphibole-bearing melt pockets from the same xenolith, i.e. amphibole was consumed in the melt pocket generation process. In melt pockets devoid of relict amphibole, mass-balance calculations show remarkable differences between the calculated amphibole and the measured amphibole compositions in melt pockets from the same xenolith. The participation of minor proportions of a consumed reactant phase could be a reasonable explanation. In some samples the calculated phase proportion of glass is in excess compared to modal estimations based on backscattered electron images, probably because a portion of the generated melt was able to migrate out of the melt pockets. Compositional inhomogeneity of cpx2 and variable Ti Kd in cpx2 vs. glass in the same melt pocket reflect fast nucleation and growth and disequilibrium crystallisation, respectively. This and the difference between forsterite content in calculated equilibrium olivine and second generation olivine, suggest that mineral equilibrium was inhibited by rapid quenching of melt pockets.
publishDate 2009
dc.date.none.fl_str_mv 2009-12
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/77154
Aliani, Paola; Ntaflos, Theodoros; Bjerg, Ernesto Alfredo; Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina; Pergamon-Elsevier Science Ltd; Journal of South American Earth Sciences; 28; 4; 12-2009; 419-428
0895-9811
CONICET Digital
CONICET
url http://hdl.handle.net/11336/77154
identifier_str_mv Aliani, Paola; Ntaflos, Theodoros; Bjerg, Ernesto Alfredo; Origin of melt pockets in mantle xenoliths from southern Patagonia, Argentina; Pergamon-Elsevier Science Ltd; Journal of South American Earth Sciences; 28; 4; 12-2009; 419-428
0895-9811
CONICET Digital
CONICET
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/doi/10.1016/j.jsames.2009.04.009
info:eu-repo/semantics/altIdentifier/url/https://www.sciencedirect.com/science/article/pii/S0895981109000601
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv Pergamon-Elsevier Science Ltd
publisher.none.fl_str_mv Pergamon-Elsevier Science Ltd
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
collection CONICET Digital (CONICET)
instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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score 13.070432

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